1 files changed, 52 insertions, 0 deletions
diff --git a/lib/sqfs/id_table.c b/lib/sqfs/id_table.c
new file mode 100644
index 0000000..cd31360
--- /dev/null
+++ b/lib/sqfs/id_table.c
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+#include "id_table.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+
+int id_table_init(id_table_t *tbl)
+{
+	memset(tbl, 0, sizeof(*tbl));
+	return 0;
+}
+
+void id_table_cleanup(id_table_t *tbl)
+{
+	free(tbl->ids);
+}
+
+int id_table_id_to_index(id_table_t *tbl, uint32_t id, uint16_t *out)
+{
+	size_t i, sz;
+	void *ptr;
+
+	for (i = 0; i < tbl->num_ids; ++i) {
+		if (tbl->ids[i] == id) {
+			*out = i;
+			return 0;
+		}
+	}
+
+	if (tbl->num_ids == 0x10000) {
+		fputs("Too many unique UIDs/GIDs (more than 64k)!\n", stderr);
+		return -1;
+	}
+
+	if (tbl->num_ids == tbl->max_ids) {
+		sz = (tbl->max_ids ? tbl->max_ids * 2 : 16);
+		ptr = realloc(tbl->ids, sizeof(tbl->ids[0]) * sz);
+
+		if (ptr == NULL) {
+			perror("growing ID table");
+			return -1;
+		}
+
+		tbl->ids = ptr;
+		tbl->max_ids = sz;
+	}
+
+	*out = tbl->num_ids;
+	tbl->ids[tbl->num_ids++] = id;
+	return 0;
+}