+/**
+ * Append data to an existing session file.
+ *
+ * @param filename The name of the filename to append to. Must not be NULL.
+ * @param buf The data to be appended.
+ * @param unitsize The number of bytes per sample.
+ * @param units The number of samples.
+ *
+ * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments, or SR_ERR
+ * upon other errors.
+ */
+SR_API int sr_session_append(const char *filename, unsigned char *buf,
+ int unitsize, int units)
+{
+ struct zip *archive;
+ struct zip_source *logicsrc;
+ zip_int64_t num_files;
+ int chunk_num, next_chunk_num, ret, i;
+ const char *entry_name;
+ char chunkname[16];
+
+ if ((ret = sr_sessionfile_check(filename)) != SR_OK)
+ return ret;
+
+ if (!(archive = zip_open(filename, 0, &ret)))
+ return SR_ERR;
+
+ next_chunk_num = 1;
+ num_files = zip_get_num_entries(archive, 0);
+ for (i = 0; i < num_files; i++) {
+ entry_name = zip_get_name(archive, i, 0);
+ if (strncmp(entry_name, "logic-1", 7))
+ continue;
+ if (strlen(entry_name) == 7) {
+ /* This file has no extra chunks, just a single "logic-1".
+ * Rename it to "logic-1-1" * and continue with chunk 2. */
+ if (zip_rename(archive, i, "logic-1-1") == -1) {
+ sr_err("Failed to rename 'logic-1' to 'logic-1-1'.");
+ return SR_ERR;
+ }
+ next_chunk_num = 2;
+ break;
+ } else if (strlen(entry_name) > 8 && entry_name[7] == '-') {
+ chunk_num = strtoull(entry_name + 8, NULL, 10);
+ if (chunk_num >= next_chunk_num)
+ next_chunk_num = chunk_num + 1;
+ }
+ }
+ snprintf(chunkname, 15, "logic-1-%d", next_chunk_num);
+ if (!(logicsrc = zip_source_buffer(archive, buf, units * unitsize, FALSE)))
+ return SR_ERR;
+ if (zip_add(archive, chunkname, logicsrc) == -1)
+ return SR_ERR;
+ if ((ret = zip_close(archive)) == -1) {
+ sr_info("error saving session file: %s", zip_strerror(archive));
+ return SR_ERR;
+ }
+
+ return SR_OK;
+}
+
+/** @} */