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Make futexes cancellable by pthreads

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Justine Tunney 2022-11-04 18:19:05 -07:00
parent 2278327eba
commit 022536cab6
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101 changed files with 627 additions and 391 deletions
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78
libc/intrin/pthread_setcancelstate.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/errno.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread.h"
#include "libc/thread/tls.h"
/**
* Sets cancelability state.
*
* This function may be used to temporarily disable cancellation for the
* calling thread, which is necessary in cases when a @cancellationpoint
* function is invoked from an @asyncsignalsafe function.
*
* Cosmopolitan Libc supports the Musl Libc `PTHREAD_CANCEL_MASKED`
* non-POSIX extension. Any thread may use this setting, in which case
* the thread won't be abruptly destroyed upon a cancellation and have
* its stack unwound; instead, the thread will encounter an `ECANCELED`
* errno the next time it calls a cancellation point.
*
* @param state may be one of:
* - `PTHREAD_CANCEL_ENABLE` (default)
* - `PTHREAD_CANCEL_DISABLE`
* - `PTHREAD_CANCEL_MASKED`
* @param oldstate optionally receives old value
* @return 0 on success, or errno on error
* @raise EINVAL if `state` has bad value
* @asyncsignalsafe
*/
errno_t pthread_setcancelstate(int state, int *oldstate) {
struct PosixThread *pt;
if (__tls_enabled && (pt = (struct PosixThread *)__get_tls()->tib_pthread)) {
switch (state) {
case PTHREAD_CANCEL_ENABLE:
case PTHREAD_CANCEL_DISABLE:
case PTHREAD_CANCEL_MASKED:
if (oldstate) {
if (pt->flags & PT_NOCANCEL) {
*oldstate = PTHREAD_CANCEL_DISABLE;
} else if (pt->flags & PT_MASKED) {
*oldstate = PTHREAD_CANCEL_MASKED;
} else {
*oldstate = PTHREAD_CANCEL_ENABLE;
}
}
pt->flags &= ~(PT_NOCANCEL | PT_MASKED);
if (state == PTHREAD_CANCEL_MASKED) {
pt->flags |= PT_MASKED;
} else if (state == PTHREAD_CANCEL_DISABLE) {
pt->flags |= PT_NOCANCEL;
}
return 0;
default:
return EINVAL;
}
} else {
if (oldstate) {
*oldstate = 0;
}
return 0;
}
}