ensure only one signal handler is set

Author: withinboredom

Zend/zend_max_execution_timer.c

@@ -33,6 +33,8 @@
 # define sigev_notify_thread_id _sigev_un._tid
 # endif
 
+int is_handler_set = 0; // global flag
+
 ZEND_API void zend_max_execution_timer_init(void) /* {{{ */
 {
 	struct sigevent sev;
@@ -41,6 +43,13 @@ ZEND_API void zend_max_execution_timer_init(void) /* {{{ */
 	sev.sigev_signo = SIGRTMIN;
 	sev.sigev_notify_thread_id = (pid_t) syscall(SYS_gettid);
 
+	// Now check to see if a we've already set a signal handler
+	if(is_handler_set) {
+		// emit a warning and return
+		zend_error(E_WARNING, "A max execution timer was already configured and will not be configured again.");
+		return;
+	}
+
 	// 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");
@@ -53,6 +62,7 @@ ZEND_API void zend_max_execution_timer_init(void) /* {{{ */
 #  endif
 
 	sigaction(sev.sigev_signo, NULL, &EG(oldact));
+	is_handler_set = 1;
 }
 /* }}} */
 
@@ -107,6 +117,7 @@ void zend_max_execution_timer_shutdown(void) /* {{{ */
 	if(sigaction(SIGRTMIN, &ign_sigrtmin, &prev) < 0) {
 		zend_strerror_noreturn(E_ERROR, errno, "Could not clear pending timer signal");
 	}
+	is_handler_set = 0;
 }
 /* }}}} */