glibc/stdio-common/tmpnam.c

52 lines
1.6 KiB
C

/* Copyright (C) 1991-2017 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <string.h>
static char tmpnam_buffer[L_tmpnam];
/* 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. */
char tmpbufmem[L_tmpnam];
char *tmpbuf = s ?: tmpbufmem;
/* 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 L_tmpnam characters in any case. */
if (__builtin_expect (__path_search (tmpbuf, L_tmpnam, NULL, NULL, 0),
0))
return NULL;
if (__glibc_unlikely (__gen_tempname (tmpbuf, 0, 0, __GT_NOCREATE)))
return NULL;
if (s == NULL)
return (char *) memcpy (tmpnam_buffer, tmpbuf, L_tmpnam);
return s;
}
link_warning (tmpnam,
"the use of `tmpnam' is dangerous, better use `mkstemp'")