system/host/fidl/include/fidl/utils.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef ZIRCON_SYSTEM_HOST_FIDL_INCLUDE_FIDL_UTILS_H_
#define ZIRCON_SYSTEM_HOST_FIDL_INCLUDE_FIDL_UTILS_H_

#include <string>

namespace fidl {
namespace utils {

enum class ParseNumericResult {
    kSuccess,
    kOutOfBounds,
    kMalformed,
};

template <typename NumericType>
ParseNumericResult ParseNumeric(const std::string& input,
                                NumericType* out_value,
                                int base = 0) {
    assert(out_value != nullptr);

    // Set locale to "C" for numeric types, since all strtox() functions are locale-dependent
    setlocale(LC_NUMERIC, "C");

    char* endptr;
    if constexpr (std::is_unsigned<NumericType>::value) {
        if (input[0] == '-')
            return ParseNumericResult::kOutOfBounds;
        errno = 0;
        unsigned long long value = strtoull(input.data(), &endptr, base);
        if (errno != 0)
            return ParseNumericResult::kMalformed;
        if (value > std::numeric_limits<NumericType>::max())
            return ParseNumericResult::kOutOfBounds;
        *out_value = static_cast<NumericType>(value);
    } else if constexpr (std::is_floating_point<NumericType>::value) {
        errno = 0;
        long double value = strtold(input.data(), &endptr);
        if (errno != 0)
            return ParseNumericResult::kMalformed;
        if (value > std::numeric_limits<NumericType>::max())
            return ParseNumericResult::kOutOfBounds;
        if (value < std::numeric_limits<NumericType>::lowest())
            return ParseNumericResult::kOutOfBounds;
        *out_value = static_cast<NumericType>(value);
    } else {
        errno = 0;
        long long value = strtoll(input.data(), &endptr, base);
        if (errno != 0)
            return ParseNumericResult::kMalformed;
        if (value > std::numeric_limits<NumericType>::max())
            return ParseNumericResult::kOutOfBounds;
        if (value < std::numeric_limits<NumericType>::lowest())
            return ParseNumericResult::kOutOfBounds;
        *out_value = static_cast<NumericType>(value);
    }
    if (endptr != (input.c_str() + input.size()))
        return ParseNumericResult::kMalformed;
    return ParseNumericResult::kSuccess;
}

} // namespace utils
} // namespace fidl

#endif // ZIRCON_SYSTEM_HOST_FIDL_INCLUDE_FIDL_UTILS_H_