mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-01-31 19:43:32 +00:00
d5910e2673
- Fixed bug where stdio eof wasn't being sticky - Fixed bug where fseeko() wasn't clearing eof state - Removed assert() usage from libc favoring _unassert() / _npassert()
74 lines
3.3 KiB
C
74 lines
3.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/errno.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/weaken.h"
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#include "libc/thread/thread.h"
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#include "third_party/nsync/once.h"
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#define INIT 0
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#define CALLING 1
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#define FINISHED 2
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/**
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* Ensures initialization function is called exactly once, e.g.
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*
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* static void *g_factory;
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*
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* static void InitFactory(void) {
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* g_factory = expensive();
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* }
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*
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* void *GetFactory(void) {
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* static pthread_once_t once = PTHREAD_ONCE_INIT;
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* pthread_once(&once, InitFactory);
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* return g_factory;
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* }
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*
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* @return 0 on success, or errno on error
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*/
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errno_t pthread_once(pthread_once_t *once, void init(void)) {
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uint32_t old;
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if (_weaken(nsync_run_once)) {
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_weaken(nsync_run_once)((nsync_once *)once, init);
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return 0;
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}
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switch ((old = atomic_load_explicit(&once->_lock, memory_order_relaxed))) {
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case INIT:
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if (atomic_compare_exchange_strong_explicit(&once->_lock, &old, CALLING,
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memory_order_acquire,
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memory_order_relaxed)) {
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init();
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atomic_store_explicit(&once->_lock, FINISHED, memory_order_release);
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return 0;
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}
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// fallthrough
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case CALLING:
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do {
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pthread_yield();
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} while (atomic_load_explicit(&once->_lock, memory_order_acquire) ==
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CALLING);
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return 0;
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case FINISHED:
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return 0;
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default:
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return EINVAL;
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}
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}
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