[ubus PATCH] libubus: remove global variables

Simon Tate simontate94 at gmail.com
Thu Jan 5 06:30:18 PST 2023


Remove the use of global blob_buf and blob_attr variables to allow
for better thread safety with a ctx per thread on client invoke
and sends.

Add the same variables to within each calling function's scope,
encapsulating the memory usage there.

Fixes a multithreaded use case and has been verified 10,000
threads multiple times running invokes and send events.

Signed-off-by: Simon Tate <simon.tate at bt.com>
---
 cli.c              | 38 ++++++++++++++++++++------
 libubus-internal.h |  2 +-
 libubus-io.c       | 10 ++++---
 libubus-obj.c      | 63 ++++++++++++++++++++++++++-----------------
 libubus-req.c      | 44 +++++++++++++++++++++---------
 libubus-sub.c      | 13 ++++++---
 libubus.c          | 67 ++++++++++++++++++++++++++++++----------------
 7 files changed, 161 insertions(+), 76 deletions(-)

diff --git a/cli.c b/cli.c
index 81591ec..e6d7a1b 100644
--- a/cli.c
+++ b/cli.c
@@ -16,7 +16,6 @@
 #include <libubox/blobmsg_json.h>
 #include "libubus.h"
 
-static struct blob_buf b;
 static int listen_timeout;
 static int timeout = 30;
 static bool simple_output = false;
@@ -140,18 +139,29 @@ static int ubus_cli_call(struct ubus_context *ctx, int argc, char **argv)
 	if (argc < 2 || argc > 3)
 		return -2;
 
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 	if (argc == 3 && !blobmsg_add_json_from_string(&b, argv[2])) {
 		if (!simple_output)
 			fprintf(stderr, "Failed to parse message data\n");
-		return -1;
+		ret = -1;
+		goto error;
 	}
 
 	ret = ubus_lookup_id(ctx, argv[0], &id);
-	if (ret)
-		return ret;
+	if (ret) {
+		goto error;
+	}
+
+	ret = ubus_invoke(ctx, id, argv[1], b.head, receive_call_result_data, NULL, timeout * 1000);
+	if (ret) {
+		goto error;
+	}
 
-	return ubus_invoke(ctx, id, argv[1], b.head, receive_call_result_data, NULL, timeout * 1000);
+error:
+	blob_buf_free(&b);
+
+	return ret;
 }
 
 struct cli_listen_data {
@@ -265,15 +275,23 @@ static int ubus_cli_send(struct ubus_context *ctx, int argc, char **argv)
 	if (argc < 1 || argc > 2)
 		return -2;
 
+	int ret = UBUS_STATUS_OK;
+
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 
 	if (argc == 2 && !blobmsg_add_json_from_string(&b, argv[1])) {
 		if (!simple_output)
 			fprintf(stderr, "Failed to parse message data\n");
-		return -1;
+		ret = -1;
+		goto error;
 	}
 
-	return ubus_send_event(ctx, argv[0], b.head);
+	ret = ubus_send_event(ctx, argv[0], b.head);
+
+error:
+	blob_buf_free(&b);
+	return ret;
 }
 
 struct cli_wait_data {
@@ -428,6 +446,7 @@ ubus_cli_get_monitor_data(struct blob_attr *data)
 	struct blob_attr *tb[UBUS_ATTR_MAX];
 	int i;
 
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 	blob_parse(data, tb, policy, UBUS_ATTR_MAX);
 
@@ -454,7 +473,10 @@ ubus_cli_get_monitor_data(struct blob_attr *data)
 		}
 	}
 
-	return blobmsg_format_json(b.head, true);
+	char* ret = blobmsg_format_json(b.head, true);
+
+	blob_buf_free(&b);
+	return ret;
 }
 
 static void
diff --git a/libubus-internal.h b/libubus-internal.h
index 24477a0..5b23668 100644
--- a/libubus-internal.h
+++ b/libubus-internal.h
@@ -17,7 +17,7 @@
 extern struct blob_buf b;
 extern const struct ubus_method watch_method;
 
-struct blob_attr **ubus_parse_msg(struct blob_attr *msg, size_t len);
+void ubus_parse_msg(struct blob_attr *msg, size_t len, struct blob_attr **attrbuf, size_t attrbuf_len);
 bool ubus_validate_hdr(struct ubus_msghdr *hdr);
 void ubus_handle_data(struct uloop_fd *u, unsigned int events);
 int ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
diff --git a/libubus-io.c b/libubus-io.c
index 3561ac4..143d3be 100644
--- a/libubus-io.c
+++ b/libubus-io.c
@@ -41,12 +41,10 @@ static const struct blob_attr_info ubus_policy[UBUS_ATTR_MAX] = {
 	[UBUS_ATTR_SUBSCRIBERS] = { .type = BLOB_ATTR_NESTED },
 };
 
