Add mfree utility to show the freelist

libraries/libmdb/Makefile

@@ -28,6 +28,7 @@ mtest3:	mtest3.o libmdb.a
 mtest4:	mtest4.o libmdb.a
 mtest5:	mtest5.o libmdb.a
 mtest6:	mtest6.o libmdb.a
+mfree:	mfree.o libmdb.a
 
 mdb.o: mdb.c mdb.h midl.h
 	$(CC) $(CFLAGS) -fPIC $(CPPFLAGS) -c mdb.c

libraries/libmdb/mfree.c

@@ -0,0 +1,56 @@
+/* mfree.c - memory-mapped database freelist scanner */
+/*
+ * Copyright 2011 Howard Chu, Symas Corp.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+#define _XOPEN_SOURCE 500		/* srandom(), random() */
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include "mdb.h"
+#include "midl.h"
+
+int main(int argc,char * argv[])
+{
+	int rc;
+	MDB_env *env;
+	MDB_dbi dbi;
+	MDB_val key, data;
+	MDB_txn *txn;
+	MDB_stat mst;
+	MDB_cursor *cursor;
+	ID i, j, *iptr;
+
+	if (argc != 2) {
+		fprintf(stderr, "usage: %s <pathname>\n", argv[0]);
+		exit(1);
+	}
+
+	rc = mdb_env_create(&env);
+	rc = mdb_env_open(env, argv[1], MDB_RDONLY, 0664);
+	rc = mdb_txn_begin(env, NULL, MDB_RDONLY, &txn);
+	dbi = 0;
+	rc = mdb_cursor_open(txn, dbi, &cursor);
+	while ((rc = mdb_cursor_get(cursor, &key, &data, MDB_NEXT)) == 0) {
+		printf("key: %p %zu, data: %p\n",
+			key.mv_data,  *(ID *) key.mv_data,
+			data.mv_data);
+		iptr = data.mv_data;
+		j = *iptr++;
+		for (i=0; i<j; i++)
+			printf(" %zu\n", iptr[i]);
+	}
+	mdb_cursor_close(cursor);
+	mdb_txn_abort(txn);
+	mdb_env_close(env);
+
+	return 0;
+}