From: Timo Sirainen <timo.sirainen@open-xchange.com>
Date: Tue, 30 May 2023 20:17:21 +0000 (+0300)
Subject: lib: Fix MODULE_CONTEXT_REQUIRE() to always panic if context is unset
X-Git-Tag: 2.4.0~2723
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=54b205e72e6c60e76f61fb89b48ba4fd0034981b;p=thirdparty%2Fdovecot%2Fcore.git

lib: Fix MODULE_CONTEXT_REQUIRE() to always panic if context is unset

Previously panic happened only if the module_contexts array was too small,
not when the element inside the array was NULL.

This required rewriting the macros partially as inline functions, which also
simplifies how they work.
---

diff --git a/src/lib/module-context.h b/src/lib/module-context.h
index 3d2b1d6cb0..6cf7ffd44e 100644
--- a/src/lib/module-context.h
+++ b/src/lib/module-context.h
@@ -45,21 +45,6 @@
 #define OBJ_REGISTER_COMPATIBLE(obj, id_ctx) \
 	COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE(OBJ_REGISTER(obj), (id_ctx).reg)
 
-#define MODULE_CONTEXT(obj, id_ctx) \
-	(module_get_context_id(&(id_ctx).id) < array_count(&(obj)->module_contexts) ? \
-	 (*((void **)array_idx_modifiable(&(obj)->module_contexts,	\
- 		module_get_context_id(&(id_ctx).id)) + \
-	    OBJ_REGISTER_COMPATIBLE(obj, id_ctx))) : NULL)
-
-/* Will crash if context is missing. This is mainly used to simplify code and
-   keep static analyzers happy. This syntax discards result of i_panic and
-   returns NULL instead to keep compilers happy. */
-#define MODULE_CONTEXT_REQUIRE(obj, id_ctx) \
-	(module_get_context_id(&(id_ctx).id) < array_count(&(obj)->module_contexts) ? \
-	 (*((void **)array_idx_modifiable(&(obj)->module_contexts,      \
-		module_get_context_id(&(id_ctx).id)) + \
-	    OBJ_REGISTER_COMPATIBLE(obj, id_ctx))) : (i_panic("Module context " #id_ctx " missing"), NULL))
-
 #ifdef HAVE_TYPEOF
 #  define MODULE_CONTEXT_DEFINE(_name, _reg) \
 	struct _name { \
@@ -96,6 +81,35 @@ static inline unsigned int module_get_context_id(struct module_context_id *id)
 	return id->module_id;
 }
 
+static inline void *
+module_context_get(struct array *array, struct module_context_id *id)
+{
+	unsigned int module_id = module_get_context_id(id);
+	if (module_id >= array_count_i(array))
+		return NULL;
+	void **ctx = (void **)array_idx_modifiable_i(array, module_id);
+	return *ctx;
+}
+#define MODULE_CONTEXT(obj, id_ctx) \
+	(TRUE ? module_context_get(&(obj)->module_contexts.arr, &(id_ctx).id) : \
+	OBJ_REGISTER_COMPATIBLE(obj, id_ctx))
+
+static inline void *
+module_context_get_require(struct array *array, struct module_context_id *id,
+			   const char *panic_message)
+{
+	void *ctx = module_context_get(array, id);
+	if (ctx == NULL)
+		i_panic("%s", panic_message);
+	return ctx;
+}
+/* Will crash if context is missing. This is mainly used to simplify code and
+   prevent static analyzers from complaining about NULL pointer dereferences. */
+#define MODULE_CONTEXT_REQUIRE(obj, id_ctx) \
+	(TRUE ? module_context_get_require(&(obj)->module_contexts.arr, \
+		&(id_ctx).id, "Module context " #id_ctx " missing") : \
+	OBJ_REGISTER_COMPATIBLE(obj, id_ctx))
+
 #define MODULE_CONTEXT_SET_FULL(obj, id_ctx, ctx, module_ctx) STMT_START { \
 	(void)COMPILE_ERROR_IF_TYPES_NOT_COMPATIBLE(module_ctx, \
 			(**(obj)->module_contexts.v)); \