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Merge pull request #4273 from ThomasWaldmann/fix-empty-segment-crash

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recover_segment: handle too small segment files correctly, see #4272
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TW 2019-01-29 19:18:21 +01:00 committed by GitHub
commit e35091596d
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1 changed files with 7 additions and 1 deletions
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8
src/borg/repository.py
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@ -1360,8 +1360,14 @@ class LoggedIO:
del self.fds[segment]
backup_filename = filename + '.beforerecover'
os.rename(filename, backup_filename)
if os.path.getsize(backup_filename) < MAGIC_LEN + self.header_fmt.size:
# this is either a zero-byte file (which would crash mmap() below) or otherwise
# just too small to be a valid non-empty segment file, so do a shortcut here:
with open(filename, 'wb') as fd:
fd.write(MAGIC)
return
with open(backup_filename, 'rb') as backup_fd:
# note: file must not be 0 size (windows can't create 0 size mapping)
# note: file must not be 0 size or mmap() will crash.
with mmap.mmap(backup_fd.fileno(), 0, access=mmap.ACCESS_READ) as mm:
# memoryview context manager is problematic, see https://bugs.python.org/issue35686
data = memoryview(mm)