Got basic webpage working. Need to make base page, static folders

flex/lib/python3.6/site-packages/django/core/cache/__init__.py

@@ -0,0 +1,125 @@
+"""
+Caching framework.
+
+This package defines set of cache backends that all conform to a simple API.
+In a nutshell, a cache is a set of values -- which can be any object that
+may be pickled -- identified by string keys.  For the complete API, see
+the abstract BaseCache class in django.core.cache.backends.base.
+
+Client code should use the `cache` variable defined here to access the default
+cache backend and look up non-default cache backends in the `caches` dict-like
+object.
+
+See docs/topics/cache.txt for information on the public API.
+"""
+from threading import local
+
+from django.conf import settings
+from django.core import signals
+from django.core.cache.backends.base import (
+    BaseCache, CacheKeyWarning, InvalidCacheBackendError,
+)
+from django.utils.module_loading import import_string
+
+__all__ = [
+    'cache', 'DEFAULT_CACHE_ALIAS', 'InvalidCacheBackendError',
+    'CacheKeyWarning', 'BaseCache',
+]
+
+DEFAULT_CACHE_ALIAS = 'default'
+
+
+def _create_cache(backend, **kwargs):
+    try:
+        # Try to get the CACHES entry for the given backend name first
+        try:
+            conf = settings.CACHES[backend]
+        except KeyError:
+            try:
+                # Trying to import the given backend, in case it's a dotted path
+                import_string(backend)
+            except ImportError as e:
+                raise InvalidCacheBackendError("Could not find backend '%s': %s" % (
+                    backend, e))
+            location = kwargs.pop('LOCATION', '')
+            params = kwargs
+        else:
+            params = conf.copy()
+            params.update(kwargs)
+            backend = params.pop('BACKEND')
+            location = params.pop('LOCATION', '')
+        backend_cls = import_string(backend)
+    except ImportError as e:
+        raise InvalidCacheBackendError(
+            "Could not find backend '%s': %s" % (backend, e))
+    return backend_cls(location, params)
+
+
+class CacheHandler:
+    """
+    A Cache Handler to manage access to Cache instances.
+
+    Ensure only one instance of each alias exists per thread.
+    """
+    def __init__(self):
+        self._caches = local()
+
+    def __getitem__(self, alias):
+        try:
+            return self._caches.caches[alias]
+        except AttributeError:
+            self._caches.caches = {}
+        except KeyError:
+            pass
+
+        if alias not in settings.CACHES:
+            raise InvalidCacheBackendError(
+                "Could not find config for '%s' in settings.CACHES" % alias
+            )
+
+        cache = _create_cache(alias)
+        self._caches.caches[alias] = cache
+        return cache
+
+    def all(self):
+        return getattr(self._caches, 'caches', {}).values()
+
+
+caches = CacheHandler()
+
+
+class DefaultCacheProxy:
+    """
+    Proxy access to the default Cache object's attributes.
+
+    This allows the legacy `cache` object to be thread-safe using the new
+    ``caches`` API.
+    """
+    def __getattr__(self, name):
+        return getattr(caches[DEFAULT_CACHE_ALIAS], name)
+
+    def __setattr__(self, name, value):
+        return setattr(caches[DEFAULT_CACHE_ALIAS], name, value)
+
+    def __delattr__(self, name):
+        return delattr(caches[DEFAULT_CACHE_ALIAS], name)
+
+    def __contains__(self, key):
+        return key in caches[DEFAULT_CACHE_ALIAS]
+
+    def __eq__(self, other):
+        return caches[DEFAULT_CACHE_ALIAS] == other
+
+
+cache = DefaultCacheProxy()
+
+
+def close_caches(**kwargs):
+    # Some caches -- python-memcached in particular -- need to do a cleanup at the
+    # end of a request cycle. If not implemented in a particular backend
+    # cache.close is a no-op
+    for cache in caches.all():
+        cache.close()
+
+
+signals.request_finished.connect(close_caches)

flex/lib/python3.6/site-packages/django/core/cache/backends/base.py

@@ -0,0 +1,276 @@
+"Base Cache class."
+import time
+import warnings
+
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.module_loading import import_string
+
+
+class InvalidCacheBackendError(ImproperlyConfigured):
+    pass
+
+
+class CacheKeyWarning(RuntimeWarning):
+    pass
+
+
+# Stub class to ensure not passing in a `timeout` argument results in
+# the default timeout
+DEFAULT_TIMEOUT = object()
+
+# Memcached does not accept keys longer than this.
+MEMCACHE_MAX_KEY_LENGTH = 250
+
+
+def default_key_func(key, key_prefix, version):
+    """
+    Default function to generate keys.
+
+    Construct the key used by all other methods. By default, prepend
+    the `key_prefix'. KEY_FUNCTION can be used to specify an alternate
+    function with custom key making behavior.
+    """
+    return '%s:%s:%s' % (key_prefix, version, key)
+
+
+def get_key_func(key_func):
+    """
+    Function to decide which key function to use.
+
+    Default to ``default_key_func``.
+    """
+    if key_func is not None:
+        if callable(key_func):
+            return key_func
+        else:
+            return import_string(key_func)
+    return default_key_func
+
+
+class BaseCache:
+    def __init__(self, params):
+        timeout = params.get('timeout', params.get('TIMEOUT', 300))
+        if timeout is not None:
+            try:
+                timeout = int(timeout)
+            except (ValueError, TypeError):
+                timeout = 300
+        self.default_timeout = timeout
+
+        options = params.get('OPTIONS', {})
+        max_entries = params.get('max_entries', options.get('MAX_ENTRIES', 300))
+        try:
+            self._max_entries = int(max_entries)
+        except (ValueError, TypeError):
+            self._max_entries = 300
+
+        cull_frequency = params.get('cull_frequency', options.get('CULL_FREQUENCY', 3))
+        try:
+            self._cull_frequency = int(cull_frequency)
+        except (ValueError, TypeError):
+            self._cull_frequency = 3
+
+        self.key_prefix = params.get('KEY_PREFIX', '')
+        self.version = params.get('VERSION', 1)
+        self.key_func = get_key_func(params.get('KEY_FUNCTION'))
+
+    def get_backend_timeout(self, timeout=DEFAULT_TIMEOUT):
+        """
+        Return the timeout value usable by this backend based upon the provided
+        timeout.
+        """
+        if timeout == DEFAULT_TIMEOUT:
+            timeout = self.default_timeout
+        elif timeout == 0:
+            # ticket 21147 - avoid time.time() related precision issues
+            timeout = -1
+        return None if timeout is None else time.time() + timeout
+
+    def make_key(self, key, version=None):
+        """
+        Construct the key used by all other methods. By default, use the
+        key_func to generate a key (which, by default, prepends the
+        `key_prefix' and 'version'). A different key function can be provided
+        at the time of cache construction; alternatively, you can subclass the
+        cache backend to provide custom key making behavior.
+        """
+        if version is None:
+            version = self.version
+
+        new_key = self.key_func(key, self.key_prefix, version)
+        return new_key
+
+    def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        """
+        Set a value in the cache if the key does not already exist. If
+        timeout is given, use that timeout for the key; otherwise use the
+        default cache timeout.
+
+        Return True if the value was stored, False otherwise.
+        """
+        raise NotImplementedError('subclasses of BaseCache must provide an add() method')
+
+    def get(self, key, default=None, version=None):
+        """
+        Fetch a given key from the cache. If the key does not exist, return
+        default, which itself defaults to None.
+        """
+        raise NotImplementedError('subclasses of BaseCache must provide a get() method')
+
+    def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        """
+        Set a value in the cache. If timeout is given, use that timeout for the
+        key; otherwise use the default cache timeout.
+        """
+        raise NotImplementedError('subclasses of BaseCache must provide a set() method')
+
+    def delete(self, key, version=None):
+        """
+        Delete a key from the cache, failing silently.
+        """
+        raise NotImplementedError('subclasses of BaseCache must provide a delete() method')
+
+    def get_many(self, keys, version=None):
+        """
+        Fetch a bunch of keys from the cache. For certain backends (memcached,
+        pgsql) this can be *much* faster when fetching multiple values.
+
+        Return a dict mapping each key in keys to its value. If the given
+        key is missing, it will be missing from the response dict.
+        """
+        d = {}
+        for k in keys:
+            val = self.get(k, version=version)
+            if val is not None:
+                d[k] = val
+        return d
+
+    def get_or_set(self, key, default, timeout=DEFAULT_TIMEOUT, version=None):
+        """
+        Fetch a given key from the cache. If the key does not exist,
+        add the key and set it to the default value. The default value can
+        also be any callable. If timeout is given, use that timeout for the
+        key; otherwise use the default cache timeout.
+
+        Return the value of the key stored or retrieved.
+        """
+        val = self.get(key, version=version)
+        if val is None:
+            if callable(default):
+                default = default()
+            if default is not None:
+                self.add(key, default, timeout=timeout, version=version)
+                # Fetch the value again to avoid a race condition if another
+                # caller added a value between the first get() and the add()
+                # above.
+                return self.get(key, default, version=version)
+        return val
+
+    def has_key(self, key, version=None):
+        """
+        Return True if the key is in the cache and has not expired.
+        """
+        return self.get(key, version=version) is not None
+
+    def incr(self, key, delta=1, version=None):
+        """
+        Add delta to value in the cache. If the key does not exist, raise a
+        ValueError exception.
+        """
+        value = self.get(key, version=version)
+        if value is None:
+            raise ValueError("Key '%s' not found" % key)
+        new_value = value + delta
+        self.set(key, new_value, version=version)
+        return new_value
+
+    def decr(self, key, delta=1, version=None):
+        """
+        Subtract delta from value in the cache. If the key does not exist, raise
+        a ValueError exception.
+        """
+        return self.incr(key, -delta, version=version)
+
+    def __contains__(self, key):
+        """
+        Return True if the key is in the cache and has not expired.
+        """
+        # This is a separate method, rather than just a copy of has_key(),
+        # so that it always has the same functionality as has_key(), even
+        # if a subclass overrides it.
+        return self.has_key(key)
+
+    def set_many(self, data, timeout=DEFAULT_TIMEOUT, version=None):
+        """
+        Set a bunch of values in the cache at once from a dict of key/value
+        pairs.  For certain backends (memcached), this is much more efficient
+        than calling set() multiple times.
+
+        If timeout is given, use that timeout for the key; otherwise use the
+        default cache timeout.
+
+        On backends that support it, return a list of keys that failed
+        insertion, or an empty list if all keys were inserted successfully.
+        """
+        for key, value in data.items():
+            self.set(key, value, timeout=timeout, version=version)
+        return []
+
+    def delete_many(self, keys, version=None):
+        """
+        Delete a bunch of values in the cache at once. For certain backends
+        (memcached), this is much more efficient than calling delete() multiple
+        times.
+        """
+        for key in keys:
+            self.delete(key, version=version)
+
+    def clear(self):
+        """Remove *all* values from the cache at once."""
+        raise NotImplementedError('subclasses of BaseCache must provide a clear() method')
+
+    def validate_key(self, key):
+        """
+        Warn about keys that would not be portable to the memcached
+        backend. This encourages (but does not force) writing backend-portable
+        cache code.
+        """
+        if len(key) > MEMCACHE_MAX_KEY_LENGTH:
+            warnings.warn(
+                'Cache key will cause errors if used with memcached: %r '
+                '(longer than %s)' % (key, MEMCACHE_MAX_KEY_LENGTH), CacheKeyWarning
+            )
+        for char in key:
+            if ord(char) < 33 or ord(char) == 127:
+                warnings.warn(
+                    'Cache key contains characters that will cause errors if '
+                    'used with memcached: %r' % key, CacheKeyWarning
+                )
+                break
+
+    def incr_version(self, key, delta=1, version=None):
+        """
+        Add delta to the cache version for the supplied key. Return the new
+        version.
+        """
+        if version is None:
+            version = self.version
+
+        value = self.get(key, version=version)
+        if value is None:
+            raise ValueError("Key '%s' not found" % key)
+
+        self.set(key, value, version=version + delta)
+        self.delete(key, version=version)
+        return version + delta
+
+    def decr_version(self, key, delta=1, version=None):
+        """
+        Subtract delta from the cache version for the supplied key. Return the
+        new version.
+        """
+        return self.incr_version(key, -delta, version)
+
+    def close(self, **kwargs):
+        """Close the cache connection"""
+        pass

flex/lib/python3.6/site-packages/django/core/cache/backends/db.py

@@ -0,0 +1,208 @@
+"Database cache backend."
+import base64
+import pickle
+from datetime import datetime
+
+from django.conf import settings
+from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
+from django.db import DatabaseError, connections, models, router, transaction
+from django.utils import timezone
+from django.utils.encoding import force_bytes
+from django.utils.inspect import func_supports_parameter
+
+
+class Options:
+    """A class that will quack like a Django model _meta class.
+
+    This allows cache operations to be controlled by the router
+    """
+    def __init__(self, table):
+        self.db_table = table
+        self.app_label = 'django_cache'
+        self.model_name = 'cacheentry'
+        self.verbose_name = 'cache entry'
+        self.verbose_name_plural = 'cache entries'
+        self.object_name = 'CacheEntry'
+        self.abstract = False
+        self.managed = True
+        self.proxy = False
+        self.swapped = False
+
+
+class BaseDatabaseCache(BaseCache):
+    def __init__(self, table, params):
+        BaseCache.__init__(self, params)
+        self._table = table
+
+        class CacheEntry:
+            _meta = Options(table)
+        self.cache_model_class = CacheEntry
+
+
+class DatabaseCache(BaseDatabaseCache):
+
+    # This class uses cursors provided by the database connection. This means
+    # it reads expiration values as aware or naive datetimes, depending on the
+    # value of USE_TZ and whether the database supports time zones. The ORM's
+    # conversion and adaptation infrastructure is then used to avoid comparing
+    # aware and naive datetimes accidentally.
+
+    def get(self, key, default=None, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        db = router.db_for_read(self.cache_model_class)
+        connection = connections[db]
+        table = connection.ops.quote_name(self._table)
+
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT cache_key, value, expires FROM %s "
+                           "WHERE cache_key = %%s" % table, [key])
+            row = cursor.fetchone()
+        if row is None:
+            return default
+
+        expires = row[2]
+        expression = models.Expression(output_field=models.DateTimeField())
+        for converter in (connection.ops.get_db_converters(expression) +
+                          expression.get_db_converters(connection)):
+            if func_supports_parameter(converter, 'context'):  # RemovedInDjango30Warning
+                expires = converter(expires, expression, connection, {})
+            else:
+                expires = converter(expires, expression, connection)
+
+        if expires < timezone.now():
+            db = router.db_for_write(self.cache_model_class)
+            connection = connections[db]
+            with connection.cursor() as cursor:
+                cursor.execute("DELETE FROM %s "
+                               "WHERE cache_key = %%s" % table, [key])
+            return default
+
+        value = connection.ops.process_clob(row[1])
+        return pickle.loads(base64.b64decode(force_bytes(value)))
+
+    def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        self._base_set('set', key, value, timeout)
+
+    def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        return self._base_set('add', key, value, timeout)
+
+    def _base_set(self, mode, key, value, timeout=DEFAULT_TIMEOUT):
+        timeout = self.get_backend_timeout(timeout)
+        db = router.db_for_write(self.cache_model_class)
+        connection = connections[db]
+        table = connection.ops.quote_name(self._table)
+
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT COUNT(*) FROM %s" % table)
+            num = cursor.fetchone()[0]
+            now = timezone.now()
+            now = now.replace(microsecond=0)
+            if timeout is None:
+                exp = datetime.max
+            elif settings.USE_TZ:
+                exp = datetime.utcfromtimestamp(timeout)
+            else:
+                exp = datetime.fromtimestamp(timeout)
+            exp = exp.replace(microsecond=0)
+            if num > self._max_entries:
+                self._cull(db, cursor, now)
+            pickled = pickle.dumps(value, pickle.HIGHEST_PROTOCOL)
+            # The DB column is expecting a string, so make sure the value is a
+            # string, not bytes. Refs #19274.
+            b64encoded = base64.b64encode(pickled).decode('latin1')
+            try:
+                # Note: typecasting for datetimes is needed by some 3rd party
+                # database backends. All core backends work without typecasting,
+                # so be careful about changes here - test suite will NOT pick
+                # regressions.
+                with transaction.atomic(using=db):
+                    cursor.execute("SELECT cache_key, expires FROM %s "
+                                   "WHERE cache_key = %%s" % table, [key])
+                    result = cursor.fetchone()
+
+                    if result:
+                        current_expires = result[1]
+                        expression = models.Expression(output_field=models.DateTimeField())
+                        for converter in (connection.ops.get_db_converters(expression) +
+                                          expression.get_db_converters(connection)):
+                            if func_supports_parameter(converter, 'context'):  # RemovedInDjango30Warning
+                                current_expires = converter(current_expires, expression, connection, {})
+                            else:
+                                current_expires = converter(current_expires, expression, connection)
+
+                    exp = connection.ops.adapt_datetimefield_value(exp)
+                    if result and (mode == 'set' or (mode == 'add' and current_expires < now)):
+                        cursor.execute("UPDATE %s SET value = %%s, expires = %%s "
+                                       "WHERE cache_key = %%s" % table,
+                                       [b64encoded, exp, key])
+                    else:
+                        cursor.execute("INSERT INTO %s (cache_key, value, expires) "
+                                       "VALUES (%%s, %%s, %%s)" % table,
+                                       [key, b64encoded, exp])
+            except DatabaseError:
+                # To be threadsafe, updates/inserts are allowed to fail silently
+                return False
+            else:
+                return True
+
+    def delete(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+
+        db = router.db_for_write(self.cache_model_class)
+        connection = connections[db]
+        table = connection.ops.quote_name(self._table)
+
+        with connection.cursor() as cursor:
+            cursor.execute("DELETE FROM %s WHERE cache_key = %%s" % table, [key])
+
+    def has_key(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+
+        db = router.db_for_read(self.cache_model_class)
+        connection = connections[db]
+        table = connection.ops.quote_name(self._table)
+
+        if settings.USE_TZ:
+            now = datetime.utcnow()
+        else:
+            now = datetime.now()
+        now = now.replace(microsecond=0)
+
+        with connection.cursor() as cursor:
+            cursor.execute("SELECT cache_key FROM %s "
+                           "WHERE cache_key = %%s and expires > %%s" % table,
+                           [key, connection.ops.adapt_datetimefield_value(now)])
+            return cursor.fetchone() is not None
+
+    def _cull(self, db, cursor, now):
+        if self._cull_frequency == 0:
+            self.clear()
+        else:
+            connection = connections[db]
+            table = connection.ops.quote_name(self._table)
+            cursor.execute("DELETE FROM %s WHERE expires < %%s" % table,
+                           [connection.ops.adapt_datetimefield_value(now)])
+            cursor.execute("SELECT COUNT(*) FROM %s" % table)
+            num = cursor.fetchone()[0]
+            if num > self._max_entries:
+                cull_num = num // self._cull_frequency
+                cursor.execute(
+                    connection.ops.cache_key_culling_sql() % table,
+                    [cull_num])
+                cursor.execute("DELETE FROM %s "
+                               "WHERE cache_key < %%s" % table,
+                               [cursor.fetchone()[0]])
+
+    def clear(self):
+        db = router.db_for_write(self.cache_model_class)
+        connection = connections[db]
+        table = connection.ops.quote_name(self._table)
+        with connection.cursor() as cursor:
+            cursor.execute('DELETE FROM %s' % table)

flex/lib/python3.6/site-packages/django/core/cache/backends/dummy.py

@@ -0,0 +1,43 @@
+"Dummy cache backend"
+
+from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
+
+
+class DummyCache(BaseCache):
+    def __init__(self, host, *args, **kwargs):
+        BaseCache.__init__(self, *args, **kwargs)
+
+    def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        return True
+
+    def get(self, key, default=None, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        return default
+
+    def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+
+    def delete(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+
+    def get_many(self, keys, version=None):
+        return {}
+
+    def has_key(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        return False
+
+    def set_many(self, data, timeout=DEFAULT_TIMEOUT, version=None):
+        return []
+
+    def delete_many(self, keys, version=None):
+        pass
+
+    def clear(self):
+        pass

