86 lines
2.8 KiB
Python
86 lines
2.8 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 django.core.files import locks
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try:
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from shutil import copystat
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except ImportError:
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import stat
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def copystat(src, dst):
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"""Copy all stat info (mode bits, atime and mtime) from src to dst"""
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st = os.stat(src)
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mode = stat.S_IMODE(st.st_mode)
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if hasattr(os, 'utime'):
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os.utime(dst, (st.st_atime, st.st_mtime))
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if hasattr(os, 'chmod'):
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os.chmod(dst, mode)
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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)) ==
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os.path.normcase(os.path.abspath(dst)))
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def file_move_safe(old_file_name, new_file_name, chunk_size = 1024*64, allow_overwrite=False):
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"""
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Moves a file from one location to another in the safest way possible.
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First, tries ``os.rename``, which is simple but will break across filesystems.
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If that fails, streams manually from one file to another in pure Python.
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If the destination file exists and ``allow_overwrite`` is ``False``, this
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function will throw an ``IOError``.
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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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os.rename(old_file_name, new_file_name)
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return
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except OSError:
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# This will happen with os.rename if moving to another filesystem
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# or 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(new_file_name, os.O_WRONLY | os.O_CREAT | getattr(os, 'O_BINARY', 0) |
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(not allow_overwrite and os.O_EXCL or 0))
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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 != '':
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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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copystat(old_file_name, new_file_name)
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try:
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os.remove(old_file_name)
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except OSError 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 and getattr(e, 'errno', 0) != 13:
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raise
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