1/* Copyright (C) 1991-2020 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 Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the 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 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <stdio.h>
19#include <string.h>
20
21static char tmpnam_buffer[L_tmpnam];
22
23/* Generate a unique filename in P_tmpdir.
24
25 This function is *not* thread safe! */
26char *
27tmpnam (char *s)
28{
29 /* By using two buffers we manage to be thread safe in the case
30 where S != NULL. */
31 char tmpbufmem[L_tmpnam];
32 char *tmpbuf = s ?: tmpbufmem;
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 (__builtin_expect (__path_search (tmpbuf, L_tmpnam, NULL, NULL, 0),
38 0))
39 return NULL;
40
41 if (__glibc_unlikely (__gen_tempname (tmpbuf, 0, 0, __GT_NOCREATE)))
42 return NULL;
43
44 if (s == NULL)
45 return (char *) memcpy (tmpnam_buffer, tmpbuf, L_tmpnam);
46
47 return s;
48}
49
50link_warning (tmpnam,
51 "the use of `tmpnam' is dangerous, better use `mkstemp'")
52