Add a fuzzer for SfntlyWrapper::SubsetFont().

base/test/fuzzed_data_provider.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 "base/test/fuzzed_data_provider.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/logging.h"
@@ skipping 16 matching lines @@
   return ConsumeBytes(remaining_data_.length());
 }
 
 uint32_t FuzzedDataProvider::ConsumeUint32InRange(uint32_t min, uint32_t max) {
   CHECK_LE(min, max);
 
   uint32_t range = max - min;
   uint32_t offset = 0;
   uint32_t result = 0;
 
-  while ((range >> offset) > 0 && !remaining_data_.empty()) {
+  while (offset < 32 && (range >> offset) > 0 && !remaining_data_.empty()) {
     // Pull bytes off the end of the seed data. Experimentally, this seems to

[hal.canary, 2016/08/23 15:49:04]

does this effect anything else?

[Lei Zhang, 2016/08/23 18:05:50]

Hmm?

     // allow the fuzzer to more easily explore the input space. This makes
     // sense, since it works by modifying inputs that caused new code to run,
     // and this data is often used to encode length of data read by
     // ConsumeBytes. Separating out read lengths makes it easier modify the
     // contents of the data that is actually read.
     uint8_t next_byte = remaining_data_.back();
     remaining_data_.remove_suffix(1);
     result = (result << 8) | next_byte;
     offset += 8;
   }
@@ skipping 18 matching lines @@
 
 uint8_t FuzzedDataProvider::ConsumeUint8() {
   return ConsumeUint32InRange(0, 0xFF);
 }
 
 uint16_t FuzzedDataProvider::ConsumeUint16() {
   return ConsumeUint32InRange(0, 0xFFFF);
 }
 
 }  // namespace base