flex/lib/python3.6/site-packages/django/core/cache/backends/filebased.py

@@ -0,0 +1,143 @@
+"File-based cache backend"
+import glob
+import hashlib
+import os
+import pickle
+import random
+import tempfile
+import time
+import zlib
+
+from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
+from django.core.files.move import file_move_safe
+from django.utils.encoding import force_bytes
+
+
+class FileBasedCache(BaseCache):
+    cache_suffix = '.djcache'
+
+    def __init__(self, dir, params):
+        super().__init__(params)
+        self._dir = os.path.abspath(dir)
+        self._createdir()
+
+    def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        if self.has_key(key, version):
+            return False
+        self.set(key, value, timeout, version)
+        return True
+
+    def get(self, key, default=None, version=None):
+        fname = self._key_to_file(key, version)
+        try:
+            with open(fname, 'rb') as f:
+                if not self._is_expired(f):
+                    return pickle.loads(zlib.decompress(f.read()))
+        except FileNotFoundError:
+            pass
+        return default
+
+    def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        self._createdir()  # Cache dir can be deleted at any time.
+        fname = self._key_to_file(key, version)
+        self._cull()  # make some room if necessary
+        fd, tmp_path = tempfile.mkstemp(dir=self._dir)
+        renamed = False
+        try:
+            with open(fd, 'wb') as f:
+                expiry = self.get_backend_timeout(timeout)
+                f.write(pickle.dumps(expiry, pickle.HIGHEST_PROTOCOL))
+                f.write(zlib.compress(pickle.dumps(value, pickle.HIGHEST_PROTOCOL)))
+            file_move_safe(tmp_path, fname, allow_overwrite=True)
+            renamed = True
+        finally:
+            if not renamed:
+                os.remove(tmp_path)
+
+    def delete(self, key, version=None):
+        self._delete(self._key_to_file(key, version))
+
+    def _delete(self, fname):
+        if not fname.startswith(self._dir) or not os.path.exists(fname):
+            return
+        try:
+            os.remove(fname)
+        except FileNotFoundError:
+            # The file may have been removed by another process.
+            pass
+
+    def has_key(self, key, version=None):
+        fname = self._key_to_file(key, version)
+        if os.path.exists(fname):
+            with open(fname, 'rb') as f:
+                return not self._is_expired(f)
+        return False
+
+    def _cull(self):
+        """
+        Remove random cache entries if max_entries is reached at a ratio
+        of num_entries / cull_frequency. A value of 0 for CULL_FREQUENCY means
+        that the entire cache will be purged.
+        """
+        filelist = self._list_cache_files()
+        num_entries = len(filelist)
+        if num_entries < self._max_entries:
+            return  # return early if no culling is required
+        if self._cull_frequency == 0:
+            return self.clear()  # Clear the cache when CULL_FREQUENCY = 0
+        # Delete a random selection of entries
+        filelist = random.sample(filelist,
+                                 int(num_entries / self._cull_frequency))
+        for fname in filelist:
+            self._delete(fname)
+
+    def _createdir(self):
+        if not os.path.exists(self._dir):
+            try:
+                os.makedirs(self._dir, 0o700)
+            except FileExistsError:
+                pass
+
+    def _key_to_file(self, key, version=None):
+        """
+        Convert a key into a cache file path. Basically this is the
+        root cache path joined with the md5sum of the key and a suffix.
+        """
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        return os.path.join(self._dir, ''.join(
+            [hashlib.md5(force_bytes(key)).hexdigest(), self.cache_suffix]))
+
+    def clear(self):
+        """
+        Remove all the cache files.
+        """
+        if not os.path.exists(self._dir):
+            return
+        for fname in self._list_cache_files():
+            self._delete(fname)
+
+    def _is_expired(self, f):
+        """
+        Take an open cache file `f` and delete it if it's expired.
+        """
+        try:
+            exp = pickle.load(f)
+        except EOFError:
+            exp = 0  # An empty file is considered expired.
+        if exp is not None and exp < time.time():
+            f.close()  # On Windows a file has to be closed before deleting
+            self._delete(f.name)
+            return True
+        return False
+
+    def _list_cache_files(self):
+        """
+        Get a list of paths to all the cache files. These are all the files
+        in the root cache dir that end on the cache_suffix.
+        """
+        if not os.path.exists(self._dir):
+            return []
+        filelist = [os.path.join(self._dir, fname) for fname
+                    in glob.glob1(self._dir, '*%s' % self.cache_suffix)]
+        return filelist

flex/lib/python3.6/site-packages/django/core/cache/backends/locmem.py

@@ -0,0 +1,131 @@
+"Thread-safe in-memory cache backend."
+import pickle
+import time
+from contextlib import contextmanager
+
+from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
+from django.utils.synch import RWLock
+
+# Global in-memory store of cache data. Keyed by name, to provide
+# multiple named local memory caches.
+_caches = {}
+_expire_info = {}
+_locks = {}
+
+
+@contextmanager
+def dummy():
+    """A context manager that does nothing special."""
+    yield
+
+
+class LocMemCache(BaseCache):
+    def __init__(self, name, params):
+        BaseCache.__init__(self, params)
+        self._cache = _caches.setdefault(name, {})
+        self._expire_info = _expire_info.setdefault(name, {})
+        self._lock = _locks.setdefault(name, RWLock())
+
+    def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        pickled = pickle.dumps(value, pickle.HIGHEST_PROTOCOL)
+        with self._lock.writer():
+            if self._has_expired(key):
+                self._set(key, pickled, timeout)
+                return True
+            return False
+
+    def get(self, key, default=None, version=None, acquire_lock=True):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        pickled = None
+        with (self._lock.reader() if acquire_lock else dummy()):
+            if not self._has_expired(key):
+                pickled = self._cache[key]
+        if pickled is not None:
+            try:
+                return pickle.loads(pickled)
+            except pickle.PickleError:
+                return default
+
+        with (self._lock.writer() if acquire_lock else dummy()):
+            try:
+                del self._cache[key]
+                del self._expire_info[key]
+            except KeyError:
+                pass
+            return default
+
+    def _set(self, key, value, timeout=DEFAULT_TIMEOUT):
+        if len(self._cache) >= self._max_entries:
+            self._cull()
+        self._cache[key] = value
+        self._expire_info[key] = self.get_backend_timeout(timeout)
+
+    def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        pickled = pickle.dumps(value, pickle.HIGHEST_PROTOCOL)
+        with self._lock.writer():
+            self._set(key, pickled, timeout)
+
+    def incr(self, key, delta=1, version=None):
+        with self._lock.writer():
+            value = self.get(key, version=version, acquire_lock=False)
+            if value is None:
+                raise ValueError("Key '%s' not found" % key)
+            new_value = value + delta
+            key = self.make_key(key, version=version)
+            pickled = pickle.dumps(new_value, pickle.HIGHEST_PROTOCOL)
+            self._cache[key] = pickled
+        return new_value
+
+    def has_key(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        with self._lock.reader():
+            if not self._has_expired(key):
+                return True
+
+        with self._lock.writer():
+            try:
+                del self._cache[key]
+                del self._expire_info[key]
+            except KeyError:
+                pass
+            return False
+
+    def _has_expired(self, key):
+        exp = self._expire_info.get(key, -1)
+        if exp is None or exp > time.time():
+            return False
+        return True
+
+    def _cull(self):
+        if self._cull_frequency == 0:
+            self.clear()
+        else:
+            doomed = [k for (i, k) in enumerate(self._cache) if i % self._cull_frequency == 0]
+            for k in doomed:
+                self._delete(k)
+
+    def _delete(self, key):
+        try:
+            del self._cache[key]
+        except KeyError:
+            pass
+        try:
+            del self._expire_info[key]
+        except KeyError:
+            pass
+
+    def delete(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self.validate_key(key)
+        with self._lock.writer():
+            self._delete(key)
+
+    def clear(self):
+        self._cache.clear()
+        self._expire_info.clear()

flex/lib/python3.6/site-packages/django/core/cache/backends/memcached.py

@@ -0,0 +1,200 @@
+"Memcached cache backend"
+
+import pickle
+import re
+import time
+import warnings
+
+from django.core.cache.backends.base import DEFAULT_TIMEOUT, BaseCache
+from django.utils.deprecation import RemovedInDjango21Warning
+from django.utils.functional import cached_property
+
+
+class BaseMemcachedCache(BaseCache):
+    def __init__(self, server, params, library, value_not_found_exception):
+        super().__init__(params)
+        if isinstance(server, str):
+            self._servers = re.split('[;,]', server)
+        else:
+            self._servers = server
+
+        # The exception type to catch from the underlying library for a key
+        # that was not found. This is a ValueError for python-memcache,
+        # pylibmc.NotFound for pylibmc, and cmemcache will return None without
+        # raising an exception.
+        self.LibraryValueNotFoundException = value_not_found_exception
+
+        self._lib = library
+        self._options = params.get('OPTIONS') or {}
+
+    @property
+    def _cache(self):
+        """
+        Implement transparent thread-safe access to a memcached client.
+        """
+        if getattr(self, '_client', None) is None:
+            self._client = self._lib.Client(self._servers, **self._options)
+
+        return self._client
+
+    def get_backend_timeout(self, timeout=DEFAULT_TIMEOUT):
+        """
+        Memcached deals with long (> 30 days) timeouts in a special
+        way. Call this function to obtain a safe value for your timeout.
+        """
+        if timeout == DEFAULT_TIMEOUT:
+            timeout = self.default_timeout
+
+        if timeout is None:
+            # Using 0 in memcache sets a non-expiring timeout.
+            return 0
+        elif int(timeout) == 0:
+            # Other cache backends treat 0 as set-and-expire. To achieve this
+            # in memcache backends, a negative timeout must be passed.
+            timeout = -1
+
+        if timeout > 2592000:  # 60*60*24*30, 30 days
+            # See https://github.com/memcached/memcached/wiki/Programming#expiration
+            # "Expiration times can be set from 0, meaning "never expire", to
+            # 30 days. Any time higher than 30 days is interpreted as a Unix
+            # timestamp date. If you want to expire an object on January 1st of
+            # next year, this is how you do that."
+            #
+            # This means that we have to switch to absolute timestamps.
+            timeout += int(time.time())
+        return int(timeout)
+
+    def add(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        return self._cache.add(key, value, self.get_backend_timeout(timeout))
+
+    def get(self, key, default=None, version=None):
+        key = self.make_key(key, version=version)
+        val = self._cache.get(key)
+        if val is None:
+            return default
+        return val
+
+    def set(self, key, value, timeout=DEFAULT_TIMEOUT, version=None):
+        key = self.make_key(key, version=version)
+        if not self._cache.set(key, value, self.get_backend_timeout(timeout)):
+            # make sure the key doesn't keep its old value in case of failure to set (memcached's 1MB limit)
+            self._cache.delete(key)
+
+    def delete(self, key, version=None):
+        key = self.make_key(key, version=version)
+        self._cache.delete(key)
+
+    def get_many(self, keys, version=None):
+        new_keys = [self.make_key(x, version=version) for x in keys]
+        ret = self._cache.get_multi(new_keys)
+        if ret:
+            m = dict(zip(new_keys, keys))
+            return {m[k]: v for k, v in ret.items()}
+        return ret
+
+    def close(self, **kwargs):
+        # Many clients don't clean up connections properly.
+        self._cache.disconnect_all()
+
+    def incr(self, key, delta=1, version=None):
+        key = self.make_key(key, version=version)
+        # memcached doesn't support a negative delta
+        if delta < 0:
+            return self._cache.decr(key, -delta)
+        try:
+            val = self._cache.incr(key, delta)
+
+        # python-memcache responds to incr on nonexistent keys by
+        # raising a ValueError, pylibmc by raising a pylibmc.NotFound
+        # and Cmemcache returns None. In all cases,
+        # we should raise a ValueError though.
+        except self.LibraryValueNotFoundException:
+            val = None
+        if val is None:
+            raise ValueError("Key '%s' not found" % key)
+        return val
+
+    def decr(self, key, delta=1, version=None):
+        key = self.make_key(key, version=version)
+        # memcached doesn't support a negative delta
+        if delta < 0:
+            return self._cache.incr(key, -delta)
+        try:
+            val = self._cache.decr(key, delta)
+
+        # python-memcache responds to incr on nonexistent keys by
+        # raising a ValueError, pylibmc by raising a pylibmc.NotFound
+        # and Cmemcache returns None. In all cases,
+        # we should raise a ValueError though.
+        except self.LibraryValueNotFoundException:
+            val = None
+        if val is None:
+            raise ValueError("Key '%s' not found" % key)
+        return val
+
+    def set_many(self, data, timeout=DEFAULT_TIMEOUT, version=None):
+        safe_data = {}
+        original_keys = {}
+        for key, value in data.items():
+            safe_key = self.make_key(key, version=version)
+            safe_data[safe_key] = value
+            original_keys[safe_key] = key
+        failed_keys = self._cache.set_multi(safe_data, self.get_backend_timeout(timeout))
+        return [original_keys[k] for k in failed_keys]
+
+    def delete_many(self, keys, version=None):
+        self._cache.delete_multi(self.make_key(key, version=version) for key in keys)
+
+    def clear(self):
+        self._cache.flush_all()
+
+
+class MemcachedCache(BaseMemcachedCache):
+    "An implementation of a cache binding using python-memcached"
+    def __init__(self, server, params):
+        import memcache
+        super().__init__(server, params, library=memcache, value_not_found_exception=ValueError)
+
+    @property
+    def _cache(self):
+        if getattr(self, '_client', None) is None:
+            client_kwargs = {'pickleProtocol': pickle.HIGHEST_PROTOCOL}
+            client_kwargs.update(self._options)
+            self._client = self._lib.Client(self._servers, **client_kwargs)
+        return self._client
+
+
+class PyLibMCCache(BaseMemcachedCache):
+    "An implementation of a cache binding using pylibmc"
+    def __init__(self, server, params):
+        import pylibmc
+        super().__init__(server, params, library=pylibmc, value_not_found_exception=pylibmc.NotFound)
+
+        # The contents of `OPTIONS` was formerly only used to set the behaviors
+        # attribute, but is now passed directly to the Client constructor. As such,
+        # any options that don't match a valid keyword argument are removed and set
+        # under the `behaviors` key instead, to maintain backwards compatibility.
+        legacy_behaviors = {}
+        for option in list(self._options):
+            if option not in ('behaviors', 'binary', 'username', 'password'):
+                warnings.warn(
+                    "Specifying pylibmc cache behaviors as a top-level property "
+                    "within `OPTIONS` is deprecated. Move `%s` into a dict named "
+                    "`behaviors` inside `OPTIONS` instead." % option,
+                    RemovedInDjango21Warning,
+                    stacklevel=2,
+                )
+                legacy_behaviors[option] = self._options.pop(option)
+
+        if legacy_behaviors:
+            self._options.setdefault('behaviors', {}).update(legacy_behaviors)
+
+    @cached_property
+    def _cache(self):
+        return self._lib.Client(self._servers, **self._options)
+
+    def close(self, **kwargs):
+        # libmemcached manages its own connections. Don't call disconnect_all()
+        # as it resets the failover state and creates unnecessary reconnects.
+        pass

flex/lib/python3.6/site-packages/django/core/cache/utils.py

@@ -0,0 +1,14 @@
+import hashlib
+from urllib.parse import quote
+
+from django.utils.encoding import force_bytes
+
+TEMPLATE_FRAGMENT_KEY_TEMPLATE = 'template.cache.%s.%s'
+
+
+def make_template_fragment_key(fragment_name, vary_on=None):
+    if vary_on is None:
+        vary_on = ()
+    key = ':'.join(quote(str(var)) for var in vary_on)
+    args = hashlib.md5(force_bytes(key))
+    return TEMPLATE_FRAGMENT_KEY_TEMPLATE % (fragment_name, args.hexdigest())

flex/lib/python3.6/site-packages/django/core/checks/__init__.py

@@ -0,0 +1,23 @@
+from .messages import (
+    CRITICAL, DEBUG, ERROR, INFO, WARNING, CheckMessage, Critical, Debug,
+    Error, Info, Warning,
+)
+from .registry import Tags, register, run_checks, tag_exists
+
+# Import these to force registration of checks
+import django.core.checks.caches  # NOQA isort:skip
+import django.core.checks.database  # NOQA isort:skip
+import django.core.checks.model_checks  # NOQA isort:skip
+import django.core.checks.security.base  # NOQA isort:skip
+import django.core.checks.security.csrf  # NOQA isort:skip
+import django.core.checks.security.sessions  # NOQA isort:skip
+import django.core.checks.templates  # NOQA isort:skip
+import django.core.checks.urls  # NOQA isort:skip
+
+
+__all__ = [
+    'CheckMessage',
+    'Debug', 'Info', 'Warning', 'Error', 'Critical',
+    'DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL',
+    'register', 'run_checks', 'tag_exists', 'Tags',
+]

flex/lib/python3.6/site-packages/django/core/checks/caches.py

@@ -0,0 +1,16 @@
+from django.conf import settings
+from django.core.cache import DEFAULT_CACHE_ALIAS
+
+from . import Error, Tags, register
+
+E001 = Error(
+    "You must define a '%s' cache in your CACHES setting." % DEFAULT_CACHE_ALIAS,
+    id='caches.E001',
+)
+
+
+@register(Tags.caches)
+def check_default_cache_is_configured(app_configs, **kwargs):
+    if DEFAULT_CACHE_ALIAS not in settings.CACHES:
+        return [E001]
+    return []

flex/lib/python3.6/site-packages/django/core/checks/database.py

@@ -0,0 +1,11 @@
+from django.db import connections
+
+from . import Tags, register
+
+
+@register(Tags.database)
+def check_database_backends(*args, **kwargs):
+    issues = []
+    for conn in connections.all():
+        issues.extend(conn.validation.check(**kwargs))
+    return issues

flex/lib/python3.6/site-packages/django/core/checks/messages.py

@@ -0,0 +1,75 @@
+# Levels
+DEBUG = 10
+INFO = 20
+WARNING = 30
+ERROR = 40
+CRITICAL = 50
+
+
+class CheckMessage:
+
+    def __init__(self, level, msg, hint=None, obj=None, id=None):
+        assert isinstance(level, int), "The first argument should be level."
+        self.level = level
+        self.msg = msg
+        self.hint = hint
+        self.obj = obj
+        self.id = id
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, self.__class__) and
+            all(getattr(self, attr) == getattr(other, attr)
+                for attr in ['level', 'msg', 'hint', 'obj', 'id'])
+        )
+
+    def __str__(self):
+        from django.db import models
+
+        if self.obj is None:
+            obj = "?"
+        elif isinstance(self.obj, models.base.ModelBase):
+            # We need to hardcode ModelBase and Field cases because its __str__
+            # method doesn't return "applabel.modellabel" and cannot be changed.
+            obj = self.obj._meta.label
+        else:
+            obj = str(self.obj)
+        id = "(%s) " % self.id if self.id else ""
+        hint = "\n\tHINT: %s" % self.hint if self.hint else ''
+        return "%s: %s%s%s" % (obj, id, self.msg, hint)
+
+    def __repr__(self):
+        return "<%s: level=%r, msg=%r, hint=%r, obj=%r, id=%r>" % \
+            (self.__class__.__name__, self.level, self.msg, self.hint, self.obj, self.id)
+
+    def is_serious(self, level=ERROR):
+        return self.level >= level
+
+    def is_silenced(self):
+        from django.conf import settings
+        return self.id in settings.SILENCED_SYSTEM_CHECKS
+
+
+class Debug(CheckMessage):
+    def __init__(self, *args, **kwargs):
+        super().__init__(DEBUG, *args, **kwargs)
+
+
+class Info(CheckMessage):
+    def __init__(self, *args, **kwargs):
+        super().__init__(INFO, *args, **kwargs)
+
+
+class Warning(CheckMessage):
+    def __init__(self, *args, **kwargs):
+        super().__init__(WARNING, *args, **kwargs)
+
+
+class Error(CheckMessage):
+    def __init__(self, *args, **kwargs):
+        super().__init__(ERROR, *args, **kwargs)
+
+
+class Critical(CheckMessage):
+    def __init__(self, *args, **kwargs):
+        super().__init__(CRITICAL, *args, **kwargs)

