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pythongh-88233: zipfile: handle extras after a zip64 extra (pythonGH-…
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…96161)

Previously, any data _after_ the zip64 extra would be removed.

With many new tests.

Fixes python#88233

Automerge-Triggered-By: GH:jaraco
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thatch authored and python-sidebar committed Sep 1, 2024
1 parent 57cde1f commit 12d27d8
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62 changes: 62 additions & 0 deletions Lib/test/test_zipfile/test_core.py
Original file line number Diff line number Diff line change
Expand Up @@ -3010,5 +3010,67 @@ def test_cli_with_metadata_encoding_extract(self):
self.assertIn(name, listing)


class StripExtraTests(unittest.TestCase):
# Note: all of the "z" characters are technically invalid, but up
# to 3 bytes at the end of the extra will be passed through as they
# are too short to encode a valid extra.

ZIP64_EXTRA = 1

def test_no_data(self):
s = struct.Struct("<HH")
a = s.pack(self.ZIP64_EXTRA, 0)
b = s.pack(2, 0)
c = s.pack(3, 0)

self.assertEqual(b'', zipfile._strip_extra(a, (self.ZIP64_EXTRA,)))
self.assertEqual(b, zipfile._strip_extra(b, (self.ZIP64_EXTRA,)))
self.assertEqual(
b+b"z", zipfile._strip_extra(b+b"z", (self.ZIP64_EXTRA,)))

self.assertEqual(b+c, zipfile._strip_extra(a+b+c, (self.ZIP64_EXTRA,)))
self.assertEqual(b+c, zipfile._strip_extra(b+a+c, (self.ZIP64_EXTRA,)))
self.assertEqual(b+c, zipfile._strip_extra(b+c+a, (self.ZIP64_EXTRA,)))

def test_with_data(self):
s = struct.Struct("<HH")
a = s.pack(self.ZIP64_EXTRA, 1) + b"a"
b = s.pack(2, 2) + b"bb"
c = s.pack(3, 3) + b"ccc"

self.assertEqual(b"", zipfile._strip_extra(a, (self.ZIP64_EXTRA,)))
self.assertEqual(b, zipfile._strip_extra(b, (self.ZIP64_EXTRA,)))
self.assertEqual(
b+b"z", zipfile._strip_extra(b+b"z", (self.ZIP64_EXTRA,)))

self.assertEqual(b+c, zipfile._strip_extra(a+b+c, (self.ZIP64_EXTRA,)))
self.assertEqual(b+c, zipfile._strip_extra(b+a+c, (self.ZIP64_EXTRA,)))
self.assertEqual(b+c, zipfile._strip_extra(b+c+a, (self.ZIP64_EXTRA,)))

def test_multiples(self):
s = struct.Struct("<HH")
a = s.pack(self.ZIP64_EXTRA, 1) + b"a"
b = s.pack(2, 2) + b"bb"

self.assertEqual(b"", zipfile._strip_extra(a+a, (self.ZIP64_EXTRA,)))
self.assertEqual(b"", zipfile._strip_extra(a+a+a, (self.ZIP64_EXTRA,)))
self.assertEqual(
b"z", zipfile._strip_extra(a+a+b"z", (self.ZIP64_EXTRA,)))
self.assertEqual(
b+b"z", zipfile._strip_extra(a+a+b+b"z", (self.ZIP64_EXTRA,)))

self.assertEqual(b, zipfile._strip_extra(a+a+b, (self.ZIP64_EXTRA,)))
self.assertEqual(b, zipfile._strip_extra(a+b+a, (self.ZIP64_EXTRA,)))
self.assertEqual(b, zipfile._strip_extra(b+a+a, (self.ZIP64_EXTRA,)))

def test_too_short(self):
self.assertEqual(b"", zipfile._strip_extra(b"", (self.ZIP64_EXTRA,)))
self.assertEqual(b"z", zipfile._strip_extra(b"z", (self.ZIP64_EXTRA,)))
self.assertEqual(
b"zz", zipfile._strip_extra(b"zz", (self.ZIP64_EXTRA,)))
self.assertEqual(
b"zzz", zipfile._strip_extra(b"zzz", (self.ZIP64_EXTRA,)))


if __name__ == "__main__":
unittest.main()
2 changes: 2 additions & 0 deletions Lib/zipfile/__init__.py
Original file line number Diff line number Diff line change
Expand Up @@ -207,6 +207,8 @@ def _strip_extra(extra, xids):
i = j
if not modified:
return extra
if start != len(extra):
buffer.append(extra[start:])
return b''.join(buffer)

def _check_zipfile(fp):
Expand Down
Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Correctly preserve "extra" fields in ``zipfile`` regardless of their
ordering relative to a zip64 "extra."

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