ntdb: make database read-only during ntdb_parse() callback.

Since we have a readlock, any write will grab a write lock: if it happens
to be on the same bucket, we'll fail.

For that reason, enforce read-only so every write operation fails
(even for NTDB_NOLOCK or NTDB_INTERNAL dbs), and document it!

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

1 files changed, 94 insertions, 0 deletions

diff --git a/lib/ntdb/test/api-95-read-only-during-parse.c b/lib/ntdb/test/api-95-read-only-during-parse.c
new file mode 100644
index 0000000000..8252b812d2
--- /dev/null
+++ b/lib/ntdb/test/api-95-read-only-during-parse.c
@@ -0,0 +1,94 @@
+/* Make sure write operations fail during ntdb_parse(). */
+#include "config.h"
+#include "ntdb.h"
+#include "tap-interface.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include "logging.h"
+
+static struct ntdb_context *ntdb;
+
+/* We could get either of these. */
+static bool xfail(enum NTDB_ERROR ecode)
+{
+	return ecode == NTDB_ERR_RDONLY || ecode == NTDB_ERR_LOCK;
+}
+
+static enum NTDB_ERROR parse(NTDB_DATA key, NTDB_DATA data,
+			     NTDB_DATA *expected)
+{
+	NTDB_DATA add = ntdb_mkdata("another", strlen("another"));
+
+	if (!ntdb_deq(data, *expected)) {
+		return NTDB_ERR_EINVAL;
+	}
+
+	/* These should all fail.*/
+	if (!xfail(ntdb_store(ntdb, add, add, NTDB_INSERT))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_append(ntdb, key, add))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_delete(ntdb, key))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_transaction_start(ntdb))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_chainlock(ntdb, key))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_lockall(ntdb))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_wipe_all(ntdb))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	if (!xfail(ntdb_repack(ntdb))) {
+		return NTDB_ERR_EINVAL;
+	}
+	tap_log_messages--;
+
+	/* Access the record one more time. */
+	if (!ntdb_deq(data, *expected)) {
+		return NTDB_ERR_EINVAL;
+	}
+
+	return NTDB_SUCCESS;
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned int i;
+	int flags[] = { NTDB_DEFAULT, NTDB_NOMMAP, NTDB_CONVERT };
+	NTDB_DATA key = ntdb_mkdata("hello", 5), data = ntdb_mkdata("world", 5);
+
+	plan_tests(sizeof(flags) / sizeof(flags[0]) * 2 + 1);
+	for (i = 0; i < sizeof(flags) / sizeof(flags[0]); i++) {
+		ntdb = ntdb_open("api-95-read-only-during-parse.ntdb",
+				 flags[i]|MAYBE_NOSYNC,
+				 O_RDWR|O_CREAT|O_TRUNC, 0600, &tap_log_attr);
+		ok1(ntdb_store(ntdb, key, data, NTDB_INSERT) == NTDB_SUCCESS);
+		ok1(ntdb_parse_record(ntdb, key, parse, &data) == NTDB_SUCCESS);
+		ntdb_close(ntdb);
+	}
+
+	ok1(tap_log_messages == 0);
+	return exit_status();
+}