stdio-common/tmpnam.c

   1 /* Copyright (C) 1991, 1993, 1996 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <stdio.h>
  20 #include <string.h>
  21
  22
  23 /* Generate a unique filename in P_tmpdir.
  24
  25    This function is *not* thread safe!  */
  26 char *
  27 tmpnam (char *s)
  28 {
  29   /* By using two buffers we manage to be thread safe in the case
  30      where S != NULL.  */
  31   static char buf[L_tmpnam];
  32   char tmpbuf[L_tmpnam];
  33   char *result;
  34
  35   /* In the following call we use the buffer pointed to by S if
  36      non-NULL although we don't know the size.  But we limit the size
  37      to FILENAME_MAX characters in any case.  */
  38   result = __stdio_gen_tempname (s ?: tmpbuf, L_tmpnam, (const char *) NULL,
  39                                  (const char *) NULL, 0,
  40                                  (size_t *) NULL, (FILE **) NULL);
  41
  42   if (result != NULL && s == NULL)
  43     {
  44       memcpy (buf, result, L_tmpnam);
  45       result = buf;
  46     }
  47
  48   return result;
  49 }