Zend: always populate error pointer on failure of zend_is_callable()

Zend/tests/error_handler/gh_21699.phpt

@@ -24,7 +24,7 @@ Stack trace:
 #1 %s(%d): bar->test()
 #2 {main}
 
-Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, (null) in %s:%d
+Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, cannot use "self"/"parent"/"static" in callables in %s:%d
 Stack trace:
 #0 %s(%d): bar->test()
 #1 {main}

Zend/tests/error_handler/gh_21699_parent.phpt

@@ -25,7 +25,7 @@ Stack trace:
 #1 %s(%d): Child->test()
 #2 {main}
 
-Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, (null) in %s:%d
+Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, cannot use "self"/"parent"/"static" in callables in %s:%d
 Stack trace:
 #0 %s(%d): Child->test()
 #1 {main}

Zend/tests/error_handler/gh_21699_static.phpt

@@ -24,7 +24,7 @@ Stack trace:
 #1 %s(%d): bar->test()
 #2 {main}
 
-Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, (null) in %s:%d
+Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, cannot use "self"/"parent"/"static" in callables in %s:%d
 Stack trace:
 #0 %s(%d): bar->test()
 #1 {main}

Zend/tests/gh16799.phpt

@@ -19,7 +19,7 @@ Stack trace:
 #1 %s(%d): Test::test()
 #2 {main}
 
-Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, (null) in %s:%d
+Next TypeError: call_user_func(): Argument #1 ($callback) must be a valid callback, cannot use "self"/"parent"/"static" in callables in %s:%d
 Stack trace:
 #0 %s(%d): Test::test()
 #1 {main}

Zend/zend_API.c

@@ -3817,6 +3817,11 @@ static bool zend_is_callable_check_class(zend_string *name, zend_class_entry *sc
 	ZSTR_ALLOCA_FREE(lcname, use_heap);
 	/* User error handlers may throw from deprecations above; do not report callable as valid. */
 	if (UNEXPECTED(EG(exception))) {
+		/* We allocate an error string that will not be used as callers of zend_is_callable() expect an
+		 * error to be assigned on failure */
+		if (error && *error == NULL) {
+			*error = estrdup("cannot use \"self\"/\"parent\"/\"static\" in callables");
+		}
 		return false;
 	}
 	return ret;

Zend/zend_execute_API.c

@@ -848,13 +848,11 @@ zend_result zend_call_function(zend_fcall_info *fci, zend_fcall_info_cache *fci_
 		}
 
 		if (!zend_is_callable_ex(&fci->function_name, fci->object, 0, NULL, fci_cache, &error)) {
+			ZEND_ASSERT(error && "Should have error if not callable");
 			if (EG(exception)) {
-				if (error) {
-					efree(error);
-				}
+				efree(error);
 				return SUCCESS;
 			}
-			ZEND_ASSERT(error && "Should have error if not callable");
 			zend_string *callable_name
 				= zend_get_callable_name_ex(&fci->function_name, fci->object);
 			zend_throw_error(NULL, "Invalid callback %s, %s", ZSTR_VAL(callable_name), error);

docs/source/core/data-structures/fci-fcc.rst

@@ -80,8 +80,9 @@ There are some functions that do not require the use of either the FCI or the FC
       -  Check if the ``callable`` zval is a PHP callable. Returns true if it is, false otherwise.
          ``fcc`` is an out parameter constructing the FCC struct, see below for details. ``error``
          is an optional out parameter holding the error message if ``callable`` is not a PHP
-         callable. Note: the signature used to be ``bool zend_is_callable(zval *callable, uint32_t
-         check_flags, zend_string **callable_name)`` prior to PHP 8.7.
+         callable. If ``error`` is non-NULL and false is returned it is *always* populated. Note:
+         the signature used to be ``bool zend_is_callable(zval *callable, uint32_t check_flags,
+         zend_string **callable_name)`` prior to PHP 8.7.
 
