Fix: Dereference after NULL check in consumer

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

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 2ea5fa114223f101362e4d780d106b25b3812238..32169034095be1b9fe8889e3c9aee0906dc1e58f 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -141,6 +141,8 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
        }
 
        cds_list_for_each_entry(stream, &channel->streams.head, send_node) {
+               /* Are we at a position _before_ the first available packet ? */
+               bool before_first_packet = true;
 
                health_code_update();
 
@@ -227,6 +229,7 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                while (consumed_pos < produced_pos) {
                        ssize_t read_len;
                        unsigned long len, padded_len;
+                       int lost_packet = 0;
 
                        health_code_update();
 
@@ -241,6 +244,15 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                                }
                                DBG("Kernel consumer get subbuf failed. Skipping it.");
                                consumed_pos += stream->max_sb_size;
+
+                               /*
+                                * Start accounting lost packets only when we
+                                * already have extracted packets (to match the
+                                * content of the final snapshot).
+                                */
+                               if (!before_first_packet) {
+                                       lost_packet = 1;
+                               }
                                continue;
                        }
 
@@ -284,6 +296,16 @@ int lttng_kconsumer_snapshot_channel(uint64_t key, char *path,
                                goto end_unlock;
                        }
                        consumed_pos += stream->max_sb_size;
+
+                       /*
+                        * Only account lost packets located between
+                        * succesfully extracted packets (do not account before
+                        * and after since they are not visible in the
+                        * resulting snapshot).
+                        */
+                       stream->chan->lost_packets += lost_packet;
+                       lost_packet = 0;
+                       before_first_packet = false;
                }
 
                if (relayd_id == (uint64_t) -1ULL) {
@@ -947,18 +969,18 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                uint64_t id = msg.u.discarded_events.session_id;
                uint64_t key = msg.u.discarded_events.channel_key;
 
+               DBG("Kernel consumer discarded events command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
                channel = consumer_find_channel(key);
                if (!channel) {
                        ERR("Kernel consumer discarded events channel %"
                                        PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+                       ret = 0;
+               } else {
+                       ret = channel->discarded_events;
                }
 
-               DBG("Kernel consumer discarded events command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               ret = channel->discarded_events;
-
                health_code_update();
 
                /* Send back returned value to session daemon */
@@ -977,18 +999,18 @@ int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
                uint64_t id = msg.u.lost_packets.session_id;
                uint64_t key = msg.u.lost_packets.channel_key;
 
+               DBG("Kernel consumer lost packets command for session id %"
+                               PRIu64 ", channel key %" PRIu64, id, key);
+
                channel = consumer_find_channel(key);
                if (!channel) {
                        ERR("Kernel consumer lost packets channel %"
                                        PRIu64 " not found", key);
-                       ret_code = LTTCOMM_CONSUMERD_CHAN_NOT_FOUND;
+                       ret = 0;
+               } else {
+                       ret = channel->lost_packets;
                }
 
-               DBG("Kernel consumer lost packets command for session id %"
-                               PRIu64 ", channel key %" PRIu64, id, key);
-
-               ret = channel->lost_packets;
-
                health_code_update();
 
                /* Send back returned value to session daemon */
@@ -1071,6 +1093,20 @@ static int get_index_values(struct ctf_packet_index *index, int infd)
        }
        index->stream_id = htobe64(index->stream_id);
 
+       ret = kernctl_get_instance_id(infd, &index->stream_instance_id);
+       if (ret < 0) {
+               PERROR("kernctl_get_instance_id");
+               goto error;
+       }
+       index->stream_instance_id = htobe64(index->stream_instance_id);
+
+       ret = kernctl_get_sequence_number(infd, &index->packet_seq_num);
+       if (ret < 0) {
+               PERROR("kernctl_get_sequence_number");
+               goto error;
+       }
+       index->packet_seq_num = htobe64(index->packet_seq_num);
+
 error:
        return ret;
 }
@@ -1166,6 +1202,37 @@ end:
        return ret;
 }
 
+/*
+ * Check if the local version of the metadata stream matches with the version
+ * of the metadata stream in the kernel. If it was updated, set the reset flag
+ * on the stream.
+ */
+static
+int metadata_stream_check_version(int infd, struct lttng_consumer_stream *stream)
+{
+       int ret;
+       uint64_t cur_version;
+
+       ret = kernctl_get_metadata_version(infd, &cur_version);
+       if (ret < 0) {
+               ERR("Failed to get the metadata version");
+               goto end;
+       }
+
+       if (stream->metadata_version == cur_version) {
+               ret = 0;
+               goto end;
+       }
+
+       DBG("New metadata version detected");
+       stream->metadata_version = cur_version;
+       stream->reset_metadata_flag = 1;
+       ret = 0;
+
+end:
+       return ret;
+}
+
 /*
  * Consume data on a file descriptor and write it on a trace file.
  */
@@ -1236,6 +1303,10 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                }
        } else {
                write_index = 0;
+               ret = metadata_stream_check_version(infd, stream);
+               if (ret < 0) {
+                       goto end;
+               }
        }
 
        switch (stream->chan->output) {