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| author | Jokimax <77680901+Jokimax@users.noreply.github.com> | 2023-10-24 21:15:42 (GMT) |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2023-10-24 21:15:42 (GMT) |
| commit | c73b0f35602abf5f283bf64266641f19bc82fce0 (patch) | |
| tree | 6ea01fed896eed84ea5c710604270b682588b8b9 | |
| parent | e5168ff3f8abe651d0a96d9e2d49028183e21b15 (diff) | |
| download | cpython-c73b0f35602abf5f283bf64266641f19bc82fce0.zip cpython-c73b0f35602abf5f283bf64266641f19bc82fce0.tar.gz cpython-c73b0f35602abf5f283bf64266641f19bc82fce0.tar.bz2 | |
gh-102956: Fix returning of empty byte strings after seek in zipfile … (#103565)
gh-102956: Fix returning of empty byte strings after seek in zipfile module. This was a regression in 3.12.0 due to a performance enhancement.
| -rw-r--r-- | Lib/test/test_zipfile/test_core.py | 16 | ||||
| -rw-r--r-- | Lib/zipfile/__init__.py | 10 | ||||
| -rw-r--r-- | Misc/NEWS.d/next/Library/2023-04-15-14-45-21.gh-issue-102956.Z6qeUy.rst | 1 |
3 files changed, 22 insertions, 5 deletions
diff --git a/Lib/test/test_zipfile/test_core.py b/Lib/test/test_zipfile/test_core.py index 519d2ba..fb6b0b3 100644 --- a/Lib/test/test_zipfile/test_core.py +++ b/Lib/test/test_zipfile/test_core.py @@ -2246,6 +2246,22 @@ class OtherTests(unittest.TestCase): fp.seek(0, os.SEEK_SET) self.assertEqual(fp.tell(), 0) + def test_read_after_seek(self): + # Issue 102956: Make sure seek(x, os.SEEK_CUR) doesn't break read() + txt = b"Charge men!" + bloc = txt.find(b"men") + with zipfile.ZipFile(TESTFN, "w") as zipf: + zipf.writestr("foo.txt", txt) + with zipfile.ZipFile(TESTFN, mode="r") as zipf: + with zipf.open("foo.txt", "r") as fp: + fp.seek(bloc, os.SEEK_CUR) + self.assertEqual(fp.read(-1), b'men!') + with zipfile.ZipFile(TESTFN, mode="r") as zipf: + with zipf.open("foo.txt", "r") as fp: + fp.read(6) + fp.seek(1, os.SEEK_CUR) + self.assertEqual(fp.read(-1), b'men!') + @requires_bz2() def test_decompress_without_3rd_party_library(self): data = b'PK\x05\x06\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00' diff --git a/Lib/zipfile/__init__.py b/Lib/zipfile/__init__.py index 995d267..2b28a07 100644 --- a/Lib/zipfile/__init__.py +++ b/Lib/zipfile/__init__.py @@ -1136,8 +1136,12 @@ class ZipExtFile(io.BufferedIOBase): read_offset = new_pos - curr_pos buff_offset = read_offset + self._offset + if buff_offset >= 0 and buff_offset < len(self._readbuffer): + # Just move the _offset index if the new position is in the _readbuffer + self._offset = buff_offset + read_offset = 0 # Fast seek uncompressed unencrypted file - if self._compress_type == ZIP_STORED and self._decrypter is None and read_offset > 0: + elif self._compress_type == ZIP_STORED and self._decrypter is None and read_offset > 0: # disable CRC checking after first seeking - it would be invalid self._expected_crc = None # seek actual file taking already buffered data into account @@ -1148,10 +1152,6 @@ class ZipExtFile(io.BufferedIOBase): # flush read buffer self._readbuffer = b'' self._offset = 0 - elif buff_offset >= 0 and buff_offset < len(self._readbuffer): - # Just move the _offset index if the new position is in the _readbuffer - self._offset = buff_offset - read_offset = 0 elif read_offset < 0: # Position is before the current position. Reset the ZipExtFile self._fileobj.seek(self._orig_compress_start) diff --git a/Misc/NEWS.d/next/Library/2023-04-15-14-45-21.gh-issue-102956.Z6qeUy.rst b/Misc/NEWS.d/next/Library/2023-04-15-14-45-21.gh-issue-102956.Z6qeUy.rst new file mode 100644 index 0000000..1a4bb9b --- /dev/null +++ b/Misc/NEWS.d/next/Library/2023-04-15-14-45-21.gh-issue-102956.Z6qeUy.rst @@ -0,0 +1 @@ +Fix returning of empty byte strings after seek in zipfile module |