Fix: bad check of accept() return value

[lttng-tools.git] / src / common / consumer.c

diff --git a/src/common/consumer.c b/src/common/consumer.c
index 1af69ef93015c7e397c8028781dc3c97895c1790..1045bfb46101d8a6bb63a8c91157f3ffbf5199a2 100644 (file)
--- a/src/common/consumer.c
+++ b/src/common/consumer.c
@@ -782,6 +782,13 @@ static int write_relayd_stream_header(struct lttng_consumer_stream *stream,
                data_hdr.stream_id = htobe64(stream->relayd_stream_id);
                data_hdr.data_size = htobe32(data_size);
                data_hdr.padding_size = htobe32(padding);
+               /*
+                * Note that net_seq_num below is assigned with the *current* value of
+                * next_net_seq_num and only after that the next_net_seq_num will be
+                * increment. This is why when issuing a command on the relayd using
+                * this next value, 1 should always be substracted in order to compare
+                * the last seen sequence number on the relayd side to the last sent.
+                */
                data_hdr.net_seq_num = htobe64(stream->next_net_seq_num++);
                /* Other fields are zeroed previously */
 
@@ -1099,7 +1106,7 @@ void lttng_consumer_should_exit(struct lttng_consumer_local_data *ctx)
        do {
                ret = write(ctx->consumer_should_quit[1], "4", 1);
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0) {
+       if (ret < 0 || ret != 1) {
                PERROR("write consumer quit");
        }
 
@@ -1317,8 +1324,22 @@ static int write_relayd_metadata_id(int fd,
        do {
                ret = write(fd, (void *) &hdr, sizeof(hdr));
        } while (ret < 0 && errno == EINTR);
-       if (ret < 0) {
-               PERROR("write metadata stream id");
+       if (ret < 0 || ret != sizeof(hdr)) {
+               /*
+                * This error means that the fd's end is closed so ignore the perror
+                * not to clubber the error output since this can happen in a normal
+                * code path.
+                */
+               if (errno != EPIPE) {
+                       PERROR("write metadata stream id");
+               }
+               DBG3("Consumer failed to write relayd metadata id (errno: %d)", errno);
+               /*
+                * Set ret to a negative value because if ret != sizeof(hdr), we don't
+                * handle writting the missing part so report that as an error and
+                * don't lie to the caller.
+                */
+               ret = -1;
                goto end;
        }
        DBG("Metadata stream id %" PRIu64 " with padding %lu written before data",
@@ -1435,7 +1456,13 @@ ssize_t lttng_consumer_on_read_subbuffer_mmap(
                } while (ret < 0 && errno == EINTR);
                DBG("Consumer mmap write() ret %zd (len %lu)", ret, len);
                if (ret < 0) {
-                       PERROR("Error in file write");
+                       /*
+                        * This is possible if the fd is closed on the other side (outfd)
+                        * or any write problem. It can be verbose a bit for a normal
+                        * execution if for instance the relayd is stopped abruptly. This
+                        * can happen so set this to a DBG statement.
+                        */
+                       DBG("Error in file write mmap");
                        if (written == 0) {
                                written = ret;
                        }
@@ -2576,7 +2603,7 @@ void *consumer_thread_sessiond_poll(void *data)
 
        /* Blocking call, waiting for transmission */
        sock = lttcomm_accept_unix_sock(client_socket);
-       if (sock <= 0) {
+       if (sock < 0) {
                WARN("On accept");
                goto end;
        }
@@ -2738,6 +2765,7 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                relayd = consumer_allocate_relayd_sock_pair(net_seq_idx);
                if (relayd == NULL) {
                        lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
+                       ret = -1;
                        goto error;
                }
                relayd->sessiond_session_id = (uint64_t) sessiond_id;
@@ -2787,11 +2815,17 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                relayd->control_sock.fd = fd;
 
                /*
-                * Create a session on the relayd and store the returned id. No need to
-                * grab the socket lock since the relayd object is not yet visible.
+                * Create a session on the relayd and store the returned id. Lock the
+                * control socket mutex if the relayd was NOT created before.
                 */
+               if (!relayd_created) {
+                       pthread_mutex_lock(&relayd->ctrl_sock_mutex);
+               }
                ret = relayd_create_session(&relayd->control_sock,
                                &relayd->relayd_session_id);
+               if (!relayd_created) {
+                       pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
+               }
                if (ret < 0) {
                        goto error;
                }
@@ -2800,6 +2834,7 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                relayd_id_node = zmalloc(sizeof(struct consumer_relayd_session_id));
                if (!relayd_id_node) {
                        PERROR("zmalloc relayd id node");
+                       ret = -1;
                        goto error;
                }
 
@@ -2834,6 +2869,7 @@ int consumer_add_relayd_socket(int net_seq_idx, int sock_type,
                break;
        default:
                ERR("Unknown relayd socket type (%d)", sock_type);
+               ret = -1;
                goto error;
        }
 
@@ -3015,7 +3051,8 @@ int consumer_data_pending(uint64_t id)
                                                stream->relayd_stream_id);
                        } else {
                                ret = relayd_data_pending(&relayd->control_sock,
-                                               stream->relayd_stream_id, stream->next_net_seq_num);
+                                               stream->relayd_stream_id,
+                                               stream->next_net_seq_num - 1);
                        }
                        pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
                        if (ret == 1) {