-static struct blob_attr *attrbuf[UBUS_ATTR_MAX];
 
-__hidden struct blob_attr **ubus_parse_msg(struct blob_attr *msg, size_t len)
+__hidden void ubus_parse_msg(struct blob_attr *msg, size_t len, struct blob_attr **attrbuf, size_t attrbuf_len)
 {
-	blob_parse_untrusted(msg, len, attrbuf, ubus_policy, UBUS_ATTR_MAX);
-	return attrbuf;
+	blob_parse_untrusted(msg, len, attrbuf, ubus_policy, attrbuf_len);
 }
 
 static void wait_data(int fd, bool write)
@@ -137,6 +135,8 @@ int __hidden ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
 	hdr.seq = cpu_to_be16(seq);
 	hdr.peer = cpu_to_be32(peer);
 
+	struct blob_buf b = {0};
+
 	if (!msg) {
 		blob_buf_init(&b, 0);
 		msg = b.head;
@@ -152,6 +152,8 @@ int __hidden ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
 	if (fd >= 0)
 		close(fd);
 
+	blob_buf_free(&b);
+
 	return ret;
 }
 
diff --git a/libubus-obj.c b/libubus-obj.c
index 29cbb2b..8506737 100644
--- a/libubus-obj.c
+++ b/libubus-obj.c
@@ -117,11 +117,11 @@ void __hidden ubus_process_obj_msg(struct ubus_context *ctx, struct ubus_msghdr_
 	void (*cb)(struct ubus_context *, struct ubus_msghdr *,
 		   struct ubus_object *, struct blob_attr **, int fd);
 	struct ubus_msghdr *hdr = &buf->hdr;
-	struct blob_attr **attrbuf;
+	struct blob_attr *attrbuf[UBUS_ATTR_MAX];
 	struct ubus_object *obj;
 	uint32_t objid;
 	void *prev_data = NULL;
-	attrbuf = ubus_parse_msg(buf->data, blob_raw_len(buf->data));
+	ubus_parse_msg(buf->data, blob_raw_len(buf->data), attrbuf, UBUS_ATTR_MAX);
 	if (!attrbuf[UBUS_ATTR_OBJID])
 		return;
 
@@ -160,7 +160,8 @@ void __hidden ubus_process_obj_msg(struct ubus_context *ctx, struct ubus_msghdr_
 static void ubus_add_object_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 {
 	struct ubus_object *obj = req->priv;
-	struct blob_attr **attrbuf = ubus_parse_msg(msg, blob_raw_len(msg));
+	struct blob_attr *attrbuf[UBUS_ATTR_MAX];
+	ubus_parse_msg(msg, blob_raw_len(msg), attrbuf, UBUS_ATTR_MAX);
 
 	if (!attrbuf[UBUS_ATTR_OBJID])
 		return;
@@ -174,34 +175,34 @@ static void ubus_add_object_cb(struct ubus_request *req, int type, struct blob_a
 	avl_insert(&req->ctx->objects, &obj->avl);
 }
 
-static void ubus_push_method_data(const struct ubus_method *m)
+static void ubus_push_method_data(struct blob_buf *b, const struct ubus_method *m)
 {
 	void *mtbl;
 	int i;
 
-	mtbl = blobmsg_open_table(&b, m->name);
+	mtbl = blobmsg_open_table(b, m->name);
 
 	for (i = 0; i < m->n_policy; i++) {
 		if (m->mask && !(m->mask & (1 << i)))
 			continue;
 
-		blobmsg_add_u32(&b, m->policy[i].name, m->policy[i].type);
+		blobmsg_add_u32(b, m->policy[i].name, m->policy[i].type);
 	}
 
-	blobmsg_close_table(&b, mtbl);
+	blobmsg_close_table(b, mtbl);
 }
 
-static bool ubus_push_object_type(const struct ubus_object_type *type)
+static bool ubus_push_object_type(struct blob_buf *b, const struct ubus_object_type *type)
 {
 	void *s;
 	int i;
 
