[lttng-dev] [PATCH] Fix I/O-related error values in ustctl

[mathieu.desnoyers@efficios.com (Mathieu Desnoyers)]

These internal ustctl API members document >=0 as OK values. Make sure
reply recv errors are returned as errors.

Clarify ustctl_create_stream() error values.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
diff --git a/include/lttng/ust-ctl.h b/include/lttng/ust-ctl.h
index c2b255c..11beaba 100644
--- a/include/lttng/ust-ctl.h
+++ b/include/lttng/ust-ctl.h
@@ -23,7 +23,7 @@
 
 /*
  * Error values: all the following functions return:
- * >= 0: Sucess (LTTNG_UST_OK)
+ * >= 0: Success (LTTNG_UST_OK)
  * < 0: error code.
  */
 int ustctl_register_done(int sock);
@@ -34,8 +34,6 @@ int ustctl_open_metadata(int sock, int session_handle,
 int ustctl_create_channel(int sock, int session_handle,
 		struct lttng_ust_channel_attr *chops,
 		struct lttng_ust_object_data **channel_data);
-int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
-		struct lttng_ust_object_data **stream_data);
 int ustctl_create_event(int sock, struct lttng_ust_event *ev,
 		struct lttng_ust_object_data *channel_data,
 		struct lttng_ust_object_data **event_data);
@@ -51,6 +49,15 @@ int ustctl_start_session(int sock, int handle);
 int ustctl_stop_session(int sock, int handle);
 
 /*
+ * Return -ENOENT if no more stream is available for creation.
+ * Return 0 on success.
+ * Return negative error value on system error.
+ * Return positive error value on UST error.
+ */
+int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
+		struct lttng_ust_object_data **stream_data);
+
+/*
  * ustctl_tracepoint_list returns a tracepoint list handle, or negative
  * error value.
  */
diff --git a/liblttng-ust-comm/lttng-ust-comm.c b/liblttng-ust-comm/lttng-ust-comm.c
index 9a67ea1..db9910d 100644
--- a/liblttng-ust-comm/lttng-ust-comm.c
+++ b/liblttng-ust-comm/lttng-ust-comm.c
@@ -435,7 +435,10 @@ int ustcomm_send_app_cmd(int sock,
 	ret = ustcomm_send_app_msg(sock, lum);
 	if (ret)
 		return ret;
-	return ustcomm_recv_app_reply(sock, lur, lum->handle, lum->cmd);
+	ret = ustcomm_recv_app_reply(sock, lur, lum->handle, lum->cmd);
+	if (ret > 0)
+		return -EIO;
+	return ret;
 }
 
 /*

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com