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