fix: support for timeouts with ZTS on Linux

Zend/Zend.m4

@@ -269,6 +269,28 @@ fi
 AC_MSG_CHECKING(whether to enable zend signal handling)
 AC_MSG_RESULT($ZEND_SIGNALS)
 
+dnl Don't enable Zend Max Execution Timers by default until PHP 8.3 to not break the ABI
+AC_ARG_ENABLE([zend-max-execution-timers],
+  [AS_HELP_STRING([--enable-zend-max-execution-timers],
+    [whether to enable zend max execution timers])],
+    [ZEND_MAX_EXECUTION_TIMERS=$enableval],
+    [ZEND_MAX_EXECUTION_TIMERS='no'])
+
+AS_CASE(["$host_alias"], [*linux*], [], [ZEND_MAX_EXECUTION_TIMERS='no'])
+
+PHP_CHECK_FUNC(timer_create, rt)
+if test "$ac_cv_func_timer_create" != "yes"; then
+  ZEND_MAX_EXECUTION_TIMERS='no'
+fi
+
+if test "$ZEND_MAX_EXECUTION_TIMERS" = "yes"; then
+  AC_DEFINE(ZEND_MAX_EXECUTION_TIMERS, 1, [Use zend max execution timers])
+  CFLAGS="$CFLAGS -DZEND_MAX_EXECUTION_TIMERS"
+fi
+
+AC_MSG_CHECKING(whether to enable zend max execution timers)
+AC_MSG_RESULT($ZEND_MAX_EXECUTION_TIMERS)
+
 ])
 
 AC_MSG_CHECKING(whether /dev/urandom exists)

Zend/zend.c

@@ -35,6 +35,7 @@
 #include "zend_attributes.h"
 #include "zend_observer.h"
 #include "zend_fibers.h"
+#include "zend_max_execution_timer.h"
 #include "Optimizer/zend_optimizer.h"
 
 static size_t global_map_ptr_last = 0;
@@ -800,6 +801,10 @@ static void executor_globals_ctor(zend_executor_globals *executor_globals) /* {{
 	executor_globals->record_errors = false;
 	executor_globals->num_errors = 0;
 	executor_globals->errors = NULL;
+#ifdef ZEND_MAX_EXECUTION_TIMERS
+	executor_globals->pid = 0;
+	executor_globals->oldact = (struct sigaction){0};
+#endif
 }
 /* }}} */
 
@@ -821,6 +826,7 @@ static void zend_new_thread_end_handler(THREAD_T thread_id) /* {{{ */
 {
 	zend_copy_ini_directives();
 	zend_ini_refresh_caches(ZEND_INI_STAGE_STARTUP);
+	zend_max_execution_timer_init();
 }
 /* }}} */
 #endif
@@ -1612,6 +1618,18 @@ ZEND_API ZEND_COLD ZEND_NORETURN void zend_error_noreturn(int type, const char *
 	abort();
 }
 
+ZEND_API ZEND_COLD ZEND_NORETURN void zend_strerror_noreturn(int type, int errn, const char *message)
+{
+#ifdef HAVE_STR_ERROR_R
+	char buf[1024];
+	strerror_r(errn, buf, sizeof(buf));
+#else
+	char *buf = strerror(errn);
+#endif
+
+	zend_error_noreturn(type, "%s: %s (%d)", message, buf, errn);
+}
+
 ZEND_API ZEND_COLD void zend_error_zstr(int type, zend_string *message) {
 	zend_string *filename;
 	uint32_t lineno;

Zend/zend.h

@@ -39,6 +39,7 @@
 #include "zend_smart_str_public.h"
 #include "zend_smart_string_public.h"
 #include "zend_signal.h"
+#include "zend_max_execution_timer.h"
 
 #define zend_sprintf sprintf
 
@@ -353,6 +354,9 @@ ZEND_API ZEND_COLD void zend_value_error(const char *format, ...) ZEND_ATTRIBUTE
 
 ZEND_COLD void zenderror(const char *error);
 
+/* For internal C errors */
+ZEND_API ZEND_COLD ZEND_NORETURN void zend_strerror_noreturn(int type, int errn, const char *message);
+
 /* The following #define is used for code duality in PHP for Engine 1 & 2 */
 #define ZEND_STANDARD_CLASS_DEF_PTR zend_standard_class_def
 extern ZEND_API zend_class_entry *zend_standard_class_def;

