1 /* libc-internal interface for mutex locks. Mach cthreads version.
2 Copyright (C) 1996-2022 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 #ifndef _LIBC_LOCK_H
20 #define _LIBC_LOCK_H 1
21
22 #ifdef _LIBC
23
24 #include <tls.h>
25 #include <lowlevellock.h>
26
27 typedef unsigned int __libc_lock_t;
28 typedef struct
29 {
30 __libc_lock_t lock;
31 int cnt;
32 void *owner;
33 } __libc_lock_recursive_t;
34
35 typedef __libc_lock_recursive_t __rtld_lock_recursive_t;
36
37 extern char __libc_lock_self0[0];
38 #define __libc_lock_owner_self() \
39 (__LIBC_NO_TLS () ? (void *)&__libc_lock_self0 : THREAD_SELF)
40
41 #else
42 typedef struct __libc_lock_opaque__ __libc_lock_t;
43 typedef struct __libc_lock_recursive_opaque__ __libc_lock_recursive_t;
44 #endif
45
46 /* Define a lock variable NAME with storage class CLASS. The lock must be
47 initialized with __libc_lock_init before it can be used (or define it
48 with __libc_lock_define_initialized, below). Use `extern' for CLASS to
49 declare a lock defined in another module. In public structure
50 definitions you must use a pointer to the lock structure (i.e., NAME
51 begins with a `*'), because its storage size will not be known outside
52 of libc. */
53 #define __libc_lock_define(CLASS,NAME) \
54 CLASS __libc_lock_t NAME;
55
56 /* Define an initialized lock variable NAME with storage class CLASS. */
57 #define _LIBC_LOCK_INITIALIZER LLL_LOCK_INITIALIZER
58 #define __libc_lock_define_initialized(CLASS,NAME) \
59 CLASS __libc_lock_t NAME = LLL_LOCK_INITIALIZER;
60
61 /* Initialize the named lock variable, leaving it in a consistent, unlocked
62 state. */
63 #define __libc_lock_init(NAME) (NAME) = LLL_LOCK_INITIALIZER
64
65 /* Finalize the named lock variable, which must be locked. It cannot be
66 used again until __libc_lock_init is called again on it. This must be
67 called on a lock variable before the containing storage is reused. */
68 #define __libc_lock_fini __libc_lock_unlock
69 #define __libc_lock_fini_recursive __libc_lock_unlock_recursive
70 #define __rtld_lock_fini_recursive __rtld_lock_unlock_recursive
71
72 /* Lock the named lock variable. */
73 #define __libc_lock_lock(NAME) \
74 ({ lll_lock ((NAME), LLL_PRIVATE); 0; })
75
76 /* Lock the named lock variable. */
77 #define __libc_lock_trylock(NAME) lll_trylock (NAME)
78
79 /* Unlock the named lock variable. */
80 #define __libc_lock_unlock(NAME) \
81 ({ lll_unlock ((NAME), LLL_PRIVATE); 0; })
82
83 #define __libc_lock_define_recursive(CLASS,NAME) \
84 CLASS __libc_lock_recursive_t NAME;
85
86 #define _LIBC_LOCK_RECURSIVE_INITIALIZER { LLL_LOCK_INITIALIZER, 0, 0 }
87
88 #define __libc_lock_define_initialized_recursive(CLASS,NAME) \
89 CLASS __libc_lock_recursive_t NAME = _LIBC_LOCK_RECURSIVE_INITIALIZER;
90
91 #define __rtld_lock_define_recursive(CLASS,NAME) \
92 __libc_lock_define_recursive (CLASS, NAME)
93 #define _RTLD_LOCK_RECURSIVE_INITIALIZER \
94 _LIBC_LOCK_RECURSIVE_INITIALIZER
95 #define __rtld_lock_define_initialized_recursive(CLASS,NAME) \
96 __libc_lock_define_initialized_recursive (CLASS, NAME)
97
98 #define __libc_lock_init_recursive(NAME) \
99 ({ \
100 (NAME) = (__libc_lock_recursive_t)_LIBC_LOCK_RECURSIVE_INITIALIZER; \
101 0; \
102 })
103
104 #define __libc_lock_trylock_recursive(NAME) \
105 ({ \
106 __libc_lock_recursive_t *const __lock = &(NAME); \
107 void *__self = __libc_lock_owner_self (); \
108 int __r = 0; \
109 if (__self == __lock->owner) \
110 ++__lock->cnt; \
111 else if ((__r = lll_trylock (__lock->lock)) == 0) \
112 __lock->owner = __self, __lock->cnt = 1; \
