1 files changed, 116 insertions, 0 deletions
diff --git a/src/lib/module-context.h b/src/lib/module-context.h
new file mode 100644
index 0000000..3d2b1d6
--- /dev/null
+++ b/src/lib/module-context.h
@@ -0,0 +1,116 @@
+#ifndef MODULE_CONTEXT_H
+#define MODULE_CONTEXT_H
+
+#include "array.h"
+
+/*
+   This is a bit complex to use, but it prevents using wrong module IDs
+   in module_contexts arrays.
+
+   ---------
+   The main structure is implemented like this:
+
+   struct STRUCT_NAME_module_register {
+	   unsigned int id;
+   };
+   union STRUCT_NAME_module_context {
+	   struct STRUCT_NAME_module_register *reg;
+	   // it's allowed to have some structure here so it won't waste space.
+	   // for example: struct STRUCT_NAME_vfuncs super;
+   };
+   struct STRUCT_NAME {
+	ARRAY(union STRUCT_NAME_module_context *) module_contexts;
+   };
+   extern struct STRUCT_NAME_module_register STRUCT_NAME_module_register;
+
+   ---------
+   The usage in modules goes like:
+
+   static MODULE_CONTEXT_DEFINE(mymodule_STRUCT_NAME_module,
+				&STRUCT_NAME_module_register);
+   struct mymodule_STRUCT_NAME {
+	union STRUCT_NAME_module_context module_ctx;
+	// module-specific data
+   };
+
+   struct mymodule_STRUCT_NAME *ctx = i_new(...);
+   MODULE_CONTEXT_SET(obj, mymodule_STRUCT_NAME_module, ctx);
+
+   struct mymodule_STRUCT_NAME *ctx =
+	MODULE_CONTEXT(obj, mymodule_STRUCT_NAME_module);
+*/
+
+#define OBJ_REGISTER(obj) \
+	((**(obj)->module_contexts.v)->reg)
+#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 { \
+		struct module_context_id id; \
+		typeof(_reg) reg; \
+	} _name
+#  define MODULE_CONTEXT_INIT(_reg) \
+	{ { &(_reg)->id, 0, FALSE }, NULL }
+#else
+#  define MODULE_CONTEXT_DEFINE(_name, _reg) \
+	struct _name { \
+		struct module_context_id id; \
+	} _name
+#  define MODULE_CONTEXT_INIT(_reg) \
+	{ { &(_reg)->id, 0, FALSE } }
+#endif
+
+#define MODULE_CONTEXT_DEFINE_INIT(_name, _reg) \
+	MODULE_CONTEXT_DEFINE(_name, _reg) = MODULE_CONTEXT_INIT(_reg)
+
+struct module_context_id {
+	unsigned int *module_id_register;
+	unsigned int module_id;
+	bool module_id_set;
+};
+
+static inline unsigned int module_get_context_id(struct module_context_id *id)
+{
+	if (!id->module_id_set) {
+		id->module_id = *id->module_id_register;
+		id->module_id_set = TRUE;
+		*id->module_id_register += 1;
+	}
+	return id->module_id;
+}
+
+#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)); \
+	(void)OBJ_REGISTER_COMPATIBLE(obj, id_ctx); \
+	void *_module_tmp = ctx; \
+	array_idx_set_i(&(obj)->module_contexts.arr, \
+		module_get_context_id(&(id_ctx).id), &_module_tmp); \
+	} STMT_END
+
+#define MODULE_CONTEXT_SET(obj, id_ctx, context) \
+	MODULE_CONTEXT_SET_FULL(obj, id_ctx, context, &(context)->module_ctx)
+#define MODULE_CONTEXT_SET_SELF(obj, id_ctx, context) \
+	MODULE_CONTEXT_SET_FULL(obj, id_ctx, context, context)
+
+#define MODULE_CONTEXT_UNSET(obj, id_ctx) \
+	array_idx_clear(&(obj)->module_contexts, (id_ctx).id.module_id)
+
+#endif