//===- Errno.cpp - errno support --------------------------------*- C++ -*-===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

//

// This file implements the errno wrappers.

//

//===----------------------------------------------------------------------===//

#include "llvm/Support/Errno.h"

#include "llvm/Config/config.h"

#include "llvm/Support/raw_ostream.h"

#include <string.h>

#if HAVE_ERRNO_H

#include <errno.h>

#endif

//===----------------------------------------------------------------------===//

//=== WARNING: Implementation here must contain only TRULY operating system

//===          independent code.

//===----------------------------------------------------------------------===//

namespace llvm {

namespace sys {

#if HAVE_ERRNO_H

std::string StrError() {

  return StrError(errno);

}

#endif  // HAVE_ERRNO_H

std::string StrError(int errnum) {

  std::string str;

  if (errnum == 0)

    return str;

#if defined(HAVE_STRERROR_R) || HAVE_DECL_STRERROR_S

  const int MaxErrStrLen = 2000;

  char buffer[MaxErrStrLen];

  buffer[0] = '\0';

#endif

#ifdef HAVE_STRERROR_R

  // strerror_r is thread-safe.

#if defined(__GLIBC__) && defined(_GNU_SOURCE)

  // glibc defines its own incompatible version of strerror_r

  // which may not use the buffer supplied.

  str = strerror_r(errnum, buffer, MaxErrStrLen - 1);

#else

  strerror_r(errnum, buffer, MaxErrStrLen - 1);

  str = buffer;

#endif

#elif HAVE_DECL_STRERROR_S // "Windows Secure API"

  strerror_s(buffer, MaxErrStrLen - 1, errnum);

  str = buffer;

#elif defined(HAVE_STRERROR)

  // Copy the thread un-safe result of strerror into

  // the buffer as fast as possible to minimize impact

  // of collision of strerror in multiple threads.

  str = strerror(errnum);

#else

  // Strange that this system doesn't even have strerror

  // but, oh well, just use a generic message

  raw_string_ostream stream(str);

  stream << "Error #" << errnum;

  stream.flush();

#endif

  return str;

}

}  // namespace sys

}  // namespace llvm