Fixing compatibility with the truncated images tests

ThoughtSynth · Apr 4, 2016 · 90378c8 · 90378c8
1 parent 77da73c
commit 90378c8
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Showing 2 changed files with 17 additions and 15 deletions.
diff --git a/PIL/PngImagePlugin.py b/PIL/PngImagePlugin.py
@@ -108,18 +108,16 @@ def __init__(self, fp):
     def read(self):
         "Fetch a new chunk. Returns header information."
         cid = None
-        try:
-            if self.queue:
-                cid, pos, length = self.queue[-1]
-                del self.queue[-1]
-                self.fp.seek(pos)
-            else:
-                s = self.fp.read(8)
-                cid = s[4:]
-                pos = self.fp.tell()
-                length = i32(s)
-        except struct.error:
-            SyntaxError("truncated PNG file (chunk %s)" % repr(cid))
+
+        if self.queue:
+            cid, pos, length = self.queue[-1]
+            del self.queue[-1]
+            self.fp.seek(pos)
+        else:
+            s = self.fp.read(8)
+            cid = s[4:]
+            pos = self.fp.tell()
+            length = i32(s)
 
         if not is_cid(cid):
             raise SyntaxError("broken PNG file (chunk %s)" % repr(cid))
@@ -165,7 +163,11 @@ def verify(self, endchunk=b"IEND"):
         cids = []
 
         while True:
-            cid, pos, length = self.read()
+            try:
+                cid, pos, length = self.read()
+            except struct.error:
+                raise IOError("truncated PNG file")
+
             if cid == endchunk:
                 break
             self.crc(cid, ImageFile._safe_read(self.fp, length))

diff --git a/Tests/test_file_png.py b/Tests/test_file_png.py
@@ -256,7 +256,7 @@ def test_load_verify(self):
     def test_verify_struct_error(self):
         # Check open/load/verify exception (#1755)
 
-        # offsets to test, -10: breaks in i32() in read.
+        # offsets to test, -10: breaks in i32() in read. (IOError)
         #                  -13: breaks in crc, txt chunk.
         #                  -14: malformed chunk
 
@@ -266,7 +266,7 @@ def test_verify_struct_error(self):
 
             im = Image.open(BytesIO(test_file))
             self.assertTrue(im.fp is not None)
-            self.assertRaises(SyntaxError, im.verify)
+            self.assertRaises((IOError, SyntaxError), im.verify)
 
 
     def test_roundtrip_dpi(self):