Use base::StringPieceInput instead of std::string for string_to_int_fuzzer.

std::string is null-terminated and can hide some overflow bugs.
Use base::StringPieceInput instead which is not null-terminated.

Change-Id: Ib3f6f00dfc47491ddc5ce7c347dd894f0c043268
Reviewed-on: https://chromium-review.googlesource.com/960564Reviewed-by: Robert Sesek <rsesek@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#542806}

testing/libfuzzer/fuzzers/string_to_int_fuzzer.cc

@@ -12,26 +12,30 @@
 
 // Entry point for LibFuzzer.
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  std::string input(reinterpret_cast<const char*>(data), size);
+  base::StringPiece string_piece_input(reinterpret_cast<const char*>(data),
+                                       size);
+  std::string string_input(reinterpret_cast<const char*>(data), size);
+
   int out_int;
-  base::StringToInt(input, &out_int);
+  base::StringToInt(string_piece_input, &out_int);
   unsigned out_uint;
-  base::StringToUint(input, &out_uint);
+  base::StringToUint(string_piece_input, &out_uint);
   int64_t out_int64;
-  base::StringToInt64(input, &out_int64);
+  base::StringToInt64(string_piece_input, &out_int64);
   uint64_t out_uint64;
-  base::StringToUint64(input, &out_uint64);
+  base::StringToUint64(string_piece_input, &out_uint64);
   size_t out_size;
-  base::StringToSizeT(input, &out_size);
+  base::StringToSizeT(string_piece_input, &out_size);
+
   double out_double;
-  base::StringToDouble(input, &out_double);
-  base::HexStringToInt(input, &out_int);
-  base::HexStringToUInt(input, &out_uint);
-  base::HexStringToInt64(input, &out_int64);
-  base::HexStringToUInt64(input, &out_uint64);
+  base::StringToDouble(string_input, &out_double);
 
+  base::HexStringToInt(string_piece_input, &out_int);
+  base::HexStringToUInt(string_piece_input, &out_uint);
+  base::HexStringToInt64(string_piece_input, &out_int64);
+  base::HexStringToUInt64(string_piece_input, &out_uint64);
   std::vector<uint8_t> out_bytes;
-  base::HexStringToBytes(input, &out_bytes);
+  base::HexStringToBytes(string_piece_input, &out_bytes);
 
   base::HexEncode(data, size);
   return 0;