sapi/was: set HTTP status 404 if opening the primary script fails

All other SAPIs detect this by doing a stat() on the primary script,
but that's a system call I'd like to avoid.  It should be enough to
open() it later from within persistent_compile_file().  That however
throws a fatal error if the file could not be opened; therefore, that
function needs to be patched to avoid the fatal error when opening the
primary script, allowing the caller to handle the error condition.

Now to be able to detect whether the status has been set already,
initialize it to zero and set it in sapi_was_send_headers().  If
php_execute_script() fails and "opened_path" is still NULL, we can set
status 404 (instead of the previous 500 which was misleading).

Author: MaxKellermann

ext/opcache/ZendAccelerator.c

@@ -2098,7 +2098,7 @@ static zend_op_array *persistent_compile_file_inner(zend_file_handle *file_handl
 			/* open file to resolve the path */
 		    if (file_handle->type == ZEND_HANDLE_FILENAME
 		     && accelerator_orig_zend_stream_open_function(file_handle) == FAILURE) {
-				if (!EG(exception)) {
+				if (!EG(exception) && !file_handle->primary_script) {
 					if (type == ZEND_REQUIRE) {
 						zend_message_dispatcher(ZMSG_FAILED_REQUIRE_FOPEN, ZSTR_VAL(filename));
 					} else {

sapi/was/was_main.c

@@ -171,6 +171,9 @@ static int sapi_was_send_headers(sapi_headers_struct *sapi_headers)
 		/* special case for "--precompile" mode */
 		return SAPI_HEADER_SENT_SUCCESSFULLY;
 
+	if (SG(sapi_headers).http_response_code == 0)
+		SG(sapi_headers).http_response_code = 200;
+
 	if (!was_simple_status(w, SG(sapi_headers).http_response_code))
 		return SAPI_HEADER_SEND_FAILED;
 
@@ -445,7 +448,8 @@ static void init_request_info(struct was_simple *w, const char *request_uri)
 	const char *content_type = was_simple_get_header(w, "content-type");
 	SG(request_info).content_type = content_type ? content_type : "";
 
-	SG(sapi_headers).http_response_code = 200;
+	/* 0 means the http_response_code has not yet been set */
+	SG(sapi_headers).http_response_code = 0;
 }
 
 static zend_result was_module_main(struct was_simple *w)
@@ -456,7 +460,16 @@ static zend_result was_module_main(struct was_simple *w)
 	zend_file_handle file_handle;
 	zend_stream_init_filename(&file_handle, SG(request_info).path_translated);
 	file_handle.primary_script = true;
-	php_execute_script(&file_handle);
+
+	if (!php_execute_script(&file_handle) &&
+	    file_handle.opened_path == NULL &&
+	    SG(sapi_headers).http_response_code == 0) {
+		/* the primary script could not be opened and no
+		   response has been sent: change the HTTP status to
+		   "404 Not Found" */
+		SG(sapi_headers).http_response_code = 404;
+	}
+
 	zend_destroy_file_handle(&file_handle);
 
 	finish_was_metrics(w);