stdio-common/tmpnam.c

   1 /* Copyright (C) 1991, 1993, 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <stdio.h>
  20 #include <string.h>
  21
  22 /* Generate a unique filename in P_tmpdir.
  23
  24    This function is *not* thread safe!  */
  25 char *
  26 tmpnam (char *s)
  27 {
  28   /* By using two buffers we manage to be thread safe in the case
  29      where S != NULL.  */
  30   static char buf[L_tmpnam];
  31   char tmpbuf[L_tmpnam];
  32
  33   /* In the following call we use the buffer pointed to by S if
  34      non-NULL although we don't know the size.  But we limit the size
  35      to L_tmpnam characters in any case.  */
  36   if (__path_search (s ? : tmpbuf, L_tmpnam, NULL, NULL))
  37     return NULL;
  38
  39   if (__gen_tempname (s ? : tmpbuf, 0, 0))
  40     return NULL;
  41
  42   if (s == NULL)
  43     {
  44       memcpy (buf, tmpbuf, L_tmpnam);
  45       return buf;
  46     }
  47   else
  48     return s;
  49 }