stdio-common/errname.c

   1 /* Internal errno names mapping definition.
   2    Copyright (C) 2022-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <errno.h>
  21 #include <libintl.h>
  22 #include <array_length.h>
  23
  24 #ifndef ERR_MAP
  25 # define ERR_MAP(n) n
  26 #endif
  27
  28 static const union sys_errname_t
  29 {
  30   struct
  31   {
  32 #define MSGSTRFIELD1(line) str##line
  33 #define MSGSTRFIELD(line)  MSGSTRFIELD1(line)
  34 #define _S(n, str)         char MSGSTRFIELD(__LINE__)[sizeof(#n)];
  35 #include <errlist.h>
  36 #undef _S
  37   };
  38   char str[0];
  39 } _sys_errname = { {
  40 #define _S(n, s) #n,
  41 #include <errlist.h>
  42 #undef _S
  43 } };
  44
  45 static const unsigned short _sys_errnameidx[] =
  46 {
  47 #define _S(n, s) \
  48   [ERR_MAP(n)] = offsetof(union sys_errname_t, MSGSTRFIELD(__LINE__)),
  49 #include <errlist.h>
  50 #undef _S
  51 };
  52
  53 const char *
  54 __get_errname (int errnum)
  55 {
  56   int mapped = ERR_MAP (errnum);
  57   if (mapped < 0 || mapped >= array_length (_sys_errnameidx)
  58       || (mapped > 0 && _sys_errnameidx[mapped] == 0))
  59     return NULL;
  60   return _sys_errname.str + _sys_errnameidx[mapped];
  61 }