-	s = blob_nest_start(&b, UBUS_ATTR_SIGNATURE);
+	s = blob_nest_start(b, UBUS_ATTR_SIGNATURE);
 
 	for (i = 0; i < type->n_methods; i++)
-		ubus_push_method_data(&type->methods[i]);
+		ubus_push_method_data(b, &type->methods[i]);
 
-	blob_nest_end(&b, s);
+	blob_nest_end(b, s);
 
 	return true;
 }
@@ -211,6 +212,7 @@ int ubus_add_object(struct ubus_context *ctx, struct ubus_object *obj)
 	struct ubus_request req;
 	int ret;
 
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 
 	if (obj->name && obj->type) {
@@ -218,29 +220,35 @@ int ubus_add_object(struct ubus_context *ctx, struct ubus_object *obj)
 
 		if (obj->type->id)
 			blob_put_int32(&b, UBUS_ATTR_OBJTYPE, obj->type->id);
-		else if (!ubus_push_object_type(obj->type))
+		else if (!ubus_push_object_type(&b, obj->type))
 			return UBUS_STATUS_INVALID_ARGUMENT;
 	}
 
-	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_ADD_OBJECT, 0) < 0)
+	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_ADD_OBJECT, 0) < 0) {
 		return UBUS_STATUS_INVALID_ARGUMENT;
+	}
 
 	req.raw_data_cb = ubus_add_object_cb;
 	req.priv = obj;
 	ret = ubus_complete_request(ctx, &req, 0);
 	if (ret)
-		return ret;
+		goto error;
 
-	if (!obj->id)
-		return UBUS_STATUS_NO_DATA;
+	if (!obj->id) {
+		ret = UBUS_STATUS_NO_DATA;
+		goto error;
+	}
 
-	return 0;
+error:
+	blob_buf_free(&b);
+	return ret;
 }
 
 static void ubus_remove_object_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 {
 	struct ubus_object *obj = req->priv;
-	struct blob_attr **attrbuf = ubus_parse_msg(msg, blob_raw_len(msg));
+	struct blob_attr *attrbuf[UBUS_ATTR_MAX];
+	ubus_parse_msg(msg, blob_raw_len(msg), attrbuf, UBUS_ATTR_MAX);
 
 	if (!attrbuf[UBUS_ATTR_OBJID])
 		return;
@@ -258,20 +266,27 @@ int ubus_remove_object(struct ubus_context *ctx, struct ubus_object *obj)
 	struct ubus_request req;
 	int ret;
 
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id);
 
-	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_REMOVE_OBJECT, 0) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
+	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_REMOVE_OBJECT, 0) < 0) {
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
+		goto error;
+	}
 
 	req.raw_data_cb = ubus_remove_object_cb;
 	req.priv = obj;
 	ret = ubus_complete_request(ctx, &req, 0);
 	if (ret)
-		return ret;
+		goto error;
 
-	if (obj->id)
-		return UBUS_STATUS_NO_DATA;
+	if (obj->id) {
+		ret = UBUS_STATUS_NO_DATA;
+		goto error;
+	}
 
-	return 0;
+error:
+	blob_buf_free(&b);
+	return ret;
 }
diff --git a/libubus-req.c b/libubus-req.c
index ae9d192..378680b 100644
--- a/libubus-req.c
+++ b/libubus-req.c
@@ -23,7 +23,7 @@ struct ubus_pending_data {
 
 static void req_data_cb(struct ubus_request *req, int type, struct blob_attr *data)
 {
-	struct blob_attr **attr;
+	struct blob_attr *attr[UBUS_ATTR_MAX];
 
 	if (req->raw_data_cb)
 		req->raw_data_cb(req, type, data);
@@ -31,7 +31,7 @@ static void req_data_cb(struct ubus_request *req, int type, struct blob_attr *da
 	if (!req->data_cb)
 		return;
 
-	attr = ubus_parse_msg(data, blob_raw_len(data));
+	ubus_parse_msg(data, blob_raw_len(data), attr, UBUS_ATTR_MAX);
 	if (!attr[UBUS_ATTR_DATA])
 		return;
 
@@ -188,10 +188,12 @@ int ubus_complete_request(struct ubus_context *ctx, struct ubus_request *req,
 
 void ubus_complete_deferred_request(struct ubus_context *ctx, struct ubus_request_data *req, int ret)
 {
+	struct blob_buf b = {0};
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_STATUS, ret);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, req->object);
 	ubus_send_msg(ctx, req->seq, b.head, UBUS_MSG_STATUS, req->peer, req->fd);
+	blob_buf_free(&b);
 }
 
 static void ubus_put_data(struct blob_buf *buf, struct blob_attr *msg)
@@ -207,20 +209,26 @@ int ubus_send_reply(struct ubus_context *ctx, struct ubus_request_data *req,
 {
 	int ret;
 
