mirror of
https://github.com/jart/cosmopolitan.git
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7b26b42769
This makes breaking changes to add underscores to many non-standard
function names provided by the c library. MODE=tiny is now tinier and
we now use smaller locks that are better for tiny apps in this mode.
Some headers have been renamed to be in the same folder as the build
package, so it'll be easier to know which build dependency is needed.
Certain old misguided interfaces have been removed. Intel intrinsics
headers are now listed in libc/isystem (but not in the amalgamation)
to help further improve open source compatibility. Header complexity
has also been reduced. Lastly, more shell scripts are now available.
Compared to 6f7d0cb1c3, some tiny corrections were made in libc/intrin/g_fds.c and libc/zipos/open.c including double semi colons and incorrect indentation for existing vista changes that were manually pulled from this commit previously.
124 lines
4.8 KiB
C
124 lines
4.8 KiB
C
/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
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│vi: set et ft=c ts=8 tw=8 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/intrin/strace.internal.h"
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#include "libc/calls/struct/timespec.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/sysv/consts/futex.h"
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#include "libc/thread/thread.h"
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#include "third_party/nsync/common.internal.h"
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#include "third_party/nsync/futex.internal.h"
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// clang-format off
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/* futex() polyfill w/ sched_yield() fallback */
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#define FUTEX_WAIT_BITS_ FUTEX_BITSET_MATCH_ANY
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int _futex (int *, int, int, const struct timespec *, int *, int);
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static int FUTEX_WAIT_;
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static int FUTEX_WAKE_;
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static int FUTEX_PRIVATE_FLAG_;
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static bool FUTEX_IS_SUPPORTED;
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bool FUTEX_TIMEOUT_IS_ABSOLUTE;
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__attribute__((__constructor__)) static void sync_futex_init_ (void) {
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int x = 0;
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FUTEX_WAKE_ = FUTEX_WAKE;
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if (IsLinux () &&
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_futex (&x, FUTEX_WAIT_BITSET, 1, 0, 0,
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FUTEX_BITSET_MATCH_ANY) == -EAGAIN) {
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FUTEX_WAIT_ = FUTEX_WAIT_BITSET;
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FUTEX_TIMEOUT_IS_ABSOLUTE = true;
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} else {
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FUTEX_WAIT_ = FUTEX_WAIT;
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}
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if (IsOpenbsd () ||
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(IsLinux () &&
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!_futex (&x, FUTEX_WAKE_PRIVATE, 1, 0, 0, 0))) {
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FUTEX_PRIVATE_FLAG_ = FUTEX_PRIVATE_FLAG;
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}
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// In our testing, we found that the monotonic clock on various
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// popular systems (such as Linux, and some BSD variants) was no
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// better behaved than the realtime clock, and routinely took
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// large steps backwards, especially on multiprocessors. Given
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// that "monotonic" doesn't seem to mean what it says,
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// implementers of nsync_time might consider retaining the
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// simplicity of a single epoch within an address space, by
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// configuring any time synchronization mechanism (like ntp) to
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// adjust for leap seconds by adjusting the rate, rather than
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// with a backwards step.
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if (IsLinux () &&
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_futex (&x, FUTEX_WAIT_BITSET | FUTEX_CLOCK_REALTIME,
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1, 0, 0, FUTEX_BITSET_MATCH_ANY) == -EAGAIN) {
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FUTEX_WAIT_ |= FUTEX_CLOCK_REALTIME;
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}
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FUTEX_IS_SUPPORTED = IsLinux() || IsOpenbsd();
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}
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int nsync_futex_wait_ (int *p, int expect, char pshare, struct timespec *timeout) {
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int rc, op;
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if (FUTEX_IS_SUPPORTED) {
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op = FUTEX_WAIT_;
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if (pshare == PTHREAD_PROCESS_PRIVATE) {
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op |= FUTEX_PRIVATE_FLAG_;
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}
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rc = _futex (p, op, expect, timeout, 0, FUTEX_WAIT_BITS_);
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if (IsOpenbsd() && rc > 0) {
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// [jart] openbsd does this without setting carry flag
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rc = -rc;
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}
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STRACE("futex(%t, %s, %d, %s) → %s",
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p, DescribeFutexOp(op), expect,
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DescribeTimespec(0, timeout), DescribeFutexResult(rc));
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} else {
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nsync_yield_ ();
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if (timeout) {
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rc = -ETIMEDOUT;
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} else {
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rc = 0;
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}
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}
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return rc;
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}
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int nsync_futex_wake_ (int *p, int count, char pshare) {
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int rc, op;
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int wake (void *, int, int) asm ("_futex");
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if (FUTEX_IS_SUPPORTED) {
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op = FUTEX_WAKE_;
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if (pshare == PTHREAD_PROCESS_PRIVATE) {
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op |= FUTEX_PRIVATE_FLAG_;
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}
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rc = wake (p, op, count);
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STRACE("futex(%t, %s, %d) → %s", p,
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DescribeFutexOp(op),
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count, DescribeFutexResult(rc));
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} else {
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nsync_yield_ ();
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rc = 0;
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}
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return rc;
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}
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