From 3e5b027a64e9eccc8d2100e717c19f61d3a51d62 Mon Sep 17 00:00:00 2001
From: Amaury Forgeot d'Arc <amauryfa@gmail.com>
Date: Tue, 28 Jul 2009 22:15:30 +0000
Subject: [PATCH] #6511: ZipFile will now raise BadZipfile when opening an
 empty or tiny file, like it does for larger invalid files.

---
 Lib/test/test_zipfile.py | 10 ++++++++++
 Lib/zipfile.py           |  5 ++++-
 Misc/NEWS                |  3 +++
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Lib/test/test_zipfile.py b/Lib/test/test_zipfile.py
index ee1eecb983d..652274f8fe3 100644
--- a/Lib/test/test_zipfile.py
+++ b/Lib/test/test_zipfile.py
@@ -703,6 +703,16 @@ class OtherTests(unittest.TestCase):
         # quickly.
         self.assertRaises(IOError, zipfile.ZipFile, TESTFN)
 
+    def test_empty_file_raises_BadZipFile(self):
+        f = open(TESTFN, 'w')
+        f.close()
+        self.assertRaises(zipfile.BadZipfile, zipfile.ZipFile, TESTFN)
+
+        f = open(TESTFN, 'w')
+        f.write("short file")
+        f.close()
+        self.assertRaises(zipfile.BadZipfile, zipfile.ZipFile, TESTFN)
+
     def test_closed_zip_raises_RuntimeError(self):
         # Verify that testzip() doesn't swallow inappropriate exceptions.
         data = StringIO()
diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 6ee9923e796..2aa4bffc428 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -198,7 +198,10 @@ def _EndRecData(fpin):
     # Check to see if this is ZIP file with no archive comment (the
     # "end of central directory" structure should be the last item in the
     # file if this is the case).
-    fpin.seek(-sizeEndCentDir, 2)
+    try:
+        fpin.seek(-sizeEndCentDir, 2)
+    except IOError:
+        return None
     data = fpin.read()
     if data[0:4] == stringEndArchive and data[-2:] == "\000\000":
         # the signature is correct and there's no comment, unpack structure
diff --git a/Misc/NEWS b/Misc/NEWS
index 6731fb93e16..37ccbeb4060 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -354,6 +354,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #6511: ZipFile now raises BadZipfile (instead of an IOError) when
+  opening an empty or very small file.
+
 - Issue #6553: Fixed a crash in cPickle.load(), when given a file-like object
   containing incomplete data.