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warsaw merged 2 commits into from
Sep 25, 2018
Merged

bpo-5950: Support reading zips with comments in zipimport #9548

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bpo-5950: Support reading zips with comments in zipimport
ZackerySpytz Sep 24, 2018
09dbd17
Address comments.
ZackerySpytz Sep 25, 2018
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3 changes: 2 additions & 1 deletion Doc/library/zipimport.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,8 @@ Any files may be present in the ZIP archive, but only files :file:`.py` and
corresponding :file:`.pyc` file, meaning that if a ZIP archive
doesn't contain :file:`.pyc` files, importing may be rather slow.

ZIP archives with an archive comment are currently not supported.
.. versionchanged:: 3.8
Previously, ZIP archives with an archive comment were not supported.

.. seealso::

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15 changes: 15 additions & 0 deletions Lib/test/test_zipimport.py
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Expand Up @@ -116,6 +116,9 @@ def makeZip(self, files, zipName=TEMP_ZIP, **kw):
zinfo = ZipInfo(name, time.localtime(mtime))
zinfo.compress_type = self.compression
z.writestr(zinfo, data)
comment = kw.get("comment", None)
if comment is not None:
z.comment = comment

stuff = kw.get("stuff", None)
if stuff is not None:
Expand Down Expand Up @@ -665,6 +668,18 @@ def testBytesPath(self):
with self.assertRaises(TypeError):
zipimport.zipimporter(memoryview(os.fsencode(filename)))

def testComment(self):
files = {TESTMOD + ".py": (NOW, test_src)}
self.doTest(".py", files, TESTMOD, comment=b"comment")
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def testBeginningCruftAndComment(self):
files = {TESTMOD + ".py": (NOW, test_src)}
self.doTest(".py", files, TESTMOD, stuff=b"cruft" * 64, comment=b"hi")

def testLargestPossibleComment(self):
files = {TESTMOD + ".py": (NOW, test_src)}
self.doTest(".py", files, TESTMOD, comment=b"c" * ((1 << 16) - 1))


@support.requires_zlib
class CompressedZipImportTestCase(UncompressedZipImportTestCase):
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36 changes: 31 additions & 5 deletions Lib/zipimport.py
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Expand Up @@ -38,6 +38,9 @@ class ZipImportError(ImportError):

_module_type = type(sys)

END_CENTRAL_DIR_SIZE = 22
STRING_END_ARCHIVE = b'PK\x05\x06'
MAX_COMMENT_LEN = (1 << 16) - 1

class zipimporter:
"""zipimporter(archivepath) -> zipimporter object
Expand Down Expand Up @@ -354,16 +357,39 @@ def _read_directory(archive):

with fp:
try:
fp.seek(-22, 2)
fp.seek(-END_CENTRAL_DIR_SIZE, 2)
header_position = fp.tell()
buffer = fp.read(22)
buffer = fp.read(END_CENTRAL_DIR_SIZE)
except OSError:
raise ZipImportError(f"can't read Zip file: {archive!r}", path=archive)
if len(buffer) != 22:
if len(buffer) != END_CENTRAL_DIR_SIZE:
raise ZipImportError(f"can't read Zip file: {archive!r}", path=archive)
if buffer[:4] != b'PK\x05\x06':
if buffer[:4] != STRING_END_ARCHIVE:
# Bad: End of Central Dir signature
raise ZipImportError(f'not a Zip file: {archive!r}', path=archive)
# Check if there's a comment.
try:
fp.seek(0, 2)
file_size = fp.tell()
except OSError:
raise ZipImportError(f"can't read Zip file: {archive!r}",
path=archive)
max_comment_start = max(file_size - MAX_COMMENT_LEN -
END_CENTRAL_DIR_SIZE, 0)
try:
fp.seek(max_comment_start)
data = fp.read()
except OSError:
raise ZipImportError(f"can't read Zip file: {archive!r}",
path=archive)
pos = data.rfind(STRING_END_ARCHIVE)
if pos < 0:
raise ZipImportError(f'not a Zip file: {archive!r}',
path=archive)
buffer = data[pos:pos+END_CENTRAL_DIR_SIZE]
if len(buffer) != END_CENTRAL_DIR_SIZE:
raise ZipImportError(f"corrupt Zip file: {archive!r}",
path=archive)
header_position = file_size - len(data) + pos

header_size = _unpack_uint32(buffer[12:16])
header_offset = _unpack_uint32(buffer[16:20])
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2018-09-24-14-21-58.bpo-5950.xH0ekQ.rst
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@@ -0,0 +1 @@
Support reading zip files with archive comments in :mod:`zipimport`.
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