ComputeRowBytes must not overflow width when it shifts

tests/BitmapTest.cpp

Index: tests/BitmapTest.cpp
diff --git a/tests/BitmapTest.cpp b/tests/BitmapTest.cpp
index 250b6da32c2aa748db19d8996a6dfc3d2384ec06..aaa297e674570d2007149c8e805565897c6f4f21 100644
--- a/tests/BitmapTest.cpp
+++ b/tests/BitmapTest.cpp
@@ -10,6 +10,22 @@
 #include "Test.h"
 #include "TestClassDef.h"
 
+static void test_bigwidth(skiatest::Reporter* reporter) {
+    SkBitmap bm;
+    int width = 1 << 29;    // *4 will be the high-bit of 32bit int
+
+    REPORTER_ASSERT(reporter, bm.setConfig(SkBitmap::kA8_Config, width, 1));
+    REPORTER_ASSERT(reporter, bm.setConfig(SkBitmap::kRGB_565_Config, width, 1));
+    
+    // for a 4-byte config, this width will compute a rowbytes of 0x80000000,
+    // which does not fit in a int32_t. setConfig should detect this, and fail.
+
+    // TODO: perhaps skia can relax this, and only require that rowBytes fit
+    //       in a uint32_t (or larger), but for now this is the constraint.
+
+    REPORTER_ASSERT(reporter, !bm.setConfig(SkBitmap::kARGB_8888_Config, width, 1));
+}
+
 /**
  *  This test contains basic sanity checks concerning bitmaps.
  */
@@ -27,4 +43,6 @@ DEF_TEST(Bitmap, reporter) {
             REPORTER_ASSERT(reporter, SkToBool(width & height) != bm.empty());
         }
     }
+    
+    test_bigwidth(reporter);
 }