Merged revisions 77472-77473 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r77472 | antoine.pitrou | 2010-01-13 15:32:10 +0100 (mer., 13 janv. 2010) | 5 lines

  Issue #2846: Add support for gzip.GzipFile reading zero-padded files.
  Patch by Brian Curtin.
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  r77473 | antoine.pitrou | 2010-01-13 15:32:51 +0100 (mer., 13 janv. 2010) | 3 lines

  Add ACKS entry for r77472.
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2 files changed, 21 insertions, 0 deletions

diff --git a/Lib/gzip.py b/Lib/gzip.py
index 66fc88d..ef6befc 100644
--- a/Lib/gzip.py
+++ b/Lib/gzip.py
@@ -348,6 +348,15 @@ class GzipFile(io.BufferedIOBase):
         elif isize != (self.size & 0xffffffff):
             raise IOError("Incorrect length of data produced")
 
+        # Gzip files can be padded with zeroes and still have archives.
+        # Consume all zero bytes and set the file position to the first
+        # non-zero byte. See http://www.gzip.org/#faq8
+        c = b"\x00"
+        while c == b"\x00":
+            c = self.fileobj.read(1)
+        if c:
+            self.fileobj.seek(-1, 1)
+
     @property
     def closed(self):
         return self.fileobj is None
diff --git a/Lib/test/test_gzip.py b/Lib/test/test_gzip.py
index 320adfd..429ada0 100644
--- a/Lib/test/test_gzip.py
+++ b/Lib/test/test_gzip.py
@@ -253,6 +253,18 @@ class TestGzip(unittest.TestCase):
         else:
             self.fail("1/0 didn't raise an exception")
 
+    def test_zero_padded_file(self):
+        with gzip.GzipFile(self.filename, "wb") as f:
+            f.write(data1 * 50)
+
+        # Pad the file with zeroes
+        with open(self.filename, "ab") as f:
+            f.write(b"\x00" * 50)
+
+        with gzip.GzipFile(self.filename, "rb") as f:
+            d = f.read()
+            self.assertEqual(d, data1 * 50, "Incorrect data in file")
+
 def test_main(verbose=None):
     support.run_unittest(TestGzip)