/* strerror.c --- POSIX compatible system error routine

   Copyright (C) 2007-2017 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include <string.h>

#include <errno.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "intprops.h"

#include "strerror-override.h"

#include "verify.h"

/* Use the system functions, not the gnulib overrides in this file.  */

#undef sprintf

char *

strerror (int n)

#undef strerror

{

  static char buf[STACKBUF_LEN];

  size_t len;

  /* Cast away const, due to the historical signature of strerror;

     callers should not be modifying the string.  */

  const char *msg = strerror_override (n);

  if (msg)

    return (char *) msg;

  msg = strerror (n);

  /* Our strerror_r implementation might use the system's strerror

     buffer, so all other clients of strerror have to see the error

     copied into a buffer that we manage.  This is not thread-safe,

     even if the system strerror is, but portable programs shouldn't

     be using strerror if they care about thread-safety.  */

  if (!msg || !*msg)

    {

      static char const fmt[] = "Unknown error %d";

      verify (sizeof buf >= sizeof (fmt) + INT_STRLEN_BOUND (n));

      sprintf (buf, fmt, n);

      errno = EINVAL;

      return buf;

    }

  /* Fix STACKBUF_LEN if this ever aborts.  */

  len = strlen (msg);

  if (sizeof buf <= len)

    abort ();

  memcpy (buf, msg, len + 1);

  return buf;

}