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- """
- 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
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