+	struct blob_buf b = {0};
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, req->object);
 	ubus_put_data(&b, msg);
 	ret = ubus_send_msg(ctx, req->seq, b.head, UBUS_MSG_DATA, req->peer, -1);
 	if (ret < 0)
-		return UBUS_STATUS_NO_DATA;
+		ret = UBUS_STATUS_NO_DATA;
+	else
+		ret = 0;
+
+	blob_buf_free(&b);
 
-	return 0;
+	return ret;
 }
 
 int ubus_invoke_async_fd(struct ubus_context *ctx, uint32_t obj,
 			 const char *method, struct blob_attr *msg,
 			 struct ubus_request *req, int fd)
 {
+	struct blob_buf b = {0};
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, obj);
 	blob_put_string(&b, UBUS_ATTR_METHOD, method);
@@ -228,9 +236,12 @@ int ubus_invoke_async_fd(struct ubus_context *ctx, uint32_t obj,
 
 	memset(req, 0, sizeof(*req));
 	req->fd = fd;
+	int ret = 0;
 	if (__ubus_start_request(ctx, req, b.head, UBUS_MSG_INVOKE, obj) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
-	return 0;
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
+
+	blob_buf_free(&b);
+	return ret;
 }
 
 int ubus_invoke_fd(struct ubus_context *ctx, uint32_t obj, const char *method,
@@ -280,6 +291,7 @@ __ubus_notify_async(struct ubus_context *ctx, struct ubus_object *obj,
 {
 	memset(req, 0, sizeof(*req));
 
+	struct blob_buf b = {0};
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id);
 	blob_put_string(&b, UBUS_ATTR_METHOD, type);
@@ -288,8 +300,9 @@ __ubus_notify_async(struct ubus_context *ctx, struct ubus_object *obj,
 	if (!reply)
 		blob_put_int8(&b, UBUS_ATTR_NO_REPLY, true);
 
+	int ret = 0;
 	if (ubus_start_request(ctx, &req->req, b.head, UBUS_MSG_NOTIFY, obj->id) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
 
 	/* wait for status message from ubusd first */
 	req->req.notify = true;
@@ -297,8 +310,9 @@ __ubus_notify_async(struct ubus_context *ctx, struct ubus_object *obj,
 	req->id[0] = obj->id;
 	req->req.complete_cb = ubus_notify_complete_cb;
 	req->req.data_cb = ubus_notify_data_cb;
+	blob_buf_free(&b);
 
-	return 0;
+	return ret;
 }
 
 int ubus_notify_async(struct ubus_context *ctx, struct ubus_object *obj,
@@ -328,7 +342,8 @@ int ubus_notify(struct ubus_context *ctx, struct ubus_object *obj,
 
 static bool ubus_get_status(struct ubus_msghdr_buf *buf, int *ret)
 {
-	struct blob_attr **attrbuf = ubus_parse_msg(buf->data, blob_raw_len(buf->data));
+	struct blob_attr *attrbuf[UBUS_ATTR_MAX];
+	ubus_parse_msg(buf->data, blob_raw_len(buf->data), attrbuf, UBUS_ATTR_MAX);
 
 	if (!attrbuf[UBUS_ATTR_STATUS])
 		return false;
@@ -340,7 +355,7 @@ static bool ubus_get_status(struct ubus_msghdr_buf *buf, int *ret)
 static int
 ubus_process_req_status(struct ubus_request *req, struct ubus_msghdr_buf *buf)
 {
-	int ret = UBUS_STATUS_INVALID_ARGUMENT;
+	int ret = UBUS_STATUS_UNKNOWN_ERROR;
 
 	ubus_get_status(buf, &ret);
 	req->peer = buf->hdr.peer;
@@ -424,7 +439,7 @@ ubus_find_request(struct ubus_context *ctx, uint32_t seq, uint32_t peer, int *id
 static void ubus_process_notify_status(struct ubus_request *req, int id, struct ubus_msghdr_buf *buf)
 {
 	struct ubus_notify_request *nreq;
-	struct blob_attr **tb;
+	struct blob_attr *tb[UBUS_ATTR_MAX];
 	struct blob_attr *cur;
 	size_t rem;
 	int idx = 1;
@@ -435,7 +450,7 @@ static void ubus_process_notify_status(struct ubus_request *req, int id, struct
 