Zend/zend_execute_API.c

@@ -43,6 +43,9 @@
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+#ifdef ZEND_MAX_EXECUTION_TIMERS
+#include <sys/syscall.h>
+#endif
 
 ZEND_API void (*zend_execute_ex)(zend_execute_data *execute_data);
 ZEND_API void (*zend_execute_internal)(zend_execute_data *execute_data, zval *return_value);
@@ -192,6 +195,7 @@ void init_executor(void) /* {{{ */
 	EG(num_errors) = 0;
 	EG(errors) = NULL;
 
+	zend_max_execution_timer_init();
 	zend_fiber_init();
 	zend_weakrefs_init();
 
@@ -403,6 +407,7 @@ void shutdown_executor(void) /* {{{ */
 	zend_shutdown_executor_values(fast_shutdown);
 
 	zend_weakrefs_shutdown();
+	zend_max_execution_timer_shutdown();
 	zend_fiber_shutdown();
 
 	zend_try {
@@ -1314,8 +1319,27 @@ ZEND_API ZEND_NORETURN void ZEND_FASTCALL zend_timeout(void) /* {{{ */
 /* }}} */
 
 #ifndef ZEND_WIN32
+# ifdef ZEND_MAX_EXECUTION_TIMERS
+static void zend_timeout_handler(int dummy, siginfo_t *si, void *uc) /* {{{ */
+{
+	if (si->si_value.sival_ptr != &EG(max_execution_timer_timer)) {
+#ifdef MAX_EXECUTION_TIMERS_DEBUG
+		fprintf(stderr, "Executing previous handler (if set) for unexpected signal SIGRTMIN received on thread %d\n", (pid_t) syscall(SYS_gettid));
+#endif
+
+		if (EG(oldact).sa_sigaction) {
+			EG(oldact).sa_sigaction(dummy, si, uc);
+
+			return;
+		}
+		if (EG(oldact).sa_handler) EG(oldact).sa_handler(dummy);
+
+		return;
+	}
+# else
 static void zend_timeout_handler(int dummy) /* {{{ */
 {
+# endif
 #ifndef ZTS
 	if (EG(timed_out)) {
 		/* Die on hard timeout */
@@ -1415,6 +1439,21 @@ static void zend_set_timeout_ex(zend_long seconds, bool reset_signals) /* {{{ */
 		zend_error_noreturn(E_ERROR, "Could not queue new timer");
 		return;
 	}
+#elif defined(ZEND_MAX_EXECUTION_TIMERS)
+	zend_max_execution_timer_settime(seconds);
+
+	if (reset_signals) {
+		sigset_t sigset;
+		struct sigaction act;
+
+		act.sa_sigaction = zend_timeout_handler;
+		sigemptyset(&act.sa_mask);
+		act.sa_flags = SA_ONSTACK | SA_SIGINFO;
+		sigaction(SIGRTMIN, &act, NULL);
+		sigemptyset(&sigset);
+		sigaddset(&sigset, SIGRTMIN);
+		sigprocmask(SIG_UNBLOCK, &sigset, NULL);
+	}
 #elif defined(HAVE_SETITIMER)
 	{
 		struct itimerval t_r;		/* timeout requested */
@@ -1480,6 +1519,8 @@ void zend_unset_timeout(void) /* {{{ */
 		}
 		tq_timer = NULL;
 	}
+#elif ZEND_MAX_EXECUTION_TIMERS
+	zend_max_execution_timer_settime(0);
 #elif defined(HAVE_SETITIMER)
 	if (EG(timeout_seconds)) {
 		struct itimerval no_timeout;

Zend/zend_globals.h

@@ -22,6 +22,7 @@
 
 
 #include <setjmp.h>
+#include <sys/types.h>
 
 #include "zend_globals_macros.h"
 
@@ -36,6 +37,7 @@
 #include "zend_multibyte.h"
 #include "zend_multiply.h"
 #include "zend_arena.h"
+#include "zend_max_execution_timer.h"
 
 /* Define ZTS if you want a thread-safe Zend */
 /*#undef ZTS*/
@@ -266,6 +268,12 @@ struct _zend_executor_globals {
 	uint32_t num_errors;
 	zend_error_info **errors;
 
