1 /* $NetBSD: flockfile.c,v 1.11 2012/03/15 18:22:30 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2002 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Nathan J. Williams.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: flockfile.c,v 1.11 2012/03/15 18:22:30 christos Exp $");
35 #endif /* LIBC_SCCS and not lint */
36
37 #include "namespace.h"
38
39 #include <assert.h>
40 #include <errno.h>
41 #include <stdio.h>
42 #include <string.h>
43 #include "reentrant.h"
44 #include "local.h"
45
46 #ifdef __weak_alias
__weak_alias(flockfile,_flockfile)47 __weak_alias(flockfile,_flockfile)
48 __weak_alias(ftrylockfile,_ftrylockfile)
49 __weak_alias(funlockfile,_funlockfile)
50 #endif
51
52 #ifdef _REENTRANT
53 /*
54 * XXX This code makes the assumption that a thr_t (pthread_t) is a
55 * XXX pointer.
56 */
57
58 void
59 flockfile(FILE *fp)
60 {
61
62 __flockfile_internal(fp, 0);
63 }
64
65 int
ftrylockfile(FILE * fp)66 ftrylockfile(FILE *fp)
67 {
68 int retval;
69
70 if (__isthreaded == 0)
71 return 0;
72
73 retval = 0;
74 mutex_lock(&_LOCK(fp));
75
76 if (_LOCKOWNER(fp) == thr_self()) {
77 _LOCKCOUNT(fp)++;
78 } else if (_LOCKOWNER(fp) == NULL) {
79 _LOCKOWNER(fp) = thr_self();
80 _LOCKCOUNT(fp) = 1;
81 } else
82 retval = -1;
83
84 mutex_unlock(&_LOCK(fp));
85
86 return retval;
87 }
88
89 void
funlockfile(FILE * fp)90 funlockfile(FILE *fp)
91 {
92
93 __funlockfile_internal(fp, 0);
94 }
95
96 void
__flockfile_internal(FILE * fp,int internal)97 __flockfile_internal(FILE *fp, int internal)
98 {
99
100 if (__isthreaded == 0)
101 return;
102
103 mutex_lock(&_LOCK(fp));
104
105 if (_LOCKOWNER(fp) == thr_self()) {
106 _LOCKCOUNT(fp)++;
107 if (internal)
108 _LOCKINTERNAL(fp)++;
109 } else {
110 /* danger! cond_wait() is a cancellation point. */
111 int oldstate;
112 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
113 while (_LOCKOWNER(fp) != NULL)
114 cond_wait(&_LOCKCOND(fp), &_LOCK(fp));
115 thr_setcancelstate(oldstate, NULL);
116 _LOCKOWNER(fp) = thr_self();
117 _LOCKCOUNT(fp) = 1;
118 if (internal)
119 _LOCKINTERNAL(fp) = 1;
120 }
121
122 if (_LOCKINTERNAL(fp) == 1)
123 /* stash cancellation state and disable */
124 thr_setcancelstate(PTHREAD_CANCEL_DISABLE,
125 &_LOCKCANCELSTATE(fp));
126
127 mutex_unlock(&_LOCK(fp));
128 }
129
130 void
__funlockfile_internal(FILE * fp,int internal)131 __funlockfile_internal(FILE *fp, int internal)
132 {
133
134 if (__isthreaded == 0)
135 return;
136
137 mutex_lock(&_LOCK(fp));
138
139 if (internal) {
140 _LOCKINTERNAL(fp)--;
141 if (_LOCKINTERNAL(fp) == 0)
142 thr_setcancelstate(_LOCKCANCELSTATE(fp), NULL);
143 }
144
145 _LOCKCOUNT(fp)--;
146 if (_LOCKCOUNT(fp) == 0) {
147 _LOCKOWNER(fp) = NULL;
148 cond_signal(&_LOCKCOND(fp));
149 }
150
151 mutex_unlock(&_LOCK(fp));
152 }
153
154 #else /* _REENTRANT */
155
156 void
157 flockfile(FILE *fp)
158 {
159 /* LINTED deliberate lack of effect */
160 (void)fp;
161
162 return;
163 }
164
165 int
166 ftrylockfile(FILE *fp)
167 {
168 /* LINTED deliberate lack of effect */
169 (void)fp;
170
171 return 0;
172 }
173
174 void
175 funlockfile(FILE *fp)
176 {
177 /* LINTED deliberate lack of effect */
178 (void)fp;
179
180 return;
181 }
182
183 #endif /* _REENTRANT */
184