+ if (unlink_existing_file) {
+ /*
+ * For tracefile rotation. We need to unlink the old
+ * file if present to synchronize with the tail of the
+ * live viewer which could be working on this same file.
+ * By doing so, any reference to the old index file
+ * stays valid even if we re-create a new file with the
+ * same name afterwards.
+ */
+ chunk_status = lttng_trace_chunk_unlink_file(
+ chunk, index_file_path);
+ if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK &&
+ !(chunk_status == LTTNG_TRACE_CHUNK_STATUS_ERROR &&
+ errno == ENOENT)) {
+ goto error;
+ }
+ }
+
+ chunk_status = lttng_trace_chunk_open_file(chunk, index_file_path,
+ flags, mode, &fd);
+ if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
+ goto error;
+ }
+
+ if (flags == WRITE_FILE_FLAGS) {
+ ctf_packet_index_file_hdr_init(&hdr, index_major, index_minor);
+ size_ret = lttng_write(fd, &hdr, sizeof(hdr));
+ if (size_ret < sizeof(hdr)) {
+ PERROR("Failed to write index header");
+ goto error;
+ }
+ index_file->element_len = ctf_packet_index_len(index_major, index_minor);
+ } else {
+ uint32_t element_len;
+
+ size_ret = lttng_read(fd, &hdr, sizeof(hdr));
+ if (size_ret < 0) {
+ PERROR("Failed to read index header");
+ goto error;
+ }
+ if (be32toh(hdr.magic) != CTF_INDEX_MAGIC) {
+ ERR("Invalid header magic");
+ goto error;
+ }
+ if (index_major != be32toh(hdr.index_major)) {
+ ERR("Index major number mismatch: %u, expect %u",
+ be32toh(hdr.index_major), index_major);
+ goto error;
+ }
+ if (index_minor != be32toh(hdr.index_minor)) {
+ ERR("Index minor number mismatch: %u, expect %u",
+ be32toh(hdr.index_minor), index_minor);
+ goto error;
+ }
+ element_len = be32toh(hdr.packet_index_len);
+ if (element_len > sizeof(struct ctf_packet_index)) {
+ ERR("Index element length too long");
+ goto error;
+ }
+ index_file->element_len = element_len;
+ }
+ index_file->fd = fd;
+ index_file->major = index_major;
+ index_file->minor = index_minor;
+ urcu_ref_init(&index_file->ref);
+
+ return index_file;