113 __r; \
114 })
115
116 #define __libc_lock_lock_recursive(NAME) \
117 ({ \
118 __libc_lock_recursive_t *const __lock = &(NAME); \
119 void *__self = __libc_lock_owner_self (); \
120 if (__self != __lock->owner) \
121 { \
122 lll_lock (__lock->lock, 0); \
123 __lock->owner = __self; \
124 } \
125 ++__lock->cnt; \
126 (void)0; \
127 })
128
129 #define __libc_lock_unlock_recursive(NAME) \
130 ({ \
131 __libc_lock_recursive_t *const __lock = &(NAME); \
132 if (--__lock->cnt == 0) \
133 { \
134 __lock->owner = 0; \
135 lll_unlock (__lock->lock, 0); \
136 } \
137 })
138
139
140 #define __rtld_lock_initialize(NAME) \
141 (void) ((NAME) = (__rtld_lock_recursive_t) _RTLD_LOCK_RECURSIVE_INITIALIZER)
142 #define __rtld_lock_trylock_recursive(NAME) \
143 __libc_lock_trylock_recursive (NAME)
144 #define __rtld_lock_lock_recursive(NAME) \
145 __libc_lock_lock_recursive(NAME)
146 #define __rtld_lock_unlock_recursive(NAME) \
147 __libc_lock_unlock_recursive (NAME)
148
149 /* XXX for now */
150 #define __libc_rwlock_define __libc_lock_define
151 #define __libc_rwlock_define_initialized __libc_lock_define_initialized
152 #define __libc_rwlock_init __libc_lock_init
153 #define __libc_rwlock_fini __libc_lock_fini
154 #define __libc_rwlock_rdlock __libc_lock_lock
155 #define __libc_rwlock_wrlock __libc_lock_lock
156 #define __libc_rwlock_tryrdlock __libc_lock_trylock
157 #define __libc_rwlock_trywrlock __libc_lock_trylock
158 #define __libc_rwlock_unlock __libc_lock_unlock
159
160 struct __libc_cleanup_frame
161 {
162 void (*__fct) (void *);
163 void *__argp;
164 int __doit;
165 };
166
167 __extern_inline void
__libc_cleanup_fct(struct __libc_cleanup_frame * framep)168 __libc_cleanup_fct (struct __libc_cleanup_frame *framep)
169 {
170 if (framep->__doit)
171 framep->__fct (framep->__argp);
172 }
173
174 /* Start a critical region with a cleanup function */
175 #define __libc_cleanup_region_start(DOIT, FCT, ARG) \
176 do \
177 { \
178 struct __libc_cleanup_frame __cleanup \
179 __attribute__ ((__cleanup__ (__libc_cleanup_fct))) = \
180 { .__fct = (FCT), .__argp = (ARG), .__doit = (DOIT) };
181
182 /* This one closes the brace above. */
183 #define __libc_cleanup_region_end(DOIT) \
184 __cleanup.__doit = (DOIT); \
185 } \
186 while (0)
187
188 #define __libc_cleanup_end(DOIT) __cleanup.__doit = (DOIT);
189
190 #define __libc_cleanup_push(fct, arg) __libc_cleanup_region_start (1, fct, arg)
191 #define __libc_cleanup_pop(execute) __libc_cleanup_region_end (execute)
192
193 /* Use mutexes as once control variables. */
194
195 struct __libc_once
196 {
197 __libc_lock_t lock;
198 int done;
199 };
200
201 #define __libc_once_define(CLASS,NAME) \
202 CLASS struct __libc_once NAME = { _LIBC_LOCK_INITIALIZER, 0 }
203
204 /* Call handler iff the first call. */
205 #define __libc_once(ONCE_CONTROL, INIT_FUNCTION) \
206 do { \
207 __libc_lock_lock (ONCE_CONTROL.lock); \
208 if (!ONCE_CONTROL.done) \
209 (INIT_FUNCTION) (); \
210 ONCE_CONTROL.done = 1; \
211 __libc_lock_unlock (ONCE_CONTROL.lock); \
212 } while (0)
213
214 /* Get once control variable. */
215 #define __libc_once_get(ONCE_CONTROL) ((ONCE_CONTROL).done != 0)
216
217 #ifdef _LIBC
218 /* We need portable names for some functions. E.g., when they are
219 used as argument to __libc_cleanup_region_start. */
220 #define __libc_mutex_unlock __libc_lock_unlock
221
222 /* Hide the definitions which are only supposed to be used inside libc in
223 a separate file. This file is not present in the installation! */
224 # include <libc-lockP.h>
225 #endif
226
227 #endif /* libc-lock.h */
228