flex/lib/python3.6/site-packages/django/core/checks/model_checks.py

@@ -0,0 +1,154 @@
+import inspect
+import types
+from itertools import chain
+
+from django.apps import apps
+from django.core.checks import Error, Tags, register
+
+
+@register(Tags.models)
+def check_all_models(app_configs=None, **kwargs):
+    errors = []
+    if app_configs is None:
+        models = apps.get_models()
+    else:
+        models = chain.from_iterable(app_config.get_models() for app_config in app_configs)
+    for model in models:
+        if not inspect.ismethod(model.check):
+            errors.append(
+                Error(
+                    "The '%s.check()' class method is currently overridden by %r."
+                    % (model.__name__, model.check),
+                    obj=model,
+                    id='models.E020'
+                )
+            )
+        else:
+            errors.extend(model.check(**kwargs))
+    return errors
+
+
+def _check_lazy_references(apps, ignore=None):
+    """
+    Ensure all lazy (i.e. string) model references have been resolved.
+
+    Lazy references are used in various places throughout Django, primarily in
+    related fields and model signals. Identify those common cases and provide
+    more helpful error messages for them.
+
+    The ignore parameter is used by StateApps to exclude swappable models from
+    this check.
+    """
+    pending_models = set(apps._pending_operations) - (ignore or set())
+
+    # Short circuit if there aren't any errors.
+    if not pending_models:
+        return []
+
+    from django.db.models import signals
+    model_signals = {
+        signal: name for name, signal in vars(signals).items()
+        if isinstance(signal, signals.ModelSignal)
+    }
+
+    def extract_operation(obj):
+        """
+        Take a callable found in Apps._pending_operations and identify the
+        original callable passed to Apps.lazy_model_operation(). If that
+        callable was a partial, return the inner, non-partial function and
+        any arguments and keyword arguments that were supplied with it.
+
+        obj is a callback defined locally in Apps.lazy_model_operation() and
+        annotated there with a `func` attribute so as to imitate a partial.
+        """
+        operation, args, keywords = obj, [], {}
+        while hasattr(operation, 'func'):
+            # The or clauses are redundant but work around a bug (#25945) in
+            # functools.partial in Python <= 3.5.1.
+            args.extend(getattr(operation, 'args', []) or [])
+            keywords.update(getattr(operation, 'keywords', {}) or {})
+            operation = operation.func
+        return operation, args, keywords
+
+    def app_model_error(model_key):
+        try:
+            apps.get_app_config(model_key[0])
+            model_error = "app '%s' doesn't provide model '%s'" % model_key
+        except LookupError:
+            model_error = "app '%s' isn't installed" % model_key[0]
+        return model_error
+
+    # Here are several functions which return CheckMessage instances for the
+    # most common usages of lazy operations throughout Django. These functions
+    # take the model that was being waited on as an (app_label, modelname)
+    # pair, the original lazy function, and its positional and keyword args as
+    # determined by extract_operation().
+
+    def field_error(model_key, func, args, keywords):
+        error_msg = (
+            "The field %(field)s was declared with a lazy reference "
+            "to '%(model)s', but %(model_error)s."
+        )
+        params = {
+            'model': '.'.join(model_key),
+            'field': keywords['field'],
+            'model_error': app_model_error(model_key),
+        }
+        return Error(error_msg % params, obj=keywords['field'], id='fields.E307')
+
+    def signal_connect_error(model_key, func, args, keywords):
+        error_msg = (
+            "%(receiver)s was connected to the '%(signal)s' signal with a "
+            "lazy reference to the sender '%(model)s', but %(model_error)s."
+        )
+        receiver = args[0]
+        # The receiver is either a function or an instance of class
+        # defining a `__call__` method.
+        if isinstance(receiver, types.FunctionType):
+            description = "The function '%s'" % receiver.__name__
+        elif isinstance(receiver, types.MethodType):
+            description = "Bound method '%s.%s'" % (receiver.__self__.__class__.__name__, receiver.__name__)
+        else:
+            description = "An instance of class '%s'" % receiver.__class__.__name__
+        signal_name = model_signals.get(func.__self__, 'unknown')
+        params = {
+            'model': '.'.join(model_key),
+            'receiver': description,
+            'signal': signal_name,
+            'model_error': app_model_error(model_key),
+        }
+        return Error(error_msg % params, obj=receiver.__module__, id='signals.E001')
+
+    def default_error(model_key, func, args, keywords):
+        error_msg = "%(op)s contains a lazy reference to %(model)s, but %(model_error)s."
+        params = {
+            'op': func,
+            'model': '.'.join(model_key),
+            'model_error': app_model_error(model_key),
+        }
+        return Error(error_msg % params, obj=func, id='models.E022')
+
+    # Maps common uses of lazy operations to corresponding error functions
+    # defined above. If a key maps to None, no error will be produced.
+    # default_error() will be used for usages that don't appear in this dict.
+    known_lazy = {
+        ('django.db.models.fields.related', 'resolve_related_class'): field_error,
+        ('django.db.models.fields.related', 'set_managed'): None,
+        ('django.dispatch.dispatcher', 'connect'): signal_connect_error,
+    }
+
+    def build_error(model_key, func, args, keywords):
+        key = (func.__module__, func.__name__)
+        error_fn = known_lazy.get(key, default_error)
+        return error_fn(model_key, func, args, keywords) if error_fn else None
+
+    return sorted(filter(None, (
+        build_error(model_key, *extract_operation(func))
+        for model_key in pending_models
+        for func in apps._pending_operations[model_key]
+    )), key=lambda error: error.msg)
+
+
+@register(Tags.models)
+def check_lazy_references(app_configs=None, **kwargs):
+    return _check_lazy_references(apps)

flex/lib/python3.6/site-packages/django/core/checks/registry.py

@@ -0,0 +1,98 @@
+from itertools import chain
+
+from django.utils.itercompat import is_iterable
+
+
+class Tags:
+    """
+    Built-in tags for internal checks.
+    """
+    admin = 'admin'
+    caches = 'caches'
+    compatibility = 'compatibility'
+    database = 'database'
+    models = 'models'
+    security = 'security'
+    signals = 'signals'
+    templates = 'templates'
+    urls = 'urls'
+
+
+class CheckRegistry:
+
+    def __init__(self):
+        self.registered_checks = set()
+        self.deployment_checks = set()
+
+    def register(self, check=None, *tags, **kwargs):
+        """
+        Can be used as a function or a decorator. Register given function
+        `f` labeled with given `tags`. The function should receive **kwargs
+        and return list of Errors and Warnings.
+
+        Example::
+
+            registry = CheckRegistry()
+            @registry.register('mytag', 'anothertag')
+            def my_check(apps, **kwargs):
+                # ... perform checks and collect `errors` ...
+                return errors
+            # or
+            registry.register(my_check, 'mytag', 'anothertag')
+        """
+        kwargs.setdefault('deploy', False)
+
+        def inner(check):
+            check.tags = tags
+            checks = self.deployment_checks if kwargs['deploy'] else self.registered_checks
+            checks.add(check)
+            return check
+
+        if callable(check):
+            return inner(check)
+        else:
+            if check:
+                tags += (check, )
+            return inner
+
+    def run_checks(self, app_configs=None, tags=None, include_deployment_checks=False):
+        """
+        Run all registered checks and return list of Errors and Warnings.
+        """
+        errors = []
+        checks = self.get_checks(include_deployment_checks)
+
+        if tags is not None:
+            checks = [check for check in checks if not set(check.tags).isdisjoint(tags)]
+        else:
+            # By default, 'database'-tagged checks are not run as they do more
+            # than mere static code analysis.
+            checks = [check for check in checks if Tags.database not in check.tags]
+
+        for check in checks:
+            new_errors = check(app_configs=app_configs)
+            assert is_iterable(new_errors), (
+                "The function %r did not return a list. All functions registered "
+                "with the checks registry must return a list." % check)
+            errors.extend(new_errors)
+        return errors
+
+    def tag_exists(self, tag, include_deployment_checks=False):
+        return tag in self.tags_available(include_deployment_checks)
+
+    def tags_available(self, deployment_checks=False):
+        return set(chain.from_iterable(
+            check.tags for check in self.get_checks(deployment_checks)
+        ))
+
+    def get_checks(self, include_deployment_checks=False):
+        checks = list(self.registered_checks)
+        if include_deployment_checks:
+            checks.extend(self.deployment_checks)
+        return checks
+
+
+registry = CheckRegistry()
+register = registry.register
+run_checks = registry.run_checks
+tag_exists = registry.tag_exists

flex/lib/python3.6/site-packages/django/core/checks/security/base.py

@@ -0,0 +1,210 @@
+from django.conf import settings
+
+from .. import Tags, Warning, register
+
+SECRET_KEY_MIN_LENGTH = 50
+SECRET_KEY_MIN_UNIQUE_CHARACTERS = 5
+
+W001 = Warning(
+    "You do not have 'django.middleware.security.SecurityMiddleware' "
+    "in your MIDDLEWARE so the SECURE_HSTS_SECONDS, "
+    "SECURE_CONTENT_TYPE_NOSNIFF, "
+    "SECURE_BROWSER_XSS_FILTER, and SECURE_SSL_REDIRECT settings "
+    "will have no effect.",
+    id='security.W001',
+)
+
+W002 = Warning(
+    "You do not have "
+    "'django.middleware.clickjacking.XFrameOptionsMiddleware' in your "
+    "MIDDLEWARE, so your pages will not be served with an "
+    "'x-frame-options' header. Unless there is a good reason for your "
+    "site to be served in a frame, you should consider enabling this "
+    "header to help prevent clickjacking attacks.",
+    id='security.W002',
+)
+
+W004 = Warning(
+    "You have not set a value for the SECURE_HSTS_SECONDS setting. "
+    "If your entire site is served only over SSL, you may want to consider "
+    "setting a value and enabling HTTP Strict Transport Security. "
+    "Be sure to read the documentation first; enabling HSTS carelessly "
+    "can cause serious, irreversible problems.",
+    id='security.W004',
+)
+
+W005 = Warning(
+    "You have not set the SECURE_HSTS_INCLUDE_SUBDOMAINS setting to True. "
+    "Without this, your site is potentially vulnerable to attack "
+    "via an insecure connection to a subdomain. Only set this to True if "
+    "you are certain that all subdomains of your domain should be served "
+    "exclusively via SSL.",
+    id='security.W005',
+)
+
+W006 = Warning(
+    "Your SECURE_CONTENT_TYPE_NOSNIFF setting is not set to True, "
+    "so your pages will not be served with an "
+    "'x-content-type-options: nosniff' header. "
+    "You should consider enabling this header to prevent the "
+    "browser from identifying content types incorrectly.",
+    id='security.W006',
+)
+
+W007 = Warning(
+    "Your SECURE_BROWSER_XSS_FILTER setting is not set to True, "
+    "so your pages will not be served with an "
+    "'x-xss-protection: 1; mode=block' header. "
+    "You should consider enabling this header to activate the "
+    "browser's XSS filtering and help prevent XSS attacks.",
+    id='security.W007',
+)
+
+W008 = Warning(
+    "Your SECURE_SSL_REDIRECT setting is not set to True. "
+    "Unless your site should be available over both SSL and non-SSL "
+    "connections, you may want to either set this setting True "
+    "or configure a load balancer or reverse-proxy server "
+    "to redirect all connections to HTTPS.",
+    id='security.W008',
+)
+
+W009 = Warning(
+    "Your SECRET_KEY has less than %(min_length)s characters or less than "
+    "%(min_unique_chars)s unique characters. Please generate a long and random "
+    "SECRET_KEY, otherwise many of Django's security-critical features will be "
+    "vulnerable to attack." % {
+        'min_length': SECRET_KEY_MIN_LENGTH,
+        'min_unique_chars': SECRET_KEY_MIN_UNIQUE_CHARACTERS,
+    },
+    id='security.W009',
+)
+
+W018 = Warning(
+    "You should not have DEBUG set to True in deployment.",
+    id='security.W018',
+)
+
+W019 = Warning(
+    "You have "
+    "'django.middleware.clickjacking.XFrameOptionsMiddleware' in your "
+    "MIDDLEWARE, but X_FRAME_OPTIONS is not set to 'DENY'. "
+    "The default is 'SAMEORIGIN', but unless there is a good reason for "
+    "your site to serve other parts of itself in a frame, you should "
+    "change it to 'DENY'.",
+    id='security.W019',
+)
+
+W020 = Warning(
+    "ALLOWED_HOSTS must not be empty in deployment.",
+    id='security.W020',
+)
+
+W021 = Warning(
+    "You have not set the SECURE_HSTS_PRELOAD setting to True. Without this, "
+    "your site cannot be submitted to the browser preload list.",
+    id='security.W021',
+)
+
+
+def _security_middleware():
+    return 'django.middleware.security.SecurityMiddleware' in settings.MIDDLEWARE
+
+
+def _xframe_middleware():
+    return 'django.middleware.clickjacking.XFrameOptionsMiddleware' in settings.MIDDLEWARE
+
+
+@register(Tags.security, deploy=True)
+def check_security_middleware(app_configs, **kwargs):
+    passed_check = _security_middleware()
+    return [] if passed_check else [W001]
+
+
+@register(Tags.security, deploy=True)
+def check_xframe_options_middleware(app_configs, **kwargs):
+    passed_check = _xframe_middleware()
+    return [] if passed_check else [W002]
+
+
+@register(Tags.security, deploy=True)
+def check_sts(app_configs, **kwargs):
+    passed_check = not _security_middleware() or settings.SECURE_HSTS_SECONDS
+    return [] if passed_check else [W004]
+
+
+@register(Tags.security, deploy=True)
+def check_sts_include_subdomains(app_configs, **kwargs):
+    passed_check = (
+        not _security_middleware() or
+        not settings.SECURE_HSTS_SECONDS or
+        settings.SECURE_HSTS_INCLUDE_SUBDOMAINS is True
+    )
+    return [] if passed_check else [W005]
+
+
+@register(Tags.security, deploy=True)
+def check_sts_preload(app_configs, **kwargs):
+    passed_check = (
+        not _security_middleware() or
+        not settings.SECURE_HSTS_SECONDS or
+        settings.SECURE_HSTS_PRELOAD is True
+    )
+    return [] if passed_check else [W021]
+
+
+@register(Tags.security, deploy=True)
+def check_content_type_nosniff(app_configs, **kwargs):
+    passed_check = (
+        not _security_middleware() or
+        settings.SECURE_CONTENT_TYPE_NOSNIFF is True
+    )
+    return [] if passed_check else [W006]
+
+
+@register(Tags.security, deploy=True)
+def check_xss_filter(app_configs, **kwargs):
+    passed_check = (
+        not _security_middleware() or
+        settings.SECURE_BROWSER_XSS_FILTER is True
+    )
+    return [] if passed_check else [W007]
+
+
+@register(Tags.security, deploy=True)
+def check_ssl_redirect(app_configs, **kwargs):
+    passed_check = (
+        not _security_middleware() or
+        settings.SECURE_SSL_REDIRECT is True
+    )
+    return [] if passed_check else [W008]
+
+
+@register(Tags.security, deploy=True)
+def check_secret_key(app_configs, **kwargs):
+    passed_check = (
+        getattr(settings, 'SECRET_KEY', None) and
+        len(set(settings.SECRET_KEY)) >= SECRET_KEY_MIN_UNIQUE_CHARACTERS and
+        len(settings.SECRET_KEY) >= SECRET_KEY_MIN_LENGTH
+    )
+    return [] if passed_check else [W009]
+
+
+@register(Tags.security, deploy=True)
+def check_debug(app_configs, **kwargs):
+    passed_check = not settings.DEBUG
+    return [] if passed_check else [W018]
+
+
+@register(Tags.security, deploy=True)
+def check_xframe_deny(app_configs, **kwargs):
+    passed_check = (
+        not _xframe_middleware() or
+        settings.X_FRAME_OPTIONS == 'DENY'
+    )
+    return [] if passed_check else [W019]
+
+
+@register(Tags.security, deploy=True)
+def check_allowed_hosts(app_configs, **kwargs):
+    return [] if settings.ALLOWED_HOSTS else [W020]

flex/lib/python3.6/site-packages/django/core/checks/security/csrf.py

@@ -0,0 +1,40 @@
+from django.conf import settings
+
+from .. import Tags, Warning, register
+
+W003 = Warning(
+    "You don't appear to be using Django's built-in "
+    "cross-site request forgery protection via the middleware "
+    "('django.middleware.csrf.CsrfViewMiddleware' is not in your "
+    "MIDDLEWARE). Enabling the middleware is the safest approach "
+    "to ensure you don't leave any holes.",
+    id='security.W003',
+)
+
+W016 = Warning(
+    "You have 'django.middleware.csrf.CsrfViewMiddleware' in your "
+    "MIDDLEWARE, but you have not set CSRF_COOKIE_SECURE to True. "
+    "Using a secure-only CSRF cookie makes it more difficult for network "
+    "traffic sniffers to steal the CSRF token.",
+    id='security.W016',
+)
+
+
+def _csrf_middleware():
+    return 'django.middleware.csrf.CsrfViewMiddleware' in settings.MIDDLEWARE
+
+
+@register(Tags.security, deploy=True)
+def check_csrf_middleware(app_configs, **kwargs):
+    passed_check = _csrf_middleware()
+    return [] if passed_check else [W003]
+
+
+@register(Tags.security, deploy=True)
+def check_csrf_cookie_secure(app_configs, **kwargs):
+    passed_check = (
+        settings.CSRF_USE_SESSIONS or
+        not _csrf_middleware() or
+        settings.CSRF_COOKIE_SECURE
+    )
+    return [] if passed_check else [W016]

flex/lib/python3.6/site-packages/django/core/checks/security/sessions.py

@@ -0,0 +1,97 @@
+from django.conf import settings
+
+from .. import Tags, Warning, register
+
+
+def add_session_cookie_message(message):
+    return message + (
+        " Using a secure-only session cookie makes it more difficult for "
+        "network traffic sniffers to hijack user sessions."
+    )
+
+
+W010 = Warning(
+    add_session_cookie_message(
+        "You have 'django.contrib.sessions' in your INSTALLED_APPS, "
+        "but you have not set SESSION_COOKIE_SECURE to True."
+    ),
+    id='security.W010',
+)
+
+W011 = Warning(
+    add_session_cookie_message(
+        "You have 'django.contrib.sessions.middleware.SessionMiddleware' "
+        "in your MIDDLEWARE, but you have not set "
+        "SESSION_COOKIE_SECURE to True."
+    ),
+    id='security.W011',
+)
+
+W012 = Warning(
+    add_session_cookie_message("SESSION_COOKIE_SECURE is not set to True."),
+    id='security.W012',
+)
+
+
+def add_httponly_message(message):
+    return message + (
+        " Using an HttpOnly session cookie makes it more difficult for "
+        "cross-site scripting attacks to hijack user sessions."
+    )
+
+
+W013 = Warning(
+    add_httponly_message(
+        "You have 'django.contrib.sessions' in your INSTALLED_APPS, "
+        "but you have not set SESSION_COOKIE_HTTPONLY to True.",
+    ),
+    id='security.W013',
+)
+
+W014 = Warning(
+    add_httponly_message(
+        "You have 'django.contrib.sessions.middleware.SessionMiddleware' "
+        "in your MIDDLEWARE, but you have not set "
+        "SESSION_COOKIE_HTTPONLY to True."
+    ),
+    id='security.W014',
+)
+
+W015 = Warning(
+    add_httponly_message("SESSION_COOKIE_HTTPONLY is not set to True."),
+    id='security.W015',
+)
+
+
+@register(Tags.security, deploy=True)
+def check_session_cookie_secure(app_configs, **kwargs):
+    errors = []
+    if not settings.SESSION_COOKIE_SECURE:
+        if _session_app():
+            errors.append(W010)
+        if _session_middleware():
+            errors.append(W011)
+        if len(errors) > 1:
+            errors = [W012]
+    return errors
+
+
+@register(Tags.security, deploy=True)
+def check_session_cookie_httponly(app_configs, **kwargs):
+    errors = []
+    if not settings.SESSION_COOKIE_HTTPONLY:
+        if _session_app():
+            errors.append(W013)
+        if _session_middleware():
+            errors.append(W014)
+        if len(errors) > 1:
+            errors = [W015]
+    return errors
+
+
+def _session_middleware():
+    return 'django.contrib.sessions.middleware.SessionMiddleware' in settings.MIDDLEWARE
+
+
+def _session_app():
+    return "django.contrib.sessions" in settings.INSTALLED_APPS

