| 1 | /* Creating and controlling threads.
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| 2 | Copyright (C) 2005-2021 Free Software Foundation, Inc.
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| 3 |
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| 4 | This file is free software: you can redistribute it and/or modify
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| 5 | it under the terms of the GNU Lesser General Public License as
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| 6 | published by the Free Software Foundation; either version 2.1 of the
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| 7 | License, or (at your option) any later version.
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| 8 |
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| 9 | This file is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU Lesser General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU Lesser General Public License
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| 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | /* Written by Bruno Haible <bruno@clisp.org>, 2005.
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| 18 | Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-win32.h. */
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| 19 |
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| 20 | /* This file contains primitives for creating and controlling threads.
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| 21 |
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| 22 | Thread data type: gl_thread_t.
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| 23 |
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| 24 | Creating a thread:
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| 25 | thread = gl_thread_create (func, arg);
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| 26 | Or with control of error handling:
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| 27 | err = glthread_create (&thread, func, arg);
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| 28 | extern int glthread_create (gl_thread_t *result,
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| 29 | void *(*func) (void *), void *arg);
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| 30 |
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| 31 | Querying and changing the signal mask of a thread (not supported on all
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| 32 | platforms):
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| 33 | gl_thread_sigmask (how, newmask, oldmask);
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| 34 | Or with control of error handling:
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| 35 | err = glthread_sigmask (how, newmask, oldmask);
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| 36 | extern int glthread_sigmask (int how, const sigset_t *newmask, sigset_t *oldmask);
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| 37 |
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| 38 | Waiting for termination of another thread:
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| 39 | gl_thread_join (thread, &return_value);
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| 40 | Or with control of error handling:
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| 41 | err = glthread_join (thread, &return_value);
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| 42 | extern int glthread_join (gl_thread_t thread, void **return_value_ptr);
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| 43 |
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| 44 | Getting a reference to the current thread:
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| 45 | current = gl_thread_self ();
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| 46 | extern gl_thread_t gl_thread_self (void);
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| 47 |
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| 48 | Getting a reference to the current thread as a pointer, for debugging:
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| 49 | ptr = gl_thread_self_pointer ();
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| 50 | extern void * gl_thread_self_pointer (void);
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| 51 |
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| 52 | Terminating the current thread:
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| 53 | gl_thread_exit (return_value);
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| 54 | extern _Noreturn void gl_thread_exit (void *return_value);
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| 55 |
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| 56 | Requesting custom code to be executed at fork() time (not supported on all
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| 57 | platforms):
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| 58 | gl_thread_atfork (prepare_func, parent_func, child_func);
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| 59 | Or with control of error handling:
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| 60 | err = glthread_atfork (prepare_func, parent_func, child_func);
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| 61 | extern int glthread_atfork (void (*prepare_func) (void),
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| 62 | void (*parent_func) (void),
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| 63 | void (*child_func) (void));
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| 64 | Note that even on platforms where this is supported, use of fork() and
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| 65 | threads together is problematic, see
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| 66 | <https://lists.gnu.org/r/bug-gnulib/2008-08/msg00062.html>
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| 67 | */
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| 68 |
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| 69 |
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| 70 | #ifndef _GLTHREAD_THREAD_H
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| 71 | #define _GLTHREAD_THREAD_H
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| 72 |
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| 73 | #include <errno.h>
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| 74 | #include <stdlib.h>
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| 75 |
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| 76 | #if !defined c11_threads_in_use
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| 77 | # if HAVE_THREADS_H && USE_POSIX_THREADS_FROM_LIBC
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| 78 | # define c11_threads_in_use() 1
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| 79 | # elif HAVE_THREADS_H && USE_POSIX_THREADS_WEAK
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| 80 | # include <threads.h>
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| 81 | # pragma weak thrd_exit
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| 82 | # define c11_threads_in_use() (thrd_exit != NULL)
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| 83 | # else
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| 84 | # define c11_threads_in_use() 0
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| 85 | # endif
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| 86 | #endif