 	if (!id) {
 		/* first id: ubusd's status message with a list of ids */
-		tb = ubus_parse_msg(buf->data, blob_raw_len(buf->data));
+		ubus_parse_msg(buf->data, blob_raw_len(buf->data), tb, UBUS_ATTR_MAX);
 		if (tb[UBUS_ATTR_SUBSCRIBERS]) {
 			blob_for_each_attr(cur, tb[UBUS_ATTR_SUBSCRIBERS], rem) {
 				if (!blob_check_type(blob_data(cur), blob_len(cur), BLOB_ATTR_INT32))
@@ -494,6 +509,9 @@ void __hidden ubus_process_req_msg(struct ubus_context *ctx, struct ubus_msghdr_
 
 int __ubus_monitor(struct ubus_context *ctx, const char *type)
 {
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
-	return ubus_invoke(ctx, UBUS_SYSTEM_OBJECT_MONITOR, type, b.head, NULL, NULL, 1000);
+	int rc = ubus_invoke(ctx, UBUS_SYSTEM_OBJECT_MONITOR, type, b.head, NULL, NULL, 1000);
+	blob_buf_free(&b);
+	return rc;
 }
diff --git a/libubus-sub.c b/libubus-sub.c
index 8793133..4906c2a 100644
--- a/libubus-sub.c
+++ b/libubus-sub.c
@@ -45,15 +45,22 @@ static int
 __ubus_subscribe_request(struct ubus_context *ctx, struct ubus_object *obj, uint32_t id, int type)
 {
 	struct ubus_request req;
+	int ret;
 
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, obj->id);
 	blob_put_int32(&b, UBUS_ATTR_TARGET, id);
 
-	if (ubus_start_request(ctx, &req, b.head, type, 0) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
+	if (ubus_start_request(ctx, &req, b.head, type, 0) < 0) {
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
+		goto error;
+	}
 
-	return ubus_complete_request(ctx, &req, 0);
+	ret = ubus_complete_request(ctx, &req, 0);
+error:
+	blob_buf_free(&b);
+	return ret;
 
 }
 
diff --git a/libubus.c b/libubus.c
index 91f317c..8cf4cf1 100644
--- a/libubus.c
+++ b/libubus.c
@@ -36,8 +36,6 @@ const char *__ubus_strerror[__UBUS_STATUS_LAST] = {
 	[UBUS_STATUS_CONNECTION_FAILED] = "Connection failed",
 };
 
-struct blob_buf b __hidden = {};
-
 struct ubus_pending_msg {
 	struct list_head list;
 	struct ubus_msghdr_buf hdr;
@@ -136,10 +134,10 @@ static void ubus_lookup_cb(struct ubus_request *ureq, int type, struct blob_attr
 {
 	struct ubus_lookup_request *req;
 	struct ubus_object_data obj = {};
-	struct blob_attr **attr;
+	struct blob_attr *attr[UBUS_ATTR_MAX];
 
 	req = container_of(ureq, struct ubus_lookup_request, req);
-	attr = ubus_parse_msg(msg, blob_raw_len(msg));
+	ubus_parse_msg(msg, blob_raw_len(msg), attr, UBUS_ATTR_MAX);
 
 	if (!attr[UBUS_ATTR_OBJID] || !attr[UBUS_ATTR_OBJPATH] ||
 	    !attr[UBUS_ATTR_OBJTYPE])
@@ -156,26 +154,34 @@ int ubus_lookup(struct ubus_context *ctx, const char *path,
 		ubus_lookup_handler_t cb, void *priv)
 {
 	struct ubus_lookup_request lookup;
+	int ret;
 
+	struct blob_buf b = { 0 };
 	blob_buf_init(&b, 0);
 	if (path)
 		blob_put_string(&b, UBUS_ATTR_OBJPATH, path);
 
-	if (ubus_start_request(ctx, &lookup.req, b.head, UBUS_MSG_LOOKUP, 0) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
+	if (ubus_start_request(ctx, &lookup.req, b.head, UBUS_MSG_LOOKUP, 0) < 0) {
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
+		goto error;
+	}
 
 	lookup.req.raw_data_cb = ubus_lookup_cb;
 	lookup.req.priv = priv;
 	lookup.cb = cb;
-	return ubus_complete_request(ctx, &lookup.req, 0);
+
+	ret = ubus_complete_request(ctx, &lookup.req, 0);
+error:
+	blob_buf_free(&b);
+	return ret;
 }
 
 static void ubus_lookup_id_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 {
-	struct blob_attr **attr;
+	struct blob_attr *attr[UBUS_ATTR_MAX];
 	uint32_t *id = req->priv;
 
