Add better bounds checking in PngImage::printStructure(). (#862)

tests/bugfixes/github/test_issue_828.py

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+
+from system_tests import CaseMeta, path
+import unittest
+
+@unittest.skip("Skipping test using option -pR (only for Debug mode)")
+class SegmentationFaultPngImage(metaclass=CaseMeta):
+    """
+    Regression test for the bug described in:
+    https://github.com/Exiv2/exiv2/issues/828
+    """
+    url = "https://github.com/Exiv2/exiv2/issues/828"
+
+    filename = path("$data_path/issue_828_poc.png")
+    commands = ["$exiv2 -pR $filename"]
+    stdout = ["""STRUCTURE OF PNG FILE: $filename
+ address | chunk |  length | data                           | checksum
+       8 | IHDR  |      13 | .............                  | 0x085f152d
+      33 | gAMA  |       4 | ....                           | 0x0bfc6105
+      49 | PLTE  |     717 | .........].....Y..q..}..q..y.. | 0x7b35a4a5
+     778 | tRNS  |     238 | -U...............}...=..e..... | 0xebd29012
+    1028 | bKGD  |       1 | .                              | 0xcfb7d237
+    1041 | tEXt  |      14 | Title.IceAlpha                 | 0xc562f8cb
+    1067 | tEXt  |      31 | Author.Pieter S. van der Meule | 0x6bfe26a8
+    1110 | tEXt  |     411 | Description.The original image | 0xe12effe4
+"""
+]
+    stderr = [
+        """$exiv2_exception_message $filename:
+$kerCorruptedMetadata
+"""]
+    retval = [1]