Fixed django#2070: refactored Django's file upload capabilities.

A description of the new features can be found in the new [http://www.djangoproject.com/documentation/upload_handing/ upload handling documentation]; the executive summary is that Django will now happily handle uploads of large files without issues.

This changes the representation of uploaded files from dictionaries to bona fide objects; see BackwardsIncompatibleChanges for details.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@7814 bcc190cf-cafb-0310-a4f2-bffc1f526a37

AUTHORS

@@ -59,7 +59,7 @@ answer newbie questions, and generally made Django that much better:
     Arthur <avandorp@gmail.com>
     av0000@mail.ru
     David Avsajanishvili <avsd05@gmail.com>
-    axiak@mit.edu
+    Mike Axiak <axiak@mit.edu>
     Niran Babalola <niran@niran.org>
     Morten Bagai <m@bagai.com>
     Mikaël Barbero <mikael.barbero nospam at nospam free.fr>
@@ -141,7 +141,9 @@ answer newbie questions, and generally made Django that much better:
     Marc Fargas <telenieko@telenieko.com>
     Szilveszter Farkas <szilveszter.farkas@gmail.com>
     favo@exoweb.net
+    fdr <drfarina@gmail.com>
     Dmitri Fedortchenko <zeraien@gmail.com>
+    Jonathan Feignberg <jdf@pobox.com>
     Liang Feng <hutuworm@gmail.com>
     Bill Fenner <fenner@gmail.com>
     Stefane Fermgier <sf@fermigier.com>

django/conf/global_settings.py

@@ -231,6 +231,21 @@
 # Example: "http://media.lawrence.com"
 MEDIA_URL = ''
 
+# List of upload handler classes to be applied in order.
+FILE_UPLOAD_HANDLERS = (
+    'django.core.files.uploadhandler.MemoryFileUploadHandler',
+    'django.core.files.uploadhandler.TemporaryFileUploadHandler',
+)
+
+# Maximum size, in bytes, of a request before it will be streamed to the
+# file system instead of into memory.
+FILE_UPLOAD_MAX_MEMORY_SIZE = 2621440 # i.e. 2.5 MB
+
+# Directory in which upload streamed files will be temporarily saved. A value of
+# `None` will make Django use the operating system's default temporary directory
+# (i.e. "/tmp" on *nix systems).
+FILE_UPLOAD_TEMP_DIR = None
+
 # Default formatting for date objects. See all available format strings here:
 # http://www.djangoproject.com/documentation/templates/#now
 DATE_FORMAT = 'N j, Y'

django/core/files/locks.py

@@ -0,0 +1,66 @@
+"""
+Portable file locking utilities.
+
+Based partially on example by Jonathan Feignberg <jdf@pobox.com> in the Python
+Cookbook, licensed under the Python Software License.
+
+    http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65203
+
+Example Usage::
+
+    >>> from django.core.files import locks
+    >>> f = open('./file', 'wb')
+    >>> locks.lock(f, locks.LOCK_EX)
+    >>> f.write('Django')
+    >>> f.close()
+"""
+
+__all__ = ('LOCK_EX','LOCK_SH','LOCK_NB','lock','unlock')
+
+system_type = None
+
+try:
+    import win32con
+    import win32file
+    import pywintypes
+    LOCK_EX = win32con.LOCKFILE_EXCLUSIVE_LOCK
+    LOCK_SH = 0
+    LOCK_NB = win32con.LOCKFILE_FAIL_IMMEDIATELY
+    __overlapped = pywintypes.OVERLAPPED()
+    system_type = 'nt'
+except (ImportError, AttributeError):
+    pass
+
+try:
+    import fcntl
+    LOCK_EX = fcntl.LOCK_EX
+    LOCK_SH = fcntl.LOCK_SH
+    LOCK_NB = fcntl.LOCK_NB
+    system_type = 'posix'
+except (ImportError, AttributeError):
+    pass
+
+if system_type == 'nt':
+    def lock(file, flags):
+        hfile = win32file._get_osfhandle(file.fileno())
+        win32file.LockFileEx(hfile, flags, 0, -0x10000, __overlapped)
+
+    def unlock(file):
+        hfile = win32file._get_osfhandle(file.fileno())
+        win32file.UnlockFileEx(hfile, 0, -0x10000, __overlapped)
+elif system_type == 'posix':
+    def lock(file, flags):
+        fcntl.flock(file.fileno(), flags)
+
+    def unlock(file):
+        fcntl.flock(file.fileno(), fcntl.LOCK_UN)
+else:
+    # File locking is not supported.
+    LOCK_EX = LOCK_SH = LOCK_NB = None
+
+    # Dummy functions that don't do anything.
+    def lock(file, flags):
+        pass
+
+    def unlock(file):
+        pass