flex/lib/python3.6/site-packages/django/core/checks/templates.py

@@ -0,0 +1,38 @@
+import copy
+
+from django.conf import settings
+
+from . import Error, Tags, register
+
+E001 = Error(
+    "You have 'APP_DIRS': True in your TEMPLATES but also specify 'loaders' "
+    "in OPTIONS. Either remove APP_DIRS or remove the 'loaders' option.",
+    id='templates.E001',
+)
+E002 = Error(
+    "'string_if_invalid' in TEMPLATES OPTIONS must be a string but got: {} ({}).",
+    id="templates.E002",
+)
+
+
+@register(Tags.templates)
+def check_setting_app_dirs_loaders(app_configs, **kwargs):
+    passed_check = True
+    for conf in settings.TEMPLATES:
+        if not conf.get('APP_DIRS'):
+            continue
+        if 'loaders' in conf.get('OPTIONS', {}):
+            passed_check = False
+    return [] if passed_check else [E001]
+
+
+@register(Tags.templates)
+def check_string_if_invalid_is_string(app_configs, **kwargs):
+    errors = []
+    for conf in settings.TEMPLATES:
+        string_if_invalid = conf.get('OPTIONS', {}).get('string_if_invalid', '')
+        if not isinstance(string_if_invalid, str):
+            error = copy.copy(E002)
+            error.msg = error.msg.format(string_if_invalid, type(string_if_invalid).__name__)
+            errors.append(error)
+    return errors

flex/lib/python3.6/site-packages/django/core/checks/urls.py

@@ -0,0 +1,110 @@
+from collections import Counter
+
+from django.conf import settings
+
+from . import Error, Tags, Warning, register
+
+
+@register(Tags.urls)
+def check_url_config(app_configs, **kwargs):
+    if getattr(settings, 'ROOT_URLCONF', None):
+        from django.urls import get_resolver
+        resolver = get_resolver()
+        return check_resolver(resolver)
+    return []
+
+
+def check_resolver(resolver):
+    """
+    Recursively check the resolver.
+    """
+    check_method = getattr(resolver, 'check', None)
+    if check_method is not None:
+        return check_method()
+    elif not hasattr(resolver, 'resolve'):
+        return get_warning_for_invalid_pattern(resolver)
+    else:
+        return []
+
+
+@register(Tags.urls)
+def check_url_namespaces_unique(app_configs, **kwargs):
+    """
+    Warn if URL namespaces used in applications aren't unique.
+    """
+    if not getattr(settings, 'ROOT_URLCONF', None):
+        return []
+
+    from django.urls import get_resolver
+    resolver = get_resolver()
+    all_namespaces = _load_all_namespaces(resolver)
+    counter = Counter(all_namespaces)
+    non_unique_namespaces = [n for n, count in counter.items() if count > 1]
+    errors = []
+    for namespace in non_unique_namespaces:
+        errors.append(Warning(
+            "URL namespace '{}' isn't unique. You may not be able to reverse "
+            "all URLs in this namespace".format(namespace),
+            id="urls.W005",
+        ))
+    return errors
+
+
+def _load_all_namespaces(resolver, parents=()):
+    """
+    Recursively load all namespaces from URL patterns.
+    """
+    url_patterns = getattr(resolver, 'url_patterns', [])
+    namespaces = [
+        ':'.join(parents + (url.namespace,)) for url in url_patterns
+        if getattr(url, 'namespace', None) is not None
+    ]
+    for pattern in url_patterns:
+        namespace = getattr(pattern, 'namespace', None)
+        current = parents
+        if namespace is not None:
+            current += (namespace,)
+        namespaces.extend(_load_all_namespaces(pattern, current))
+    return namespaces
+
+
+def get_warning_for_invalid_pattern(pattern):
+    """
+    Return a list containing a warning that the pattern is invalid.
+
+    describe_pattern() cannot be used here, because we cannot rely on the
+    urlpattern having regex or name attributes.
+    """
+    if isinstance(pattern, str):
+        hint = (
+            "Try removing the string '{}'. The list of urlpatterns should not "
+            "have a prefix string as the first element.".format(pattern)
+        )
+    elif isinstance(pattern, tuple):
+        hint = "Try using path() instead of a tuple."
+    else:
+        hint = None
+
+    return [Error(
+        "Your URL pattern {!r} is invalid. Ensure that urlpatterns is a list "
+        "of path() and/or re_path() instances.".format(pattern),
+        hint=hint,
+        id="urls.E004",
+    )]
+
+
+@register(Tags.urls)
+def check_url_settings(app_configs, **kwargs):
+    errors = []
+    for name in ('STATIC_URL', 'MEDIA_URL'):
+        value = getattr(settings, name)
+        if value and not value.endswith('/'):
+            errors.append(E006(name))
+    return errors
+
+
+def E006(name):
+    return Error(
+        'The {} setting must end with a slash.'.format(name),
+        id='urls.E006',
+    )

flex/lib/python3.6/site-packages/django/core/exceptions.py

@@ -0,0 +1,183 @@
+"""
+Global Django exception and warning classes.
+"""
+
+
+class FieldDoesNotExist(Exception):
+    """The requested model field does not exist"""
+    pass
+
+
+class AppRegistryNotReady(Exception):
+    """The django.apps registry is not populated yet"""
+    pass
+
+
+class ObjectDoesNotExist(Exception):
+    """The requested object does not exist"""
+    silent_variable_failure = True
+
+
+class MultipleObjectsReturned(Exception):
+    """The query returned multiple objects when only one was expected."""
+    pass
+
+
+class SuspiciousOperation(Exception):
+    """The user did something suspicious"""
+
+
+class SuspiciousMultipartForm(SuspiciousOperation):
+    """Suspect MIME request in multipart form data"""
+    pass
+
+
+class SuspiciousFileOperation(SuspiciousOperation):
+    """A Suspicious filesystem operation was attempted"""
+    pass
+
+
+class DisallowedHost(SuspiciousOperation):
+    """HTTP_HOST header contains invalid value"""
+    pass
+
+
+class DisallowedRedirect(SuspiciousOperation):
+    """Redirect to scheme not in allowed list"""
+    pass
+
+
+class TooManyFieldsSent(SuspiciousOperation):
+    """
+    The number of fields in a GET or POST request exceeded
+    settings.DATA_UPLOAD_MAX_NUMBER_FIELDS.
+    """
+    pass
+
+
+class RequestDataTooBig(SuspiciousOperation):
+    """
+    The size of the request (excluding any file uploads) exceeded
+    settings.DATA_UPLOAD_MAX_MEMORY_SIZE.
+    """
+    pass
+
+
+class PermissionDenied(Exception):
+    """The user did not have permission to do that"""
+    pass
+
+
+class ViewDoesNotExist(Exception):
+    """The requested view does not exist"""
+    pass
+
+
+class MiddlewareNotUsed(Exception):
+    """This middleware is not used in this server configuration"""
+    pass
+
+
+class ImproperlyConfigured(Exception):
+    """Django is somehow improperly configured"""
+    pass
+
+
+class FieldError(Exception):
+    """Some kind of problem with a model field."""
+    pass
+
+
+NON_FIELD_ERRORS = '__all__'
+
+
+class ValidationError(Exception):
+    """An error while validating data."""
+    def __init__(self, message, code=None, params=None):
+        """
+        The `message` argument can be a single error, a list of errors, or a
+        dictionary that maps field names to lists of errors. What we define as
+        an "error" can be either a simple string or an instance of
+        ValidationError with its message attribute set, and what we define as
+        list or dictionary can be an actual `list` or `dict` or an instance
+        of ValidationError with its `error_list` or `error_dict` attribute set.
+        """
+        super().__init__(message, code, params)
+
+        if isinstance(message, ValidationError):
+            if hasattr(message, 'error_dict'):
+                message = message.error_dict
+            elif not hasattr(message, 'message'):
+                message = message.error_list
+            else:
+                message, code, params = message.message, message.code, message.params
+
+        if isinstance(message, dict):
+            self.error_dict = {}
+            for field, messages in message.items():
+                if not isinstance(messages, ValidationError):
+                    messages = ValidationError(messages)
+                self.error_dict[field] = messages.error_list
+
+        elif isinstance(message, list):
+            self.error_list = []
+            for message in message:
+                # Normalize plain strings to instances of ValidationError.
+                if not isinstance(message, ValidationError):
+                    message = ValidationError(message)
+                if hasattr(message, 'error_dict'):
+                    self.error_list.extend(sum(message.error_dict.values(), []))
+                else:
+                    self.error_list.extend(message.error_list)
+
+        else:
+            self.message = message
+            self.code = code
+            self.params = params
+            self.error_list = [self]
+
+    @property
+    def message_dict(self):
+        # Trigger an AttributeError if this ValidationError
+        # doesn't have an error_dict.
+        getattr(self, 'error_dict')
+
+        return dict(self)
+
+    @property
+    def messages(self):
+        if hasattr(self, 'error_dict'):
+            return sum(dict(self).values(), [])
+        return list(self)
+
+    def update_error_dict(self, error_dict):
+        if hasattr(self, 'error_dict'):
+            for field, error_list in self.error_dict.items():
+                error_dict.setdefault(field, []).extend(error_list)
+        else:
+            error_dict.setdefault(NON_FIELD_ERRORS, []).extend(self.error_list)
+        return error_dict
+
+    def __iter__(self):
+        if hasattr(self, 'error_dict'):
+            for field, errors in self.error_dict.items():
+                yield field, list(ValidationError(errors))
+        else:
+            for error in self.error_list:
+                message = error.message
+                if error.params:
+                    message %= error.params
+                yield str(message)
+
+    def __str__(self):
+        if hasattr(self, 'error_dict'):
+            return repr(dict(self))
+        return repr(list(self))
+
+    def __repr__(self):
+        return 'ValidationError(%s)' % self
+
+
+class EmptyResultSet(Exception):
+    """A database query predicate is impossible."""
+    pass

flex/lib/python3.6/site-packages/django/core/files/__init__.py

@@ -0,0 +1,3 @@
+from django.core.files.base import File
+
+__all__ = ['File']

flex/lib/python3.6/site-packages/django/core/files/base.py

@@ -0,0 +1,169 @@
+import os
+from io import BytesIO, StringIO, UnsupportedOperation
+
+from django.core.files.utils import FileProxyMixin
+
+
+class File(FileProxyMixin):
+    DEFAULT_CHUNK_SIZE = 64 * 2 ** 10
+
+    def __init__(self, file, name=None):
+        self.file = file
+        if name is None:
+            name = getattr(file, 'name', None)
+        self.name = name
+        if hasattr(file, 'mode'):
+            self.mode = file.mode
+
+    def __str__(self):
+        return self.name or ''
+
+    def __repr__(self):
+        return "<%s: %s>" % (self.__class__.__name__, self or "None")
+
+    def __bool__(self):
+        return bool(self.name)
+
+    def __len__(self):
+        return self.size
+
+    def _get_size_from_underlying_file(self):
+        if hasattr(self.file, 'size'):
+            return self.file.size
+        if hasattr(self.file, 'name'):
+            try:
+                return os.path.getsize(self.file.name)
+            except (OSError, TypeError):
+                pass
+        if hasattr(self.file, 'tell') and hasattr(self.file, 'seek'):
+            pos = self.file.tell()
+            self.file.seek(0, os.SEEK_END)
+            size = self.file.tell()
+            self.file.seek(pos)
+            return size
+        raise AttributeError("Unable to determine the file's size.")
+
+    def _get_size(self):
+        if hasattr(self, '_size'):
+            return self._size
+        self._size = self._get_size_from_underlying_file()
+        return self._size
+
+    def _set_size(self, size):
+        self._size = size
+
+    size = property(_get_size, _set_size)
+
+    def chunks(self, chunk_size=None):
+        """
+        Read the file and yield chunks of ``chunk_size`` bytes (defaults to
+        ``UploadedFile.DEFAULT_CHUNK_SIZE``).
+        """
+        if not chunk_size:
+            chunk_size = self.DEFAULT_CHUNK_SIZE
+
+        try:
+            self.seek(0)
+        except (AttributeError, UnsupportedOperation):
+            pass
+
+        while True:
+            data = self.read(chunk_size)
+            if not data:
+                break
+            yield data
+
+    def multiple_chunks(self, chunk_size=None):
+        """
+        Return ``True`` if you can expect multiple chunks.
+
+        NB: If a particular file representation is in memory, subclasses should
+        always return ``False`` -- there's no good reason to read from memory in
+        chunks.
+        """
+        if not chunk_size:
+            chunk_size = self.DEFAULT_CHUNK_SIZE
+        return self.size > chunk_size
+
+    def __iter__(self):
+        # Iterate over this file-like object by newlines
+        buffer_ = None
+        for chunk in self.chunks():
+            for line in chunk.splitlines(True):
+                if buffer_:
+                    if endswith_cr(buffer_) and not equals_lf(line):
+                        # Line split after a \r newline; yield buffer_.
+                        yield buffer_
+                        # Continue with line.
+                    else:
+                        # Line either split without a newline (line
+                        # continues after buffer_) or with \r\n
+                        # newline (line == b'\n').
+                        line = buffer_ + line
+                    # buffer_ handled, clear it.
+                    buffer_ = None
+
+                # If this is the end of a \n or \r\n line, yield.
+                if endswith_lf(line):
+                    yield line
+                else:
+                    buffer_ = line
+
+        if buffer_ is not None:
+            yield buffer_
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_value, tb):
+        self.close()
+
+    def open(self, mode=None):
+        if not self.closed:
+            self.seek(0)
+        elif self.name and os.path.exists(self.name):
+            self.file = open(self.name, mode or self.mode)
+        else:
+            raise ValueError("The file cannot be reopened.")
+        return self
+
+    def close(self):
+        self.file.close()
+
+
+class ContentFile(File):
+    """
+    A File-like object that take just raw content, rather than an actual file.
+    """
+    def __init__(self, content, name=None):
+        stream_class = StringIO if isinstance(content, str) else BytesIO
+        super().__init__(stream_class(content), name=name)
+        self.size = len(content)
+
+    def __str__(self):
+        return 'Raw content'
+
+    def __bool__(self):
+        return True
+
+    def open(self, mode=None):
+        self.seek(0)
+        return self
+
+    def close(self):
+        pass
+
+
+def endswith_cr(line):
+    """Return True if line (a text or byte string) ends with '\r'."""
+    return line.endswith('\r' if isinstance(line, str) else b'\r')
+
+
+def endswith_lf(line):
+    """Return True if line (a text or byte string) ends with '\n'."""
+    return line.endswith('\n' if isinstance(line, str) else b'\n')
+
+
+def equals_lf(line):
+    """Return True if line (a text or byte string) equals '\n'."""
+    return line == ('\n' if isinstance(line, str) else b'\n')

flex/lib/python3.6/site-packages/django/core/files/images.py

@@ -0,0 +1,80 @@
+"""
+Utility functions for handling images.
+
+Requires Pillow as you might imagine.
+"""
+import struct
+import zlib
+
+from django.core.files import File
+
+
+class ImageFile(File):
+    """
+    A mixin for use alongside django.core.files.base.File, which provides
+    additional features for dealing with images.
+    """
+    @property
+    def width(self):
+        return self._get_image_dimensions()[0]
+
+    @property
+    def height(self):
+        return self._get_image_dimensions()[1]
+
+    def _get_image_dimensions(self):
+        if not hasattr(self, '_dimensions_cache'):
+            close = self.closed
+            self.open()
+            self._dimensions_cache = get_image_dimensions(self, close=close)
+        return self._dimensions_cache
+
+
+def get_image_dimensions(file_or_path, close=False):
+    """
+    Return the (width, height) of an image, given an open file or a path.  Set
+    'close' to True to close the file at the end if it is initially in an open
+    state.
+    """
+    from PIL import ImageFile as PillowImageFile
+
+    p = PillowImageFile.Parser()
+    if hasattr(file_or_path, 'read'):
+        file = file_or_path
+        file_pos = file.tell()
+        file.seek(0)
+    else:
+        file = open(file_or_path, 'rb')
+        close = True
+    try:
+        # Most of the time Pillow only needs a small chunk to parse the image
+        # and get the dimensions, but with some TIFF files Pillow needs to
+        # parse the whole file.
+        chunk_size = 1024
+        while 1:
+            data = file.read(chunk_size)
+            if not data:
+                break
+            try:
+                p.feed(data)
+            except zlib.error as e:
+                # ignore zlib complaining on truncated stream, just feed more
+                # data to parser (ticket #19457).
+                if e.args[0].startswith("Error -5"):
+                    pass
+                else:
+                    raise
+            except struct.error:
+                # Ignore PIL failing on a too short buffer when reads return
+                # less bytes than expected. Skip and feed more data to the
+                # parser (ticket #24544).
+                pass
+            if p.image:
+                return p.image.size
+            chunk_size *= 2
+        return (None, None)
+    finally:
+        if close:
+            file.close()
+        else:
+            file.seek(file_pos)

flex/lib/python3.6/site-packages/django/core/files/locks.py

@@ -0,0 +1,113 @@
+"""
+Portable file locking utilities.
+
+Based partially on an example by Jonathan Feignberg in the Python
+Cookbook [1] (licensed under the Python Software License) and a ctypes port by
+Anatoly Techtonik for Roundup [2] (license [3]).
+
+[1] http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203
+[2] http://sourceforge.net/p/roundup/code/ci/default/tree/roundup/backends/portalocker.py
+[3] http://sourceforge.net/p/roundup/code/ci/default/tree/COPYING.txt
+
+Example Usage::
+
+    >>> from django.core.files import locks
+    >>> with open('./file', 'wb') as f:
+    ...     locks.lock(f, locks.LOCK_EX)
+    ...     f.write('Django')
+"""
+import os
+
+__all__ = ('LOCK_EX', 'LOCK_SH', 'LOCK_NB', 'lock', 'unlock')
+
+
+def _fd(f):
+    """Get a filedescriptor from something which could be a file or an fd."""
+    return f.fileno() if hasattr(f, 'fileno') else f
+
+
+if os.name == 'nt':
+    import msvcrt
+    from ctypes import (sizeof, c_ulong, c_void_p, c_int64,
+                        Structure, Union, POINTER, windll, byref)
+    from ctypes.wintypes import BOOL, DWORD, HANDLE
+
+    LOCK_SH = 0  # the default
+    LOCK_NB = 0x1  # LOCKFILE_FAIL_IMMEDIATELY
+    LOCK_EX = 0x2  # LOCKFILE_EXCLUSIVE_LOCK
+
+    # --- Adapted from the pyserial project ---
+    # detect size of ULONG_PTR
+    if sizeof(c_ulong) != sizeof(c_void_p):
+        ULONG_PTR = c_int64
+    else:
+        ULONG_PTR = c_ulong
+    PVOID = c_void_p
+
+    # --- Union inside Structure by stackoverflow:3480240 ---
+    class _OFFSET(Structure):
+        _fields_ = [
+            ('Offset', DWORD),
+            ('OffsetHigh', DWORD)]
+
+    class _OFFSET_UNION(Union):
+        _anonymous_ = ['_offset']
+        _fields_ = [
+            ('_offset', _OFFSET),
+            ('Pointer', PVOID)]
+
+    class OVERLAPPED(Structure):
+        _anonymous_ = ['_offset_union']
+        _fields_ = [
+            ('Internal', ULONG_PTR),
+            ('InternalHigh', ULONG_PTR),
+            ('_offset_union', _OFFSET_UNION),
+            ('hEvent', HANDLE)]
+
+    LPOVERLAPPED = POINTER(OVERLAPPED)
+
+    # --- Define function prototypes for extra safety ---
+    LockFileEx = windll.kernel32.LockFileEx
+    LockFileEx.restype = BOOL
+    LockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, DWORD, LPOVERLAPPED]
+    UnlockFileEx = windll.kernel32.UnlockFileEx
+    UnlockFileEx.restype = BOOL
+    UnlockFileEx.argtypes = [HANDLE, DWORD, DWORD, DWORD, LPOVERLAPPED]
+
+    def lock(f, flags):
+        hfile = msvcrt.get_osfhandle(_fd(f))
+        overlapped = OVERLAPPED()
+        ret = LockFileEx(hfile, flags, 0, 0, 0xFFFF0000, byref(overlapped))
+        return bool(ret)
+
+    def unlock(f):
+        hfile = msvcrt.get_osfhandle(_fd(f))
+        overlapped = OVERLAPPED()
+        ret = UnlockFileEx(hfile, 0, 0, 0xFFFF0000, byref(overlapped))
+        return bool(ret)
+else:
+    try:
+        import fcntl
+        LOCK_SH = fcntl.LOCK_SH  # shared lock
+        LOCK_NB = fcntl.LOCK_NB  # non-blocking
+        LOCK_EX = fcntl.LOCK_EX
+    except (ImportError, AttributeError):
+        # File locking is not supported.
+        LOCK_EX = LOCK_SH = LOCK_NB = 0
+
+        # Dummy functions that don't do anything.
+        def lock(f, flags):
+            # File is not locked
+            return False
+
+        def unlock(f):
+            # File is unlocked
+            return True
+    else:
+        def lock(f, flags):
+            ret = fcntl.flock(_fd(f), flags)
+            return ret == 0
+
+        def unlock(f):
+            ret = fcntl.flock(_fd(f), fcntl.LOCK_UN)
+            return ret == 0

