xapian-core/common/errno_to_string.cc

   1 /** @file errno_to_string.cc
   2  * @brief Convert errno value to std::string, thread-safely if possible
   3  */
   4 /* Copyright (C) 2014,2015,2016 Olly Betts
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to
   8  * deal in the Software without restriction, including without limitation the
   9  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  10  * sell copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  */
  24
  25 #include <config.h>
  26
  27 #include "errno_to_string.h"
  28
  29 #include <cerrno>
  30 // <cstring> doesn't give us strerror_r() with Sun C++ 5.9.
  31 #include <string.h>
  32 #if defined HAVE__SYS_ERRLIST_AND__SYS_NERR || \
  33     defined HAVE_SYS_ERRLIST_AND_SYS_NERR
  34 # include <stdio.h>
  35 // Under mingw, these are in stdlib.h.
  36 # include <stdlib.h>
  37 #endif
  38
  39 #include "str.h"
  40
  41 using namespace std;
  42
  43 void
  44 errno_to_string(int e, string & s) {
  45 #if defined HAVE__SYS_ERRLIST_AND__SYS_NERR
  46     if (e >= 0 && e < _sys_nerr && _sys_errlist[e]) {
  47         s += _sys_errlist[e];
  48     } else {
  49         s += "Unknown error ";
  50         s += str(e);
  51     }
  52 #elif defined HAVE_SYS_ERRLIST_AND_SYS_NERR
  53     if (e >= 0 && e < sys_nerr && sys_errlist[e]) {
  54         s += sys_errlist[e];
  55     } else {
  56         s += "Unknown error ";
  57         s += str(e);
  58     }
  59 #elif defined HAVE_STRERROR_R
  60     // Actual longest on Linux in English is EILSEQ which needs 50 bytes.
  61     char buf[128];
  62 # ifdef STRERROR_R_CHAR_P
  63     // Returns char* containing string.
  64     s += strerror_r(e, buf, sizeof(buf));
  65 # else
  66     // XSI-compliant strerror_r returns int:  0 means success; a positive error
  67     // number should be returned on error, but glibc < 2.13 returns -1 and sets
  68     // errno.
  69     int r = strerror_r(e, buf, sizeof(buf));
  70     if (r == 0) {
  71         s += buf;
  72     } else {
  73         s += "Unknown error ";
  74         s += str(e);
  75     }
  76 # endif
  77 #else
  78     // Not thread safe.  "C99 and POSIX.1-2008 require the return value to be
  79     // non-NULL" and we require C++11 which incorporates C99.
  80     s += strerror(e);
  81 #endif
  82 }