H264SPS: Centralize computation of coded size and visible rect.

media/filters/h264_parser_fuzzertest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stddef.h>
 
 #include "base/numerics/safe_conversions.h"
+#include "base/optional.h"
 #include "media/filters/h264_parser.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+
+static volatile size_t volatile_sink;
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (!size)
     return 0;
 
   media::H264Parser parser;
   parser.SetStream(data, base::checked_cast<off_t>(size));
 
   // Parse until the end of stream/unsupported stream/error in stream is
   // found.
   while (true) {
     media::H264NALU nalu;
     media::H264Parser::Result res = parser.AdvanceToNextNALU(&nalu);
     if (res != media::H264Parser::kOk)
       break;
 
     switch (nalu.nal_unit_type) {
       case media::H264NALU::kIDRSlice:
       case media::H264NALU::kNonIDRSlice: {
         media::H264SliceHeader shdr;
         res = parser.ParseSliceHeader(nalu, &shdr);
         break;
       }
 
       case media::H264NALU::kSPS: {
         int id;
         res = parser.ParseSPS(&id);
+        if (res != media::H264Parser::kOk)
+          break;
+        const media::H264SPS* sps = parser.GetSPS(id);
+        if (!sps)
+          break;
+        // Also test the SPS helper methods. We make sure that the results are
+        // used so that the calls are not optimized away.
+        base::Optional<gfx::Size> coded_size = sps->GetCodedSize();
+        volatile_sink = coded_size.value_or(gfx::Size()).ToString().length();
+        base::Optional<gfx::Rect> visible_rect = sps->GetVisibleRect();
+        volatile_sink = visible_rect.value_or(gfx::Rect()).ToString().length();
         break;
       }
 
       case media::H264NALU::kPPS: {
         int id;
         res = parser.ParsePPS(&id);
         break;
       }
 
       case media::H264NALU::kSEIMessage: {
         media::H264SEIMessage sei_msg;
         res = parser.ParseSEI(&sei_msg);
         break;
       }
 
       default:
         // Skip any other NALU.
         break;
     }
     if (res != media::H264Parser::kOk)
       break;
   }
 
   return 0;
 }