Rice decode removals and additions and use them to update the store.

components/safe_browsing_db/v4_rice.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/logging.h"
 #include "base/numerics/safe_math.h"
 #include "base/strings/stringprintf.h"
 #include "components/safe_browsing_db/v4_rice.h"
 
 using ::google::protobuf::RepeatedField;
@@ skipping 88 matching lines @@
                                           const int32 num_entries,
                                           const std::string& encoded_data,
                                           std::string* out) {
   DCHECK(out);
 
   V4DecodeResult result =
       ValidateInput(rice_parameter, num_entries, encoded_data);
   if (result != DECODE_SUCCESS) {
     return result;
   }
+  out->reserve((num_entries + 1) * 4);
 
-  out->reserve((num_entries + 1) * 4);
+  // Cast to unsigned since we don't look at the sign bit as a sign bit.
+  // first_value should have been an unsigned to begin with but proto don't
+  // allow that.
+  uint32_t first_value_unsigned = static_cast<uint32_t>(first_value);
+  base::CheckedNumeric<uint32_t> last_value(first_value_unsigned);
   char bytes[4];
-  base::CheckedNumeric<uint32_t> last_value(first_value);
   GetBytesFromUInt32(last_value.ValueOrDie(), bytes);
   out->append(bytes, 4);
 
   if (num_entries == 0) {
     return DECODE_SUCCESS;
   }
 
   V4RiceDecoder decoder(rice_parameter, num_entries, encoded_data);
   while (decoder.HasAnotherValue()) {
     uint32_t offset;
@@ skipping 143 matching lines @@
       current_word_, data_byte_index_, current_word_bit_index_,
       rice_parameter_);
 }
 
 std::ostream& operator<<(std::ostream& os, const V4RiceDecoder& rice_decoder) {
   os << rice_decoder.DebugString();
   return os;
 }
 
 }  // namespace safe_browsing