2 files changed, 82 insertions, 0 deletions
diff --git a/include/str_table.h b/include/str_table.h
new file mode 100644
index 0000000..61f8aa5
--- /dev/null
+++ b/include/str_table.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * str_table.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef STR_TABLE_H
+#define STR_TABLE_H
+
+#include "sqfs/predef.h"
+
+typedef struct str_bucket_t {
+	struct str_bucket_t *next;
+	char *str;
+	size_t index;
+	size_t refcount;
+} str_bucket_t;
+
+/* Stores strings in a hash table and assigns an incremental, unique ID to
+   each string. Subsequent additions return the existing ID. The ID can be
+   used for (hopefully) constant time lookup of the original string. */
+typedef struct {
+	str_bucket_t **buckets;
+	size_t num_buckets;
+
+	char **strings;
+	size_t num_strings;
+	size_t max_strings;
+} str_table_t;
+
+/* `size` is the number of hash table buckets to use internally. */
+SQFS_INTERNAL int str_table_init(str_table_t *table, size_t size);
+
+SQFS_INTERNAL void str_table_cleanup(str_table_t *table);
+
+/* Resolve a string to an incremental, unique ID. */
+SQFS_INTERNAL
+int str_table_get_index(str_table_t *table, const char *str, size_t *idx);
+
+/* Resolve a unique ID to the string it represents.
+   Returns NULL if the ID is unknown, i.e. out of bounds. */
+SQFS_INTERNAL
+const char *str_table_get_string(str_table_t *table, size_t index);
+
+SQFS_INTERNAL void str_table_add_ref(str_table_t *table, size_t index);
+
+SQFS_INTERNAL void str_table_del_ref(str_table_t *table, size_t index);
+
+SQFS_INTERNAL size_t str_table_get_ref_count(str_table_t *table, size_t index);
+
+#endif /* STR_TABLE_H */
diff --git a/include/util.h b/include/util.h
new file mode 100644
index 0000000..a379c0d
--- /dev/null
+++ b/include/util.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * util.h
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#ifndef SQFS_UTIL_H
+#define SQFS_UTIL_H
+
+#include "config.h"
+#include "sqfs/predef.h"
+#include "compat.h"
+
+#include <stddef.h>
+
+/*
+  Helper for allocating data structures with flexible array members.
+
+  'base_size' is the size of the struct itself, 'item_size' the size of a
+  single array element and 'nmemb' the number of elements.
+
+  Iternally checks for arithmetic overflows when allocating the combined thing.
+ */
+SQFS_INTERNAL
+void *alloc_flex(size_t base_size, size_t item_size, size_t nmemb);
+
+/* Basically the same as calloc, but *ALWAYS* does overflow checking */
+SQFS_INTERNAL
+void *alloc_array(size_t item_size, size_t nmemb);
+
+#endif /* SQFS_UTIL_H */