1//===- Errno.cpp - errno support --------------------------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements the errno wrappers.
10//
11//===----------------------------------------------------------------------===//
12
13#include "llvm/Support/Errno.h"
14#include "llvm/Config/config.h"
15#include "llvm/Support/raw_ostream.h"
16#include <string.h>
17
18#if HAVE_ERRNO_H
19#include <errno.h>
20#endif
21
22//===----------------------------------------------------------------------===//
23//=== WARNING: Implementation here must contain only TRULY operating system
24//===          independent code.
25//===----------------------------------------------------------------------===//
26
27namespace llvm {
28namespace sys {
29
30#if HAVE_ERRNO_H
31std::string StrError() {
32  return StrError(errno);
33}
34#endif  // HAVE_ERRNO_H
35
36std::string StrError(int errnum) {
37  std::string str;
38  if (errnum == 0)
39    return str;
40#if defined(HAVE_STRERROR_R) || HAVE_DECL_STRERROR_S
41  const int MaxErrStrLen = 2000;
42  char buffer[MaxErrStrLen];
43  buffer[0] = '\0';
44#endif
45
46#ifdef HAVE_STRERROR_R
47  // strerror_r is thread-safe.
48#if defined(__GLIBC__) && defined(_GNU_SOURCE)
49  // glibc defines its own incompatible version of strerror_r
50  // which may not use the buffer supplied.
51  str = strerror_r(errnum, buffer, MaxErrStrLen - 1);
52#else
53  strerror_r(errnum, buffer, MaxErrStrLen - 1);
54  str = buffer;
55#endif
56#elif HAVE_DECL_STRERROR_S // "Windows Secure API"
57  strerror_s(buffer, MaxErrStrLen - 1, errnum);
58  str = buffer;
59#elif defined(HAVE_STRERROR)
60  // Copy the thread un-safe result of strerror into
61  // the buffer as fast as possible to minimize impact
62  // of collision of strerror in multiple threads.
63  str = strerror(errnum);
64#else
65  // Strange that this system doesn't even have strerror
66  // but, oh well, just use a generic message
67  raw_string_ostream stream(str);
68  stream << "Error #" << errnum;
69  stream.flush();
70#endif
71  return str;
72}
73
74}  // namespace sys
75}  // namespace llvm
76