--- /dev/null
+/*
+ * General header of nsscash
+ *
+ * Copyright (C) 2019 Simon Ruderich
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef CASH_H
+#define CASH_H
+
+#include <stdint.h>
+
+
+// Global constants
+
+#define MAGIC "NSS-CASH"
+
+// Defined in Makefile
+#ifndef NSSCASH_PASSWD_FILE
+# define NSSCASH_PASSWD_FILE "/etc/passwd.nsscash"
+#endif
+
+
+// Global structs
+
+struct header {
+ char magic[8]; // magic string
+ uint64_t version; // also doubles as byte-order check
+
+ uint64_t count;
+
+ // All offsets are relative to data
+ uint64_t off_orig_index;
+ uint64_t off_id_index;
+ uint64_t off_name_index;
+ uint64_t off_data;
+
+ char data[];
+} __attribute__((packed));
+
+#endif