Fix bug #76895

There are two parts here: First, opcache should not be blocking
signals while invoking compile_file. Second, we should have noticed
this issue a long time ago, but apparently we don't use
zend_signal_deactivate as part of the standard shutdown sequence.
In addition to calling deactivate, also make sure that we always
check for zero depth, independent of SIGG(check), which is currently
not enabled.

Author: nikic

Zend/zend_signal.c

@@ -330,20 +330,21 @@ void zend_signal_activate(void)
 
 	SIGG(active) = 1;
 	SIGG(depth)  = 0;
+	SIGG(check)  = ZEND_DEBUG;
 } /* }}} */
 
 /* {{{ zend_signal_deactivate
  * */
 void zend_signal_deactivate(void)
 {
-
 	if (SIGG(check)) {
 		size_t x;
 		struct sigaction sa;
 
 		if (SIGG(depth) != 0) {
 			zend_error(E_CORE_WARNING, "zend_signal: shutdown with non-zero blocking depth (%d)", SIGG(depth));
 		}
+
 		/* did anyone steal our installed handler */
 		for (x = 0; x < sizeof(zend_sigs) / sizeof(*zend_sigs); x++) {
 			sigaction(zend_sigs[x], NULL, &sa);
@@ -353,12 +354,21 @@ void zend_signal_deactivate(void)
 		}
 	}
 
-	SIGNAL_BEGIN_CRITICAL();
-	SIGG(active) = 0;
+	/* After active=0 is set, signal handlers will be called directly and other
+	 * state that is reset below will not be accessed. */
+	*((volatile int *) &SIGG(active)) = 0;
+
 	SIGG(running) = 0;
 	SIGG(blocked) = 0;
 	SIGG(depth) = 0;
-	SIGNAL_END_CRITICAL();
+
+	/* If there are any queued signals because of a missed unblock, drop them. */
+	if (SIGG(phead) && SIGG(ptail)) {
+		SIGG(ptail)->next = SIGG(pavail);
+		SIGG(pavail) = SIGG(phead);
+		SIGG(phead) = NULL;
+		SIGG(ptail) = NULL;
+	}
 }
 /* }}} */
 

ext/opcache/ZendAccelerator.c

@@ -1570,7 +1570,9 @@ static zend_persistent_script *opcache_compile_file(zend_file_handle *file_handl
 
 	/* check blacklist right after ensuring that file was opened */
 	if (file_handle->opened_path && zend_accel_blacklist_is_blacklisted(&accel_blacklist, ZSTR_VAL(file_handle->opened_path))) {
+		SHM_UNPROTECT();
 		ZCSG(blacklist_misses)++;
+		SHM_PROTECT();
 		*op_array_p = accelerator_orig_compile_file(file_handle, type);
 		return NULL;
 	}
@@ -1601,7 +1603,9 @@ static zend_persistent_script *opcache_compile_file(zend_file_handle *file_handl
 		}
 
 		if (ZCG(accel_directives).max_file_size > 0 && size > (size_t)ZCG(accel_directives).max_file_size) {
+			SHM_UNPROTECT();
 			ZCSG(blacklist_misses)++;
+			SHM_PROTECT();
 			*op_array_p = accelerator_orig_compile_file(file_handle, type);
 			return NULL;
 		}
@@ -2003,11 +2007,16 @@ zend_op_array *persistent_compile_file(zend_file_handle *file_handle, int type)
 			return accelerator_orig_compile_file(file_handle, type);
 		}
 
+		SHM_PROTECT();
+		HANDLE_UNBLOCK_INTERRUPTIONS();
+		persistent_script = opcache_compile_file(file_handle, type, key, &op_array);
+		HANDLE_BLOCK_INTERRUPTIONS();
+		SHM_UNPROTECT();
+
 		/* Try and cache the script and assume that it is returned from_shared_memory.
          * If it isn't compile_and_cache_file() changes the flag to 0
          */
        	from_shared_memory = 0;
-		persistent_script = opcache_compile_file(file_handle, type, key, &op_array);
 		if (persistent_script) {
 			persistent_script = cache_script_in_shared_memory(persistent_script, key, key ? key_length : 0, &from_shared_memory);
 		}

main/main.c

@@ -1932,6 +1932,11 @@ void php_request_shutdown(void *dummy)
 		zend_unset_timeout();
 	} zend_end_try();
 
+	/* 17. Deactivate Zend signals */
+#ifdef ZEND_SIGNALS
+	zend_signal_deactivate();
+#endif
+
 #ifdef PHP_WIN32
 	if (PG(com_initialized)) {
 		CoUninitialize();