+#ifdef ZEND_MAX_EXECUTION_TIMERS
+	timer_t max_execution_timer_timer;
+	pid_t pid;
+	struct sigaction oldact;
+#endif
+
 	void *reserved[ZEND_MAX_RESERVED_RESOURCES];
 };
 

Zend/zend_max_execution_timer.c

@@ -0,0 +1,103 @@
+/*
+   +----------------------------------------------------------------------+
+   | 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
+
+#include <stdio.h>
+#include <signal.h>
+#include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+
+#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
+
+ZEND_API void zend_max_execution_timer_init(void) /* {{{ */
+{
+	struct sigevent sev;
+	sev.sigev_notify = SIGEV_THREAD_ID;
+	sev.sigev_value.sival_ptr = &EG(max_execution_timer_timer);
+	sev.sigev_signo = SIGRTMIN;
+	sev.sigev_notify_thread_id = (pid_t) syscall(SYS_gettid);
+
+	EG(pid) = getpid();
+	// 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(CLOCK_BOOTTIME, &sev, &EG(max_execution_timer_timer)) != 0) {
+		zend_strerror_noreturn(E_ERROR, errno, "Could not create timer");
+	}
+
+#  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

Zend/zend_max_execution_timer.h

@@ -0,0 +1,36 @@
+/*
+   +----------------------------------------------------------------------+
+   | 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>                            |
+   +----------------------------------------------------------------------+
+ */
+
+#ifndef ZEND_MAX_EXECUTION_TIMER_H
+#define ZEND_MAX_EXECUTION_TIMER_H
+
+# ifdef ZEND_MAX_EXECUTION_TIMERS
+
+#include "zend_long.h"
+
+/* Must be called after calls to fork() */
+ZEND_API void zend_max_execution_timer_init(void);
+void zend_max_execution_timer_settime(zend_long seconds);
+void zend_max_execution_timer_shutdown(void);
+
+# else
+
+#define zend_max_execution_timer_init()
+#define zend_max_execution_timer_settime(seconds)
+#define zend_max_execution_timer_shutdown()
+
+# endif
+#endif

configure.ac

@@ -609,6 +609,7 @@ vasprintf \
 asprintf \
 nanosleep \
 memmem \
+strerror_r \
 )
 
 AX_FUNC_WHICH_GETHOSTBYNAME_R
@@ -1633,7 +1634,7 @@ PHP_ADD_SOURCES(Zend, \
     zend_closures.c zend_weakrefs.c zend_float.c zend_string.c zend_signal.c zend_generators.c \
     zend_virtual_cwd.c zend_ast.c zend_objects.c zend_object_handlers.c zend_objects_API.c \
     zend_default_classes.c zend_inheritance.c zend_smart_str.c zend_cpuinfo.c zend_gdb.c \
-    zend_observer.c zend_system_id.c zend_enum.c zend_fibers.c \
+    zend_observer.c zend_system_id.c zend_enum.c zend_fibers.c zend_max_execution_timer.c \
 	Optimizer/zend_optimizer.c \
 	Optimizer/pass1.c \
 	Optimizer/pass3.c \

ext/pcntl/pcntl.c

@@ -50,6 +50,8 @@
 # define NSIG 32
 #endif
 
+#include "Zend/zend_max_execution_timer.h"
+
 ZEND_DECLARE_MODULE_GLOBALS(pcntl)
 static PHP_GINIT_FUNCTION(pcntl);
 
@@ -531,6 +533,8 @@ PHP_FUNCTION(pcntl_fork)
 	if (id == -1) {
 		PCNTL_G(last_error) = errno;
 		php_error_docref(NULL, E_WARNING, "Error %d", errno);
+	} else if (id == 0) {
+		zend_max_execution_timer_init();
 	}
 
 	RETURN_LONG((zend_long) id);

ext/standard/info.c

@@ -891,6 +891,12 @@ PHPAPI ZEND_COLD void php_print_info(int flag)
 			efree(descr);
 		}
 
+#ifdef ZEND_MAX_EXECUTION_TIMERS
+		php_info_print_table_row(2, "Zend Max Execution Timers", "enabled" );
+#else
+		php_info_print_table_row(2, "Zend Max Execution Timers", "disabled" );
+#endif
+
 #if HAVE_IPV6
 		php_info_print_table_row(2, "IPv6 Support", "enabled" );
 #else