skynet_context: skynet_context_new 改为返回 handle 避免调用者拿到悬垂指针 (#2095)

* skynet_context: skynet_context_new 改为返回 handle 避免调用者拿到悬垂指针

* 推迟 skynet_handle_grab(logger_handle) 到 bootstrap 失败阶段

---------

Co-authored-by: efve.zff <efve.zff@alibaba-inc.com>

skynet-src/skynet_server.c

@@ -121,22 +121,22 @@ drop_message(struct skynet_message *msg, void *ud) {
 	skynet_send(NULL, source, msg->source, PTYPE_ERROR, msg->session, NULL, 0);
 }
 
-struct skynet_context * 
+uint32_t
 skynet_context_new(const char * name, const char *param) {
 	struct skynet_module * mod = skynet_module_query(name);
 
 	if (mod == NULL)
-		return NULL;
+		return 0;
 
 	void *inst = skynet_module_instance_create(mod);
 	if (inst == NULL)
-		return NULL;
+		return 0;
 	struct skynet_context * ctx = skynet_malloc(sizeof(*ctx));
 	CHECKCALLING_INIT(ctx)
 
 	ctx->mod = mod;
 	ctx->instance = inst;
-	ATOM_INIT(&ctx->ref , 2);
+	ATOM_INIT(&ctx->ref , 2); // skynet_handle_register + skynet_module_instance_init
 	ctx->cb = NULL;
 	ctx->cb_ud = NULL;
 	ctx->session_id = 0;
@@ -151,8 +151,9 @@ skynet_context_new(const char * name, const char *param) {
 	ctx->profile = G_NODE.profile;
 	// Should set to 0 first to avoid skynet_handle_retireall get an uninitialized handle
 	ctx->handle = 0;
-	ctx->handle = skynet_handle_register(ctx);
-	struct message_queue * queue = ctx->queue = skynet_mq_create(ctx->handle);
+	const uint32_t handle = skynet_handle_register(ctx);
+	ctx->handle = handle;
+	struct message_queue * queue = ctx->queue = skynet_mq_create(handle);
 	// init function maybe use ctx->handle, so it must init at last
 	context_inc();
 
@@ -160,15 +161,11 @@ skynet_context_new(const char * name, const char *param) {
 	int r = skynet_module_instance_init(mod, inst, ctx, param);
 	CHECKCALLING_END(ctx)
 	if (r == 0) {
-		struct skynet_context * ret = skynet_context_release(ctx);
-		if (ret) {
 		ctx->init = true;
-		}
 		skynet_globalmq_push(queue);
-		if (ret) {
-			skynet_error(ret, "LAUNCH %s %s", name, param ? param : "");
-		}
-		return ret;
+		skynet_error(ctx, "LAUNCH %s %s", name, param ? param : "");
+		skynet_context_release(ctx);
+		return handle;
 	} else {
 		skynet_error(ctx, "error: launch %s FAILED", name);
 		uint32_t handle = ctx->handle;
@@ -176,7 +173,7 @@ skynet_context_new(const char * name, const char *param) {
 		skynet_handle_retire(handle);
 		struct drop_t d = { handle };
 		skynet_mq_release(queue, drop_message, &d);
-		return NULL;
+		return 0;
 	}
 }
 
@@ -217,13 +214,11 @@ delete_context(struct skynet_context *ctx) {
 	context_dec();
 }
 
-struct skynet_context * 
+void
 skynet_context_release(struct skynet_context *ctx) {
 	if (ATOM_FDEC(&ctx->ref) == 1) {
 		delete_context(ctx);
-		return NULL;
 	}
-	return ctx;
 }
 
 int
@@ -488,11 +483,11 @@ cmd_launch(struct skynet_context * context, const char * param) {
 	char * args = tmp;
 	char * mod = strsep(&args, " \t\r\n");
 	args = strsep(&args, "\r\n");
-	struct skynet_context * inst = skynet_context_new(mod,args);
-	if (inst == NULL) {
+	const uint32_t handle = skynet_context_new(mod,args);
+	if (handle == 0) {
 		return NULL;
 	} else {
-		id_to_hex(context->result, inst->handle);
+		id_to_hex(context->result, handle);
 		return context->result;
 	}
 }

skynet-src/skynet_server.h

@@ -8,10 +8,10 @@ struct skynet_context;
 struct skynet_message;
 struct skynet_monitor;
 
-struct skynet_context * skynet_context_new(const char * name, const char * parm);
+uint32_t skynet_context_new(const char * name, const char * parm);
 void skynet_context_grab(struct skynet_context *);
 void skynet_context_reserve(struct skynet_context *ctx);
-struct skynet_context * skynet_context_release(struct skynet_context *);
+void skynet_context_release(struct skynet_context *);
 uint32_t skynet_context_handle(struct skynet_context *);
 int skynet_context_push(uint32_t handle, struct skynet_message *message);
 void skynet_context_send(struct skynet_context * context, void * msg, size_t sz, uint32_t source, int type, int session);

skynet-src/skynet_start.c

@@ -231,7 +231,7 @@ start(int thread) {
 }
 
 static void
-bootstrap(struct skynet_context * logger, const char * cmdline) {
+bootstrap(uint32_t logger_handle, const char * cmdline) {
 	int sz = strlen(cmdline);
 	char name[sz+1];
 	char args[sz+1];
@@ -246,10 +246,14 @@ bootstrap(struct skynet_context * logger, const char * cmdline) {
 	} else {
 		args[0] = '\0';
 	}
-	struct skynet_context *ctx = skynet_context_new(name, args);
-	if (ctx == NULL) {
+	const uint32_t handle = skynet_context_new(name, args);
+	if (handle == 0) {
+		struct skynet_context *logger = skynet_handle_grab(logger_handle);
+		if (logger != NULL) {
 			skynet_error(NULL, "Bootstrap error : %s\n", cmdline);
 			skynet_context_dispatchall(logger);
+			skynet_context_release(logger);
+		}
 		exit(1);
 	}
 }
@@ -276,15 +280,15 @@ skynet_start(struct skynet_config * config) {
 	skynet_socket_init();
 	skynet_profile_enable(config->profile);
 
-	struct skynet_context *ctx = skynet_context_new(config->logservice, config->logger);
-	if (ctx == NULL) {
+	const uint32_t logger_handle = skynet_context_new(config->logservice, config->logger);
+	if (logger_handle == 0) {
 		fprintf(stderr, "Can't launch %s service\n", config->logservice);
 		exit(1);
 	}
 
-	skynet_handle_namehandle(skynet_context_handle(ctx), "logger");
+	skynet_handle_namehandle(logger_handle, "logger");
 
-	bootstrap(ctx, config->bootstrap);
+	bootstrap(logger_handle, config->bootstrap);
 
 	start(config->thread);