1 /* Implement fopen_unlocked and related functions.
2    Copyright (C) 2005-2020 Free Software Foundation, Inc.
3    Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.
4 
5 This file is part of the libiberty library.
6 Libiberty is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Library General Public
8 License as published by the Free Software Foundation; either
9 version 2 of the License, or (at your option) any later version.
10 
11 Libiberty is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
14 Library General Public License for more details.
15 
16 You should have received a copy of the GNU Library General Public
17 License along with libiberty; see the file COPYING.LIB.  If
18 not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
19 Boston, MA 02110-1301, USA.  */
20 
21 /*
22 
23 @deftypefn Extension void unlock_stream (FILE * @var{stream})
24 
25 If the OS supports it, ensure that the supplied stream is setup to
26 avoid any multi-threaded locking.  Otherwise leave the @code{FILE}
27 pointer unchanged.  If the @var{stream} is @code{NULL} do nothing.
28 
29 @end deftypefn
30 
31 @deftypefn Extension void unlock_std_streams (void)
32 
33 If the OS supports it, ensure that the standard I/O streams,
34 @code{stdin}, @code{stdout} and @code{stderr} are setup to avoid any
35 multi-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 
42 Opens and returns a @code{FILE} pointer via @code{fopen}.  If the
43 operating system supports it, ensure that the stream is setup to avoid
44 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
45 unchanged.
46 
47 @end deftypefn
48 
49 @deftypefn Extension {FILE *} fdopen_unlocked (int @var{fildes}, @
50   const char * @var{mode})
51 
52 Opens and returns a @code{FILE} pointer via @code{fdopen}.  If the
53 operating system supports it, ensure that the stream is setup to avoid
54 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
55 unchanged.
56 
57 @end deftypefn
58 
59 @deftypefn Extension {FILE *} freopen_unlocked (const char * @var{path}, @
60   const char * @var{mode}, FILE * @var{stream})
61 
62 Opens and returns a @code{FILE} pointer via @code{freopen}.  If the
63 operating system supports it, ensure that the stream is setup to avoid
64 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
65 unchanged.
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 
84 static inline void
85 unlock_1 (FILE *const fp ATTRIBUTE_UNUSED)
86 {
87 #if defined(HAVE___FSETLOCKING) && defined(FSETLOCKING_BYCALLER)
88   if (fp)
89     __fsetlocking (fp, FSETLOCKING_BYCALLER);
90 #endif
91 }
92 
93 void
94 unlock_stream (FILE *fp)
95 {
96   unlock_1 (fp);
97 }
98 
99 void
100 unlock_std_streams (void)
101 {
102   unlock_1 (stdin);
103   unlock_1 (stdout);
104   unlock_1 (stderr);
105 }
106 
107 FILE *
108 fopen_unlocked (const char *path, const char *mode)
109 {
110   FILE *const fp = fopen (path, mode);
111   unlock_1 (fp);
112   return fp;
113 }
114 
115 FILE *
116 fdopen_unlocked (int fildes, const char *mode)
117 {
118   FILE *const fp = fdopen (fildes, mode);
119   unlock_1 (fp);
120   return fp;
121 }
122 
123 FILE *
124 freopen_unlocked (const char *path, const char *mode, FILE *stream)
125 {
126   FILE *const fp = freopen (path, mode, stream);
127   unlock_1 (fp);
128   return fp;
129 }
130