glibc/stdio-common/tmpnam.c

/* Copyright (C) 1991, 1993, 1996, 1997 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>


/* Generate a unique filename in P_tmpdir.

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

  /* 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 FILENAME_MAX characters in any case.  */
  result = __stdio_gen_tempname (s ?: tmpbuf, L_tmpnam, (const char *) NULL,
				 (const char *) NULL, 0,
				 (size_t *) NULL, (FILE **) NULL, 0);

  if (result != NULL && s == NULL)
    {
      memcpy (buf, result, L_tmpnam);
      result = buf;
    }

  return result;
}