tdb: test that new-style TDBs with non-default hashes can't be opened.

We currently allow opening of a TDB without any idea if we're using the
right hash function.  Since most people use the default, this hasn't been
a big issue.

The next change will put an example hash value in the rwlocks field in
the header: current TDB already refuses to open a TDB with this field
non-zero.  This commit simply adds tests that that occurs.

ccan/tdb/_info

 #include <string.h>
+#include <stdio.h>
 
 /**
  * tdb - The trivial (transactional) database
@@ -63,14 +64,18 @@
  * Author: Andrew Tridgell, Jeremy Allison, Rusty Russell
  *
  * Licence: LGPLv3 (or later)
+ *
+ * Fails: valgrind-tests // valgrind breaks fcntl locks.
  */
 int main(int argc, char *argv[])
 {
 	if (argc != 2)
 		return 1;
 
-	if (strcmp(argv[1], "depends") == 0)
+	if (strcmp(argv[1], "depends") == 0) {
+		printf("ccan/hash\n");
 		return 0;
+	}
 
 	return 1;
 }

ccan/tdb/test/run-wronghash-old.c

+#define _XOPEN_SOURCE 500
+#include <ccan/tdb/tdb.h>
+#include <ccan/tdb/io.c>
+#include <ccan/tdb/tdb.c>
+#include <ccan/tdb/lock.c>
+#include <ccan/tdb/freelist.c>
+#include <ccan/tdb/traverse.c>
+#include <ccan/tdb/transaction.c>
+#include <ccan/tdb/error.c>
+#include <ccan/tdb/open.c>
+#include <ccan/tdb/check.c>
+#include <ccan/hash/hash.h>
+#include <ccan/tap/tap.h>
+#include <stdlib.h>
+#include <err.h>
+
+static unsigned int non_jenkins_hash(TDB_DATA *key)
+{
+	return ~hash_stable(key->dptr, key->dsize, 0);
+}
+
+static void log_fn(struct tdb_context *tdb, enum tdb_debug_level level, const char *fmt, ...)
+{
+	unsigned int *count = tdb_get_logging_private(tdb);
+	/* Old code used to complain about spinlocks on new databases. */
+	if (strstr(fmt, "spinlock"))
+		(*count)++;
+}
+
+/* The old code should barf on new-style TDBs created with a non-default hash.
+ */
+int main(int argc, char *argv[])
+{
+	struct tdb_context *tdb;
+	unsigned int log_count;
+	struct tdb_logging_context log_ctx = { log_fn, &log_count };
+
+	plan_tests(8);
+
+	/* We should fail to open new-style non-default-hash tdbs of
+	 * either endian. */
+	log_count = 0;
+	tdb = tdb_open_ex("test/jenkins-le-hash.tdb", 0, 0, O_RDWR, 0,
+			  &log_ctx, NULL);
+	ok1(!tdb);
+	ok1(log_count == 1);
+
+	log_count = 0;
+	tdb = tdb_open_ex("test/jenkins-be-hash.tdb", 0, 0, O_RDWR, 0,
+			  &log_ctx, NULL);
+	ok1(!tdb);
+	ok1(log_count == 1);
+
+	/* And of course, if we use the wrong hash it will still fail. */
+	log_count = 0;
+	tdb = tdb_open_ex("test/jenkins-le-hash.tdb", 0, 0, O_RDWR, 0,
+			  &log_ctx, non_jenkins_hash);
+	ok1(!tdb);
+	ok1(log_count == 1);
+
+	log_count = 0;
+	tdb = tdb_open_ex("test/jenkins-be-hash.tdb", 0, 0, O_RDWR, 0,
+			  &log_ctx, non_jenkins_hash);
+	ok1(!tdb);
+	ok1(log_count == 1);
+
+	return exit_status();
+}