Improve sesson write failure message for user error handlers

NEWS

@@ -35,4 +35,8 @@ PHP                                                                        NEWS
   . add ZipArchive::getStreamName() method
   . add ZipArchive::getStreamIndex() method
 
+- Session:
+  . Fixed bug GH-7787 (Improve session write failure message for user error
+    handlers). (ilutov)
+
 <<< NOTE: Insert NEWS from last stable release here prior to actual release! >>>

ext/session/php_session.h

@@ -176,6 +176,7 @@ typedef struct _php_ps_globals {
 	} mod_user_names;
 	int mod_user_implemented;
 	int mod_user_is_open;
+	zend_string *mod_user_class_name;
 	const struct ps_serializer_struct *serializer;
 	zval http_session_vars;
 	bool auto_start;

ext/session/session.c

@@ -472,6 +472,9 @@ static void php_session_save_current_state(int write) /* {{{ */
 
 	if (write) {
 		IF_SESSION_VARS() {
+			zend_string *handler_class_name = PS(mod_user_class_name);
+			const char *handler_function_name;
+
 			if (PS(mod_data) || PS(mod_user_implemented)) {
 				zend_string *val;
 
@@ -483,12 +486,15 @@ static void php_session_save_current_state(int write) /* {{{ */
 						&& zend_string_equals(val, PS(session_vars))
 					) {
 						ret = PS(mod)->s_update_timestamp(&PS(mod_data), PS(id), val, PS(gc_maxlifetime));
+						handler_function_name = handler_class_name != NULL ? "updateTimestamp" : "update_timestamp";
 					} else {
 						ret = PS(mod)->s_write(&PS(mod_data), PS(id), val, PS(gc_maxlifetime));
+						handler_function_name = "write";
 					}
 					zend_string_release_ex(val, 0);
 				} else {
 					ret = PS(mod)->s_write(&PS(mod_data), PS(id), ZSTR_EMPTY_ALLOC(), PS(gc_maxlifetime));
+					handler_function_name = "write";
 				}
 			}
 
@@ -499,9 +505,14 @@ static void php_session_save_current_state(int write) /* {{{ */
 									 "is correct (%s)",
 									 PS(mod)->s_name,
 									 PS(save_path));
+				} else if (handler_class_name != NULL) {
+					php_error_docref(NULL, E_WARNING, "Failed to write session data using user "
+									 "defined save handler. (session.save_path: %s, handler: %s::%s)", PS(save_path),
+									 ZSTR_VAL(handler_class_name), handler_function_name);
 				} else {
 					php_error_docref(NULL, E_WARNING, "Failed to write session data using user "
-									 "defined save handler. (session.save_path: %s)", PS(save_path));
+									 "defined save handler. (session.save_path: %s, handler: %s)", PS(save_path),
+									 handler_function_name);
 				}
 			}
 		}
@@ -2042,6 +2053,12 @@ PHP_FUNCTION(session_set_save_handler)
 			++i;
 		} ZEND_HASH_FOREACH_END();
 
+
+		if (PS(mod_user_class_name)) {
+			zend_string_release(PS(mod_user_class_name));
+		}
+		PS(mod_user_class_name) = zend_string_copy(Z_OBJCE_P(obj)->name);
+
 		if (register_shutdown) {
 			/* create shutdown function */
 			php_shutdown_function_entry shutdown_function_entry;
@@ -2095,6 +2112,11 @@ PHP_FUNCTION(session_set_save_handler)
 		RETURN_FALSE;
 	}
 
+	if (PS(mod_user_class_name)) {
+		zend_string_release(PS(mod_user_class_name));
+	}
+	PS(mod_user_class_name) = NULL;
+
 	/* remove shutdown function */
 	remove_user_shutdown_function("session_shutdown", sizeof("session_shutdown") - 1);
 
@@ -2775,6 +2797,7 @@ static PHP_GINIT_FUNCTION(ps) /* {{{ */
 	ps_globals->session_status = php_session_none;
 	ps_globals->default_mod = NULL;
 	ps_globals->mod_user_implemented = 0;
+	ps_globals->mod_user_class_name = NULL;
 	ps_globals->mod_user_is_open = 0;
 	ps_globals->session_vars = NULL;
 	ps_globals->set_handler = 0;

ext/session/tests/gh7787.phpt

@@ -0,0 +1,90 @@
+--TEST--
+GH-7787: Provide more SessionHandler failure information
+--EXTENSIONS--
+session
+--SKIPIF--
+<?php include('skipif.inc'); ?>
+--INI--
+session.use_strict_mode=0
+session.save_handler=files
+--FILE--
+<?php
+class MySessionHandler extends SessionHandler implements SessionUpdateTimestampHandlerInterface
+{
+    public function open($path, $sessname): bool {
+        return true;
+    }
+
+    public function close(): bool {
+        return true;
+    }
+
+    public function read($sessid): string|false {
+        return 'foo|s:3:"foo";';
+    }
+
+    public function write($sessid, $sessdata): bool {
+        return false;
+    }
+
+    public function destroy($sessid): bool {
+        return true;
+    }
+
+    public function gc($maxlifetime): int|false {
+        return true;
+    }
+
+    public function create_sid(): string {
+        return sha1(random_bytes(32));
+    }
+
+    public function validateId($sid): bool {
+        return true;
+    }
+
+    public function updateTimestamp($sessid, $sessdata): bool {
+        return false;
+    }
+}
+
+ob_start();
+
+$handler = new MySessionHandler();
+session_set_save_handler($handler);
+
+session_start();
+$_SESSION['foo'] = 'bar';
+session_write_close();
+
+session_start();
+session_write_close();
+
+session_set_save_handler(
+    fn() => true,
+    fn() => true,
+    fn() => 'foo|s:3:"foo";',
+    fn() => false,
+    fn() => true,
+    fn() => true,
+    fn() => sha1(random_bytes(32)),
+    fn() => true,
+    fn() => false,
+);
+
+session_start();
+$_SESSION['foo'] = 'bar';
+session_write_close();
+
+session_start();
+session_write_close();
+
+?>
+--EXPECTF--
+Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: , handler: MySessionHandler::write) in %s on line %d
+
+Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: , handler: MySessionHandler::updateTimestamp) in %s on line %d
+
+Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: , handler: write) in %s on line %d
+
+Warning: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: , handler: update_timestamp) in %s on line %d