+ * Check if a name is safe to use in a path.
+ *
+ * A name that is deemed "path-safe":
+ * - Does not contains a path separator (/ or \, platform dependant),
+ * - Does not start with a '.' (hidden file/folder),
+ * - Is not empty.
+ */
+static bool is_name_path_safe(const char *name)
+{
+ const size_t name_len = strlen(name);
+
+ /* Not empty. */
+ if (name_len == 0) {
+ WARN("An empty name is not allowed to be used in a path");
+ return false;
+ }
+ /* Does not start with '.'. */
+ if (name[0] == '.') {
+ WARN("Name \"%s\" is not allowed to be used in a path since it starts with '.'", name);
+ return false;
+ }
+ /* Does not contain a path-separator. */
+ if (strchr(name, LTTNG_PATH_SEPARATOR)) {
+ WARN("Name \"%s\" is not allowed to be used in a path since it contains a path separator", name);
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * Create a new session by assigning a new session ID.
+ *
+ * Return allocated session or else NULL.
+ */
+struct relay_session *session_create(const char *session_name,
+ const char *hostname, const char *base_path,
+ uint32_t live_timer,
+ bool snapshot,
+ const lttng_uuid sessiond_uuid,
+ const uint64_t *id_sessiond,
+ const uint64_t *current_chunk_id,
+ const time_t *creation_time,
+ uint32_t major,
+ uint32_t minor,
+ bool session_name_contains_creation_time)
+{
+ int ret;
+ struct relay_session *session = NULL;
+
+ assert(session_name);
+ assert(hostname);
+ assert(base_path);
+
+ if (!is_name_path_safe(session_name)) {
+ ERR("Refusing to create session as the provided session name is not path-safe");
+ goto error;
+ }
+ if (!is_name_path_safe(hostname)) {
+ ERR("Refusing to create session as the provided hostname is not path-safe");
+ goto error;
+ }
+ if (strstr(base_path, "../")) {
+ ERR("Invalid session base path walks up the path hierarchy: \"%s\"",
+ base_path);
+ goto error;
+ }
+
+ session = zmalloc(sizeof(*session));
+ if (!session) {
+ PERROR("Failed to allocate session");
+ goto error;
+ }
+ if (lttng_strncpy(session->session_name, session_name,
+ sizeof(session->session_name))) {
+ WARN("Session name exceeds maximal allowed length");
+ goto error;
+ }
+ if (lttng_strncpy(session->hostname, hostname,
+ sizeof(session->hostname))) {
+ WARN("Hostname exceeds maximal allowed length");
+ goto error;
+ }
+ if (lttng_strncpy(session->base_path, base_path,
+ sizeof(session->base_path))) {
+ WARN("Base path exceeds maximal allowed length");
+ goto error;
+ }
+ if (creation_time) {
+ LTTNG_OPTIONAL_SET(&session->creation_time, *creation_time);
+ }
+ session->session_name_contains_creation_time =
+ session_name_contains_creation_time;
+
+ session->ctf_traces_ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
+ if (!session->ctf_traces_ht) {
+ goto error;
+ }
+
+ pthread_mutex_lock(&last_relay_session_id_lock);
+ session->id = ++last_relay_session_id;
+ pthread_mutex_unlock(&last_relay_session_id_lock);
+
+ session->major = major;
+ session->minor = minor;
+ lttng_ht_node_init_u64(&session->session_n, session->id);
+ urcu_ref_init(&session->ref);
+ CDS_INIT_LIST_HEAD(&session->recv_list);
+ pthread_mutex_init(&session->lock, NULL);
+ pthread_mutex_init(&session->recv_list_lock, NULL);
+
+ session->live_timer = live_timer;
+ session->snapshot = snapshot;
+ lttng_uuid_copy(session->sessiond_uuid, sessiond_uuid);
+
+ if (id_sessiond) {
+ LTTNG_OPTIONAL_SET(&session->id_sessiond, *id_sessiond);
+ }
+
+ if (major == 2 && minor >= 11) {
+ /* Only applies for 2.11+ peers using trace chunks. */
+ ret = init_session_output_path(session);
+ if (ret) {
+ goto error;
+ }
+ }
+
+ ret = sessiond_trace_chunk_registry_session_created(
+ sessiond_trace_chunk_registry, sessiond_uuid);
+ if (ret) {
+ goto error;
+ }
+
+ if (id_sessiond && current_chunk_id) {
+ enum lttng_trace_chunk_status chunk_status;
+ struct lttng_directory_handle *session_output_directory;
+
+ session->current_trace_chunk =
+ sessiond_trace_chunk_registry_get_chunk(
+ sessiond_trace_chunk_registry,
+ session->sessiond_uuid,
+ session->id_sessiond.value,
+ *current_chunk_id);
+ if (!session->current_trace_chunk) {
+ char uuid_str[LTTNG_UUID_STR_LEN];
+
+ lttng_uuid_to_str(sessiond_uuid, uuid_str);
+ ERR("Could not find trace chunk: sessiond = {%s}, sessiond session id = %" PRIu64 ", trace chunk id = %" PRIu64,
+ uuid_str, *id_sessiond,
+ *current_chunk_id);
+ goto error;
+ }
+
+ chunk_status = lttng_trace_chunk_get_session_output_directory_handle(
+ session->current_trace_chunk,
+ &session_output_directory);
+ if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+ goto error;
+ }
+
+ assert(session_output_directory);
+ session->output_directory = session_output_directory;
+ } else if (!id_sessiond) {
+ /*
+ * Pre-2.11 peers will not announce trace chunks. An
+ * anonymous trace chunk which will remain set for the
+ * duration of the session is created.
+ */
+ ret = session_set_anonymous_chunk(session);
+ if (ret) {
+ goto error;
+ }
+ } else {
+ session->output_directory =
+ session_create_output_directory_handle(session);
+ if (!session->output_directory) {
+ goto error;
+ }
+ }
+
+ lttng_ht_add_unique_u64(sessions_ht, &session->session_n);
+ return session;
+
+error:
+ session_put(session);
+ return NULL;
+}
+
+/* Should be called with RCU read-side lock held. */
+bool session_get(struct relay_session *session)
+{
+ return urcu_ref_get_unless_zero(&session->ref);
+}
+
+/*
+ * Lookup a session within the session hash table using the session id
+ * as key. A session reference is taken when a session is returned.
+ * session_put() must be called on that session.