Revert "Revert of https://codereview.chromium.org/113823003/"

src/images/SkImageDecoder_libpng.cpp

 
 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkImageDecoder.h"
@@ skipping 589 matching lines @@
                 }
             } else if (*configp != SkBitmap::kRGB_565_Config &&
                        *configp != SkBitmap::kARGB_4444_Config) {
                 *configp = SkBitmap::kARGB_8888_Config;
             }
         }
     }
 
     // sanity check for size
     {
-        Sk64 size;
-        size.setMul(origWidth, origHeight);
-        if (size.isNeg() || !size.is32()) {
-            return false;
-        }
+        int64_t size = sk_64_mul(origWidth, origHeight);
         // now check that if we are 4-bytes per pixel, we also don't overflow
-        if (size.get32() > (0x7FFFFFFF >> 2)) {
+        if (size < 0 || size > (0x7FFFFFFF >> 2)) {
             return false;
         }
     }
 
     if (!this->chooseFromOneChoice(*configp, origWidth, origHeight)) {
         return false;
     }
 
     // If the image has alpha and the decoder wants unpremultiplied
     // colors, the only supported config is 8888.
@@ skipping 665 matching lines @@
     return SkImageDecoder::kUnknown_Format;
 }
 
 SkImageEncoder* sk_libpng_efactory(SkImageEncoder::Type t) {
     return (SkImageEncoder::kPNG_Type == t) ? SkNEW(SkPNGImageEncoder) : NULL;
 }
 
 static SkImageDecoder_DecodeReg gDReg(sk_libpng_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_png);
 static SkImageEncoder_EncodeReg gEReg(sk_libpng_efactory);