Method ConsumeRandomLengthString

src/test/fuzz/FuzzedDataProvider.h:151–177

Returns a std::string of length from 0 to |max_length|. When it runs out of input data, returns what remains of the input. Designed to be more stable with respect to a fuzzer inserting characters than just picking a random length and then consuming that many bytes with |ConsumeBytes|.

// with respect to a fuzzer inserting characters than just picking a random
// length and then consuming that many bytes with |ConsumeBytes|.
inline std::string
FuzzedDataProvider::ConsumeRandomLengthString(size_t max_length) {
  // Reads bytes from the start of |data_ptr_|. Maps "\\" to "\", and maps "\"
  // followed by anything else to the end of the string. As a result of this
  // logic, a fuzzer can insert characters into the string, and the string
  // will be lengthened to include those new characters, resulting in a more
  // stable fuzzer than picking the length of a string independently from
  // picking its contents.
  std::string result;

  // Reserve the anticipated capaticity to prevent several reallocations.
  result.reserve(std::min(max_length, remaining_bytes_));
  for (size_t i = 0; i < max_length && remaining_bytes_ != 0; ++i) {
    char next = ConvertUnsignedToSigned<char>(data_ptr_[0]);
    Advance(1);
    if (next == '\\' && remaining_bytes_ != 0) {
      next = ConvertUnsignedToSigned<char>(data_ptr_[0]);
      Advance(1);
      if (next != '\\')
        break;
    }
    result += next;
  }

  result.shrink_to_fit();
  return result;
}

// Returns a std::string of length from 0 to |remaining_bytes_|.
inline std::string FuzzedDataProvider::ConsumeRandomLengthString() {