tdb: enforce hashing, via example hash in old rwlocks entry in header.

[ccan] / ccan / tdb / open.c

diff --git a/ccan/tdb/open.c b/ccan/tdb/open.c
index bfa26dec58fd256db124fcd18ca9c50598ea4fe7..437a5fc38d1706e9b5f3e846876f8aa4e8d9da75 100644 (file)
--- a/ccan/tdb/open.c
+++ b/ccan/tdb/open.c
@@ -63,6 +63,7 @@ static int tdb_new_database(struct tdb_context *tdb, int hash_size)
        /* Fill in the header */
        newdb->version = TDB_VERSION;
        newdb->hash_size = hash_size;
+       newdb->hashcheck = hashcheck(tdb);
        if (tdb->flags & TDB_INTERNAL) {
                tdb->map_size = size;
                tdb->map_ptr = (char *)newdb;
@@ -143,6 +144,18 @@ static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, con
 {
 }
 
+uint32_t hashcheck(struct tdb_context *tdb)
+{
+       uint32_t vals[] = { TDB_VERSION, TDB_MAGIC };
+       TDB_DATA hashkey = { (unsigned char *)vals, sizeof(vals) };
+
+       /* If we're using the default hash, let old code still open the db. */
+       if (tdb->hash_fn == default_tdb_hash)
+               return 0;
+
+       /* Only let new hash-aware TDB code open it (must not be zero!) */
+       return (tdb->hash_fn(&hashkey) | 1);
+}
 
 struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
                                int open_flags, mode_t mode,
@@ -288,8 +301,8 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
        if (fstat(tdb->fd, &st) == -1)
                goto fail;
 
-       if (tdb->header.rwlocks != 0) {
-               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: spinlocks no longer supported\n"));
+       if (tdb->header.hashcheck != hashcheck(tdb)) {
+               TDB_LOG((tdb, TDB_DEBUG_ERROR, "tdb_open_ex: wrong hash?\n"));
                goto fail;
        }