zend_max_execution_timer.c

/*
   +----------------------------------------------------------------------+
   | Copyright (c) The PHP Group                                          |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | https://www.php.net/license/3_01.txt                                 |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Author: Kévin Dunglas <kevin@dunglas.dev>                            |
   +----------------------------------------------------------------------+
 */

#ifdef ZEND_MAX_EXECUTION_TIMERS

# ifdef __APPLE__

#include <dispatch/dispatch.h>
#  ifdef ZTS
#include <pthread.h>
#  else
#include "zend_execute.h"
#  endif

#include "zend.h"
#include "zend_globals.h"

// macOS doesn't support timer_create(), fallback to Grand Central Dispatch

static inline void zend_max_execution_timer_handler(void *arg)
{
#ifdef ZTS
	pthread_t *tid = (pthread_t *) arg;
	pthread_kill(*tid, ZEND_MAX_EXECUTION_TIMERS_SIGNAL);
#else
	zend_timeout_handler();
#endif
}

static inline void zend_max_execution_timer_cancel(void *arg)
{
	free(arg);
}

ZEND_API void zend_max_execution_timer_init(void) /* {{{ */
{
	pid_t pid = getpid();

	if (EG(pid) == pid) {
		return;
	}

	dispatch_queue_global_t queue = dispatch_get_global_queue(QOS_CLASS_UTILITY, 0);
	EG(max_execution_timer_source) = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, queue);
	if (EG(max_execution_timer_source) == NULL) {
		zend_strerror_noreturn(E_ERROR, errno, "Could not create dispatch source");
	}

	EG(pid) = pid;
	EG(max_execution_timer_suspended) = 1;

#  ifdef ZTS
	pthread_t tid = pthread_self();
	pthread_t *ptid = malloc(sizeof(pthread_t));
	memcpy(ptid, &tid, sizeof(pthread_t));
	dispatch_set_context(EG(max_execution_timer_source), ptid);
#else
	//dispatch_set_context(EG(max_execution_timer_source), NULL);
#  endif

	dispatch_source_set_event_handler_f(EG(max_execution_timer_source), zend_max_execution_timer_handler);
	dispatch_source_set_cancel_handler_f(EG(max_execution_timer_source), zend_max_execution_timer_cancel);
} /* }}} */

void zend_max_execution_timer_settime(zend_long seconds) /* {{{ */
{
	if (seconds == 0) {
		if (!EG(max_execution_timer_suspended)) {
			dispatch_suspend(EG(max_execution_timer_source));
			EG(max_execution_timer_suspended) = 1;
		}

		return;
	}

	dispatch_source_set_timer(
		EG(max_execution_timer_source),
		dispatch_time(DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC),
		seconds * NSEC_PER_SEC,
		0
	);
	if (EG(max_execution_timer_suspended)) {
		dispatch_resume(EG(max_execution_timer_source));
		EG(max_execution_timer_suspended) = 0;
	}
} /* }}} */

void zend_max_execution_timer_shutdown(void) /* {{{ */
{
	/* Don't try to delete a timer created before a call to fork() */
	if (EG(pid) != getpid()) {
		return;
	}

	EG(pid) = 0;

	dispatch_source_cancel(EG(max_execution_timer_source));
	//dispatch_release(EG(max_execution_timer_source));
} /* }}} */

# else

#include <stdio.h>
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <errno.h>
#include <sys/syscall.h>
#include <sys/types.h>
#  ifdef __FreeBSD__
#  include <pthread_np.h>
#  endif

#include "zend.h"
#include "zend_globals.h"

// Musl Libc defines this macro, glibc does not
// According to "man 2 timer_create" this field should always be available, but it's not: https://sourceware.org/bugzilla/show_bug.cgi?id=27417
#  ifndef sigev_notify_thread_id
#  define sigev_notify_thread_id _sigev_un._tid
#  endif

// FreeBSD doesn't support CLOCK_BOOTTIME
#  ifdef __FreeBSD__
#  define ZEND_MAX_EXECUTION_TIMERS_CLOCK CLOCK_MONOTONIC
#  else
#  define ZEND_MAX_EXECUTION_TIMERS_CLOCK CLOCK_BOOTTIME
#  endif

ZEND_API void zend_max_execution_timer_init(void) /* {{{ */
{
	pid_t pid = getpid();

	if (EG(pid) == pid) {
		return;
	}

	struct sigevent sev;
	sev.sigev_notify = SIGEV_THREAD_ID;
	sev.sigev_value.sival_ptr = &EG(max_execution_timer_timer);
	sev.sigev_signo = ZEND_MAX_EXECUTION_TIMERS_SIGNAL;
#  ifdef __FreeBSD__
	sev.sigev_notify_thread_id = pthread_getthreadid_np();
#  else
	sev.sigev_notify_thread_id = (pid_t) syscall(SYS_gettid);
#  endif

	// Measure wall time instead of CPU time as originally planned now that it is possible https://github.com/php/php-src/pull/6504#issuecomment-1370303727
	if (timer_create(ZEND_MAX_EXECUTION_TIMERS_CLOCK, &sev, &EG(max_execution_timer_timer)) != 0) {
		zend_strerror_noreturn(E_ERROR, errno, "Could not create timer");
	}

	EG(pid) = pid;

#  ifdef MAX_EXECUTION_TIMERS_DEBUG
		fprintf(stderr, "Timer %#jx created on thread %d\n", (uintmax_t) EG(max_execution_timer_timer), sev.sigev_notify_thread_id);
#  endif

	sigaction(sev.sigev_signo, NULL, &EG(oldact));
}
/* }}} */

void zend_max_execution_timer_settime(zend_long seconds) /* {{{ }*/
{
	/* Timer not initialized or shutdown. */
	if (!EG(pid)) {
		return;
	}

	timer_t timer = EG(max_execution_timer_timer);

	struct itimerspec its;
	its.it_value.tv_sec = seconds;
	its.it_value.tv_nsec = its.it_interval.tv_sec = its.it_interval.tv_nsec = 0;

#  ifdef MAX_EXECUTION_TIMERS_DEBUG
	fprintf(stderr, "Setting timer %#jx on thread %d (%ld seconds)...\n", (uintmax_t) timer, (pid_t) syscall(SYS_gettid), seconds);
#  endif

	if (timer_settime(timer, 0, &its, NULL) != 0) {
		zend_strerror_noreturn(E_ERROR, errno, "Could not set timer");
	}
}
/* }}} */

void zend_max_execution_timer_shutdown(void) /* {{{ */
{
	/* Don't try to delete a timer created before a call to fork() */
	if (EG(pid) != getpid()) {
		return;
	}

	EG(pid) = 0;

	timer_t timer = EG(max_execution_timer_timer);

#  ifdef MAX_EXECUTION_TIMERS_DEBUG
	fprintf(stderr, "Deleting timer %#jx on thread %d...\n", (uintmax_t) timer, (pid_t) syscall(SYS_gettid));
#  endif

	int err = timer_delete(timer);
	if (err != 0) {
		zend_strerror_noreturn(E_ERROR, errno, "Could not delete timer");
	}
}
/* }}}} */

# endif
#endif