update

Author: lpyu001

Lib/test/test_zipfile/test_core.py

@@ -719,6 +719,42 @@ class ZstdTestsWithSourceFile(AbstractTestsWithSourceFile,
                               unittest.TestCase):
     compression = zipfile.ZIP_ZSTANDARD
 
+    def test_read_multiframe(self):
+        first = b'first frame' * 400
+        second = b'second frame' * 400
+        data = first + second
+
+        class MultiframeCompressor:
+            def compress(self, value):
+                value = bytes(value)
+                return (zipfile.zstd.compress(value[:len(first)]) +
+                        zipfile.zstd.compress(value[len(first):]))
+
+            def flush(self):
+                return b''
+
+        archive = io.BytesIO()
+        with mock.patch.object(zipfile, '_get_compressor',
+                               return_value=MultiframeCompressor()):
+            with zipfile.ZipFile(archive, 'w', self.compression) as zipfp:
+                zipfp.writestr('multiframe', data)
+
+        with zipfile.ZipFile(archive) as zipfp:
+            self.assertEqual(zipfp.read('multiframe'), data)
+
+        with zipfile.ZipFile(archive) as zipfp:
+            with zipfp.open('multiframe') as fp:
+                chunk = fp._read1(1)
+                self.assertLessEqual(len(chunk), fp.MIN_READ_SIZE)
+                self.assertEqual(chunk + fp.read(), data)
+
+        # Exercise a frame boundary between two reads from the archive.
+        with zipfile.ZipFile(archive) as zipfp:
+            with zipfp.open('multiframe') as fp:
+                fp.MIN_READ_SIZE = 1
+                self.assertEqual(b''.join(iter(lambda: fp.read(1), b'')),
+                                 data)
+
 class AbstractTestZip64InSmallFiles:
     # These tests test the ZIP64 functionality without using large files,
     # see test_zipfile64 for proper tests.

Lib/zipfile/__init__.py

@@ -1195,6 +1195,13 @@ def _read1(self, n):
             data = self._decompressor.unconsumed_tail
             if n > len(data):
                 data += self._read2(n - len(data))
+        elif (self._compress_type == ZIP_ZSTANDARD and
+              self._decompressor.eof):
+            # Continue with the next Zstandard frame.
+            data = self._decompressor.unused_data
+            self._decompressor = _get_decompressor(self._compress_type)
+            if not data:
+                data = self._read2(n)
         elif self._compress_type == ZIP_STORED:
             data = self._read2(n)
         else:
@@ -1233,9 +1240,15 @@ def _read1(self, n):
                     remove=(3, 21),
                     stacklevel=4)
                 data = self._decompressor.decompress(data)
-            self._eof = (self._decompressor.eof or
-                         self._compress_left <= 0 and
-                         getattr(self._decompressor, "needs_input", True))
+            if self._compress_type == ZIP_ZSTANDARD:
+                self._eof = (self._compress_left <= 0 and
+                             not self._decompressor.unused_data and
+                             (self._decompressor.eof or
+                              self._decompressor.needs_input))
+            else:
+                self._eof = (self._decompressor.eof or
+                             self._compress_left <= 0 and
+                             getattr(self._decompressor, "needs_input", True))
 
         data = data[:self._left]
         self._left -= len(data)

Misc/NEWS.d/next/Library/2026-07-23-19-51-05.gh-issue-154481.6cFDFx.rst

@@ -0,0 +1,2 @@
+Fix :mod:`zipfile` to correctly read Zstandard-compressed archive members
+that could previously be truncated or incorrectly rejected.