add tests for different PCX encoding cases

Tests/test_file_pcx.py

@@ -1,6 +1,6 @@
 from helper import unittest, PillowTestCase, hopper
 
-from PIL import Image, PcxImagePlugin
+from PIL import Image, ImageFile, PcxImagePlugin
 
 
 class TestFilePcx(PillowTestCase):
@@ -46,6 +46,84 @@ class TestFilePcx(PillowTestCase):
         # Make sure all pixels are either 0 or 255.
         self.assertEqual(im.histogram()[0] + im.histogram()[255], 447*144)
 
+    def test_1px_width(self):
+        im = Image.new('L', (1, 256))
+        px = im.load()
+        for y in range(256):
+            px[0, y] = y
+        self._roundtrip(im)
+
+    def test_large_count(self):
+        im = Image.new('L', (256, 1))
+        px = im.load()
+        for x in range(256):
+            px[x, 0] = x // 67 * 67
+        self._roundtrip(im)
+
+    def _test_overflow(self, im):
+        _last = ImageFile.MAXBLOCK
+        ImageFile.MAXBLOCK = 1024
+        try:
+            self._roundtrip(im)
+        finally:
+            ImageFile.MAXBLOCK = _last
+
+    def test_break_in_count_overflow(self):
+        im = Image.new('L', (256, 5))
+        px = im.load()
+        for y in range(4):
+            for x in range(256):
+                px[x, y] = x % 128
+        self._test_overflow(im)
+
+    def test_break_one_in_loop(self):
+        im = Image.new('L', (256, 5))
+        px = im.load()
+        for y in range(5):
+            for x in range(256):
+                px[x, y] = x % 128
+        self._test_overflow(im)
+
+    def test_break_many_in_loop(self):
+        im = Image.new('L', (256, 5))
+        px = im.load()
+        for y in range(4):
+            for x in range(256):
+                px[x, y] = x % 128
+        for x in range(8):
+            px[x, 4] = 16
+        self._test_overflow(im)
+
+    def test_break_one_at_end(self):
+        im = Image.new('L', (256, 5))
+        px = im.load()
+        for y in range(5):
+            for x in range(256):
+                px[x, y] = x % 128
+        px[0, 3] = 128 + 64
+        self._test_overflow(im)
+
+    def test_break_many_at_end(self):
+        im = Image.new('L', (256, 5))
+        px = im.load()
+        for y in range(5):
+            for x in range(256):
+                px[x, y] = x % 128
+        for x in range(4):
+            px[x * 2, 3] = 128 + 64
+            px[x + 256 - 4, 3] = 0
+        self._test_overflow(im)
+
+    def test_break_padding(self):
+        im = Image.new('L', (257, 5))
+        px = im.load()
+        for y in range(5):
+            for x in range(257):
+                px[x, y] = x % 128
+        for x in range(5):
+            px[x, 3] = 0
+        self._test_overflow(im)
+
 
 if __name__ == '__main__':
     unittest.main()

libImaging/PcxEncode.c

@@ -168,9 +168,6 @@ ImagingPcxEncode(Imaging im, ImagingCodecState state, UINT8* buf, int bytes)
                         bytes -= 2;
                     }
                 }
-                if (bytes < padding) {
-                    return ptr - buf;
-                }
                 /* add the padding */
                 for (i = 0; i < padding; i++) {
                     ptr[0] = 0;