gistfile1.c

#define HOOK_CALL(lib, name, size)					\
static void (*_ ## name ## _hook)(void);				\
void name (void) {							\
	void *args = __builtin_apply_args();				\
	DBG("Calling %s", #name);					\
	if (!_ ## name ## _hook) {					\
		void *orig_p, *orig;					\
		void *hook = get_lib_hook(lib);				\
		orig = dlsym(RTLD_NEXT, #name);				\
		if (!orig) {						\
			void *orig_lib = dlopen(lib_hook_list[lib].filename, RTLD_LAZY | RTLD_GLOBAL);\
			if (!orig_lib) {				\
				fprintf(stderr, "Can't open library %s: %s\n", lib_hook_list[lib].filename, dlerror());\
				exit(-1);				\
			}						\
			orig = dlsym(orig_lib, #name);			\
			if (!orig) {					\
				fprintf(stderr, "Symbol not found "#name":%s\n", dlerror());\
				exit(-1);				\
			}						\
		}							\
		if (hook) {						\
			orig_p = dlsym(hook, "_" #name);		\
			if (orig_p) {					\
				*(void **) orig_p = orig;		\
				_ ## name ## _hook = dlsym(hook, #name);\
			}						\
		}							\
		if (!_ ## name ## _hook) {				\
			DBG("Can't hook %s, using original", #name);	\
			_ ## name ## _hook = orig;			\
		}							\
	}								\
	__builtin_return(__builtin_apply(_ ## name ## _hook, args, size));\
}