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| 87 |
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| 88 | /* ========================================================================= */
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| 89 |
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| 90 | #if USE_ISOC_THREADS
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| 91 |
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| 92 | /* Use the ISO C threads library. */
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| 93 |
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| 94 | # include <threads.h>
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| 95 |
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| 96 | # ifdef __cplusplus
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| 97 | extern "C" {
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| 98 | # endif
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| 99 |
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| 100 | /* -------------------------- gl_thread_t datatype -------------------------- */
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| 101 |
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| 102 | typedef struct thrd_with_exitvalue *gl_thread_t;
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| 103 | extern int glthread_create (gl_thread_t *threadp,
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| 104 | void *(*func) (void *), void *arg);
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| 105 | # define glthread_sigmask(HOW, SET, OSET) \
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| 106 | pthread_sigmask (HOW, SET, OSET)
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| 107 | extern int glthread_join (gl_thread_t thread, void **return_value_ptr);
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| 108 | extern gl_thread_t gl_thread_self (void);
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| 109 | # define gl_thread_self_pointer() \
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| 110 | (void *) gl_thread_self ()
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| 111 | extern _Noreturn void gl_thread_exit (void *return_value);
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| 112 | # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
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| 113 |
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| 114 | # ifdef __cplusplus
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| 115 | }
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| 116 | # endif
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| 117 |
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| 118 | #endif
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| 119 |
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| 120 | /* ========================================================================= */
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| 121 |
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| 122 | #if USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS
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| 123 |
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| 124 | /* Use the POSIX threads library. */
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| 125 |
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| 126 | # include <pthread.h>
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| 127 |
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| 128 | /* On IRIX, pthread_atfork is declared in <unistd.h>, not in <pthread.h>. */
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| 129 | # if defined __sgi
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| 130 | # include <unistd.h>
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| 131 | # endif
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| 132 |
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| 133 | # if USE_POSIX_THREADS_WEAK
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| 134 | /* Compilers other than GCC need to see the declaration of pthread_sigmask
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| 135 | before the "#pragma weak pthread_sigmask" below. */
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| 136 | # include <signal.h>
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| 137 | # endif
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| 138 |
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| 139 | # ifdef __cplusplus
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| 140 | extern "C" {
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| 141 | # endif
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| 142 |
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| 143 | # if PTHREAD_IN_USE_DETECTION_HARD
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| 144 |
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| 145 | /* The pthread_in_use() detection needs to be done at runtime. */
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| 146 | # define pthread_in_use() \
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| 147 | glthread_in_use ()
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| 148 | extern int glthread_in_use (void);
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| 149 |
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| 150 | # endif
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| 151 |
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| 152 | # if USE_POSIX_THREADS_WEAK
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| 153 |
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| 154 | /* Use weak references to the POSIX threads library. */
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| 155 |
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| 156 | /* Weak references avoid dragging in external libraries if the other parts
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| 157 | of the program don't use them. Here we use them, because we don't want
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| 158 | every program that uses libintl to depend on libpthread. This assumes
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| 159 | that libpthread would not be loaded after libintl; i.e. if libintl is
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| 160 | loaded first, by an executable that does not depend on libpthread, and
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| 161 | then a module is dynamically loaded that depends on libpthread, libintl
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| 162 | will not be multithread-safe. */
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| 163 |
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| 164 | /* The way to test at runtime whether libpthread is present is to test
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| 165 | whether a function pointer's value, such as &pthread_mutex_init, is
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| 166 | non-NULL. However, some versions of GCC have a bug through which, in
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| 167 | PIC mode, &foo != NULL always evaluates to true if there is a direct
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| 168 | call to foo(...) in the same function. To avoid this, we test the
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| 169 | address of a function in libpthread that we don't use. */
