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https://github.com/jart/cosmopolitan.git
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7e0a09feec
This change ports APE Loader to Linux AARCH64, so that Raspberry Pi users can run programs like redbean, without the executable needing to modify itself. Progress has also slipped into this change on the issue of making progress better conforming to user expectations and industry standards regarding which symbols we're allowed to declare
67 lines
3.5 KiB
C
67 lines
3.5 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/assert.h"
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#include "libc/calls/cp.internal.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/atomic.h"
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#include "libc/thread/thread.h"
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#include "libc/thread/tls.h"
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#include "libc/thread/wait0.internal.h"
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#include "third_party/nsync/futex.internal.h"
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/**
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* Blocks until memory location becomes zero.
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*
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* This is intended to be used on the child thread id, which is updated
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* by the clone() system call when a thread terminates. We need this in
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* order to know when it's safe to free a thread's stack. This function
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* uses futexes on Linux, FreeBSD, OpenBSD, and Windows. On other
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* platforms this uses polling with exponential backoff.
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*
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* @return 0 on success, or errno on error
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* @raise ECANCELED if calling thread was cancelled in masked mode
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* @raise EBUSY if `abstime` was specified and deadline expired
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* @cancellationpoint
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*/
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errno_t _wait0(const atomic_int *ctid, struct timespec *abstime) {
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int x, e, rc = 0;
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// "The behavior is undefined if the value specified by the thread
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// argument to pthread_join() refers to the calling thread."
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// ──Quoth POSIX.1-2017
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unassert(ctid != &__get_tls()->tib_tid);
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// "If the thread calling pthread_join() is canceled, then the target
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// thread shall not be detached." ──Quoth POSIX.1-2017
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if (!(rc = pthread_testcancel_np())) {
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BEGIN_CANCELLATION_POINT;
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while ((x = atomic_load_explicit(ctid, memory_order_acquire))) {
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e = nsync_futex_wait_(ctid, x, !IsWindows(), abstime);
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if (e == -ECANCELED) {
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rc = ECANCELED;
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break;
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} else if (e == -ETIMEDOUT) {
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rc = EBUSY;
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break;
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}
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}
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END_CANCELLATION_POINT;
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}
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return rc;
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}
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