llvm/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 <cstring>
  16
  17 #if HAVE_ERRNO_H
  18 #include <errno.h>
  19 #endif
  20
  21 //===----------------------------------------------------------------------===//
  22 //=== WARNING: Implementation here must contain only TRULY operating system
  23 //===          independent code.
  24 //===----------------------------------------------------------------------===//
  25
  26 namespace llvm {
  27 namespace sys {
  28
  29 #if HAVE_ERRNO_H
  30 std::string StrError() {
  31   return StrError(errno);
  32 }
  33 #endif  // HAVE_ERRNO_H
  34
  35 std::string StrError(int errnum) {
  36   std::string str;
  37   if (errnum == 0)
  38     return str;
  39 #if defined(HAVE_STRERROR_R) || HAVE_DECL_STRERROR_S
  40   const int MaxErrStrLen = 2000;
  41   char buffer[MaxErrStrLen];
  42   buffer[0] = '\0';
  43 #endif
  44
  45 #ifdef HAVE_STRERROR_R
  46   // strerror_r is thread-safe.
  47 #if defined(__GLIBC__) && defined(_GNU_SOURCE)
  48   // glibc defines its own incompatible version of strerror_r
  49   // which may not use the buffer supplied.
  50   str = strerror_r(errnum, buffer, MaxErrStrLen - 1);
  51 #else
  52   strerror_r(errnum, buffer, MaxErrStrLen - 1);
  53   str = buffer;
  54 #endif
  55 #elif HAVE_DECL_STRERROR_S // "Windows Secure API"
  56   strerror_s(buffer, MaxErrStrLen - 1, errnum);
  57   str = buffer;
  58 #else
  59   // Copy the thread un-safe result of strerror into
  60   // the buffer as fast as possible to minimize impact
  61   // of collision of strerror in multiple threads.
  62   str = strerror(errnum);
  63 #endif
  64   return str;
  65 }
  66
  67 }  // namespace sys
  68 }  // namespace llvm