gdb/gdbsupport/safe-strerror.c

   1 /* Safe version of strerror for GDB, the GNU debugger.
   2
   3    Copyright (C) 2006-2019 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #include "common-defs.h"
  21 #include "diagnostics.h"
  22 #include <string.h>
  23
  24 /* There are two different versions of strerror_r; one is GNU-specific, the
  25    other XSI-compliant.  They differ in the return type.  This overload lets
  26    us choose the right behavior for each return type.  We cannot rely on Gnulib
  27    to solve this for us because IPA does not use Gnulib but uses this
  28    function.  */
  29
  30 /* We only ever use one of the two overloads, so suppress the warning for
  31    an unused function.  */
  32 DIAGNOSTIC_PUSH
  33 DIAGNOSTIC_IGNORE_UNUSED_FUNCTION
  34
  35 /* Called if we have a XSI-compliant strerror_r.  */
  36 static char *
  37 select_strerror_r (int res, char *buf)
  38 {
  39   return res == 0 ? buf : nullptr;
  40 }
  41
  42 /* Called if we have a GNU strerror_r.  */
  43 static char *
  44 select_strerror_r (char *res, char *)
  45 {
  46   return res;
  47 }
  48
  49 DIAGNOSTIC_POP
  50
  51 /* Implementation of safe_strerror as defined in common-utils.h.  */
  52
  53 const char *
  54 safe_strerror (int errnum)
  55 {
  56   static thread_local char buf[1024];
  57
  58   char *res = select_strerror_r (strerror_r (errnum, buf, sizeof (buf)), buf);
  59   if (res != nullptr)
  60     return res;
  61
  62   xsnprintf (buf, sizeof buf, "(undocumented errno %d)", errnum);
  63   return buf;
  64 }