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Issue #26293: Fixed writing ZIP files that starts not from the start of the

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file.  Offsets in ZIP file now are relative to the start of the archive in
conforming to the specification.
This commit is contained in:
Serhiy Storchaka 2016-10-07 22:20:50 +03:00
parent cf3806026b
commit 8793b21525
3 changed files with 62 additions and 15 deletions
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30
Lib/zipfile.py
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@ -1029,10 +1029,10 @@ class ZipFile:
# even if no files are added to the archive
self._didModify = True
try:
self.start_dir = self.fp.tell()
self.start_dir = self._start_disk = self.fp.tell()
except (AttributeError, OSError):
self.fp = _Tellable(self.fp)
self.start_dir = 0
self.start_dir = self._start_disk = 0
self._seekable = False
else:
# Some file-like objects can provide tell() but not seek()
@ -1053,7 +1053,7 @@ class ZipFile:
# set the modified flag so central directory gets written
# even if no files are added to the archive
self._didModify = True
self.start_dir = self.fp.tell()
self.start_dir = self._start_disk = self.fp.tell()
else:
raise RuntimeError("Mode must be 'r', 'w', 'x', or 'a'")
except:
@ -1097,17 +1097,18 @@ class ZipFile:
offset_cd = endrec[_ECD_OFFSET] # offset of central directory
self._comment = endrec[_ECD_COMMENT] # archive comment
# "concat" is zero, unless zip was concatenated to another file
concat = endrec[_ECD_LOCATION] - size_cd - offset_cd
# self._start_disk: Position of the start of ZIP archive
# It is zero, unless ZIP was concatenated to another file
self._start_disk = endrec[_ECD_LOCATION] - size_cd - offset_cd
if endrec[_ECD_SIGNATURE] == stringEndArchive64:
# If Zip64 extension structures are present, account for them
concat -= (sizeEndCentDir64 + sizeEndCentDir64Locator)
self._start_disk -= (sizeEndCentDir64 + sizeEndCentDir64Locator)
if self.debug > 2:
inferred = concat + offset_cd
print("given, inferred, offset", offset_cd, inferred, concat)
inferred = self._start_disk + offset_cd
print("given, inferred, offset", offset_cd, inferred, self._start_disk)
# self.start_dir: Position of start of central directory
self.start_dir = offset_cd + concat
self.start_dir = offset_cd + self._start_disk
fp.seek(self.start_dir, 0)
data = fp.read(size_cd)
fp = io.BytesIO(data)
@ -1147,7 +1148,7 @@ class ZipFile:
t>>11, (t>>5)&0x3F, (t&0x1F) * 2 )
x._decodeExtra()
x.header_offset = x.header_offset + concat
x.header_offset = x.header_offset + self._start_disk
self.filelist.append(x)
self.NameToInfo[x.filename] = x
@ -1627,11 +1628,10 @@ class ZipFile:
file_size = zinfo.file_size
compress_size = zinfo.compress_size
if zinfo.header_offset > ZIP64_LIMIT:
extra.append(zinfo.header_offset)
header_offset = zinfo.header_offset - self._start_disk
if header_offset > ZIP64_LIMIT:
extra.append(header_offset)
header_offset = 0xffffffff
else:
header_offset = zinfo.header_offset
extra_data = zinfo.extra
min_version = 0
@ -1678,7 +1678,7 @@ class ZipFile:
# Write end-of-zip-archive record
centDirCount = len(self.filelist)
centDirSize = pos2 - self.start_dir
centDirOffset = self.start_dir
centDirOffset = self.start_dir - self._start_disk
requires_zip64 = None
if centDirCount > ZIP_FILECOUNT_LIMIT:
requires_zip64 = "Files count"