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Implement support for POSIX thread cancellations

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This change makes some miracle modifications to the System Five system
call support, which lets us have safe, correct, and atomic handling of
thread cancellations. It all turned out to be cheaper than anticipated
because it wasn't necessary to modify the system call veneers. We were
able to encode the cancellability of each system call into the magnums
found in libc/sysv/syscalls.sh. Since cancellations are so waq, we are
also supporting a lovely Musl Libc mask feature for raising ECANCELED.
This commit is contained in:
Justine Tunney 2022-11-04 01:04:43 -07:00
parent 37d40e087f
commit 2278327eba
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GPG key ID: BE714B4575D6E328
145 changed files with 715 additions and 265 deletions
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test/libc/thread/pthread_cancel_test.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/atomic.h"
#include "libc/calls/blocksigs.internal.h"
#include "libc/calls/calls.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/runtime/runtime.h"
#include "libc/testlib/testlib.h"
#include "libc/thread/thread.h"
int pfds[2];
atomic_bool gotcleanup;
char testlib_enable_tmp_setup_teardown;
void SetUp(void) {
gotcleanup = false;
}
void OnCleanup(void *arg) {
gotcleanup = true;
}
void *Worker(void *arg) {
int n;
char buf[8];
pthread_cleanup_push(OnCleanup, 0);
read(pfds[0], buf, sizeof(buf));
pthread_cleanup_pop(0);
return 0;
}
TEST(pthread_cancel, synchronous) {
void *rc;
pthread_t th;
ASSERT_SYS(0, 0, pipe(pfds));
ASSERT_EQ(0, pthread_create(&th, 0, Worker, 0));
ASSERT_EQ(0, pthread_cancel(th));
ASSERT_EQ(0, pthread_join(th, &rc));
ASSERT_EQ(PTHREAD_CANCELED, rc);
ASSERT_TRUE(gotcleanup);
ASSERT_SYS(0, 0, close(pfds[1]));
ASSERT_SYS(0, 0, close(pfds[0]));
}
TEST(pthread_cancel, synchronous_delayed) {
void *rc;
pthread_t th;
ASSERT_SYS(0, 0, pipe(pfds));
ASSERT_EQ(0, pthread_create(&th, 0, Worker, 0));
usleep(10);
ASSERT_EQ(0, pthread_cancel(th));
ASSERT_EQ(0, pthread_join(th, &rc));
ASSERT_EQ(PTHREAD_CANCELED, rc);
ASSERT_TRUE(gotcleanup);
ASSERT_SYS(0, 0, close(pfds[1]));
ASSERT_SYS(0, 0, close(pfds[0]));
}
void *DisabledWorker(void *arg) {
int n;
char buf[8];
pthread_setcancelstate(PTHREAD_CANCEL_MASKED, 0);
pthread_cleanup_push(OnCleanup, 0);
ASSERT_SYS(ECANCELED, -1, read(pfds[0], buf, sizeof(buf)));
pthread_cleanup_pop(0);
return 0;
}
TEST(pthread_cancel, masked) {
void *rc;
pthread_t th;
ASSERT_SYS(0, 0, pipe(pfds));
ASSERT_EQ(0, pthread_create(&th, 0, DisabledWorker, 0));
ASSERT_EQ(0, pthread_cancel(th));
ASSERT_EQ(0, pthread_join(th, &rc));
ASSERT_EQ(0, rc);
ASSERT_FALSE(gotcleanup);
ASSERT_SYS(0, 0, close(pfds[1]));
ASSERT_SYS(0, 0, close(pfds[0]));
}
TEST(pthread_cancel, masked_delayed) {
void *rc;
pthread_t th;
ASSERT_SYS(0, 0, pipe(pfds));
ASSERT_EQ(0, pthread_create(&th, 0, DisabledWorker, 0));
usleep(10);
ASSERT_EQ(0, pthread_cancel(th));
ASSERT_EQ(0, pthread_join(th, &rc));
ASSERT_EQ(0, rc);
ASSERT_FALSE(gotcleanup);
ASSERT_SYS(0, 0, close(pfds[1]));
ASSERT_SYS(0, 0, close(pfds[0]));
}