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// Copyright (c) 2020 Egor Tensin <Egor.Tensin@gmail.com>
// This file is part of the "winapi-common" project.
// For details, see https://github.com/egor-tensin/winapi-common.
// Distributed under the MIT License.
#include <winapi/error.hpp>
#include <winapi/utf8.hpp>
#include <windows.h>
#include <sstream>
#include <string>
#include <system_error>
namespace winapi {
namespace error {
namespace {
std::wstring trim_trailing_newline(const std::wstring& s) {
const auto last_pos = s.find_last_not_of(L"\r\n");
if (std::wstring::npos == last_pos)
return {};
return s.substr(0, last_pos + 1);
}
std::string build_what(DWORD code, const char* function) {
std::ostringstream what;
what << "Function " << function << " failed with error code " << code;
return what.str();
}
std::string format_message(int code) {
wchar_t* buf;
const auto len = ::FormatMessageW(
FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
NULL,
code,
MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
reinterpret_cast<wchar_t*>(&buf),
0,
NULL);
if (0 == len) {
::LocalFree(buf);
return "Couldn't format the error message";
}
std::wstring msg{buf, len};
::LocalFree(buf);
return narrow(trim_trailing_newline(msg));
}
} // namespace
std::string CategoryWindows::message(int code) const {
return format_message(code);
}
std::system_error windows(DWORD code, const char* function) {
static_assert(sizeof(DWORD) == sizeof(int), "Aren't DWORDs the same size as ints?");
return std::system_error{
static_cast<int>(code), category_windows(), build_what(code, function)};
}
} // namespace error
} // namespace winapi
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