mirror of
https://github.com/jart/cosmopolitan.git
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3f0bcdc3ef
- Exhaustively document cancellation points - Rename SIGCANCEL to SIGTHR just like BSDs - Further improve POSIX thread cancellations - Ensure asynchronous cancellations work correctly - Elevate the quality of getrandom() and getentropy() - Make futexes cancel correctly on OpenBSD 6.x and 7.x - Add reboot.com and shutdown.com to examples directory - Remove underscore prefix from awesome timespec_*() APIs - Create assertions that help verify our cancellation points - Remove bad timespec APIs (cmp generalizes eq/ne/gt/gte/lt/lte)
89 lines
4 KiB
C
89 lines
4 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/blockcancel.internal.h"
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#include "libc/errno.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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/**
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* Sets cancelability state.
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*
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* This function may be used to temporarily disable cancellation for the
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* calling thread, which is necessary in cases when a @cancellationpoint
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* function is invoked from an @asyncsignalsafe function.
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*
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* Cosmopolitan Libc supports the Musl Libc `PTHREAD_CANCEL_MASKED`
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* non-POSIX extension. Any thread may use this setting, in which case
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* the thread won't be abruptly destroyed upon a cancellation and have
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* its stack unwound; instead, the thread will encounter an `ECANCELED`
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* errno the next time it calls a cancellation point.
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*
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* @param state may be one of:
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* - `PTHREAD_CANCEL_ENABLE` (default)
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* - `PTHREAD_CANCEL_DISABLE`
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* - `PTHREAD_CANCEL_MASKED`
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* @param oldstate optionally receives old value
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* @return 0 on success, or errno on error
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* @raise EINVAL if `state` has bad value
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* @asyncsignalsafe
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*/
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errno_t pthread_setcancelstate(int state, int *oldstate) {
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struct PosixThread *pt;
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if (__tls_enabled && (pt = (struct PosixThread *)__get_tls()->tib_pthread)) {
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switch (state) {
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case PTHREAD_CANCEL_ENABLE:
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case PTHREAD_CANCEL_DISABLE:
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case PTHREAD_CANCEL_MASKED:
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if (oldstate) {
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if (pt->flags & PT_NOCANCEL) {
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*oldstate = PTHREAD_CANCEL_DISABLE;
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} else if (pt->flags & PT_MASKED) {
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*oldstate = PTHREAD_CANCEL_MASKED;
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} else {
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*oldstate = PTHREAD_CANCEL_ENABLE;
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}
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}
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pt->flags &= ~(PT_NOCANCEL | PT_MASKED);
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if (state == PTHREAD_CANCEL_MASKED) {
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pt->flags |= PT_MASKED;
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} else if (state == PTHREAD_CANCEL_DISABLE) {
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pt->flags |= PT_NOCANCEL;
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}
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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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} else {
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if (oldstate) {
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*oldstate = 0;
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}
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return 0;
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}
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}
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int _pthread_block_cancellations(void) {
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int oldstate;
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pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
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return oldstate;
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}
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void _pthread_allow_cancellations(int oldstate) {
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pthread_setcancelstate(oldstate, 0);
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}
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