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| 170 |
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| 171 | # ifndef pthread_sigmask /* Do not declare rpl_pthread_sigmask weak. */
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| 172 | # pragma weak pthread_sigmask
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| 173 | # endif
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| 174 |
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| 175 | # pragma weak pthread_join
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| 176 | # ifndef pthread_self
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| 177 | # pragma weak pthread_self
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| 178 | # endif
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| 179 | # pragma weak pthread_exit
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| 180 | # if HAVE_PTHREAD_ATFORK
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| 181 | # pragma weak pthread_atfork
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| 182 | # endif
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| 183 |
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| 184 | # if !PTHREAD_IN_USE_DETECTION_HARD
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| 185 | # pragma weak pthread_mutexattr_gettype
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| 186 | # define pthread_in_use() \
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| 187 | (pthread_mutexattr_gettype != NULL || c11_threads_in_use ())
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| 188 | # endif
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| 189 |
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| 190 | # else
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| 191 |
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| 192 | # if !PTHREAD_IN_USE_DETECTION_HARD
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| 193 | # define pthread_in_use() 1
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| 194 | # endif
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| 195 |
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| 196 | # endif
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| 197 |
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| 198 | /* -------------------------- gl_thread_t datatype -------------------------- */
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| 199 |
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| 200 | /* This choice of gl_thread_t assumes that
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| 201 | pthread_equal (a, b) is equivalent to ((a) == (b)).
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| 202 | This is the case on all platforms in use in 2008. */
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| 203 | typedef pthread_t gl_thread_t;
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| 204 | # define glthread_create(THREADP, FUNC, ARG) \
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| 205 | (pthread_in_use () ? pthread_create (THREADP, NULL, FUNC, ARG) : ENOSYS)
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| 206 | # define glthread_sigmask(HOW, SET, OSET) \
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| 207 | (pthread_in_use () ? pthread_sigmask (HOW, SET, OSET) : 0)
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| 208 | # define glthread_join(THREAD, RETVALP) \
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| 209 | (pthread_in_use () ? pthread_join (THREAD, RETVALP) : 0)
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| 210 | # ifdef PTW32_VERSION
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| 211 | /* In pthreads-win32, pthread_t is a struct with a pointer field 'p' and
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| 212 | other fields. */
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| 213 | # define gl_thread_self() \
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| 214 | (pthread_in_use () ? pthread_self () : gl_null_thread)
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| 215 | # define gl_thread_self_pointer() \
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| 216 | (pthread_in_use () ? pthread_self ().p : NULL)
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| 217 | extern const gl_thread_t gl_null_thread;
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| 218 | # elif defined __MVS__
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| 219 | /* On IBM z/OS, pthread_t is a struct with an 8-byte '__' field.
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| 220 | The first three bytes of this field appear to uniquely identify a
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| 221 | pthread_t, though not necessarily representing a pointer. */
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| 222 | # define gl_thread_self() \
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| 223 | (pthread_in_use () ? pthread_self () : gl_null_thread)
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| 224 | # define gl_thread_self_pointer() \
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| 225 | (pthread_in_use () ? *((void **) pthread_self ().__) : NULL)
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| 226 | extern const gl_thread_t gl_null_thread;
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| 227 | # else
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| 228 | # define gl_thread_self() \
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| 229 | (pthread_in_use () ? pthread_self () : (pthread_t) 0)
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| 230 | # define gl_thread_self_pointer() \
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| 231 | (pthread_in_use () ? (void *) pthread_self () : NULL)
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| 232 | # endif
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| 233 | # define gl_thread_exit(RETVAL) \
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| 234 | (void) (pthread_in_use () ? (pthread_exit (RETVAL), 0) : 0)
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| 235 |
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| 236 | # if HAVE_PTHREAD_ATFORK
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| 237 | # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) \
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| 238 | (pthread_in_use () ? pthread_atfork (PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) : 0)
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| 239 | # else
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| 240 | # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
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| 241 | # endif
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| 242 |
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| 243 | # ifdef __cplusplus
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| 244 | }
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| 245 | # endif
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| 246 |
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| 247 | #endif
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| 248 |
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| 249 | /* ========================================================================= */
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| 250 |
