Checking for division by zero with bad tile dimensions. #181

glymur/codestream.py

@@ -673,6 +673,18 @@ class Codestream(object):
                 msg = msg.format(j, subsampling[0], subsampling[1])
                 warnings.warn(msg)
 
+        try:
+            num_tiles_x = (xysiz[0] - xyosiz[0]) / (xytsiz[0] - xytosiz[0])
+            num_tiles_y = (xysiz[1] - xyosiz[1]) / (xytsiz[1] - xytosiz[1])
+        except ZeroDivisionError as err:
+            warnings.warn("Invalid tile dimensions.")
+        else:
+            numtiles = math.ceil(num_tiles_x) * math.ceil(num_tiles_y)
+            if numtiles > 65535:
+                msg = "Invalid number of tiles ({0}).".format(numtiles)
+                warnings.warn(msg)
+
+
         kwargs = {'rsiz': rsiz,
                   'xysiz': xysiz,
                   'xyosiz': xyosiz,
@@ -1514,14 +1526,6 @@ class SIZsegment(Segment):
                 lst.append(bitdepth - 1)
         self.ssiz = tuple(lst)
 
-        num_tiles_x = (self.xsiz - self.xosiz) / (self.xtsiz - self.xtosiz)
-        num_tiles_y = (self.ysiz - self.yosiz) / (self.ytsiz - self.ytosiz)
-        numtiles = math.ceil(num_tiles_x) * math.ceil(num_tiles_y)
-        if numtiles > 65535:
-            msg = "Invalid number of tiles ({0}).".format(numtiles)
-            warnings.warn(msg)
-
-
     def __repr__(self):
         msg = "glymur.codestream.SIZsegment(rsiz={rsiz}, xysiz={xysiz}, "
         msg += "xyosiz={xyosiz}, xytsiz={xytsiz}, xytosiz={xytosiz}, "

glymur/test/test_codestream.py

@@ -13,17 +13,12 @@ import struct
 import sys
 import tempfile
 import unittest
+import warnings
 
 from glymur import Jp2k
 import glymur
 
-try:
-    DATA_ROOT = os.environ['OPJ_DATA_ROOT']
-except KeyError:
-    DATA_ROOT = None
-except:
-    raise
-
+from .fixtures import opj_data_file, OPJ_DATA_ROOT
 
 class TestCodestream(unittest.TestCase):
     """Test suite for unusual codestream cases."""
@@ -34,7 +29,21 @@ class TestCodestream(unittest.TestCase):
     def tearDown(self):
         pass
 
-    @unittest.skipIf(DATA_ROOT is None,
+    @unittest.skipIf(OPJ_DATA_ROOT is None,
+                     "OPJ_DATA_ROOT environment variable not set")
+    def test_tile_height_is_zero(self):
+        """Zero tile height should not cause an exception."""
+        filename = opj_data_file('input/nonregression/2539.pdf.SIGFPE.706.1712.jp2')
+        if sys.hexversion < 0x03000000:
+            with warnings.catch_warnings():
+                warnings.simplefilter("ignore")
+                Jp2k(filename)
+        else:
+            with self.assertWarns(UserWarning):
+                Jp2k(jfile)
+
+
+    @unittest.skipIf(OPJ_DATA_ROOT is None,
                      "OPJ_DATA_ROOT environment variable not set")
     @unittest.skipIf(os.name == "nt", "Temporary file issue on window.")
     def test_reserved_marker_segment(self):
@@ -45,7 +54,7 @@ class TestCodestream(unittest.TestCase):
         #
         # Let's inject a reserved marker segment into a file that
         # we know something about to make sure we can still parse it.
-        filename = os.path.join(DATA_ROOT, 'input/conformance/p0_01.j2k')
+        filename = os.path.join(OPJ_DATA_ROOT, 'input/conformance/p0_01.j2k')
         with tempfile.NamedTemporaryFile(suffix='.j2k') as tfile:
             with open(filename, 'rb') as ifile:
                 # Everything up until the first QCD marker.
@@ -67,7 +76,7 @@ class TestCodestream(unittest.TestCase):
             self.assertEqual(codestream.segment[2].length, 3)
             self.assertEqual(codestream.segment[2].data, b'\x00')
 
-    @unittest.skipIf(DATA_ROOT is None,
+    @unittest.skipIf(OPJ_DATA_ROOT is None,
                      "OPJ_DATA_ROOT environment variable not set")
     @unittest.skipIf(sys.hexversion < 0x03020000,
                      "Uses features introduced in 3.2.")
@@ -77,7 +86,7 @@ class TestCodestream(unittest.TestCase):
         # Let's inject a marker segment whose marker does not appear to
         # be valid.  We still parse the file, but warn about the offending
         # marker.
-        filename = os.path.join(DATA_ROOT, 'input/conformance/p0_01.j2k')
+        filename = os.path.join(OPJ_DATA_ROOT, 'input/conformance/p0_01.j2k')
         with tempfile.NamedTemporaryFile(suffix='.j2k') as tfile:
             with open(filename, 'rb') as ifile:
                 # Everything up until the first QCD marker.
@@ -100,11 +109,11 @@ class TestCodestream(unittest.TestCase):
                 self.assertEqual(codestream.segment[2].length, 3)
                 self.assertEqual(codestream.segment[2].data, b'\x00')
 
-    @unittest.skipIf(DATA_ROOT is None,
+    @unittest.skipIf(OPJ_DATA_ROOT is None,
                      "OPJ_DATA_ROOT environment variable not set")
     def test_psot_is_zero(self):
         """Psot=0 in SOT is perfectly legal.  Issue #78."""
-        filename = os.path.join(DATA_ROOT,
+        filename = os.path.join(OPJ_DATA_ROOT,
                                 'input/nonregression/123.j2c')
         j = Jp2k(filename)
         codestream = j.get_codestream(header_only=False)
@@ -125,11 +134,11 @@ class TestCodestream(unittest.TestCase):
         self.assertEqual(codestream.segment[1].ssiz, (7, 7, 7))
 
 
-    @unittest.skipIf(DATA_ROOT is None,
+    @unittest.skipIf(OPJ_DATA_ROOT is None,
                      "OPJ_DATA_ROOT environment variable not set")
     def test_siz_segment_ssiz_signed(self):
         """ssiz attribute to be removed in future release"""
-        filename = os.path.join(DATA_ROOT, 'input/conformance/p0_03.j2k')
+        filename = os.path.join(OPJ_DATA_ROOT, 'input/conformance/p0_03.j2k')
         j = Jp2k(filename)
         codestream = j.get_codestream()