tdb: automatically identify Jenkins hash tdbs

If the caller to tdb_open_ex() doesn't specify a hash, and tdb_old_hash
doesn't match, try tdb_jenkins_hash.

This was Metze's idea: it makes life simpler, especially with the upcoming
TDB_INCOMPATIBLE_HASH flag.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
(cherry picked from commit ccac258d14dda7d8a994a7b80474ce6d85478a6d)

Signed-off-by: Stefan Metzmacher <metze@samba.org>

diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c
index 3d972caee225a3adaac7922d411aeddc95017464..0633bc1f5f6d8cf0a21b47adb4f6f6649519b131 100644 (file)
--- a/lib/tdb/common/open.c
+++ b/lib/tdb/common/open.c
@@ -37,7 +37,7 @@ void tdb_header_hash(struct tdb_context *tdb,
        TDB_DATA hash_key;
        uint32_t tdb_magic = TDB_MAGIC;
 
-       hash_key.dptr = (unsigned char *)TDB_MAGIC_FOOD;
+       hash_key.dptr = discard_const_p(unsigned char, TDB_MAGIC_FOOD);
        hash_key.dsize = sizeof(TDB_MAGIC_FOOD);
        *magic1_hash = tdb->hash_fn(&hash_key);
 
@@ -149,6 +149,23 @@ static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, con
 {
 }
 
+static bool check_header_hash(struct tdb_context *tdb,
+                             bool default_hash, uint32_t *m1, uint32_t *m2)
+{
+       tdb_header_hash(tdb, m1, m2);
+       if (tdb->header.magic1_hash == *m1 &&
+           tdb->header.magic2_hash == *m2) {
+               return true;
+       }
+
+       /* If they explicitly set a hash, always respect it. */
+       if (!default_hash)
+               return false;
+
+       /* Otherwise, try the other inbuilt hash. */
+       tdb->hash_fn = tdb_jenkins_hash;
+       return check_header_hash(tdb, false, m1, m2);
+}
 
 struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
                                int open_flags, mode_t mode,
@@ -161,9 +178,8 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
        unsigned char *vp;
        uint32_t vertest;
        unsigned v;
-       uint32_t magic1_hash;
-       uint32_t magic2_hash;
        const char *hash_alg;
+       uint32_t magic1, magic2;
 
        if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
                /* Can't log this */
@@ -185,10 +201,10 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
 
        if (hash_fn) {
                tdb->hash_fn = hash_fn;
-               hash_alg = "user defined";
+               hash_alg = "the user defined";
        } else {
                tdb->hash_fn = tdb_old_hash;
-               hash_alg = "default";
+               hash_alg = "either default";
        }
 
        /* cache the page size */
@@ -288,23 +304,20 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
                goto fail;
        }
 
-       tdb_header_hash(tdb, &magic1_hash, &magic2_hash);
-
        if ((tdb->header.magic1_hash == 0) && (tdb->header.magic2_hash == 0)) {
                /* older TDB without magic hash references */
-       } else if ((tdb->header.magic1_hash != magic1_hash) ||
-                  (tdb->header.magic2_hash != magic2_hash)) {
+       } else if (!check_header_hash(tdb, !hash_fn, &magic1, &magic2)) {
                TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_open_ex: "
-                        "%s was not created with the %s hash function we are using\n"
+                        "%s was not created with %s hash function we are using\n"
                         "magic1_hash[0x%08X %s 0x%08X] "
                         "magic2_hash[0x%08X %s 0x%08X]\n",
                         name, hash_alg,
                         tdb->header.magic1_hash,
-                        (tdb->header.magic1_hash == magic1_hash) ? "==" : "!=",
-                        magic1_hash,
+                        (tdb->header.magic1_hash == magic1) ? "==" : "!=",
+                        magic1,
                         tdb->header.magic2_hash,
-                        (tdb->header.magic2_hash == magic2_hash) ? "==" : "!=",
-                        magic2_hash));
+                        (tdb->header.magic2_hash == magic2) ? "==" : "!=",
+                        magic2));
                errno = EINVAL;
                goto fail;
        }