lib/Support/Errno.cpp

   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
  27 namespace llvm {
  28 namespace sys {
  29
  30 #if HAVE_ERRNO_H
  31 std::string StrError() {
  32   return StrError(errno);
  33 }
  34 #endif  // HAVE_ERRNO_H
  35
  36 std::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