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| 251 | #if USE_WINDOWS_THREADS
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| 252 |
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| 253 | # define WIN32_LEAN_AND_MEAN /* avoid including junk */
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| 254 | # include <windows.h>
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| 255 |
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| 256 | # include "windows-thread.h"
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| 257 |
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| 258 | # ifdef __cplusplus
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| 259 | extern "C" {
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| 260 | # endif
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| 261 |
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| 262 | /* -------------------------- gl_thread_t datatype -------------------------- */
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| 263 |
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| 264 | typedef glwthread_thread_t gl_thread_t;
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| 265 | # define glthread_create(THREADP, FUNC, ARG) \
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| 266 | glwthread_thread_create (THREADP, 0, FUNC, ARG)
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| 267 | # define glthread_sigmask(HOW, SET, OSET) \
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| 268 | /* unsupported */ 0
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| 269 | # define glthread_join(THREAD, RETVALP) \
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| 270 | glwthread_thread_join (THREAD, RETVALP)
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| 271 | # define gl_thread_self() \
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| 272 | glwthread_thread_self ()
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| 273 | # define gl_thread_self_pointer() \
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| 274 | gl_thread_self ()
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| 275 | # define gl_thread_exit(RETVAL) \
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| 276 | glwthread_thread_exit (RETVAL)
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| 277 | # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
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| 278 |
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| 279 | # ifdef __cplusplus
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| 280 | }
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| 281 | # endif
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| 282 |
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| 283 | #endif
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| 284 |
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| 285 | /* ========================================================================= */
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| 286 |
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| 287 | #if !(USE_ISOC_THREADS || USE_POSIX_THREADS || USE_ISOC_AND_POSIX_THREADS || USE_WINDOWS_THREADS)
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| 288 |
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| 289 | /* Provide dummy implementation if threads are not supported. */
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| 290 |
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| 291 | typedef int gl_thread_t;
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| 292 | # define glthread_create(THREADP, FUNC, ARG) ENOSYS
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| 293 | # define glthread_sigmask(HOW, SET, OSET) 0
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| 294 | # define glthread_join(THREAD, RETVALP) 0
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| 295 | # define gl_thread_self() 0
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| 296 | # define gl_thread_self_pointer() \
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| 297 | ((void *) gl_thread_self ())
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| 298 | # define gl_thread_exit(RETVAL) (void)0
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| 299 | # define glthread_atfork(PREPARE_FUNC, PARENT_FUNC, CHILD_FUNC) 0
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| 300 |
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| 301 | #endif
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| 302 |
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| 303 | /* ========================================================================= */
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| 304 |
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| 305 | /* Macros with built-in error handling. */
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| 306 |
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| 307 | #ifdef __cplusplus
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| 308 | extern "C" {
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| 309 | #endif
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| 310 |
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| 311 | extern gl_thread_t gl_thread_create (void *(*func) (void *arg), void *arg);
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| 312 | #define gl_thread_sigmask(HOW, SET, OSET) \
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| 313 | do \
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| 314 | { \
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| 315 | if (glthread_sigmask (HOW, SET, OSET)) \
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| 316 | abort (); \
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| 317 | } \
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| 318 | while (0)
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| 319 | #define gl_thread_join(THREAD, RETVAL) \
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| 320 | do \
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| 321 | { \
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| 322 | if (glthread_join (THREAD, RETVAL)) \
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| 323 | abort (); \
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| 324 | } \
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| 325 | while (0)
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| 326 | #define gl_thread_atfork(PREPARE, PARENT, CHILD) \
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| 327 | do \
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| 328 | { \
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| 329 | if (glthread_atfork (PREPARE, PARENT, CHILD)) \
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| 330 | abort (); \
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| 331 | } \
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| 332 | while (0)
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| 333 |
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| 334 | #ifdef __cplusplus
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| 335 | }
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| 336 | #endif
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| 337 |
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| 338 | #endif /* _GLTHREAD_THREAD_H */
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