tdb2: approximate INCOMPATIBLE_HASH flag with tdb1_incompatible_hash()

Rather than leak TDB_INCOMPATIBLE_HASH through to the TDB2 API, we make
it that if they use the tdb1_incompatible_hash function as their hash,
then we treat it as if they had specified the TDB_INCOMPATIBLE_HASH
flag (ie. we mark the header so it's unusable by tdb < 1.2.6).

This precludes the possibility of using TDB_INCOMPATIBLE_HASH with a
custom hash function: that used to allow the user to ensure that old TDB
versions couldn't open the TDB file (and recent ones check the header to
ensure they're using the right hash).  But that's a small loss.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
(Imported from CCAN commit 3004f7e89a5978064b4fb29c1027e6d0d39e9418)

1 files changed, 19 insertions, 7 deletions

diff --git a/lib/tdb2/test/run-tdb1-wronghash-fail.c b/lib/tdb2/test/run-tdb1-wronghash-fail.c
index 368835ed7f..97a8293e7d 100644
--- a/lib/tdb2/test/run-tdb1-wronghash-fail.c
+++ b/lib/tdb2/test/run-tdb1-wronghash-fail.c
@@ -11,6 +11,18 @@ static void log_fn(struct tdb1_context *tdb, enum tdb_log_level level,
 		(*count)++;
 }
 
+static unsigned int jenkins_hashfn(TDB_DATA *key)
+{
+	return hashlittle(key->dptr, key->dsize);
+}
+
+/* the tdb1_old_hash function is "magic" as it automatically makes us test the
+ * tdb1_incompatible_hash as well, so use this wrapper. */
+static unsigned int old_hash(TDB_DATA *key)
+{
+	return tdb1_old_hash(key);
+}
+
 int main(int argc, char *argv[])
 {
 	struct tdb1_context *tdb;
@@ -33,7 +45,7 @@ int main(int argc, char *argv[])
 
 	/* Fail to open with different hash. */
 	tdb = tdb1_open_ex("run-wronghash-fail.tdb", 0, 0, O_RDWR, 0,
-			  &log_ctx, tdb1_jenkins_hash);
+			  &log_ctx, jenkins_hashfn);
 	ok1(!tdb);
 	ok1(log_count == 1);
 
@@ -41,7 +53,7 @@ int main(int argc, char *argv[])
 	log_count = 0;
 	tdb = tdb1_open_ex("run-wronghash-fail.tdb", 0, 0,
 			  O_CREAT|O_RDWR|O_TRUNC,
-			  0600, &log_ctx, tdb1_jenkins_hash);
+			  0600, &log_ctx, jenkins_hashfn);
 	ok1(tdb);
 	ok1(log_count == 0);
 	tdb1_close(tdb);
@@ -49,26 +61,26 @@ int main(int argc, char *argv[])
 	/* Endian should be no problem. */
 	log_count = 0;
 	tdb = tdb1_open_ex("test/jenkins-le-hash.tdb1", 0, 0, O_RDWR, 0,
-			  &log_ctx, tdb1_old_hash);
+			  &log_ctx, old_hash);
 	ok1(!tdb);
 	ok1(log_count == 1);
 
 	log_count = 0;
 	tdb = tdb1_open_ex("test/jenkins-be-hash.tdb1", 0, 0, O_RDWR, 0,
-			  &log_ctx, tdb1_old_hash);
+			  &log_ctx, old_hash);
 	ok1(!tdb);
 	ok1(log_count == 1);
 
 	log_count = 0;
 	/* Fail to open with old default hash. */
 	tdb = tdb1_open_ex("run-wronghash-fail.tdb", 0, 0, O_RDWR, 0,
-			  &log_ctx, tdb1_old_hash);
+			  &log_ctx, old_hash);
 	ok1(!tdb);
 	ok1(log_count == 1);
 
 	log_count = 0;
 	tdb = tdb1_open_ex("test/jenkins-le-hash.tdb1", 0, 0, O_RDONLY,
-			  0, &log_ctx, tdb1_jenkins_hash);
+			  0, &log_ctx, tdb1_incompatible_hash);
 	ok1(tdb);
 	ok1(log_count == 0);
 	ok1(tdb1_check(tdb, NULL, NULL) == 0);
@@ -76,7 +88,7 @@ int main(int argc, char *argv[])
 
 	log_count = 0;
 	tdb = tdb1_open_ex("test/jenkins-be-hash.tdb1", 0, 0, O_RDONLY,
-			  0, &log_ctx, tdb1_jenkins_hash);
+			  0, &log_ctx, tdb1_incompatible_hash);
 	ok1(tdb);
 	ok1(log_count == 0);
 	ok1(tdb1_check(tdb, NULL, NULL) == 0);