flex/lib/python3.6/site-packages/django/core/files/move.py

@@ -0,0 +1,87 @@
+"""
+Move a file in the safest way possible::
+
+    >>> from django.core.files.move import file_move_safe
+    >>> file_move_safe("/tmp/old_file", "/tmp/new_file")
+"""
+
+import errno
+import os
+from shutil import copystat
+
+from django.core.files import locks
+
+__all__ = ['file_move_safe']
+
+
+def _samefile(src, dst):
+    # Macintosh, Unix.
+    if hasattr(os.path, 'samefile'):
+        try:
+            return os.path.samefile(src, dst)
+        except OSError:
+            return False
+
+    # All other platforms: check for same pathname.
+    return (os.path.normcase(os.path.abspath(src)) ==
+            os.path.normcase(os.path.abspath(dst)))
+
+
+def file_move_safe(old_file_name, new_file_name, chunk_size=1024 * 64, allow_overwrite=False):
+    """
+    Move a file from one location to another in the safest way possible.
+
+    First, try ``os.rename``, which is simple but will break across filesystems.
+    If that fails, stream manually from one file to another in pure Python.
+
+    If the destination file exists and ``allow_overwrite`` is ``False``, raise
+    ``IOError``.
+    """
+    # There's no reason to move if we don't have to.
+    if _samefile(old_file_name, new_file_name):
+        return
+
+    try:
+        if not allow_overwrite and os.access(new_file_name, os.F_OK):
+            raise IOError("Destination file %s exists and allow_overwrite is False" % new_file_name)
+
+        os.rename(old_file_name, new_file_name)
+        return
+    except OSError:
+        # OSError happens with os.rename() if moving to another filesystem or
+        # when moving opened files on certain operating systems.
+        pass
+
+    # first open the old file, so that it won't go away
+    with open(old_file_name, 'rb') as old_file:
+        # now open the new file, not forgetting allow_overwrite
+        fd = os.open(new_file_name, (os.O_WRONLY | os.O_CREAT | getattr(os, 'O_BINARY', 0) |
+                                     (os.O_EXCL if not allow_overwrite else 0)))
+        try:
+            locks.lock(fd, locks.LOCK_EX)
+            current_chunk = None
+            while current_chunk != b'':
+                current_chunk = old_file.read(chunk_size)
+                os.write(fd, current_chunk)
+        finally:
+            locks.unlock(fd)
+            os.close(fd)
+
+    try:
+        copystat(old_file_name, new_file_name)
+    except PermissionError as e:
+        # Certain filesystems (e.g. CIFS) fail to copy the file's metadata if
+        # the type of the destination filesystem isn't the same as the source
+        # filesystem; ignore that.
+        if e.errno != errno.EPERM:
+            raise
+
+    try:
+        os.remove(old_file_name)
+    except PermissionError as e:
+        # Certain operating systems (Cygwin and Windows)
+        # fail when deleting opened files, ignore it.  (For the
+        # systems where this happens, temporary files will be auto-deleted
+        # on close anyway.)
+        if getattr(e, 'winerror', 0) != 32:
+            raise

flex/lib/python3.6/site-packages/django/core/files/storage.py

@@ -0,0 +1,364 @@
+import os
+from datetime import datetime
+from urllib.parse import urljoin
+
+from django.conf import settings
+from django.core.exceptions import SuspiciousFileOperation
+from django.core.files import File, locks
+from django.core.files.move import file_move_safe
+from django.core.signals import setting_changed
+from django.utils import timezone
+from django.utils._os import safe_join
+from django.utils.crypto import get_random_string
+from django.utils.deconstruct import deconstructible
+from django.utils.encoding import filepath_to_uri
+from django.utils.functional import LazyObject, cached_property
+from django.utils.module_loading import import_string
+from django.utils.text import get_valid_filename
+
+__all__ = ('Storage', 'FileSystemStorage', 'DefaultStorage', 'default_storage')
+
+
+class Storage:
+    """
+    A base storage class, providing some default behaviors that all other
+    storage systems can inherit or override, as necessary.
+    """
+
+    # The following methods represent a public interface to private methods.
+    # These shouldn't be overridden by subclasses unless absolutely necessary.
+
+    def open(self, name, mode='rb'):
+        """Retrieve the specified file from storage."""
+        return self._open(name, mode)
+
+    def save(self, name, content, max_length=None):
+        """
+        Save new content to the file specified by name. The content should be
+        a proper File object or any python file-like object, ready to be read
+        from the beginning.
+        """
+        # Get the proper name for the file, as it will actually be saved.
+        if name is None:
+            name = content.name
+
+        if not hasattr(content, 'chunks'):
+            content = File(content, name)
+
+        name = self.get_available_name(name, max_length=max_length)
+        return self._save(name, content)
+
+    # These methods are part of the public API, with default implementations.
+
+    def get_valid_name(self, name):
+        """
+        Return a filename, based on the provided filename, that's suitable for
+        use in the target storage system.
+        """
+        return get_valid_filename(name)
+
+    def get_available_name(self, name, max_length=None):
+        """
+        Return a filename that's free on the target storage system and
+        available for new content to be written to.
+        """
+        dir_name, file_name = os.path.split(name)
+        file_root, file_ext = os.path.splitext(file_name)
+        # If the filename already exists, add an underscore and a random 7
+        # character alphanumeric string (before the file extension, if one
+        # exists) to the filename until the generated filename doesn't exist.
+        # Truncate original name if required, so the new filename does not
+        # exceed the max_length.
+        while self.exists(name) or (max_length and len(name) > max_length):
+            # file_ext includes the dot.
+            name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
+            if max_length is None:
+                continue
+            # Truncate file_root if max_length exceeded.
+            truncation = len(name) - max_length
+            if truncation > 0:
+                file_root = file_root[:-truncation]
+                # Entire file_root was truncated in attempt to find an available filename.
+                if not file_root:
+                    raise SuspiciousFileOperation(
+                        'Storage can not find an available filename for "%s". '
+                        'Please make sure that the corresponding file field '
+                        'allows sufficient "max_length".' % name
+                    )
+                name = os.path.join(dir_name, "%s_%s%s" % (file_root, get_random_string(7), file_ext))
+        return name
+
+    def generate_filename(self, filename):
+        """
+        Validate the filename by calling get_valid_name() and return a filename
+        to be passed to the save() method.
+        """
+        # `filename` may include a path as returned by FileField.upload_to.
+        dirname, filename = os.path.split(filename)
+        return os.path.normpath(os.path.join(dirname, self.get_valid_name(filename)))
+
+    def path(self, name):
+        """
+        Return a local filesystem path where the file can be retrieved using
+        Python's built-in open() function. Storage systems that can't be
+        accessed using open() should *not* implement this method.
+        """
+        raise NotImplementedError("This backend doesn't support absolute paths.")
+
+    # The following methods form the public API for storage systems, but with
+    # no default implementations. Subclasses must implement *all* of these.
+
+    def delete(self, name):
+        """
+        Delete the specified file from the storage system.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a delete() method')
+
+    def exists(self, name):
+        """
+        Return True if a file referenced by the given name already exists in the
+        storage system, or False if the name is available for a new file.
+        """
+        raise NotImplementedError('subclasses of Storage must provide an exists() method')
+
+    def listdir(self, path):
+        """
+        List the contents of the specified path. Return a 2-tuple of lists:
+        the first item being directories, the second item being files.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a listdir() method')
+
+    def size(self, name):
+        """
+        Return the total size, in bytes, of the file specified by name.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a size() method')
+
+    def url(self, name):
+        """
+        Return an absolute URL where the file's contents can be accessed
+        directly by a Web browser.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a url() method')
+
+    def get_accessed_time(self, name):
+        """
+        Return the last accessed time (as a datetime) of the file specified by
+        name. The datetime will be timezone-aware if USE_TZ=True.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a get_accessed_time() method')
+
+    def get_created_time(self, name):
+        """
+        Return the creation time (as a datetime) of the file specified by name.
+        The datetime will be timezone-aware if USE_TZ=True.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a get_created_time() method')
+
+    def get_modified_time(self, name):
+        """
+        Return the last modified time (as a datetime) of the file specified by
+        name. The datetime will be timezone-aware if USE_TZ=True.
+        """
+        raise NotImplementedError('subclasses of Storage must provide a get_modified_time() method')
+
+
+@deconstructible
+class FileSystemStorage(Storage):
+    """
+    Standard filesystem storage
+    """
+
+    def __init__(self, location=None, base_url=None, file_permissions_mode=None,
+                 directory_permissions_mode=None):
+        self._location = location
+        self._base_url = base_url
+        self._file_permissions_mode = file_permissions_mode
+        self._directory_permissions_mode = directory_permissions_mode
+        setting_changed.connect(self._clear_cached_properties)
+
+    def _clear_cached_properties(self, setting, **kwargs):
+        """Reset setting based property values."""
+        if setting == 'MEDIA_ROOT':
+            self.__dict__.pop('base_location', None)
+            self.__dict__.pop('location', None)
+        elif setting == 'MEDIA_URL':
+            self.__dict__.pop('base_url', None)
+        elif setting == 'FILE_UPLOAD_PERMISSIONS':
+            self.__dict__.pop('file_permissions_mode', None)
+        elif setting == 'FILE_UPLOAD_DIRECTORY_PERMISSIONS':
+            self.__dict__.pop('directory_permissions_mode', None)
+
+    def _value_or_setting(self, value, setting):
+        return setting if value is None else value
+
+    @cached_property
+    def base_location(self):
+        return self._value_or_setting(self._location, settings.MEDIA_ROOT)
+
+    @cached_property
+    def location(self):
+        return os.path.abspath(self.base_location)
+
+    @cached_property
+    def base_url(self):
+        if self._base_url is not None and not self._base_url.endswith('/'):
+            self._base_url += '/'
+        return self._value_or_setting(self._base_url, settings.MEDIA_URL)
+
+    @cached_property
+    def file_permissions_mode(self):
+        return self._value_or_setting(self._file_permissions_mode, settings.FILE_UPLOAD_PERMISSIONS)
+
+    @cached_property
+    def directory_permissions_mode(self):
+        return self._value_or_setting(self._directory_permissions_mode, settings.FILE_UPLOAD_DIRECTORY_PERMISSIONS)
+
+    def _open(self, name, mode='rb'):
+        return File(open(self.path(name), mode))
+
+    def _save(self, name, content):
+        full_path = self.path(name)
+
+        # Create any intermediate directories that do not exist.
+        directory = os.path.dirname(full_path)
+        if not os.path.exists(directory):
+            try:
+                if self.directory_permissions_mode is not None:
+                    # os.makedirs applies the global umask, so we reset it,
+                    # for consistency with file_permissions_mode behavior.
+                    old_umask = os.umask(0)
+                    try:
+                        os.makedirs(directory, self.directory_permissions_mode)
+                    finally:
+                        os.umask(old_umask)
+                else:
+                    os.makedirs(directory)
+            except FileNotFoundError:
+                # There's a race between os.path.exists() and os.makedirs().
+                # If os.makedirs() fails with FileNotFoundError, the directory
+                # was created concurrently.
+                pass
+        if not os.path.isdir(directory):
+            raise IOError("%s exists and is not a directory." % directory)
+
+        # There's a potential race condition between get_available_name and
+        # saving the file; it's possible that two threads might return the
+        # same name, at which point all sorts of fun happens. So we need to
+        # try to create the file, but if it already exists we have to go back
+        # to get_available_name() and try again.
+
+        while True:
+            try:
+                # This file has a file path that we can move.
+                if hasattr(content, 'temporary_file_path'):
+                    file_move_safe(content.temporary_file_path(), full_path)
+
+                # This is a normal uploadedfile that we can stream.
+                else:
+                    # This fun binary flag incantation makes os.open throw an
+                    # OSError if the file already exists before we open it.
+                    flags = (os.O_WRONLY | os.O_CREAT | os.O_EXCL |
+                             getattr(os, 'O_BINARY', 0))
+                    # The current umask value is masked out by os.open!
+                    fd = os.open(full_path, flags, 0o666)
+                    _file = None
+                    try:
+                        locks.lock(fd, locks.LOCK_EX)
+                        for chunk in content.chunks():
+                            if _file is None:
+                                mode = 'wb' if isinstance(chunk, bytes) else 'wt'
+                                _file = os.fdopen(fd, mode)
+                            _file.write(chunk)
+                    finally:
+                        locks.unlock(fd)
+                        if _file is not None:
+                            _file.close()
+                        else:
+                            os.close(fd)
+            except FileExistsError:
+                # A new name is needed if the file exists.
+                name = self.get_available_name(name)
+                full_path = self.path(name)
+            else:
+                # OK, the file save worked. Break out of the loop.
+                break
+
+        if self.file_permissions_mode is not None:
+            os.chmod(full_path, self.file_permissions_mode)
+
+        # Store filenames with forward slashes, even on Windows.
+        return name.replace('\\', '/')
+
+    def delete(self, name):
+        assert name, "The name argument is not allowed to be empty."
+        name = self.path(name)
+        # If the file or directory exists, delete it from the filesystem.
+        try:
+            if os.path.isdir(name):
+                os.rmdir(name)
+            else:
+                os.remove(name)
+        except FileNotFoundError:
+            # FileNotFoundError is raised if the file or directory was removed
+            # concurrently.
+            pass
+
+    def exists(self, name):
+        return os.path.exists(self.path(name))
+
+    def listdir(self, path):
+        path = self.path(path)
+        directories, files = [], []
+        for entry in os.listdir(path):
+            if os.path.isdir(os.path.join(path, entry)):
+                directories.append(entry)
+            else:
+                files.append(entry)
+        return directories, files
+
+    def path(self, name):
+        return safe_join(self.location, name)
+
+    def size(self, name):
+        return os.path.getsize(self.path(name))
+
+    def url(self, name):
+        if self.base_url is None:
+            raise ValueError("This file is not accessible via a URL.")
+        url = filepath_to_uri(name)
+        if url is not None:
+            url = url.lstrip('/')
+        return urljoin(self.base_url, url)
+
+    def _datetime_from_timestamp(self, ts):
+        """
+        If timezone support is enabled, make an aware datetime object in UTC;
+        otherwise make a naive one in the local timezone.
+        """
+        if settings.USE_TZ:
+            # Safe to use .replace() because UTC doesn't have DST
+            return datetime.utcfromtimestamp(ts).replace(tzinfo=timezone.utc)
+        else:
+            return datetime.fromtimestamp(ts)
+
+    def get_accessed_time(self, name):
+        return self._datetime_from_timestamp(os.path.getatime(self.path(name)))
+
+    def get_created_time(self, name):
+        return self._datetime_from_timestamp(os.path.getctime(self.path(name)))
+
+    def get_modified_time(self, name):
+        return self._datetime_from_timestamp(os.path.getmtime(self.path(name)))
+
+
+def get_storage_class(import_path=None):
+    return import_string(import_path or settings.DEFAULT_FILE_STORAGE)
+
+
+class DefaultStorage(LazyObject):
+    def _setup(self):
+        self._wrapped = get_storage_class()()
+
+
+default_storage = DefaultStorage()

flex/lib/python3.6/site-packages/django/core/files/temp.py

@@ -0,0 +1,74 @@
+"""
+The temp module provides a NamedTemporaryFile that can be reopened in the same
+process on any platform. Most platforms use the standard Python
+tempfile.NamedTemporaryFile class, but Windows users are given a custom class.
+
+This is needed because the Python implementation of NamedTemporaryFile uses the
+O_TEMPORARY flag under Windows, which prevents the file from being reopened
+if the same flag is not provided [1][2]. Note that this does not address the
+more general issue of opening a file for writing and reading in multiple
+processes in a manner that works across platforms.
+
+The custom version of NamedTemporaryFile doesn't support the same keyword
+arguments available in tempfile.NamedTemporaryFile.
+
+1: https://mail.python.org/pipermail/python-list/2005-December/336957.html
+2: http://bugs.python.org/issue14243
+"""
+
+import os
+import tempfile
+
+from django.core.files.utils import FileProxyMixin
+
+__all__ = ('NamedTemporaryFile', 'gettempdir',)
+
+
+if os.name == 'nt':
+    class TemporaryFile(FileProxyMixin):
+        """
+        Temporary file object constructor that supports reopening of the
+        temporary file in Windows.
+
+        Unlike tempfile.NamedTemporaryFile from the standard library,
+        __init__() doesn't support the 'delete', 'buffering', 'encoding', or
+        'newline' keyword arguments.
+        """
+        def __init__(self, mode='w+b', bufsize=-1, suffix='', prefix='', dir=None):
+            fd, name = tempfile.mkstemp(suffix=suffix, prefix=prefix, dir=dir)
+            self.name = name
+            self.file = os.fdopen(fd, mode, bufsize)
+            self.close_called = False
+
+        # Because close can be called during shutdown
+        # we need to cache os.unlink and access it
+        # as self.unlink only
+        unlink = os.unlink
+
+        def close(self):
+            if not self.close_called:
+                self.close_called = True
+                try:
+                    self.file.close()
+                except (OSError, IOError):
+                    pass
+                try:
+                    self.unlink(self.name)
+                except OSError:
+                    pass
+
+        def __del__(self):
+            self.close()
+
+        def __enter__(self):
+            self.file.__enter__()
+            return self
+
+        def __exit__(self, exc, value, tb):
+            self.file.__exit__(exc, value, tb)
+
+    NamedTemporaryFile = TemporaryFile
+else:
+    NamedTemporaryFile = tempfile.NamedTemporaryFile
+
+gettempdir = tempfile.gettempdir

