glibc/sysdeps/generic/_strerror.c

/* Copyright (C) 1991, 1993, 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.

The GNU C Library 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <stdio.h>
#include <string.h>
#include "../stdio-common/_itoa.h"

#ifndef HAVE_GNU_LD
#define _sys_errlist sys_errlist
#define _sys_nerr sys_nerr
#endif

/* Return a string describing the errno code in ERRNUM.  */
char *
_strerror_internal (int errnum,
		    char *buf,
		    size_t buflen)
{
  if (errnum < 0 || errnum >= _sys_nerr)
    {
      const char *unk = _("Unknown error ");
      const size_t unklen = strlen (unk);
      char *p = buf + buflen;
      *--p = '\0';
      p = _itoa (errnum, p, 10, 0);
      return memcpy (p - unklen, unk, unklen);
    }

  return (char *) _(_sys_errlist[errnum]);
}