uclibc-ng/libc/stdio/tmpnam.c

/* Copyright (C) 1991, 1993, 1996, 1997, 1998 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <stdio.h>
#include <string.h>

static char tmpnam_buffer[L_tmpnam];

/* Generate a unique filename in P_tmpdir.
   This function is *not* thread safe when S == NULL!  
*/
char * tmpnam (char *s)
{
    /* By using two buffers we manage to be thread safe in the case
       where S != NULL.  */
    char tmpbuf[L_tmpnam];

    /* In the following call we use the buffer pointed to by S if
       non-NULL although we don't know the size.  But we limit the size
       to L_tmpnam characters in any case.  */
    if (__path_search (s ? : tmpbuf, L_tmpnam, NULL, NULL, 0))
	return NULL;

    if (__gen_tempname (s ? : tmpbuf, __GT_NOCREATE))
	return NULL;

    if (s == NULL)
	return (char *) memcpy (tmpnam_buffer, tmpbuf, L_tmpnam);

    return s;
}