ust comm: Receive second FD even if 1st receive failed

Ensures proper protocol behavior, because the sender expects the
receiver to get the two file descriptors.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/liblttng-ust-ctl/ustctl.c b/liblttng-ust-ctl/ustctl.c
index 8dce787897a3424fe9c75c465533c8bc192a1039..fc7f57ca265173439fd4277e9ccbdf2107240ee2 100644 (file)
--- a/liblttng-ust-ctl/ustctl.c
+++ b/liblttng-ust-ctl/ustctl.c
@@ -135,7 +135,7 @@ int ustctl_open_metadata(int sock, int session_handle,
        struct ustcomm_ust_msg lum;
        struct ustcomm_ust_reply lur;
        struct lttng_ust_object_data *metadata_data;
-       int ret;
+       int ret, err = 0;
 
        metadata_data = malloc(sizeof(*metadata_data));
        if (!metadata_data)
@@ -166,13 +166,21 @@ int ustctl_open_metadata(int sock, int session_handle,
        /* get shm fd */
        ret = ustcomm_recv_fd(sock);
        if (ret < 0)
-               goto error;
-       metadata_data->shm_fd = ret;
+               err = 1;
+       else
+               metadata_data->shm_fd = ret;
+       /*
+        * We need to get the second FD even if the first fails, because
+        * libust expects us to read the two FDs.
+        */
        /* get wait fd */
        ret = ustcomm_recv_fd(sock);
        if (ret < 0)
+               err = 1;
+       else
+               metadata_data->wait_fd = ret;
+       if (err)
                goto error;
-       metadata_data->wait_fd = ret;
        *_metadata_data = metadata_data;
        return 0;
 
@@ -189,7 +197,7 @@ int ustctl_create_channel(int sock, int session_handle,
        struct ustcomm_ust_msg lum;
        struct ustcomm_ust_reply lur;
        struct lttng_ust_object_data *channel_data;
-       int ret;
+       int ret, err = 0;
 
        channel_data = malloc(sizeof(*channel_data));
        if (!channel_data)
@@ -220,13 +228,21 @@ int ustctl_create_channel(int sock, int session_handle,
        /* get shm fd */
        ret = ustcomm_recv_fd(sock);
        if (ret < 0)
-               goto error;
-       channel_data->shm_fd = ret;
+               err = 1;
+       else
+               channel_data->shm_fd = ret;
+       /*
+        * We need to get the second FD even if the first fails, because
+        * libust expects us to read the two FDs.
+        */
        /* get wait fd */
        ret = ustcomm_recv_fd(sock);
        if (ret < 0)
+               err = 1;
+       else
+               channel_data->wait_fd = ret;
+       if (err)
                goto error;
-       channel_data->wait_fd = ret;
        *_channel_data = channel_data;
        return 0;
 
@@ -247,7 +263,7 @@ int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
        struct ustcomm_ust_msg lum;
        struct ustcomm_ust_reply lur;
        struct lttng_ust_object_data *stream_data;
-       int ret, fd;
+       int ret, fd, err = 0;
 
        stream_data = malloc(sizeof(*stream_data));
        if (!stream_data)
@@ -272,13 +288,21 @@ int ustctl_create_stream(int sock, struct lttng_ust_object_data *channel_data,
        /* get shm fd */
        fd = ustcomm_recv_fd(sock);
        if (fd < 0)
-               goto error;
-       stream_data->shm_fd = fd;
+               err = 1;
+       else
+               stream_data->shm_fd = fd;
+       /*
+        * We need to get the second FD even if the first fails, because
+        * libust expects us to read the two FDs.
+        */
        /* get wait fd */
        fd = ustcomm_recv_fd(sock);
        if (fd < 0)
+               err = 1;
+       else
+               stream_data->wait_fd = fd;
+       if (err)
                goto error;
-       stream_data->wait_fd = fd;
        *_stream_data = stream_data;
        return ret;