mirror of
https://gitlab.torproject.org/tpo/core/tor.git
synced 2024-12-06 19:41:15 +01:00
Nick Mathewson
104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
/* Copyright (c) 2003-2004, Roger Dingledine
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* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
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* Copyright (c) 2007-2019, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/**
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* \file compat_mutex_pthreads.c
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*
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* \brief Implement the tor_mutex API using pthread_mutex_t.
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**/
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#include "lib/lock/compat_mutex.h"
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#include "lib/cc/compat_compiler.h"
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#include "lib/err/torerr.h"
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/** A mutex attribute that we're going to use to tell pthreads that we want
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* "recursive" mutexes (i.e., once we can re-lock if we're already holding
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* them.) */
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static pthread_mutexattr_t attr_recursive;
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static int attr_initialized = 0;
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void
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tor_locking_init(void)
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{
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if (!attr_initialized) {
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pthread_mutexattr_init(&attr_recursive);
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pthread_mutexattr_settype(&attr_recursive, PTHREAD_MUTEX_RECURSIVE);
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attr_initialized = 1;
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}
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}
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/** Initialize <b>mutex</b> so it can be locked. Every mutex must be set
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* up with tor_mutex_init() or tor_mutex_new(); not both. */
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void
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tor_mutex_init(tor_mutex_t *mutex)
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{
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if (PREDICT_UNLIKELY(!attr_initialized))
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tor_locking_init(); // LCOV_EXCL_LINE
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const int err = pthread_mutex_init(&mutex->mutex, &attr_recursive);
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if (PREDICT_UNLIKELY(err)) {
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// LCOV_EXCL_START
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raw_assert_unreached_msg("Error creating a mutex.");
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// LCOV_EXCL_STOP
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}
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}
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/** As tor_mutex_init, but initialize a mutex suitable that may be
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* non-recursive, if the OS supports that. */
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void
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tor_mutex_init_nonrecursive(tor_mutex_t *mutex)
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{
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int err;
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if (!attr_initialized)
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tor_locking_init(); // LCOV_EXCL_LINE
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err = pthread_mutex_init(&mutex->mutex, NULL);
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if (PREDICT_UNLIKELY(err)) {
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// LCOV_EXCL_START
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raw_assert_unreached_msg("Error creating a mutex.");
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// LCOV_EXCL_STOP
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}
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}
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/** Wait until <b>m</b> is free, then acquire it. */
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void
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tor_mutex_acquire(tor_mutex_t *m)
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{
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int err;
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raw_assert(m);
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err = pthread_mutex_lock(&m->mutex);
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if (PREDICT_UNLIKELY(err)) {
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// LCOV_EXCL_START
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raw_assert_unreached_msg("Error locking a mutex.");
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// LCOV_EXCL_STOP
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}
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}
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/** Release the lock <b>m</b> so another thread can have it. */
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void
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tor_mutex_release(tor_mutex_t *m)
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{
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int err;
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raw_assert(m);
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err = pthread_mutex_unlock(&m->mutex);
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if (PREDICT_UNLIKELY(err)) {
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// LCOV_EXCL_START
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raw_assert_unreached_msg("Error unlocking a mutex.");
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// LCOV_EXCL_STOP
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}
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}
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/** Clean up the mutex <b>m</b> so that it no longer uses any system
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* resources. Does not free <b>m</b>. This function must only be called on
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* mutexes from tor_mutex_init(). */
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void
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tor_mutex_uninit(tor_mutex_t *m)
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{
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int err;
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raw_assert(m);
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err = pthread_mutex_destroy(&m->mutex);
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if (PREDICT_UNLIKELY(err)) {
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// LCOV_EXCL_START
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raw_assert_unreached_msg("Error destroying a mutex.");
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// LCOV_EXCL_STOP
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}
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}
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