    -  -  .. code:: c
 

ext/curl/interface.c

@@ -1656,7 +1656,7 @@ static bool php_curl_set_callable_handler(zend_fcall_info_cache *const handler_f
 	}
 
 	char *error = NULL;
-	if (UNEXPECTED(!zend_is_callable_ex(callable, /* object */ NULL, /* check_flags */ 0, /* callable_name */ NULL, handler_fcc, /* error */ &error))) {
+	if (UNEXPECTED(!zend_is_callable(callable, handler_fcc, /* error */ &error))) {
 		if (!EG(exception)) {
 			zend_argument_type_error(2 + !is_array_config, "must be a valid callback for option %s, %s", option_name, error);
 		}

ext/curl/multi.c

@@ -485,7 +485,7 @@ static bool _php_curl_multi_setopt(php_curlm *mh, zend_long option, zval *zvalue
 			}
 
 			char *error_str = NULL;
-			if (UNEXPECTED(!zend_is_callable_ex(zvalue, /* object */ NULL, /* check_flags */ 0, /* callable_name */ NULL, &mh->handlers.server_push, /* error */ &error_str))) {
+			if (UNEXPECTED(!zend_is_callable(zvalue, &mh->handlers.server_push, &error_str))) {
 				if (!EG(exception)) {
 					zend_argument_type_error(2, "must be a valid callback for option CURLMOPT_PUSHFUNCTION, %s", error_str);
 				}

ext/openssl/xp_ssl.c

@@ -2008,13 +2008,9 @@ static zend_result php_openssl_validate_and_allocate_psk_callback(
 	char *is_callable_error = NULL;
 	zend_fcall_info_cache fcc = {0};
 	if (!zend_is_callable(callable, &fcc, &is_callable_error)) {
-		if (is_callable_error) {
-			zend_type_error("%s must be a valid callback, %s",
-					callback_name, is_callable_error);
-			efree(is_callable_error);
-		} else {
-			zend_type_error("%s must be a valid callback", callback_name);
-		}
+		zend_type_error("%s must be a valid callback, %s",
+				callback_name, is_callable_error);
+		efree(is_callable_error);
 		return FAILURE;
 	}
 
@@ -2131,12 +2127,8 @@ static zend_result php_openssl_setup_server_early_data(php_stream *stream,
 		char *is_callable_error = NULL;
 		zend_fcall_info_cache fcc = {0};
 		if (!zend_is_callable(val, &fcc, &is_callable_error)) {
-			if (is_callable_error) {
-				zend_type_error("early_data_cb must be a valid callback, %s", is_callable_error);
-				efree(is_callable_error);
-			} else {
-				zend_type_error("early_data_cb must be a valid callback");
-			}
+			zend_type_error("early_data_cb must be a valid callback, %s", is_callable_error);
+			efree(is_callable_error);
 			return FAILURE;
 		}
 
@@ -2319,12 +2311,8 @@ static zend_result php_openssl_validate_and_allocate_session_callback(
 	/* Validate callable */
 	zend_fcall_info_cache fcc;
 	if (!zend_is_callable(callable, &fcc, &is_callable_error)) {
-		if (is_callable_error) {
-			zend_type_error("%s must be a valid callback, %s", callback_name, is_callable_error);
-			efree(is_callable_error);
-		} else {
-			zend_type_error("%s must be a valid callback", callback_name);
-		}
+		zend_type_error("%s must be a valid callback, %s", callback_name, is_callable_error);
+		efree(is_callable_error);
 		return FAILURE;
 	}
 

ext/pdo/pdo_stmt.c

@@ -1137,12 +1137,8 @@ static bool pdo_get_fcc_from_zval(zend_fcall_info_cache *fcc, zval *callable) {
 
 	char *is_callable_error = NULL;
 	if (!zend_is_callable(callable, fcc, &is_callable_error)) {
-		if (is_callable_error) {
-			zend_type_error("%s", is_callable_error);
-			efree(is_callable_error);
-		} else {
-			zend_type_error("User-supplied function must be a valid callback");
-		}
+		zend_type_error("%s", is_callable_error);
+		efree(is_callable_error);
 		return false;
 	}
 	return true;

main/streams/stream_errors.c

@@ -370,10 +370,8 @@ static void php_stream_call_error_handler(const zval *handler, zval *errors_arra
 	char *is_callable_error = NULL;
 
 	if (!zend_is_callable(handler, &fcc, &is_callable_error)) {
-		if (is_callable_error) {
-			zend_type_error("stream error handler must be a valid callback, %s", is_callable_error);
-			efree(is_callable_error);
-		}
+		zend_type_error("stream error handler must be a valid callback, %s", is_callable_error);
+		efree(is_callable_error);
 		return;
 	}