Issue #9837: The read() method of ZipExtFile objects (as returned by
ZipFile.open()) could return more bytes than requested.
diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index 82b4061..380e63b 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -939,6 +939,26 @@
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))
+ with zipfile.ZipFile(io.BytesIO(), "w", compression) as zipf:
+ zipf.writestr('foo', junk)
+ with zipf.open('foo', 'r') as fp:
+ buf = fp.read(test_size)
+ self.assertEqual(len(buf), test_size)
+
+ def test_read_return_size_stored(self):
+ self.check_read_return_size(zipfile.ZIP_STORED)
+
+ @skipUnless(zlib, "requires zlib")
+ def test_read_return_size_deflated(self):
+ self.check_read_return_size(zipfile.ZIP_DEFLATED)
+
def tearDown(self):
unlink(TESTFN)
unlink(TESTFN2)
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index c47c3cc..bcdb2b8 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -564,17 +564,20 @@
"""Read and return up to n bytes.
If the argument is omitted, None, or negative, data is read and returned until EOF is reached..
"""
-
buf = b''
- while n < 0 or n is None or n > len(buf):
- data = self.read1(n)
+ if n is None:
+ n = -1
+ while True:
+ if n < 0:
+ data = self.read1(n)
+ elif n > len(buf):
+ data = self.read1(n - len(buf))
+ else:
+ return buf
if len(data) == 0:
return buf
-
buf += data
- return buf
-
def _update_crc(self, newdata, eof):
# Update the CRC using the given data.
if self._expected_crc is None: