stdio-common/tmpnam.c

   1 /* Copyright (C) 1991,1993,1996,1997,1998,1999 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 static char tmpnam_buffer[L_tmpnam];
  23
  24 /* Generate a unique filename in P_tmpdir.
  25
  26    This function is *not* thread safe!  */
  27 char *
  28 tmpnam (char *s)
  29 {
  30   /* By using two buffers we manage to be thread safe in the case
  31      where S != NULL.  */
  32   char tmpbuf[L_tmpnam];
  33
  34   /* In the following call we use the buffer pointed to by S if
  35      non-NULL although we don't know the size.  But we limit the size
  36      to L_tmpnam characters in any case.  */
  37   if (__path_search (s ? : tmpbuf, L_tmpnam, NULL, NULL, 0))
  38     return NULL;
  39
  40   if (__gen_tempname (s ? : tmpbuf, __GT_NOCREATE))
  41     return NULL;
  42
  43   if (s == NULL)
  44     return (char *) memcpy (tmpnam_buffer, tmpbuf, L_tmpnam);
  45
  46   return s;
  47 }