tdb2: add tdb_attribute_seed for setting hash seed.
[ccan] / ccan / tdb2 / tdb.c
index 9468e604a7f9fbb0d420ef0c0c7ff8a0e5d51e97..4b02755c28887667c1ca2adb157fb7520e8e4835 100644 (file)
@@ -94,7 +94,9 @@ struct new_database {
 };
 
 /* initialise a new database */
-static int tdb_new_database(struct tdb_context *tdb, struct tdb_header *hdr)
+static int tdb_new_database(struct tdb_context *tdb,
+                           struct tdb_attribute_seed *seed,
+                           struct tdb_header *hdr)
 {
        /* We make it up in memory, then write it out if not internal */
        struct new_database newdb;
@@ -105,7 +107,10 @@ static int tdb_new_database(struct tdb_context *tdb, struct tdb_header *hdr)
 
        /* Fill in the header */
        newdb.hdr.version = TDB_VERSION;
-       newdb.hdr.hash_seed = random_number(tdb);
+       if (seed)
+               newdb.hdr.hash_seed = seed->seed;
+       else
+               newdb.hdr.hash_seed = random_number(tdb);
        newdb.hdr.hash_test = TDB_HASH_MAGIC;
        newdb.hdr.hash_test = tdb->khash(&newdb.hdr.hash_test,
                                         sizeof(newdb.hdr.hash_test),
@@ -181,6 +186,7 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        uint64_t hash_test;
        unsigned v;
        struct tdb_header hdr;
+       struct tdb_attribute_seed *seed = NULL;
 
        tdb = malloc(sizeof(*tdb));
        if (!tdb) {
@@ -213,6 +219,9 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
                        tdb->khash = attr->hash.hash_fn;
                        tdb->hash_priv = attr->hash.hash_private;
                        break;
+               case TDB_ATTRIBUTE_SEED:
+                       seed = &attr->seed;
+                       break;
                default:
                        tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                                 "tdb_open: unknown attribute type %u\n",
@@ -243,7 +252,7 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
        /* internal databases don't need any of the rest. */
        if (tdb->flags & TDB_INTERNAL) {
                tdb->flags |= (TDB_NOLOCK | TDB_NOMMAP);
-               if (tdb_new_database(tdb, &hdr) != 0) {
+               if (tdb_new_database(tdb, seed, &hdr) != 0) {
                        tdb->log(tdb, TDB_DEBUG_ERROR, tdb->log_priv,
                                 "tdb_open: tdb_new_database failed!");
                        goto fail;
@@ -275,7 +284,8 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags,
 
        if (!tdb_pread_all(tdb->fd, &hdr, sizeof(hdr), 0)
            || strcmp(hdr.magic_food, TDB_MAGIC_FOOD) != 0) {
-               if (!(open_flags & O_CREAT) || tdb_new_database(tdb, &hdr) == -1) {
+               if (!(open_flags & O_CREAT)
+                   || tdb_new_database(tdb, seed, &hdr) == -1) {
                        if (errno == 0) {
                                errno = EIO; /* ie bad format or something */
                        }