-	attr = ubus_parse_msg(msg, blob_raw_len(msg));
+	ubus_parse_msg(msg, blob_raw_len(msg), attr, UBUS_ATTR_MAX);
 
 	if (!attr[UBUS_ATTR_OBJID])
 		return;
@@ -187,17 +193,26 @@ int ubus_lookup_id(struct ubus_context *ctx, const char *path, uint32_t *id)
 {
 	struct ubus_request req;
 
+	struct blob_buf b = {0};
+	int ret = 0;
 	blob_buf_init(&b, 0);
 	if (path)
 		blob_put_string(&b, UBUS_ATTR_OBJPATH, path);
 
-	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_LOOKUP, 0) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
+	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_LOOKUP, 0) < 0) {
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
+		goto error;
+	}
+
+	if (ret) return ret;
 
 	req.raw_data_cb = ubus_lookup_id_cb;
 	req.priv = id;
 
-	return ubus_complete_request(ctx, &req, 0);
+	ret = ubus_complete_request(ctx, &req, 0);
+error:
+	blob_buf_free(&b);
+	return ret;
 }
 
 static int ubus_event_cb(struct ubus_context *ctx, struct ubus_object *obj,
@@ -221,7 +236,7 @@ int ubus_register_event_handler(struct ubus_context *ctx,
 				const char *pattern)
 {
 	struct ubus_object *obj = &ev->obj;
-	struct blob_buf b2 = {};
+	struct blob_buf b = {};
 	int ret;
 
 	if (!obj->id) {
@@ -236,15 +251,14 @@ int ubus_register_event_handler(struct ubus_context *ctx,
 			return ret;
 	}
 
-	/* use a second buffer, ubus_invoke() overwrites the primary one */
-	blob_buf_init(&b2, 0);
-	blobmsg_add_u32(&b2, "object", obj->id);
+	blob_buf_init(&b, 0);
+	blobmsg_add_u32(&b, "object", obj->id);
 	if (pattern)
-		blobmsg_add_string(&b2, "pattern", pattern);
+		blobmsg_add_string(&b, "pattern", pattern);
 
-	ret = ubus_invoke(ctx, UBUS_SYSTEM_OBJECT_EVENT, "register", b2.head,
+	ret = ubus_invoke(ctx, UBUS_SYSTEM_OBJECT_EVENT, "register", b.head,
 			  NULL, NULL, 0);
-	blob_buf_free(&b2);
+	blob_buf_free(&b);
 
 	return ret;
 }
@@ -254,7 +268,9 @@ int ubus_send_event(struct ubus_context *ctx, const char *id,
 {
 	struct ubus_request req;
 	void *s;
+	int ret;
 
+	struct blob_buf b = {0};
 	blob_buf_init(&b, 0);
 	blob_put_int32(&b, UBUS_ATTR_OBJID, UBUS_SYSTEM_OBJECT_EVENT);
 	blob_put_string(&b, UBUS_ATTR_METHOD, "send");
@@ -263,10 +279,16 @@ int ubus_send_event(struct ubus_context *ctx, const char *id,
 	blobmsg_add_field(&b, BLOBMSG_TYPE_TABLE, "data", blob_data(data), blob_len(data));
 	blob_nest_end(&b, s);
 
-	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_INVOKE, UBUS_SYSTEM_OBJECT_EVENT) < 0)
-		return UBUS_STATUS_INVALID_ARGUMENT;
+	if (ubus_start_request(ctx, &req, b.head, UBUS_MSG_INVOKE, UBUS_SYSTEM_OBJECT_EVENT) < 0) {
+		ret = UBUS_STATUS_INVALID_ARGUMENT;
+		goto error;
+	}
 
-	return ubus_complete_request(ctx, &req, 0);
+	ret = ubus_complete_request(ctx, &req, 0);
+
+error:
+	blob_buf_free(&b);
+	return ret;
 }
 
 static void ubus_default_connection_lost(struct ubus_context *ctx)
@@ -359,7 +381,6 @@ struct ubus_context *ubus_connect(const char *path)
 
 void ubus_shutdown(struct ubus_context *ctx)
 {
-	blob_buf_free(&b);
 	if (!ctx)
 		return;
 	close(ctx->sock.fd);
-- 
2.35.1




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