django/core/files/move.py

@@ -0,0 +1,59 @@
+"""
+Move a file in the safest way possible::
+
+    >>> from django.core.files.move import file_move_save
+    >>> file_move_save("/tmp/old_file", "/tmp/new_file")
+"""
+
+import os
+from django.core.files import locks
+
+__all__ = ['file_move_safe']
+
+try:
+    import shutil
+    file_move = shutil.move
+except ImportError:
+    file_move = os.rename
+
+def file_move_safe(old_file_name, new_file_name, chunk_size = 1024*64, allow_overwrite=False):
+    """
+    Moves a file from one location to another in the safest way possible.
+
+    First, try using ``shutils.move``, which is OS-dependent but doesn't break
+    if moving across filesystems. Then, try ``os.rename``, which will break
+    across filesystems. Finally, streams manually from one file to another in
+    pure Python.
+
+    If the destination file exists and ``allow_overwrite`` is ``False``, this
+    function will throw an ``IOError``.
+    """
+
+    # There's no reason to move if we don't have to.
+    if old_file_name == new_file_name:
+        return
+
+    if not allow_overwrite and os.path.exists(new_file_name):
+        raise IOError("Cannot overwrite existing file '%s'." % new_file_name)
+
+    try:
+        file_move(old_file_name, new_file_name)
+        return
+    except OSError:
+        # This will happen with os.rename if moving to another filesystem
+        pass
+
+    # If the built-in didn't work, do it the hard way.
+    new_file = open(new_file_name, 'wb')
+    locks.lock(new_file, locks.LOCK_EX)
+    old_file = open(old_file_name, 'rb')
+    current_chunk = None
+
+    while current_chunk != '':
+        current_chunk = old_file.read(chunk_size)
+        new_file.write(current_chunk)
+
+    new_file.close()
+    old_file.close()
+
+    os.remove(old_file_name)

django/core/files/uploadedfile.py

@@ -0,0 +1,190 @@
+"""
+Classes representing uploaded files.
+"""
+
+import os
+try:
+    from cStringIO import StringIO
+except ImportError:
+    from StringIO import StringIO
+
+__all__ = ('UploadedFile', 'TemporaryUploadedFile', 'InMemoryUploadedFile')
+
+class UploadedFile(object):
+    """
+    A abstract uploadded 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_name=None, content_type=None, file_size=None, charset=None):
+        self.file_name = file_name
+        self.file_size = file_size
+        self.content_type = content_type
+        self.charset = charset
+
+    def __repr__(self):
+        return "<%s: %s (%s)>" % (self.__class__.__name__, self.file_name, self.content_type)
+
+    def _set_file_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)
+                name = name[:255 - len(ext)] + ext
+
+        self._file_name = name
+
+    def _get_file_name(self):
+        return self._file_name
+
+    file_name = property(_get_file_name, _set_file_name)
+
+    def chunk(self, chunk_size=None):
+        """
+        Read the file and yield chucks of ``chunk_size`` bytes (defaults to
+        ``UploadedFile.DEFAULT_CHUNK_SIZE``).
+        """
+        if not chunk_size:
+            chunk_size = UploadedFile.DEFAULT_CHUNK_SIZE
+
+        if hasattr(self, 'seek'):
+            self.seek(0)
+        # Assume the pointer is at zero...
+        counter = self.file_size
+
+        while counter > 0:
+            yield self.read(chunk_size)
+            counter -= chunk_size
+
+    def multiple_chunks(self, chunk_size=None):
+        """
+        Returns ``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 = UploadedFile.DEFAULT_CHUNK_SIZE
+        return self.file_size < chunk_size
+
+    # Abstract methods; subclasses *must* default read() and probably should
+    # define open/close.
+    def read(self, num_bytes=None):
+        raise NotImplementedError()
+
+    def open(self):
+        pass
+
+    def close(self):
+        pass
+
+    # Backwards-compatible support for uploaded-files-as-dictionaries.
+    def __getitem__(self, key):
+        import warnings
+        warnings.warn(
+            message = "The dictionary access of uploaded file objects is deprecated. Use the new object interface instead.",
+            category = DeprecationWarning,
+            stacklevel = 2
+        )
+        backwards_translate = {
+            'filename': 'file_name',
+            'content-type': 'content_type',
+            }
+
+        if key == 'content':
+            return self.read()
+        elif key == 'filename':
+            return self.file_name
+        elif key == 'content-type':
+            return self.content_type
+        else:
+            return getattr(self, key)
+
+class TemporaryUploadedFile(UploadedFile):
+    """
+    A file uploaded to a temporary location (i.e. stream-to-disk).
+    """
+
+    def __init__(self, file, file_name, content_type, file_size, charset):
+        super(TemporaryUploadedFile, self).__init__(file_name, content_type, file_size, charset)
+        self.file = file
+        self.path = file.name
+        self.file.seek(0)
+
+    def temporary_file_path(self):
+        """
+        Returns the full path of this file.
+        """
+        return self.path
+
+    def read(self, *args, **kwargs):
+        return self.file.read(*args, **kwargs)
+
+    def open(self):
+        self.seek(0)
+
+    def seek(self, *args, **kwargs):
+        self.file.seek(*args, **kwargs)
+
+class InMemoryUploadedFile(UploadedFile):
+    """
+    A file uploaded into memory (i.e. stream-to-memory).
+    """
+    def __init__(self, file, field_name, file_name, content_type, charset, file_size):
+        super(InMemoryUploadedFile, self).__init__(file_name, content_type, charset, file_size)
+        self.file = file
+        self.field_name = field_name
+        self.file.seek(0)
+
+    def seek(self, *args, **kwargs):
+        self.file.seek(*args, **kwargs)
+
+    def open(self):
+        self.seek(0)
+
+    def read(self, *args, **kwargs):
+        return self.file.read(*args, **kwargs)
+
+    def chunk(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'):
+        self.file = StringIO(content or '')
+        self.file_name = name
+        self.field_name = None
+        self.file_size = len(content or '')
+        self.content_type = content_type
+        self.charset = None
+        self.file.seek(0)
+
+    def from_dict(cls, file_dict):
+        """
+        Creates a SimpleUploadedFile object from
+        a dictionary object with the following keys:
+           - filename
+           - content-type
+           - content
+        """
+        return cls(file_dict['filename'],
+                   file_dict['content'],
+                   file_dict.get('content-type', 'text/plain'))
+
+    from_dict = classmethod(from_dict)