1/* Implement fopen_unlocked and related functions.
2 Copyright (C) 2005-2023 Free Software Foundation, Inc.
3 Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.
4
5This file is part of the libiberty library.
6Libiberty is free software; you can redistribute it and/or
7modify it under the terms of the GNU Library General Public
8License as published by the Free Software Foundation; either
9version 2 of the License, or (at your option) any later version.
10
11Libiberty is distributed in the hope that it will be useful,
12but WITHOUT ANY WARRANTY; without even the implied warranty of
13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14Library General Public License for more details.
15
16You should have received a copy of the GNU Library General Public
17License along with libiberty; see the file COPYING.LIB. If
18not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
19Boston, MA 02110-1301, USA. */
20
21/*
22
23@deftypefn Extension void unlock_stream (FILE * @var{stream})
24
25If the OS supports it, ensure that the supplied stream is setup to
26avoid any multi-threaded locking. Otherwise leave the @code{FILE}
27pointer unchanged. If the @var{stream} is @code{NULL} do nothing.
28
29@end deftypefn
30
31@deftypefn Extension void unlock_std_streams (void)
32
33If the OS supports it, ensure that the standard I/O streams,
34@code{stdin}, @code{stdout} and @code{stderr} are setup to avoid any
35multi-threaded locking. Otherwise do nothing.
36
37@end deftypefn
38
39@deftypefn Extension {FILE *} fopen_unlocked (const char *@var{path}, @
40 const char * @var{mode})
41
42Opens and returns a @code{FILE} pointer via @code{fopen}. If the
43operating system supports it, ensure that the stream is setup to avoid
44any multi-threaded locking. Otherwise return the @code{FILE} pointer
45unchanged.
46
47@end deftypefn
48
49@deftypefn Extension {FILE *} fdopen_unlocked (int @var{fildes}, @
50 const char * @var{mode})
51
52Opens and returns a @code{FILE} pointer via @code{fdopen}. If the
53operating system supports it, ensure that the stream is setup to avoid
54any multi-threaded locking. Otherwise return the @code{FILE} pointer
55unchanged.
56
57@end deftypefn
58
59@deftypefn Extension {FILE *} freopen_unlocked (const char * @var{path}, @
60 const char * @var{mode}, FILE * @var{stream})
61
62Opens and returns a @code{FILE} pointer via @code{freopen}. If the
63operating system supports it, ensure that the stream is setup to avoid
64any multi-threaded locking. Otherwise return the @code{FILE} pointer
65unchanged.
66
67@end deftypefn
68
69*/
70
71#ifdef HAVE_CONFIG_H
72#include "config.h"
73#endif
74#include <stdio.h>
75#ifdef HAVE_STDIO_EXT_H
76#include <stdio_ext.h>
77#endif
78
79#include "libiberty.h"
80
81/* This is an inline helper function to consolidate attempts to unlock
82 a stream. */
83
84static inline void
85unlock_1 (FILE *const fp ATTRIBUTE_UNUSED)
86{
87#if defined(HAVE___FSETLOCKING) && defined(FSETLOCKING_BYCALLER)
88 if (fp)
89 __fsetlocking (fp: fp, FSETLOCKING_BYCALLER);
90#endif
91}
92
93void
94unlock_stream (FILE *fp)
95{
96 unlock_1 (fp);
97}
98
99void
100unlock_std_streams (void)
101{
102 unlock_1 (stdin);
103 unlock_1 (stdout);
104 unlock_1 (stderr);
105}
106
107FILE *
108fopen_unlocked (const char *path, const char *mode)
109{
110 FILE *const fp = fopen (filename: path, modes: mode);
111 unlock_1 (fp);
112 return fp;
113}
114
115FILE *
116fdopen_unlocked (int fildes, const char *mode)
117{
118 FILE *const fp = fdopen (fd: fildes, modes: mode);
119 unlock_1 (fp);
120 return fp;
121}
122
123FILE *
124freopen_unlocked (const char *path, const char *mode, FILE *stream)
125{
126 FILE *const fp = freopen (filename: path, modes: mode, stream: stream);
127 unlock_1 (fp);
128 return fp;
129}
130

source code of libiberty/fopen_unlocked.c