flex/lib/python3.6/site-packages/django/core/files/uploadedfile.py

@@ -0,0 +1,118 @@
+"""
+Classes representing uploaded files.
+"""
+
+import os
+from io import BytesIO
+
+from django.conf import settings
+from django.core.files import temp as tempfile
+from django.core.files.base import File
+
+__all__ = ('UploadedFile', 'TemporaryUploadedFile', 'InMemoryUploadedFile',
+           'SimpleUploadedFile')
+
+
+class UploadedFile(File):
+    """
+    An abstract uploaded file (``TemporaryUploadedFile`` and
+    ``InMemoryUploadedFile`` are the built-in concrete subclasses).
+
+    An ``UploadedFile`` object behaves somewhat like a file object and
+    represents some file data that the user submitted with a form.
+    """
+    DEFAULT_CHUNK_SIZE = 64 * 2 ** 10
+
+    def __init__(self, file=None, name=None, content_type=None, size=None, charset=None, content_type_extra=None):
+        super().__init__(file, name)
+        self.size = size
+        self.content_type = content_type
+        self.charset = charset
+        self.content_type_extra = content_type_extra
+
+    def __repr__(self):
+        return "<%s: %s (%s)>" % (self.__class__.__name__, self.name, self.content_type)
+
+    def _get_name(self):
+        return self._name
+
+    def _set_name(self, name):
+        # Sanitize the file name so that it can't be dangerous.
+        if name is not None:
+            # Just use the basename of the file -- anything else is dangerous.
+            name = os.path.basename(name)
+
+            # File names longer than 255 characters can cause problems on older OSes.
+            if len(name) > 255:
+                name, ext = os.path.splitext(name)
+                ext = ext[:255]
+                name = name[:255 - len(ext)] + ext
+
+        self._name = name
+
+    name = property(_get_name, _set_name)
+
+
+class TemporaryUploadedFile(UploadedFile):
+    """
+    A file uploaded to a temporary location (i.e. stream-to-disk).
+    """
+    def __init__(self, name, content_type, size, charset, content_type_extra=None):
+        _, ext = os.path.splitext(name)
+        file = tempfile.NamedTemporaryFile(suffix='.upload' + ext, dir=settings.FILE_UPLOAD_TEMP_DIR)
+        super().__init__(file, name, content_type, size, charset, content_type_extra)
+
+    def temporary_file_path(self):
+        """Return the full path of this file."""
+        return self.file.name
+
+    def close(self):
+        try:
+            return self.file.close()
+        except FileNotFoundError:
+            # The file was moved or deleted before the tempfile could unlink
+            # it. Still sets self.file.close_called and calls
+            # self.file.file.close() before the exception.
+            pass
+
+
+class InMemoryUploadedFile(UploadedFile):
+    """
+    A file uploaded into memory (i.e. stream-to-memory).
+    """
+    def __init__(self, file, field_name, name, content_type, size, charset, content_type_extra=None):
+        super().__init__(file, name, content_type, size, charset, content_type_extra)
+        self.field_name = field_name
+
+    def open(self, mode=None):
+        self.file.seek(0)
+        return self
+
+    def chunks(self, chunk_size=None):
+        self.file.seek(0)
+        yield self.read()
+
+    def multiple_chunks(self, chunk_size=None):
+        # Since it's in memory, we'll never have multiple chunks.
+        return False
+
+
+class SimpleUploadedFile(InMemoryUploadedFile):
+    """
+    A simple representation of a file, which just has content, size, and a name.
+    """
+    def __init__(self, name, content, content_type='text/plain'):
+        content = content or b''
+        super().__init__(BytesIO(content), None, name, content_type, len(content), None, None)
+
+    @classmethod
+    def from_dict(cls, file_dict):
+        """
+        Create a SimpleUploadedFile object from a dictionary with keys:
+           - filename
+           - content-type
+           - content
+        """
+        return cls(file_dict['filename'],
+                   file_dict['content'],
+                   file_dict.get('content-type', 'text/plain'))

flex/lib/python3.6/site-packages/django/core/files/uploadhandler.py

@@ -0,0 +1,208 @@
+"""
+Base file upload handler classes, and the built-in concrete subclasses
+"""
+
+from io import BytesIO
+
+from django.conf import settings
+from django.core.files.uploadedfile import (
+    InMemoryUploadedFile, TemporaryUploadedFile,
+)
+from django.utils.module_loading import import_string
+
+__all__ = [
+    'UploadFileException', 'StopUpload', 'SkipFile', 'FileUploadHandler',
+    'TemporaryFileUploadHandler', 'MemoryFileUploadHandler', 'load_handler',
+    'StopFutureHandlers'
+]
+
+
+class UploadFileException(Exception):
+    """
+    Any error having to do with uploading files.
+    """
+    pass
+
+
+class StopUpload(UploadFileException):
+    """
+    This exception is raised when an upload must abort.
+    """
+    def __init__(self, connection_reset=False):
+        """
+        If ``connection_reset`` is ``True``, Django knows will halt the upload
+        without consuming the rest of the upload. This will cause the browser to
+        show a "connection reset" error.
+        """
+        self.connection_reset = connection_reset
+
+    def __str__(self):
+        if self.connection_reset:
+            return 'StopUpload: Halt current upload.'
+        else:
+            return 'StopUpload: Consume request data, then halt.'
+
+
+class SkipFile(UploadFileException):
+    """
+    This exception is raised by an upload handler that wants to skip a given file.
+    """
+    pass
+
+
+class StopFutureHandlers(UploadFileException):
+    """
+    Upload handers that have handled a file and do not want future handlers to
+    run should raise this exception instead of returning None.
+    """
+    pass
+
+
+class FileUploadHandler:
+    """
+    Base class for streaming upload handlers.
+    """
+    chunk_size = 64 * 2 ** 10  # : The default chunk size is 64 KB.
+
+    def __init__(self, request=None):
+        self.file_name = None
+        self.content_type = None
+        self.content_length = None
+        self.charset = None
+        self.content_type_extra = None
+        self.request = request
+
+    def handle_raw_input(self, input_data, META, content_length, boundary, encoding=None):
+        """
+        Handle the raw input from the client.
+
+        Parameters:
+
+            :input_data:
+                An object that supports reading via .read().
+            :META:
+                ``request.META``.
+            :content_length:
+                The (integer) value of the Content-Length header from the
+                client.
+            :boundary: The boundary from the Content-Type header. Be sure to
+                prepend two '--'.
+        """
+        pass
+
+    def new_file(self, field_name, file_name, content_type, content_length, charset=None, content_type_extra=None):
+        """
+        Signal that a new file has been started.
+
+        Warning: As with any data from the client, you should not trust
+        content_length (and sometimes won't even get it).
+        """
+        self.field_name = field_name
+        self.file_name = file_name
+        self.content_type = content_type
+        self.content_length = content_length
+        self.charset = charset
+        self.content_type_extra = content_type_extra
+
+    def receive_data_chunk(self, raw_data, start):
+        """
+        Receive data from the streamed upload parser. ``start`` is the position
+        in the file of the chunk.
+        """
+        raise NotImplementedError('subclasses of FileUploadHandler must provide a receive_data_chunk() method')
+
+    def file_complete(self, file_size):
+        """
+        Signal that a file has completed. File size corresponds to the actual
+        size accumulated by all the chunks.
+
+        Subclasses should return a valid ``UploadedFile`` object.
+        """
+        raise NotImplementedError('subclasses of FileUploadHandler must provide a file_complete() method')
+
+    def upload_complete(self):
+        """
+        Signal that the upload is complete. Subclasses should perform cleanup
+        that is necessary for this handler.
+        """
+        pass
+
+
+class TemporaryFileUploadHandler(FileUploadHandler):
+    """
+    Upload handler that streams data into a temporary file.
+    """
+    def new_file(self, *args, **kwargs):
+        """
+        Create the file object to append to as data is coming in.
+        """
+        super().new_file(*args, **kwargs)
+        self.file = TemporaryUploadedFile(self.file_name, self.content_type, 0, self.charset, self.content_type_extra)
+
+    def receive_data_chunk(self, raw_data, start):
+        self.file.write(raw_data)
+
+    def file_complete(self, file_size):
+        self.file.seek(0)
+        self.file.size = file_size
+        return self.file
+
+
+class MemoryFileUploadHandler(FileUploadHandler):
+    """
+    File upload handler to stream uploads into memory (used for small files).
+    """
+
+    def handle_raw_input(self, input_data, META, content_length, boundary, encoding=None):
+        """
+        Use the content_length to signal whether or not this handler should be
+        used.
+        """
+        # Check the content-length header to see if we should
+        # If the post is too large, we cannot use the Memory handler.
+        if content_length > settings.FILE_UPLOAD_MAX_MEMORY_SIZE:
+            self.activated = False
+        else:
+            self.activated = True
+
+    def new_file(self, *args, **kwargs):
+        super().new_file(*args, **kwargs)
+        if self.activated:
+            self.file = BytesIO()
+            raise StopFutureHandlers()
+
+    def receive_data_chunk(self, raw_data, start):
+        """Add the data to the BytesIO file."""
+        if self.activated:
+            self.file.write(raw_data)
+        else:
+            return raw_data
+
+    def file_complete(self, file_size):
+        """Return a file object if this handler is activated."""
+        if not self.activated:
+            return
+
+        self.file.seek(0)
+        return InMemoryUploadedFile(
+            file=self.file,
+            field_name=self.field_name,
+            name=self.file_name,
+            content_type=self.content_type,
+            size=file_size,
+            charset=self.charset,
+            content_type_extra=self.content_type_extra
+        )
+
+
+def load_handler(path, *args, **kwargs):
+    """
+    Given a path to a handler, return an instance of that handler.
+
+    E.g.::
+        >>> from django.http import HttpRequest
+        >>> request = HttpRequest()
+        >>> load_handler('django.core.files.uploadhandler.TemporaryFileUploadHandler', request)
+        <TemporaryFileUploadHandler object at 0x...>
+    """
+    return import_string(path)(*args, **kwargs)

flex/lib/python3.6/site-packages/django/core/files/utils.py

@@ -0,0 +1,52 @@
+class FileProxyMixin:
+    """
+    A mixin class used to forward file methods to an underlaying file
+    object.  The internal file object has to be called "file"::
+
+        class FileProxy(FileProxyMixin):
+            def __init__(self, file):
+                self.file = file
+    """
+
+    encoding = property(lambda self: self.file.encoding)
+    fileno = property(lambda self: self.file.fileno)
+    flush = property(lambda self: self.file.flush)
+    isatty = property(lambda self: self.file.isatty)
+    newlines = property(lambda self: self.file.newlines)
+    read = property(lambda self: self.file.read)
+    readinto = property(lambda self: self.file.readinto)
+    readline = property(lambda self: self.file.readline)
+    readlines = property(lambda self: self.file.readlines)
+    seek = property(lambda self: self.file.seek)
+    tell = property(lambda self: self.file.tell)
+    truncate = property(lambda self: self.file.truncate)
+    write = property(lambda self: self.file.write)
+    writelines = property(lambda self: self.file.writelines)
+
+    @property
+    def closed(self):
+        return not self.file or self.file.closed
+
+    def readable(self):
+        if self.closed:
+            return False
+        if hasattr(self.file, 'readable'):
+            return self.file.readable()
+        return True
+
+    def writable(self):
+        if self.closed:
+            return False
+        if hasattr(self.file, 'writable'):
+            return self.file.writable()
+        return 'w' in getattr(self.file, 'mode', '')
+
+    def seekable(self):
+        if self.closed:
+            return False
+        if hasattr(self.file, 'seekable'):
+            return self.file.seekable()
+        return True
+
+    def __iter__(self):
+        return iter(self.file)

flex/lib/python3.6/site-packages/django/core/handlers/base.py

@@ -0,0 +1,171 @@
+import logging
+import types
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured, MiddlewareNotUsed
+from django.db import connections, transaction
+from django.urls import get_resolver, set_urlconf
+from django.utils.module_loading import import_string
+
+from .exception import convert_exception_to_response, get_exception_response
+
+logger = logging.getLogger('django.request')
+
+
+class BaseHandler:
+    _request_middleware = None
+    _view_middleware = None
+    _template_response_middleware = None
+    _response_middleware = None
+    _exception_middleware = None
+    _middleware_chain = None
+
+    def load_middleware(self):
+        """
+        Populate middleware lists from settings.MIDDLEWARE.
+
+        Must be called after the environment is fixed (see __call__ in subclasses).
+        """
+        self._request_middleware = []
+        self._view_middleware = []
+        self._template_response_middleware = []
+        self._response_middleware = []
+        self._exception_middleware = []
+
+        handler = convert_exception_to_response(self._get_response)
+        for middleware_path in reversed(settings.MIDDLEWARE):
+            middleware = import_string(middleware_path)
+            try:
+                mw_instance = middleware(handler)
+            except MiddlewareNotUsed as exc:
+                if settings.DEBUG:
+                    if str(exc):
+                        logger.debug('MiddlewareNotUsed(%r): %s', middleware_path, exc)
+                    else:
+                        logger.debug('MiddlewareNotUsed: %r', middleware_path)
+                continue
+
+            if mw_instance is None:
+                raise ImproperlyConfigured(
+                    'Middleware factory %s returned None.' % middleware_path
+                )
+
+            if hasattr(mw_instance, 'process_view'):
+                self._view_middleware.insert(0, mw_instance.process_view)
+            if hasattr(mw_instance, 'process_template_response'):
+                self._template_response_middleware.append(mw_instance.process_template_response)
+            if hasattr(mw_instance, 'process_exception'):
+                self._exception_middleware.append(mw_instance.process_exception)
+
+            handler = convert_exception_to_response(mw_instance)
+
+        # We only assign to this when initialization is complete as it is used
+        # as a flag for initialization being complete.
+        self._middleware_chain = handler
+
+    def make_view_atomic(self, view):
+        non_atomic_requests = getattr(view, '_non_atomic_requests', set())
+        for db in connections.all():
+            if db.settings_dict['ATOMIC_REQUESTS'] and db.alias not in non_atomic_requests:
+                view = transaction.atomic(using=db.alias)(view)
+        return view
+
+    def get_exception_response(self, request, resolver, status_code, exception):
+        return get_exception_response(request, resolver, status_code, exception, self.__class__)
+
+    def get_response(self, request):
+        """Return an HttpResponse object for the given HttpRequest."""
+        # Setup default url resolver for this thread
+        set_urlconf(settings.ROOT_URLCONF)
+
+        response = self._middleware_chain(request)
+
+        response._closable_objects.append(request)
+
+        # If the exception handler returns a TemplateResponse that has not
+        # been rendered, force it to be rendered.
+        if not getattr(response, 'is_rendered', True) and callable(getattr(response, 'render', None)):
+            response = response.render()
+
+        if response.status_code == 404:
+            logger.warning(
+                'Not Found: %s', request.path,
+                extra={'status_code': 404, 'request': request},
+            )
+
+        return response
+
+    def _get_response(self, request):
+        """
+        Resolve and call the view, then apply view, exception, and
+        template_response middleware. This method is everything that happens
+        inside the request/response middleware.
+        """
+        response = None
+
+        if hasattr(request, 'urlconf'):
+            urlconf = request.urlconf
+            set_urlconf(urlconf)
+            resolver = get_resolver(urlconf)
+        else:
+            resolver = get_resolver()
+
+        resolver_match = resolver.resolve(request.path_info)
+        callback, callback_args, callback_kwargs = resolver_match
+        request.resolver_match = resolver_match
+
+        # Apply view middleware
+        for middleware_method in self._view_middleware:
+            response = middleware_method(request, callback, callback_args, callback_kwargs)
+            if response:
+                break
+
+        if response is None:
+            wrapped_callback = self.make_view_atomic(callback)
+            try:
+                response = wrapped_callback(request, *callback_args, **callback_kwargs)
+            except Exception as e:
+                response = self.process_exception_by_middleware(e, request)
+
+        # Complain if the view returned None (a common error).
+        if response is None:
+            if isinstance(callback, types.FunctionType):    # FBV
+                view_name = callback.__name__
+            else:                                           # CBV
+                view_name = callback.__class__.__name__ + '.__call__'
+
+            raise ValueError(
+                "The view %s.%s didn't return an HttpResponse object. It "
+                "returned None instead." % (callback.__module__, view_name)
+            )
+
+        # If the response supports deferred rendering, apply template
+        # response middleware and then render the response
+        elif hasattr(response, 'render') and callable(response.render):
+            for middleware_method in self._template_response_middleware:
+                response = middleware_method(request, response)
+                # Complain if the template response middleware returned None (a common error).
+                if response is None:
+                    raise ValueError(
+                        "%s.process_template_response didn't return an "
+                        "HttpResponse object. It returned None instead."
+                        % (middleware_method.__self__.__class__.__name__)
+                    )
+
+            try:
+                response = response.render()
+            except Exception as e:
+                response = self.process_exception_by_middleware(e, request)
+
+        return response
+
+    def process_exception_by_middleware(self, exception, request):
+        """
+        Pass the exception to the exception middleware. If no middleware
+        return a response for this exception, raise it.
+        """
+        for middleware_method in self._exception_middleware:
+            response = middleware_method(request, exception)
+            if response:
+                return response
+        raise

flex/lib/python3.6/site-packages/django/core/handlers/exception.py

@@ -0,0 +1,126 @@
+import logging
+import sys
+from functools import wraps
+
+from django.conf import settings
+from django.core import signals
+from django.core.exceptions import (
+    PermissionDenied, RequestDataTooBig, SuspiciousOperation,
+    TooManyFieldsSent,
+)
+from django.http import Http404
+from django.http.multipartparser import MultiPartParserError
+from django.urls import get_resolver, get_urlconf
+from django.views import debug
+
+logger = logging.getLogger('django.request')
+
+
+def convert_exception_to_response(get_response):
+    """
+    Wrap the given get_response callable in exception-to-response conversion.
+
+    All exceptions will be converted. All known 4xx exceptions (Http404,
+    PermissionDenied, MultiPartParserError, SuspiciousOperation) will be
+    converted to the appropriate response, and all other exceptions will be
+    converted to 500 responses.
+
+    This decorator is automatically applied to all middleware to ensure that
+    no middleware leaks an exception and that the next middleware in the stack
+    can rely on getting a response instead of an exception.
+    """
+    @wraps(get_response)
+    def inner(request):
+        try:
+            response = get_response(request)
+        except Exception as exc:
+            response = response_for_exception(request, exc)
+        return response
+    return inner
+
+
+def response_for_exception(request, exc):
+    if isinstance(exc, Http404):
+        if settings.DEBUG:
+            response = debug.technical_404_response(request, exc)
+        else:
+            response = get_exception_response(request, get_resolver(get_urlconf()), 404, exc)
+
+    elif isinstance(exc, PermissionDenied):
+        logger.warning(
+            'Forbidden (Permission denied): %s', request.path,
+            extra={'status_code': 403, 'request': request},
+        )
+        response = get_exception_response(request, get_resolver(get_urlconf()), 403, exc)
+
+    elif isinstance(exc, MultiPartParserError):
+        logger.warning(
+            'Bad request (Unable to parse request body): %s', request.path,
+            extra={'status_code': 400, 'request': request},
+        )
+        response = get_exception_response(request, get_resolver(get_urlconf()), 400, exc)
+
+    elif isinstance(exc, SuspiciousOperation):
+        if isinstance(exc, (RequestDataTooBig, TooManyFieldsSent)):
+            # POST data can't be accessed again, otherwise the original
+            # exception would be raised.
+            request._mark_post_parse_error()
+
+        # The request logger receives events for any problematic request
+        # The security logger receives events for all SuspiciousOperations
+        security_logger = logging.getLogger('django.security.%s' % exc.__class__.__name__)
+        security_logger.error(
+            str(exc),
+            extra={'status_code': 400, 'request': request},
+        )
+        if settings.DEBUG:
+            response = debug.technical_500_response(request, *sys.exc_info(), status_code=400)
+        else:
+            response = get_exception_response(request, get_resolver(get_urlconf()), 400, exc)
+
+    elif isinstance(exc, SystemExit):
+        # Allow sys.exit() to actually exit. See tickets #1023 and #4701
+        raise
+
+    else:
+        signals.got_request_exception.send(sender=None, request=request)
+        response = handle_uncaught_exception(request, get_resolver(get_urlconf()), sys.exc_info())
+
+    # Force a TemplateResponse to be rendered.
+    if not getattr(response, 'is_rendered', True) and callable(getattr(response, 'render', None)):
+        response = response.render()
+
+    return response
+
+
+def get_exception_response(request, resolver, status_code, exception, sender=None):
+    try:
+        callback, param_dict = resolver.resolve_error_handler(status_code)
+        response = callback(request, **dict(param_dict, exception=exception))
+    except Exception:
+        signals.got_request_exception.send(sender=sender, request=request)
+        response = handle_uncaught_exception(request, resolver, sys.exc_info())
+
+    return response
+
+
+def handle_uncaught_exception(request, resolver, exc_info):
+    """
+    Processing for any otherwise uncaught exceptions (those that will
+    generate HTTP 500 responses).
+    """
+    if settings.DEBUG_PROPAGATE_EXCEPTIONS:
+        raise
+
+    logger.error(
+        'Internal Server Error: %s', request.path,
+        exc_info=exc_info,
+        extra={'status_code': 500, 'request': request},
+    )
+
+    if settings.DEBUG:
+        return debug.technical_500_response(request, *exc_info)
+
+    # Return an HttpResponse that displays a friendly error message.
+    callback, param_dict = resolver.resolve_error_handler(500)
+    return callback(request, **param_dict)

