tdb: automatically identify Jenkins hash tdbs

[ccan] / ccan / tdb / open.c

diff --git a/ccan/tdb/open.c b/ccan/tdb/open.c
index aa32a45eda3957aa04e8c9444a9ba2bd749b1207..b92567b37819855a754dd4b03b94cf14fc21f800 100644 (file)
--- a/ccan/tdb/open.c
+++ b/ccan/tdb/open.c
@@ -30,20 +30,6 @@
 /* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
 static struct tdb_context *tdbs = NULL;
 
-
-/* This is based on the hash algorithm from gdbm */
-static unsigned int default_tdb_hash(TDB_DATA *key)
-{
-       uint32_t value; /* Used to compute the hash value.  */
-       uint32_t   i;   /* Used to cycle through random values. */
-
-       /* Set the initial value from the key size. */
-       for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
-               value = (value + (key->dptr[i] << (i*5 % 24)));
-
-       return (1103515243 * value + 12345);  
-}
-
 /* We use two hashes to double-check they're using the right hash function. */
 void tdb_header_hash(struct tdb_context *tdb,
                     uint32_t *magic1_hash, uint32_t *magic2_hash)
@@ -165,6 +151,23 @@ 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,
@@ -177,9 +180,8 @@ 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 */
@@ -204,10 +206,10 @@ 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 = default_tdb_hash;
-               hash_alg = "default";
+               tdb->hash_fn = tdb_old_hash;
+               hash_alg = "either default";
        }
 
        /* cache the page size */
@@ -325,23 +327,20 @@ 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;
        }