mirror of
https://github.com/jart/cosmopolitan.git
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4a6fd3d910
- fix rare thread exit race condition on openbsd - pthread_getattr_np() now supplies detached status - child threads may now pthread_join() the main thread - introduce sigandset(), sigorset(), and sigisemptyset() - introduce pthread_cleanup_push() and pthread_cleanup_pop()
93 lines
4.5 KiB
C
93 lines
4.5 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/dce.h"
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#include "libc/limits.h"
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#include "libc/mem/gc.h"
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#include "libc/runtime/runtime.h"
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#include "libc/thread/posixthread.internal.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#include "third_party/nsync/futex.internal.h"
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STATIC_YOINK("_pthread_main");
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/**
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* Terminates current POSIX thread.
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*
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* For example, a thread could terminate early as follows:
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*
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* pthread_exit((void *)123);
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*
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* The result value could then be obtained when joining the thread:
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*
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* void *rc;
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* pthread_join(id, &rc);
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* assert((intptr_t)rc == 123);
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*
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* Under normal circumstances a thread can exit by simply returning from
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* the callback function that was supplied to pthread_create(). This may
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* be used if the thread wishes to exit at any other point in the thread
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* lifecycle, in which case this function is responsible for ensuring we
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* invoke _gc(), _defer(), and pthread_cleanup_push() callbacks, as well
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* as pthread_key_create() destructors.
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*
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* If the current thread is an orphaned thread, or is the main thread
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* when no other threads were created, then this will terminated your
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* process with an exit code of zero. It's not possible to supply a
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* non-zero exit status to wait4() via this function.
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*
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* Once a thread has exited, access to its stack memory is undefined.
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* The behavior of calling pthread_exit() from cleanup handlers and key
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* destructors is also undefined.
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*
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* @param rc is reported later to pthread_join()
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* @threadsafe
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* @noreturn
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*/
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wontreturn void pthread_exit(void *rc) {
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struct PosixThread *pt;
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struct _pthread_cleanup_buffer *cb;
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pt = (struct PosixThread *)__get_tls()->tib_pthread;
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pt->rc = rc;
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// the memory of pthread cleanup objects lives on the stack
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// so we need to harvest them before calling longjmp()
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while ((cb = pt->cleanup)) {
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pt->cleanup = cb->__prev;
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cb->__routine(cb->__arg);
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}
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if (~pt->flags & PT_MAINTHREAD) {
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// this thread was created by pthread_create()
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// garbage collector memory exists on a shadow stack. we don't need
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// to use _gclongjmp() since _pthread_ungarbage() will collect them
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// at the setjmp() site.
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longjmp(pt->exiter, 1);
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} else {
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// this is the main thread
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// release as much resources and possible and mark it terminated
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_pthread_cleanup(pt);
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// it's kind of irregular for a child thread to join the main thread
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// so we don't bother freeing the main thread's stack since it makes
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// this implementation so much simpler for example we want't to call
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// set_tid_address() upon every program startup which isn't possible
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// on non-linux platforms anyway.
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__get_tls()->tib_tid = 0;
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nsync_futex_wake_((int *)&__get_tls()->tib_tid, INT_MAX, !IsWindows());
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_Exit1(0);
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}
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}
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