flex/lib/python3.6/site-packages/django/core/handlers/wsgi.py

@@ -0,0 +1,220 @@
+import cgi
+import codecs
+import re
+from io import BytesIO
+
+from django.conf import settings
+from django.core import signals
+from django.core.handlers import base
+from django.http import HttpRequest, QueryDict, parse_cookie
+from django.urls import set_script_prefix
+from django.utils.encoding import repercent_broken_unicode
+from django.utils.functional import cached_property
+
+_slashes_re = re.compile(br'/+')
+
+
+class LimitedStream:
+    """Wrap another stream to disallow reading it past a number of bytes."""
+    def __init__(self, stream, limit, buf_size=64 * 1024 * 1024):
+        self.stream = stream
+        self.remaining = limit
+        self.buffer = b''
+        self.buf_size = buf_size
+
+    def _read_limited(self, size=None):
+        if size is None or size > self.remaining:
+            size = self.remaining
+        if size == 0:
+            return b''
+        result = self.stream.read(size)
+        self.remaining -= len(result)
+        return result
+
+    def read(self, size=None):
+        if size is None:
+            result = self.buffer + self._read_limited()
+            self.buffer = b''
+        elif size < len(self.buffer):
+            result = self.buffer[:size]
+            self.buffer = self.buffer[size:]
+        else:  # size >= len(self.buffer)
+            result = self.buffer + self._read_limited(size - len(self.buffer))
+            self.buffer = b''
+        return result
+
+    def readline(self, size=None):
+        while b'\n' not in self.buffer and \
+              (size is None or len(self.buffer) < size):
+            if size:
+                # since size is not None here, len(self.buffer) < size
+                chunk = self._read_limited(size - len(self.buffer))
+            else:
+                chunk = self._read_limited()
+            if not chunk:
+                break
+            self.buffer += chunk
+        sio = BytesIO(self.buffer)
+        if size:
+            line = sio.readline(size)
+        else:
+            line = sio.readline()
+        self.buffer = sio.read()
+        return line
+
+
+class WSGIRequest(HttpRequest):
+    def __init__(self, environ):
+        script_name = get_script_name(environ)
+        path_info = get_path_info(environ)
+        if not path_info:
+            # Sometimes PATH_INFO exists, but is empty (e.g. accessing
+            # the SCRIPT_NAME URL without a trailing slash). We really need to
+            # operate as if they'd requested '/'. Not amazingly nice to force
+            # the path like this, but should be harmless.
+            path_info = '/'
+        self.environ = environ
+        self.path_info = path_info
+        # be careful to only replace the first slash in the path because of
+        # http://test/something and http://test//something being different as
+        # stated in http://www.ietf.org/rfc/rfc2396.txt
+        self.path = '%s/%s' % (script_name.rstrip('/'),
+                               path_info.replace('/', '', 1))
+        self.META = environ
+        self.META['PATH_INFO'] = path_info
+        self.META['SCRIPT_NAME'] = script_name
+        self.method = environ['REQUEST_METHOD'].upper()
+        self.content_type, self.content_params = cgi.parse_header(environ.get('CONTENT_TYPE', ''))
+        if 'charset' in self.content_params:
+            try:
+                codecs.lookup(self.content_params['charset'])
+            except LookupError:
+                pass
+            else:
+                self.encoding = self.content_params['charset']
+        self._post_parse_error = False
+        try:
+            content_length = int(environ.get('CONTENT_LENGTH'))
+        except (ValueError, TypeError):
+            content_length = 0
+        self._stream = LimitedStream(self.environ['wsgi.input'], content_length)
+        self._read_started = False
+        self.resolver_match = None
+
+    def _get_scheme(self):
+        return self.environ.get('wsgi.url_scheme')
+
+    @cached_property
+    def GET(self):
+        # The WSGI spec says 'QUERY_STRING' may be absent.
+        raw_query_string = get_bytes_from_wsgi(self.environ, 'QUERY_STRING', '')
+        return QueryDict(raw_query_string, encoding=self._encoding)
+
+    def _get_post(self):
+        if not hasattr(self, '_post'):
+            self._load_post_and_files()
+        return self._post
+
+    def _set_post(self, post):
+        self._post = post
+
+    @cached_property
+    def COOKIES(self):
+        raw_cookie = get_str_from_wsgi(self.environ, 'HTTP_COOKIE', '')
+        return parse_cookie(raw_cookie)
+
+    @property
+    def FILES(self):
+        if not hasattr(self, '_files'):
+            self._load_post_and_files()
+        return self._files
+
+    POST = property(_get_post, _set_post)
+
+
+class WSGIHandler(base.BaseHandler):
+    request_class = WSGIRequest
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.load_middleware()
+
+    def __call__(self, environ, start_response):
+        set_script_prefix(get_script_name(environ))
+        signals.request_started.send(sender=self.__class__, environ=environ)
+        request = self.request_class(environ)
+        response = self.get_response(request)
+
+        response._handler_class = self.__class__
+
+        status = '%d %s' % (response.status_code, response.reason_phrase)
+        response_headers = list(response.items())
+        for c in response.cookies.values():
+            response_headers.append(('Set-Cookie', c.output(header='')))
+        start_response(status, response_headers)
+        if getattr(response, 'file_to_stream', None) is not None and environ.get('wsgi.file_wrapper'):
+            response = environ['wsgi.file_wrapper'](response.file_to_stream)
+        return response
+
+
+def get_path_info(environ):
+    """Return the HTTP request's PATH_INFO as a string."""
+    path_info = get_bytes_from_wsgi(environ, 'PATH_INFO', '/')
+
+    return repercent_broken_unicode(path_info).decode()
+
+
+def get_script_name(environ):
+    """
+    Return the equivalent of the HTTP request's SCRIPT_NAME environment
+    variable. If Apache mod_rewrite is used, return what would have been
+    the script name prior to any rewriting (so it's the script name as seen
+    from the client's perspective), unless the FORCE_SCRIPT_NAME setting is
+    set (to anything).
+    """
+    if settings.FORCE_SCRIPT_NAME is not None:
+        return settings.FORCE_SCRIPT_NAME
+
+    # If Apache's mod_rewrite had a whack at the URL, Apache set either
+    # SCRIPT_URL or REDIRECT_URL to the full resource URL before applying any
+    # rewrites. Unfortunately not every Web server (lighttpd!) passes this
+    # information through all the time, so FORCE_SCRIPT_NAME, above, is still
+    # needed.
+    script_url = get_bytes_from_wsgi(environ, 'SCRIPT_URL', '')
+    if not script_url:
+        script_url = get_bytes_from_wsgi(environ, 'REDIRECT_URL', '')
+
+    if script_url:
+        if b'//' in script_url:
+            # mod_wsgi squashes multiple successive slashes in PATH_INFO,
+            # do the same with script_url before manipulating paths (#17133).
+            script_url = _slashes_re.sub(b'/', script_url)
+        path_info = get_bytes_from_wsgi(environ, 'PATH_INFO', '')
+        script_name = script_url[:-len(path_info)] if path_info else script_url
+    else:
+        script_name = get_bytes_from_wsgi(environ, 'SCRIPT_NAME', '')
+
+    return script_name.decode()
+
+
+def get_bytes_from_wsgi(environ, key, default):
+    """
+    Get a value from the WSGI environ dictionary as bytes.
+
+    key and default should be strings.
+    """
+    value = environ.get(key, default)
+    # Non-ASCII values in the WSGI environ are arbitrarily decoded with
+    # ISO-8859-1. This is wrong for Django websites where UTF-8 is the default.
+    # Re-encode to recover the original bytestring.
+    return value.encode('iso-8859-1')
+
+
+def get_str_from_wsgi(environ, key, default):
+    """
+    Get a value from the WSGI environ dictionary as str.
+
+    key and default should be str objects.
+    """
+    value = get_bytes_from_wsgi(environ, key, default)
+    return value.decode(errors='replace')

flex/lib/python3.6/site-packages/django/core/mail/__init__.py

@@ -0,0 +1,116 @@
+"""
+Tools for sending email.
+"""
+from django.conf import settings
+# Imported for backwards compatibility and for the sake
+# of a cleaner namespace. These symbols used to be in
+# django/core/mail.py before the introduction of email
+# backends and the subsequent reorganization (See #10355)
+from django.core.mail.message import (
+    DEFAULT_ATTACHMENT_MIME_TYPE, BadHeaderError, EmailMessage,
+    EmailMultiAlternatives, SafeMIMEMultipart, SafeMIMEText,
+    forbid_multi_line_headers, make_msgid,
+)
+from django.core.mail.utils import DNS_NAME, CachedDnsName
+from django.utils.module_loading import import_string
+
+__all__ = [
+    'CachedDnsName', 'DNS_NAME', 'EmailMessage', 'EmailMultiAlternatives',
+    'SafeMIMEText', 'SafeMIMEMultipart', 'DEFAULT_ATTACHMENT_MIME_TYPE',
+    'make_msgid', 'BadHeaderError', 'forbid_multi_line_headers',
+    'get_connection', 'send_mail', 'send_mass_mail', 'mail_admins',
+    'mail_managers',
+]
+
+
+def get_connection(backend=None, fail_silently=False, **kwds):
+    """Load an email backend and return an instance of it.
+
+    If backend is None (default), use settings.EMAIL_BACKEND.
+
+    Both fail_silently and other keyword arguments are used in the
+    constructor of the backend.
+    """
+    klass = import_string(backend or settings.EMAIL_BACKEND)
+    return klass(fail_silently=fail_silently, **kwds)
+
+
+def send_mail(subject, message, from_email, recipient_list,
+              fail_silently=False, auth_user=None, auth_password=None,
+              connection=None, html_message=None):
+    """
+    Easy wrapper for sending a single message to a recipient list. All members
+    of the recipient list will see the other recipients in the 'To' field.
+
+    If auth_user is None, use the EMAIL_HOST_USER setting.
+    If auth_password is None, use the EMAIL_HOST_PASSWORD setting.
+
+    Note: The API for this method is frozen. New code wanting to extend the
+    functionality should use the EmailMessage class directly.
+    """
+    connection = connection or get_connection(
+        username=auth_user,
+        password=auth_password,
+        fail_silently=fail_silently,
+    )
+    mail = EmailMultiAlternatives(subject, message, from_email, recipient_list, connection=connection)
+    if html_message:
+        mail.attach_alternative(html_message, 'text/html')
+
+    return mail.send()
+
+
+def send_mass_mail(datatuple, fail_silently=False, auth_user=None,
+                   auth_password=None, connection=None):
+    """
+    Given a datatuple of (subject, message, from_email, recipient_list), send
+    each message to each recipient list. Return the number of emails sent.
+
+    If from_email is None, use the DEFAULT_FROM_EMAIL setting.
+    If auth_user and auth_password are set, use them to log in.
+    If auth_user is None, use the EMAIL_HOST_USER setting.
+    If auth_password is None, use the EMAIL_HOST_PASSWORD setting.
+
+    Note: The API for this method is frozen. New code wanting to extend the
+    functionality should use the EmailMessage class directly.
+    """
+    connection = connection or get_connection(
+        username=auth_user,
+        password=auth_password,
+        fail_silently=fail_silently,
+    )
+    messages = [
+        EmailMessage(subject, message, sender, recipient, connection=connection)
+        for subject, message, sender, recipient in datatuple
+    ]
+    return connection.send_messages(messages)
+
+
+def mail_admins(subject, message, fail_silently=False, connection=None,
+                html_message=None):
+    """Send a message to the admins, as defined by the ADMINS setting."""
+    if not settings.ADMINS:
+        return
+    mail = EmailMultiAlternatives(
+        '%s%s' % (settings.EMAIL_SUBJECT_PREFIX, subject), message,
+        settings.SERVER_EMAIL, [a[1] for a in settings.ADMINS],
+        connection=connection,
+    )
+    if html_message:
+        mail.attach_alternative(html_message, 'text/html')
+    mail.send(fail_silently=fail_silently)
+
+
+def mail_managers(subject, message, fail_silently=False, connection=None,
+                  html_message=None):
+    """Send a message to the managers, as defined by the MANAGERS setting."""
+    if not settings.MANAGERS:
+        return
+    mail = EmailMultiAlternatives(
+        '%s%s' % (settings.EMAIL_SUBJECT_PREFIX, subject), message,
+        settings.SERVER_EMAIL, [a[1] for a in settings.MANAGERS],
+        connection=connection,
+    )
+    if html_message:
+        mail.attach_alternative(html_message, 'text/html')
+    mail.send(fail_silently=fail_silently)

flex/lib/python3.6/site-packages/django/core/mail/backends/__init__.py

@@ -0,0 +1 @@
+# Mail backends shipped with Django.

flex/lib/python3.6/site-packages/django/core/mail/backends/base.py

@@ -0,0 +1,59 @@
+"""Base email backend class."""
+
+
+class BaseEmailBackend:
+    """
+    Base class for email backend implementations.
+
+    Subclasses must at least overwrite send_messages().
+
+    open() and close() can be called indirectly by using a backend object as a
+    context manager:
+
+       with backend as connection:
+           # do something with connection
+           pass
+    """
+    def __init__(self, fail_silently=False, **kwargs):
+        self.fail_silently = fail_silently
+
+    def open(self):
+        """
+        Open a network connection.
+
+        This method can be overwritten by backend implementations to
+        open a network connection.
+
+        It's up to the backend implementation to track the status of
+        a network connection if it's needed by the backend.
+
+        This method can be called by applications to force a single
+        network connection to be used when sending mails. See the
+        send_messages() method of the SMTP backend for a reference
+        implementation.
+
+        The default implementation does nothing.
+        """
+        pass
+
+    def close(self):
+        """Close a network connection."""
+        pass
+
+    def __enter__(self):
+        try:
+            self.open()
+        except Exception:
+            self.close()
+            raise
+        return self
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.close()
+
+    def send_messages(self, email_messages):
+        """
+        Send one or more EmailMessage objects and return the number of email
+        messages sent.
+        """
+        raise NotImplementedError('subclasses of BaseEmailBackend must override send_messages() method')

flex/lib/python3.6/site-packages/django/core/mail/backends/console.py

@@ -0,0 +1,42 @@
+"""
+Email backend that writes messages to console instead of sending them.
+"""
+import sys
+import threading
+
+from django.core.mail.backends.base import BaseEmailBackend
+
+
+class EmailBackend(BaseEmailBackend):
+    def __init__(self, *args, **kwargs):
+        self.stream = kwargs.pop('stream', sys.stdout)
+        self._lock = threading.RLock()
+        super().__init__(*args, **kwargs)
+
+    def write_message(self, message):
+        msg = message.message()
+        msg_data = msg.as_bytes()
+        charset = msg.get_charset().get_output_charset() if msg.get_charset() else 'utf-8'
+        msg_data = msg_data.decode(charset)
+        self.stream.write('%s\n' % msg_data)
+        self.stream.write('-' * 79)
+        self.stream.write('\n')
+
+    def send_messages(self, email_messages):
+        """Write all messages to the stream in a thread-safe way."""
+        if not email_messages:
+            return
+        msg_count = 0
+        with self._lock:
+            try:
+                stream_created = self.open()
+                for message in email_messages:
+                    self.write_message(message)
+                    self.stream.flush()  # flush after each message
+                    msg_count += 1
+                if stream_created:
+                    self.close()
+            except Exception:
+                if not self.fail_silently:
+                    raise
+        return msg_count

flex/lib/python3.6/site-packages/django/core/mail/backends/dummy.py

@@ -0,0 +1,10 @@
+"""
+Dummy email backend that does nothing.
+"""
+
+from django.core.mail.backends.base import BaseEmailBackend
+
+
+class EmailBackend(BaseEmailBackend):
+    def send_messages(self, email_messages):
+        return len(list(email_messages))

flex/lib/python3.6/site-packages/django/core/mail/backends/filebased.py

@@ -0,0 +1,70 @@
+"""Email backend that writes messages to a file."""
+
+import datetime
+import os
+
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+from django.core.mail.backends.console import (
+    EmailBackend as ConsoleEmailBackend,
+)
+
+
+class EmailBackend(ConsoleEmailBackend):
+    def __init__(self, *args, file_path=None, **kwargs):
+        self._fname = None
+        if file_path is not None:
+            self.file_path = file_path
+        else:
+            self.file_path = getattr(settings, 'EMAIL_FILE_PATH', None)
+        # Make sure self.file_path is a string.
+        if not isinstance(self.file_path, str):
+            raise ImproperlyConfigured('Path for saving emails is invalid: %r' % self.file_path)
+        self.file_path = os.path.abspath(self.file_path)
+        # Make sure that self.file_path is a directory if it exists.
+        if os.path.exists(self.file_path) and not os.path.isdir(self.file_path):
+            raise ImproperlyConfigured(
+                'Path for saving email messages exists, but is not a directory: %s' % self.file_path
+            )
+        # Try to create it, if it not exists.
+        elif not os.path.exists(self.file_path):
+            try:
+                os.makedirs(self.file_path)
+            except OSError as err:
+                raise ImproperlyConfigured(
+                    'Could not create directory for saving email messages: %s (%s)' % (self.file_path, err)
+                )
+        # Make sure that self.file_path is writable.
+        if not os.access(self.file_path, os.W_OK):
+            raise ImproperlyConfigured('Could not write to directory: %s' % self.file_path)
+        # Finally, call super().
+        # Since we're using the console-based backend as a base,
+        # force the stream to be None, so we don't default to stdout
+        kwargs['stream'] = None
+        super().__init__(*args, **kwargs)
+
+    def write_message(self, message):
+        self.stream.write(message.message().as_bytes() + b'\n')
+        self.stream.write(b'-' * 79)
+        self.stream.write(b'\n')
+
+    def _get_filename(self):
+        """Return a unique file name."""
+        if self._fname is None:
+            timestamp = datetime.datetime.now().strftime("%Y%m%d-%H%M%S")
+            fname = "%s-%s.log" % (timestamp, abs(id(self)))
+            self._fname = os.path.join(self.file_path, fname)
+        return self._fname
+
+    def open(self):
+        if self.stream is None:
+            self.stream = open(self._get_filename(), 'ab')
+            return True
+        return False
+
+    def close(self):
+        try:
+            if self.stream is not None:
+                self.stream.close()
+        finally:
+            self.stream = None

flex/lib/python3.6/site-packages/django/core/mail/backends/locmem.py

@@ -0,0 +1,30 @@
+"""
+Backend for test environment.
+"""
+
+from django.core import mail
+from django.core.mail.backends.base import BaseEmailBackend
+
+
+class EmailBackend(BaseEmailBackend):
+    """
+    An email backend for use during test sessions.
+
+    The test connection stores email messages in a dummy outbox,
+    rather than sending them out on the wire.
+
+    The dummy outbox is accessible through the outbox instance attribute.
+    """
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        if not hasattr(mail, 'outbox'):
+            mail.outbox = []
+
+    def send_messages(self, messages):
+        """Redirect messages to the dummy outbox"""
+        msg_count = 0
+        for message in messages:  # .message() triggers header validation
+            message.message()
+            mail.outbox.append(message)
+            msg_count += 1
+        return msg_count

