/*

* Copyright (c) 2018 Ambroz Bizjak

* All rights reserved.

*

* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions are met:

* 1. Redistributions of source code must retain the above copyright

* notice, this list of conditions and the following disclaimer.

* 2. Redistributions in binary form must reproduce the above copyright

* notice, this list of conditions and the following disclaimer in the

* documentation and/or other materials provided with the distribution.

*

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND

* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY

* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES

* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;

* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND

* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#include <cstring>

#include <cstdarg>

#include <cstddef>

#include <string>

#include <stdexcept>

#include <limits>

#include <type_traits>

#include <aipstack/misc/MinMax.h>

#include <aipstack/event_loop/FormatString.h>

namespace AIpStack {

namespace {

constexpr std::size_t FormatSizeHint = 25;

}

std::string formatString (char const *fmt, ...)

{

std::size_t fmt_len = std::strlen(fmt);

if (fmt_len > TypeMax<std::size_t> - FormatSizeHint) {

throw std::bad_alloc();

}

std::size_t initial_size = fmt_len + FormatSizeHint;

std::string str(initial_size, '\0');

while (true) {

if (str.size() > TypeMax<int>) {

throw std::bad_alloc();

}

std::va_list args;

va_start(args, fmt);

auto print_res = std::vsnprintf(&str[0], str.size(), fmt, args);

va_end(args);

if (print_res < 0) {

throw std::runtime_error("vsnprintf failed");

}

auto print_bytes = std::make_unsigned_t<decltype(print_res)>(print_res);

if (print_bytes < str.size()) {

str.resize(print_bytes);

break;

}

// Get the common type of print_bytes and size_t, to avoid a warning

// in the check below.

using CT = decltype(false ? print_bytes : std::size_t());

if (CT(print_bytes) > CT(TypeMax<std::size_t> - 1)) {

throw std::bad_alloc();

}

str.resize(print_bytes + 1);

}

return str;

}

}