1/* Open a stdio stream on an anonymous temporary file. Generic/POSIX version.
2 Copyright (C) 1991-2022 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <fcntl.h>
20#include <stdio.h>
21#include <unistd.h>
22
23#include <iolibio.h>
24#define __fdopen _IO_fdopen
25#ifndef tmpfile
26# define tmpfile __new_tmpfile
27#endif
28
29
30/* This returns a new stream opened on a temporary file (generated
31 by tmpnam). The file is opened with mode "w+b" (binary read/write).
32 If we couldn't generate a unique filename or the file couldn't
33 be opened, NULL is returned. */
34FILE *
35tmpfile (void)
36{
37 int fd;
38 FILE *f;
39 int flags = 0;
40#ifdef FLAGS
41 flags = FLAGS;
42#endif
43
44 /* First try a system specific method. */
45 fd = __gen_tempfd (flags);
46
47 if (fd < 0)
48 {
49 char buf[FILENAME_MAX];
50
51 if (__path_search (tmpl: buf, tmpl_len: sizeof buf, NULL, pfx: "tmpf", try_tempdir: 0))
52 return NULL;
53
54 fd = __gen_tempname (tmpl: buf, suffixlen: 0, flags: flags, __GT_FILE);
55 if (fd < 0)
56 return NULL;
57
58 /* Note that this relies on the Unix semantics that
59 a file is not really removed until it is closed. */
60 (void) __unlink (name: buf);
61 }
62
63 if ((f = __fdopen (fd, "w+b")) == NULL)
64 __close (fd);
65
66 return f;
67}
68
69#if !defined O_LARGEFILE || O_LARGEFILE == 0
70weak_alias (__new_tmpfile, tmpfile64)
71#endif
72
73#ifndef FLAGS /* Not for tmpfile64. */
74# undef tmpfile
75# include <shlib-compat.h>
76versioned_symbol (libc, __new_tmpfile, tmpfile, GLIBC_2_1);
77#endif
78

source code of glibc/stdio-common/tmpfile.c