flex/lib/python3.6/site-packages/django/core/mail/backends/smtp.py

@@ -0,0 +1,131 @@
+"""SMTP email backend class."""
+import smtplib
+import socket
+import ssl
+import threading
+
+from django.conf import settings
+from django.core.mail.backends.base import BaseEmailBackend
+from django.core.mail.message import sanitize_address
+from django.core.mail.utils import DNS_NAME
+
+
+class EmailBackend(BaseEmailBackend):
+    """
+    A wrapper that manages the SMTP network connection.
+    """
+    def __init__(self, host=None, port=None, username=None, password=None,
+                 use_tls=None, fail_silently=False, use_ssl=None, timeout=None,
+                 ssl_keyfile=None, ssl_certfile=None,
+                 **kwargs):
+        super().__init__(fail_silently=fail_silently)
+        self.host = host or settings.EMAIL_HOST
+        self.port = port or settings.EMAIL_PORT
+        self.username = settings.EMAIL_HOST_USER if username is None else username
+        self.password = settings.EMAIL_HOST_PASSWORD if password is None else password
+        self.use_tls = settings.EMAIL_USE_TLS if use_tls is None else use_tls
+        self.use_ssl = settings.EMAIL_USE_SSL if use_ssl is None else use_ssl
+        self.timeout = settings.EMAIL_TIMEOUT if timeout is None else timeout
+        self.ssl_keyfile = settings.EMAIL_SSL_KEYFILE if ssl_keyfile is None else ssl_keyfile
+        self.ssl_certfile = settings.EMAIL_SSL_CERTFILE if ssl_certfile is None else ssl_certfile
+        if self.use_ssl and self.use_tls:
+            raise ValueError(
+                "EMAIL_USE_TLS/EMAIL_USE_SSL are mutually exclusive, so only set "
+                "one of those settings to True.")
+        self.connection = None
+        self._lock = threading.RLock()
+
+    @property
+    def connection_class(self):
+        return smtplib.SMTP_SSL if self.use_ssl else smtplib.SMTP
+
+    def open(self):
+        """
+        Ensure an open connection to the email server. Return whether or not a
+        new connection was required (True or False) or None if an exception
+        passed silently.
+        """
+        if self.connection:
+            # Nothing to do if the connection is already open.
+            return False
+
+        # If local_hostname is not specified, socket.getfqdn() gets used.
+        # For performance, we use the cached FQDN for local_hostname.
+        connection_params = {'local_hostname': DNS_NAME.get_fqdn()}
+        if self.timeout is not None:
+            connection_params['timeout'] = self.timeout
+        if self.use_ssl:
+            connection_params.update({
+                'keyfile': self.ssl_keyfile,
+                'certfile': self.ssl_certfile,
+            })
+        try:
+            self.connection = self.connection_class(self.host, self.port, **connection_params)
+
+            # TLS/SSL are mutually exclusive, so only attempt TLS over
+            # non-secure connections.
+            if not self.use_ssl and self.use_tls:
+                self.connection.starttls(keyfile=self.ssl_keyfile, certfile=self.ssl_certfile)
+            if self.username and self.password:
+                self.connection.login(self.username, self.password)
+            return True
+        except (smtplib.SMTPException, socket.error):
+            if not self.fail_silently:
+                raise
+
+    def close(self):
+        """Close the connection to the email server."""
+        if self.connection is None:
+            return
+        try:
+            try:
+                self.connection.quit()
+            except (ssl.SSLError, smtplib.SMTPServerDisconnected):
+                # This happens when calling quit() on a TLS connection
+                # sometimes, or when the connection was already disconnected
+                # by the server.
+                self.connection.close()
+            except smtplib.SMTPException:
+                if self.fail_silently:
+                    return
+                raise
+        finally:
+            self.connection = None
+
+    def send_messages(self, email_messages):
+        """
+        Send one or more EmailMessage objects and return the number of email
+        messages sent.
+        """
+        if not email_messages:
+            return
+        with self._lock:
+            new_conn_created = self.open()
+            if not self.connection or new_conn_created is None:
+                # We failed silently on open().
+                # Trying to send would be pointless.
+                return
+            num_sent = 0
+            for message in email_messages:
+                sent = self._send(message)
+                if sent:
+                    num_sent += 1
+            if new_conn_created:
+                self.close()
+        return num_sent
+
+    def _send(self, email_message):
+        """A helper method that does the actual sending."""
+        if not email_message.recipients():
+            return False
+        encoding = email_message.encoding or settings.DEFAULT_CHARSET
+        from_email = sanitize_address(email_message.from_email, encoding)
+        recipients = [sanitize_address(addr, encoding) for addr in email_message.recipients()]
+        message = email_message.message()
+        try:
+            self.connection.sendmail(from_email, recipients, message.as_bytes(linesep='\r\n'))
+        except smtplib.SMTPException:
+            if not self.fail_silently:
+                raise
+            return False
+        return True

flex/lib/python3.6/site-packages/django/core/mail/message.py

@@ -0,0 +1,451 @@
+import mimetypes
+import os
+from email import (
+    charset as Charset, encoders as Encoders, generator, message_from_string,
+)
+from email.errors import InvalidHeaderDefect, NonASCIILocalPartDefect
+from email.header import Header
+from email.headerregistry import Address
+from email.message import Message
+from email.mime.base import MIMEBase
+from email.mime.message import MIMEMessage
+from email.mime.multipart import MIMEMultipart
+from email.mime.text import MIMEText
+from email.utils import formatdate, getaddresses, make_msgid, parseaddr
+from io import BytesIO, StringIO
+
+from django.conf import settings
+from django.core.mail.utils import DNS_NAME
+from django.utils.encoding import force_text
+
+# Don't BASE64-encode UTF-8 messages so that we avoid unwanted attention from
+# some spam filters.
+utf8_charset = Charset.Charset('utf-8')
+utf8_charset.body_encoding = None  # Python defaults to BASE64
+utf8_charset_qp = Charset.Charset('utf-8')
+utf8_charset_qp.body_encoding = Charset.QP
+
+# Default MIME type to use on attachments (if it is not explicitly given
+# and cannot be guessed).
+DEFAULT_ATTACHMENT_MIME_TYPE = 'application/octet-stream'
+
+RFC5322_EMAIL_LINE_LENGTH_LIMIT = 998
+
+
+class BadHeaderError(ValueError):
+    pass
+
+
+# Header names that contain structured address data (RFC #5322)
+ADDRESS_HEADERS = {
+    'from',
+    'sender',
+    'reply-to',
+    'to',
+    'cc',
+    'bcc',
+    'resent-from',
+    'resent-sender',
+    'resent-to',
+    'resent-cc',
+    'resent-bcc',
+}
+
+
+def forbid_multi_line_headers(name, val, encoding):
+    """Forbid multi-line headers to prevent header injection."""
+    encoding = encoding or settings.DEFAULT_CHARSET
+    val = str(val)  # val may be lazy
+    if '\n' in val or '\r' in val:
+        raise BadHeaderError("Header values can't contain newlines (got %r for header %r)" % (val, name))
+    try:
+        val.encode('ascii')
+    except UnicodeEncodeError:
+        if name.lower() in ADDRESS_HEADERS:
+            val = ', '.join(sanitize_address(addr, encoding) for addr in getaddresses((val,)))
+        else:
+            val = Header(val, encoding).encode()
+    else:
+        if name.lower() == 'subject':
+            val = Header(val).encode()
+    return name, val
+
+
+def split_addr(addr, encoding):
+    """
+    Split the address into local part and domain and encode them.
+
+    When non-ascii characters are present in the local part, it must be
+    MIME-word encoded. The domain name must be idna-encoded if it contains
+    non-ascii characters.
+    """
+    if '@' in addr:
+        localpart, domain = addr.split('@', 1)
+        # Try to get the simplest encoding - ascii if possible so that
+        # [email protected] doesn't become [email protected]. This
+        # makes unit testing a bit easier and more readable.
+        try:
+            localpart.encode('ascii')
+        except UnicodeEncodeError:
+            localpart = Header(localpart, encoding).encode()
+        domain = domain.encode('idna').decode('ascii')
+    else:
+        localpart = Header(addr, encoding).encode()
+        domain = ''
+    return (localpart, domain)
+
+
+def sanitize_address(addr, encoding):
+    """
+    Format a pair of (name, address) or an email address string.
+    """
+    if not isinstance(addr, tuple):
+        addr = parseaddr(addr)
+    nm, addr = addr
+    localpart, domain = None, None
+    nm = Header(nm, encoding).encode()
+    try:
+        addr.encode('ascii')
+    except UnicodeEncodeError:  # IDN or non-ascii in the local part
+        localpart, domain = split_addr(addr, encoding)
+
+    # An `email.headerregistry.Address` object is used since
+    # email.utils.formataddr() naively encodes the name as ascii (see #25986).
+    if localpart and domain:
+        address = Address(nm, username=localpart, domain=domain)
+        return str(address)
+
+    try:
+        address = Address(nm, addr_spec=addr)
+    except (InvalidHeaderDefect, NonASCIILocalPartDefect):
+        localpart, domain = split_addr(addr, encoding)
+        address = Address(nm, username=localpart, domain=domain)
+    return str(address)
+
+
+class MIMEMixin:
+    def as_string(self, unixfrom=False, linesep='\n'):
+        """Return the entire formatted message as a string.
+        Optional `unixfrom' when True, means include the Unix From_ envelope
+        header.
+
+        This overrides the default as_string() implementation to not mangle
+        lines that begin with 'From '. See bug #13433 for details.
+        """
+        fp = StringIO()
+        g = generator.Generator(fp, mangle_from_=False)
+        g.flatten(self, unixfrom=unixfrom, linesep=linesep)
+        return fp.getvalue()
+
+    def as_bytes(self, unixfrom=False, linesep='\n'):
+        """Return the entire formatted message as bytes.
+        Optional `unixfrom' when True, means include the Unix From_ envelope
+        header.
+
+        This overrides the default as_bytes() implementation to not mangle
+        lines that begin with 'From '. See bug #13433 for details.
+        """
+        fp = BytesIO()
+        g = generator.BytesGenerator(fp, mangle_from_=False)
+        g.flatten(self, unixfrom=unixfrom, linesep=linesep)
+        return fp.getvalue()
+
+
+class SafeMIMEMessage(MIMEMixin, MIMEMessage):
+
+    def __setitem__(self, name, val):
+        # message/rfc822 attachments must be ASCII
+        name, val = forbid_multi_line_headers(name, val, 'ascii')
+        MIMEMessage.__setitem__(self, name, val)
+
+
+class SafeMIMEText(MIMEMixin, MIMEText):
+
+    def __init__(self, _text, _subtype='plain', _charset=None):
+        self.encoding = _charset
+        MIMEText.__init__(self, _text, _subtype=_subtype, _charset=_charset)
+
+    def __setitem__(self, name, val):
+        name, val = forbid_multi_line_headers(name, val, self.encoding)
+        MIMEText.__setitem__(self, name, val)
+
+    def set_payload(self, payload, charset=None):
+        if charset == 'utf-8':
+            has_long_lines = any(
+                len(l.encode()) > RFC5322_EMAIL_LINE_LENGTH_LIMIT
+                for l in payload.splitlines()
+            )
+            # Quoted-Printable encoding has the side effect of shortening long
+            # lines, if any (#22561).
+            charset = utf8_charset_qp if has_long_lines else utf8_charset
+        MIMEText.set_payload(self, payload, charset=charset)
+
+
+class SafeMIMEMultipart(MIMEMixin, MIMEMultipart):
+
+    def __init__(self, _subtype='mixed', boundary=None, _subparts=None, encoding=None, **_params):
+        self.encoding = encoding
+        MIMEMultipart.__init__(self, _subtype, boundary, _subparts, **_params)
+
+    def __setitem__(self, name, val):
+        name, val = forbid_multi_line_headers(name, val, self.encoding)
+        MIMEMultipart.__setitem__(self, name, val)
+
+
+class EmailMessage:
+    """A container for email information."""
+    content_subtype = 'plain'
+    mixed_subtype = 'mixed'
+    encoding = None     # None => use settings default
+
+    def __init__(self, subject='', body='', from_email=None, to=None, bcc=None,
+                 connection=None, attachments=None, headers=None, cc=None,
+                 reply_to=None):
+        """
+        Initialize a single email message (which can be sent to multiple
+        recipients).
+        """
+        if to:
+            if isinstance(to, str):
+                raise TypeError('"to" argument must be a list or tuple')
+            self.to = list(to)
+        else:
+            self.to = []
+        if cc:
+            if isinstance(cc, str):
+                raise TypeError('"cc" argument must be a list or tuple')
+            self.cc = list(cc)
+        else:
+            self.cc = []
+        if bcc:
+            if isinstance(bcc, str):
+                raise TypeError('"bcc" argument must be a list or tuple')
+            self.bcc = list(bcc)
+        else:
+            self.bcc = []
+        if reply_to:
+            if isinstance(reply_to, str):
+                raise TypeError('"reply_to" argument must be a list or tuple')
+            self.reply_to = list(reply_to)
+        else:
+            self.reply_to = []
+        self.from_email = from_email or settings.DEFAULT_FROM_EMAIL
+        self.subject = subject
+        self.body = body
+        self.attachments = []
+        if attachments:
+            for attachment in attachments:
+                if isinstance(attachment, MIMEBase):
+                    self.attach(attachment)
+                else:
+                    self.attach(*attachment)
+        self.extra_headers = headers or {}
+        self.connection = connection
+
+    def get_connection(self, fail_silently=False):
+        from django.core.mail import get_connection
+        if not self.connection:
+            self.connection = get_connection(fail_silently=fail_silently)
+        return self.connection
+
+    def message(self):
+        encoding = self.encoding or settings.DEFAULT_CHARSET
+        msg = SafeMIMEText(self.body, self.content_subtype, encoding)
+        msg = self._create_message(msg)
+        msg['Subject'] = self.subject
+        msg['From'] = self.extra_headers.get('From', self.from_email)
+        msg['To'] = self.extra_headers.get('To', ', '.join(map(str, self.to)))
+        if self.cc:
+            msg['Cc'] = ', '.join(str(cc) for cc in self.cc)
+        if self.reply_to:
+            msg['Reply-To'] = self.extra_headers.get('Reply-To', ', '.join(str(r) for r in self.reply_to))
+
+        # Email header names are case-insensitive (RFC 2045), so we have to
+        # accommodate that when doing comparisons.
+        header_names = [key.lower() for key in self.extra_headers]
+        if 'date' not in header_names:
+            # formatdate() uses stdlib methods to format the date, which use
+            # the stdlib/OS concept of a timezone, however, Django sets the
+            # TZ environment variable based on the TIME_ZONE setting which
+            # will get picked up by formatdate().
+            msg['Date'] = formatdate(localtime=settings.EMAIL_USE_LOCALTIME)
+        if 'message-id' not in header_names:
+            # Use cached DNS_NAME for performance
+            msg['Message-ID'] = make_msgid(domain=DNS_NAME)
+        for name, value in self.extra_headers.items():
+            if name.lower() in ('from', 'to'):  # From and To are already handled
+                continue
+            msg[name] = value
+        return msg
+
+    def recipients(self):
+        """
+        Return a list of all recipients of the email (includes direct
+        addressees as well as Cc and Bcc entries).
+        """
+        return [email for email in (self.to + self.cc + self.bcc) if email]
+
+    def send(self, fail_silently=False):
+        """Send the email message."""
+        if not self.recipients():
+            # Don't bother creating the network connection if there's nobody to
+            # send to.
+            return 0
+        return self.get_connection(fail_silently).send_messages([self])
+
+    def attach(self, filename=None, content=None, mimetype=None):
+        """
+        Attach a file with the given filename and content. The filename can
+        be omitted and the mimetype is guessed, if not provided.
+
+        If the first parameter is a MIMEBase subclass, insert it directly
+        into the resulting message attachments.
+
+        For a text/* mimetype (guessed or specified), when a bytes object is
+        specified as content, decode it as UTF-8. If that fails, set the
+        mimetype to DEFAULT_ATTACHMENT_MIME_TYPE and don't decode the content.
+        """
+        if isinstance(filename, MIMEBase):
+            assert content is None
+            assert mimetype is None
+            self.attachments.append(filename)
+        else:
+            assert content is not None
+
+            if not mimetype:
+                mimetype, _ = mimetypes.guess_type(filename)
+                if not mimetype:
+                    mimetype = DEFAULT_ATTACHMENT_MIME_TYPE
+            basetype, subtype = mimetype.split('/', 1)
+
+            if basetype == 'text':
+                if isinstance(content, bytes):
+                    try:
+                        content = content.decode()
+                    except UnicodeDecodeError:
+                        # If mimetype suggests the file is text but it's
+                        # actually binary, read() raises a UnicodeDecodeError.
+                        mimetype = DEFAULT_ATTACHMENT_MIME_TYPE
+
+            self.attachments.append((filename, content, mimetype))
+
+    def attach_file(self, path, mimetype=None):
+        """
+        Attach a file from the filesystem.
+
+        Set the mimetype to DEFAULT_ATTACHMENT_MIME_TYPE if it isn't specified
+        and cannot be guessed.
+
+        For a text/* mimetype (guessed or specified), decode the file's content
+        as UTF-8. If that fails, set the mimetype to
+        DEFAULT_ATTACHMENT_MIME_TYPE and don't decode the content.
+        """
+        filename = os.path.basename(path)
+
+        with open(path, 'rb') as file:
+            content = file.read()
+            self.attach(filename, content, mimetype)
+
+    def _create_message(self, msg):
+        return self._create_attachments(msg)
+
+    def _create_attachments(self, msg):
+        if self.attachments:
+            encoding = self.encoding or settings.DEFAULT_CHARSET
+            body_msg = msg
+            msg = SafeMIMEMultipart(_subtype=self.mixed_subtype, encoding=encoding)
+            if self.body or body_msg.is_multipart():
+                msg.attach(body_msg)
+            for attachment in self.attachments:
+                if isinstance(attachment, MIMEBase):
+                    msg.attach(attachment)
+                else:
+                    msg.attach(self._create_attachment(*attachment))
+        return msg
+
+    def _create_mime_attachment(self, content, mimetype):
+        """
+        Convert the content, mimetype pair into a MIME attachment object.
+
+        If the mimetype is message/rfc822, content may be an
+        email.Message or EmailMessage object, as well as a str.
+        """
+        basetype, subtype = mimetype.split('/', 1)
+        if basetype == 'text':
+            encoding = self.encoding or settings.DEFAULT_CHARSET
+            attachment = SafeMIMEText(content, subtype, encoding)
+        elif basetype == 'message' and subtype == 'rfc822':
+            # Bug #18967: per RFC2046 s5.2.1, message/rfc822 attachments
+            # must not be base64 encoded.
+            if isinstance(content, EmailMessage):
+                # convert content into an email.Message first
+                content = content.message()
+            elif not isinstance(content, Message):
+                # For compatibility with existing code, parse the message
+                # into an email.Message object if it is not one already.
+                content = message_from_string(force_text(content))
+
+            attachment = SafeMIMEMessage(content, subtype)
+        else:
+            # Encode non-text attachments with base64.
+            attachment = MIMEBase(basetype, subtype)
+            attachment.set_payload(content)
+            Encoders.encode_base64(attachment)
+        return attachment
+
+    def _create_attachment(self, filename, content, mimetype=None):
+        """
+        Convert the filename, content, mimetype triple into a MIME attachment
+        object.
+        """
+        attachment = self._create_mime_attachment(content, mimetype)
+        if filename:
+            try:
+                filename.encode('ascii')
+            except UnicodeEncodeError:
+                filename = ('utf-8', '', filename)
+            attachment.add_header('Content-Disposition', 'attachment',
+                                  filename=filename)
+        return attachment
+
+
+class EmailMultiAlternatives(EmailMessage):
+    """
+    A version of EmailMessage that makes it easy to send multipart/alternative
+    messages. For example, including text and HTML versions of the text is
+    made easier.
+    """
+    alternative_subtype = 'alternative'
+
+    def __init__(self, subject='', body='', from_email=None, to=None, bcc=None,
+                 connection=None, attachments=None, headers=None, alternatives=None,
+                 cc=None, reply_to=None):
+        """
+        Initialize a single email message (which can be sent to multiple
+        recipients).
+        """
+        super().__init__(
+            subject, body, from_email, to, bcc, connection, attachments,
+            headers, cc, reply_to,
+        )
+        self.alternatives = alternatives or []
+
+    def attach_alternative(self, content, mimetype):
+        """Attach an alternative content representation."""
+        assert content is not None
+        assert mimetype is not None
+        self.alternatives.append((content, mimetype))
+
+    def _create_message(self, msg):
+        return self._create_attachments(self._create_alternatives(msg))
+
+    def _create_alternatives(self, msg):
+        encoding = self.encoding or settings.DEFAULT_CHARSET
+        if self.alternatives:
+            body_msg = msg
+            msg = SafeMIMEMultipart(_subtype=self.alternative_subtype, encoding=encoding)
+            if self.body:
+                msg.attach(body_msg)
+            for alternative in self.alternatives:
+                msg.attach(self._create_mime_attachment(*alternative))
+        return msg