Merged revisions 84737 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/branches/py3k

Only the tests are merged, 3.1 doesn't exhibit the issue.

........
  r84737 | antoine.pitrou | 2010-09-12 16:51:20 +0200 (dim., 12 sept. 2010) | 4 lines

  Issue #9837: The read() method of ZipExtFile objects (as returned by
  ZipFile.open()) could return more bytes than requested.
........

Lib/test/test_zipfile.py

@@ -879,6 +879,29 @@ class OtherTests(unittest.TestCase):
         def test_read_with_bad_crc_deflated(self):
             self.check_read_with_bad_crc(zipfile.ZIP_DEFLATED)
 
+    def check_read_return_size(self, compression):
+        # Issue #9837: ZipExtFile.read() shouldn't return more bytes
+        # than requested.
+        for test_size in (1, 4095, 4096, 4097, 16384):
+            file_size = test_size + 1
+            junk = b''.join(struct.pack('B', randint(0, 255))
+                            for x in range(file_size))
+            zipf = zipfile.ZipFile(io.BytesIO(), "w", compression)
+            try:
+                zipf.writestr('foo', junk)
+                fp = zipf.open('foo', 'r')
+                buf = fp.read(test_size)
+                self.assertEqual(len(buf), test_size)
+            finally:
+                zipf.close()
+
+    def test_read_return_size_stored(self):
+        self.check_read_return_size(zipfile.ZIP_STORED)
+
+    if zlib:
+        def test_read_return_size_deflated(self):
+            self.check_read_return_size(zipfile.ZIP_DEFLATED)
+
     def tearDown(self):
         support.unlink(TESTFN)
         support.unlink(TESTFN2)