+ goto error;
+ }
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Read index values from the given index file.
+ *
+ * Return 0 on success, -1 on error.
+ */
+int lttng_index_file_read(const struct lttng_index_file *index_file,
+ struct ctf_packet_index *element)
+{
+ ssize_t ret;
+ int fd = index_file->fd;
+ size_t len = index_file->element_len;
+
+ assert(element);
+
+ if (fd < 0) {
+ goto error;
+ }
+
+ ret = lttng_read(fd, element, len);
+ if (ret < len) {
+ PERROR("read index file");
+ goto error;
+ }
+ return 0;
+
+error:
+ return -1;
+}
+
+/*
+ * Open index file using a given path, channel name and tracefile count.
+ *
+ * Return allocated struct lttng_index_file, NULL on error.
+ */
+struct lttng_index_file *lttng_index_file_open(const char *path_name,
+ const char *channel_name, uint64_t tracefile_count,
+ uint64_t tracefile_count_current)
+{
+ struct lttng_index_file *index_file;
+ int ret, read_fd;
+ ssize_t read_len;
+ char fullpath[PATH_MAX];
+ struct ctf_packet_index_file_hdr hdr;
+ uint32_t major, minor, element_len;
+
+ assert(path_name);
+ assert(channel_name);
+
+ index_file = zmalloc(sizeof(*index_file));
+ if (!index_file) {
+ PERROR("allocating lttng_index_file");
+ goto error;
+ }
+
+ if (tracefile_count > 0) {
+ ret = snprintf(fullpath, sizeof(fullpath), "%s/" DEFAULT_INDEX_DIR "/%s_%"
+ PRIu64 DEFAULT_INDEX_FILE_SUFFIX, path_name,
+ channel_name, tracefile_count_current);
+ } else {
+ ret = snprintf(fullpath, sizeof(fullpath), "%s/" DEFAULT_INDEX_DIR "/%s"
+ DEFAULT_INDEX_FILE_SUFFIX, path_name, channel_name);
+ }
+ if (ret < 0) {
+ PERROR("snprintf index path");
+ goto error;
+ }
+
+ DBG("Index opening file %s in read only", fullpath);
+ read_fd = open(fullpath, O_RDONLY);
+ if (read_fd < 0) {
+ if (errno == ENOENT) {
+ ret = -ENOENT;
+ } else {
+ PERROR("opening index in read-only");
+ }
+ goto error;
+ }
+
+ read_len = lttng_read(read_fd, &hdr, sizeof(hdr));
+ if (read_len < 0) {
+ PERROR("Reading index header");
+ goto error_close;
+ }
+
+ if (be32toh(hdr.magic) != CTF_INDEX_MAGIC) {
+ ERR("Invalid header magic");
+ goto error_close;
+ }
+ major = be32toh(hdr.index_major);
+ minor = be32toh(hdr.index_minor);
+ element_len = be32toh(hdr.packet_index_len);
+
+ if (major != CTF_INDEX_MAJOR) {
+ ERR("Invalid header version");
+ goto error_close;