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diff --git a/lib/generic/map.h b/lib/generic/map.h
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+/*
+ * critbit89 - A crit-bit map implementation for strings in C89
+ * Written by Jonas Gehring <jonas@jgehring.net>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+/**
+ * @file map.h
+ * @brief A Crit-bit tree key-value map implementation.
+ *
+ * @warning If the user provides a custom allocator, it must return addresses aligned to 2B boundary.
+ *
+ * # Example usage:
+ *
+ * @code{.c}
+ *      map_t map = map_make(NULL);
+ *
+ *      // Custom allocator (optional)
+ *      map.malloc = &mymalloc;
+ *      map.baton  = &mymalloc_context;
+ *
+ *      // Insert k-v pairs
+ *      int values = { 42, 53, 64 };
+ *      if (map_set(&map, "princess", &values[0]) != 0 ||
+ *          map_set(&map, "prince", &values[1])   != 0 ||
+ *          map_set(&map, "leia", &values[2])     != 0) {
+ *          fail();
+ *      }
+ *
+ *      // Test membership
+ *      if (map_contains(&map, "leia")) {
+ *          success();
+ *      }
+ *
+ *      // Prefix search
+ *      int i = 0;
+ *      int count(const char *k, void *v, void *ext) { (*(int *)ext)++; return 0; }
+ *      if (map_walk_prefixed(map, "princ", count, &i) == 0) {
+ *          printf("%d matches\n", i);
+ *      }
+ *
+ *      // Delete
+ *      if (map_del(&map, "badkey") != 0) {
+ *          fail(); // No such key
+ *      }
+ *
+ *      // Clear the map
+ *      map_clear(&map);
+ * @endcode
+ *
+ * \addtogroup generics
+ * @{
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct knot_mm; /* avoid the unnecessary include */
+
+/** Main data structure */
+typedef struct {
+	void *root;
+	struct knot_mm *pool;
+} map_t;
+
+/** Creates an new empty critbit map.  Pass NULL for malloc+free. */
+static inline map_t map_make(struct knot_mm *pool)
+{
+	return (map_t){ .root = NULL, .pool = pool };
+}
+
+/** Returns non-zero if map contains str */
+int map_contains(map_t *map, const char *str);
+
+/** Returns value if map contains str.  Note: NULL may mean two different things. */
+void *map_get(map_t *map, const char *str);
+
+/** Inserts str into map.  Returns 0 if new, 1 if replaced, or ENOMEM. */
+int map_set(map_t *map, const char *str, void *val);
+
+/** Deletes str from the map, returns 0 on suceess */
+int map_del(map_t *map, const char *str);
+
+/** Clears the given map */
+void map_clear(map_t *map);
+
+/**
+ * Calls callback for all strings in map
+ * See @fn map_walk_prefixed() for documentation on parameters.
+ */
+#define map_walk(map, callback, baton) \
+	map_walk_prefixed((map), "", (callback), (baton))
+
+/**
+ * Calls callback for all strings in map with the given prefix.
+ * Returns value immediately if a callback returns nonzero.
+ *
+ * @param map
+ * @param prefix   required string prefix (empty => all strings)
+ * @param callback callback parameters are (key, value, baton)
+ * @param baton    passed uservalue
+ */
+int map_walk_prefixed(map_t *map, const char *prefix,
+	int (*callback)(const char *, void *, void *), void *baton);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+/** @} */