libctf/ctf-error.c

   1 /* Error table.
   2    Copyright (C) 2019-2020 Free Software Foundation, Inc.
   3
   4    This file is part of libctf.
   5
   6    libctf is free software; you can redistribute it and/or modify it under
   7    the terms of the GNU General Public License as published by the Free
   8    Software Foundation; either version 3, or (at your option) any later
   9    version.
  10
  11    This program is distributed in the hope that it will be useful, but
  12    WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  14    See the GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; see the file COPYING.  If not see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <ctf-impl.h>
  21 #include <stddef.h>
  22 #include <string.h>
  23
  24 /* This construct is due to Bruno Haible: much thanks.  */
  25
  26 /* Give each structure member a unique name.  The name does not matter, so we
  27    use the line number in ctf-error.h to uniquify them.  */
  28
  29 #define ERRSTRFIELD(line) ERRSTRFIELD1 (line)
  30 #define ERRSTRFIELD1(line) ctf_errstr##line
  31
  32 /* The error message strings, each in a unique structure member precisely big
  33    enough for that error, plus a str member to access them all as a string
  34    table.  */
  35
  36 static const union _ctf_errlist_t
  37 {
  38   __extension__ struct
  39   {
  40 #define _CTF_STR(n, s) char ERRSTRFIELD (__LINE__) [sizeof (s)];
  41 #include "ctf-error.h"
  42 #undef _CTF_STR
  43   };
  44   char str[1];
  45 } _ctf_errlist =
  46   {
  47    {
  48 #define _CTF_STR(n, s) s,
  49 #include "ctf-error.h"
  50 #undef _CTF_STR
  51    }
  52   };
  53
  54 /* Offsets to each member in the string table, computed using offsetof.  */
  55
  56 static const unsigned int _ctf_erridx[] =
  57   {
  58 #define _CTF_STR(n, s) [n - ECTF_BASE] = offsetof (union _ctf_errlist_t, ERRSTRFIELD (__LINE__)),
  59 #include "ctf-error.h"
  60 #undef _CTF_STR
  61   };
  62
  63 const char *
  64 ctf_errmsg (int error)
  65 {
  66   const char *str;
  67
  68   if (error >= ECTF_BASE && (error - ECTF_BASE) < ECTF_NERR)
  69     str = _ctf_errlist.str + _ctf_erridx[error - ECTF_BASE];
  70   else
  71     str = (const char *) strerror (error);
  72
  73   return (str ? str : "Unknown error");
  74 }
  75
  76 int
  77 ctf_errno (ctf_file_t * fp)
  78 {
  79   return fp->ctf_errno;
  80 }