1  /* strerror.c --- POSIX compatible system error routine
       2  
       3     Copyright (C) 2007-2023 Free Software Foundation, Inc.
       4  
       5     This file is free software: you can redistribute it and/or modify
       6     it under the terms of the GNU Lesser General Public License as
       7     published by the Free Software Foundation; either version 2.1 of the
       8     License, or (at your option) any later version.
       9  
      10     This file 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
      13     GNU Lesser General Public License for more details.
      14  
      15     You should have received a copy of the GNU Lesser General Public License
      16     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <config.h>
      19  
      20  /* Specification.  */
      21  #include <string.h>
      22  
      23  #include <errno.h>
      24  #include <stdio.h>
      25  #include <stdlib.h>
      26  #include <string.h>
      27  
      28  #include "intprops.h"
      29  #include "strerror-override.h"
      30  
      31  /* Use the system functions, not the gnulib overrides in this file.  */
      32  #undef sprintf
      33  
      34  char *
      35  strerror (int n)
      36  #undef strerror
      37  {
      38    static char buf[STACKBUF_LEN];
      39    size_t len;
      40  
      41    /* Cast away const, due to the historical signature of strerror;
      42       callers should not be modifying the string.  */
      43    const char *msg = strerror_override (n);
      44    if (msg)
      45      return (char *) msg;
      46  
      47    msg = strerror (n);
      48  
      49    /* Our strerror_r implementation might use the system's strerror
      50       buffer, so all other clients of strerror have to see the error
      51       copied into a buffer that we manage.  This is not thread-safe,
      52       even if the system strerror is, but portable programs shouldn't
      53       be using strerror if they care about thread-safety.  */
      54    if (!msg || !*msg)
      55      {
      56        static char const fmt[] = "Unknown error %d";
      57        static_assert (sizeof buf >= sizeof (fmt) + INT_STRLEN_BOUND (n));
      58        sprintf (buf, fmt, n);
      59        errno = EINVAL;
      60        return buf;
      61      }
      62  
      63    /* Fix STACKBUF_LEN if this ever aborts.  */
      64    len = strlen (msg);
      65    if (sizeof buf <= len)
      66      abort ();
      67  
      68    memcpy (buf, msg, len + 1);
      69    return buf;
      70  }