mirror of
https://github.com/jart/cosmopolitan.git
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0b3c81dd4e
This change makes fork() go nearly as fast as sys_fork() on UNIX. As for Windows this change shaves about 4-5ms off fork() + wait() latency. This is accomplished by using WriteProcessMemory() from the parent process to setup the address space of a suspended process; it is better than a pipe
103 lines
4.2 KiB
C
103 lines
4.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et 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/errno.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/strace.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 cancelation for the
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* calling thread, which is necessary in cases when a @cancelationpoint
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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 cancelation 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 cancelation 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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int old;
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errno_t err;
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struct PosixThread *pt;
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if (__tls_enabled && (pt = _pthread_self())) {
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if (pt->pt_flags & PT_NOCANCEL) {
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old = PTHREAD_CANCEL_DISABLE;
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} else if (pt->pt_flags & PT_MASKED) {
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old = PTHREAD_CANCEL_MASKED;
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} else {
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old = PTHREAD_CANCEL_ENABLE;
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}
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switch (state) {
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case PTHREAD_CANCEL_ENABLE:
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pt->pt_flags &= ~(PT_NOCANCEL | PT_MASKED);
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err = 0;
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break;
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case PTHREAD_CANCEL_DISABLE:
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pt->pt_flags &= ~(PT_NOCANCEL | PT_MASKED);
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pt->pt_flags |= PT_NOCANCEL;
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err = 0;
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break;
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case PTHREAD_CANCEL_MASKED:
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pt->pt_flags &= ~(PT_NOCANCEL | PT_MASKED);
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pt->pt_flags |= PT_MASKED;
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err = 0;
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break;
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default:
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err = EINVAL;
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break;
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}
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} else {
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old = 0;
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err = 0;
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}
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if (!err)
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if (oldstate)
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*oldstate = old;
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#if IsModeDbg() && 0
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STRACE("pthread_setcancelstate(%s, [%s]) → %s",
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DescribeCancelState(0, &state), DescribeCancelState(err, oldstate),
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DescribeErrno(err));
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#endif
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return err;
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}
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int _pthread_block_cancelation(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_cancelation(int oldstate) {
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pthread_setcancelstate(oldstate, 0);
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}
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