archive: fix check for missing url

Running "git archive --remote" checks that we have at least one url for
the remote. It does so by looking at remote.url[0], but that won't work;
if we have no url at all, then remote.url will be NULL, and we'll
segfault.

Check url_nr instead, which is a more direct way of asking what we
want.

You can trigger the segfault like this:

  git -c remote.foo.vcs=bar archive --remote=foo

but I didn't bother adding a test. This is the tip of the iceberg for
no-url remotes, and a later patch will improve that situation. I just
wanted to clean up this bug so it didn't make further refactoring of
this code more confusing.

Signed-off-by: Jeff King <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: peff

builtin/archive.c

@@ -31,7 +31,7 @@ static int run_remote_archiver(int argc, const char **argv,
 	struct packet_reader reader;
 
 	_remote = remote_get(remote);
-	if (!_remote->url[0])
+	if (!_remote->url_nr)
 		die(_("git archive: Remote with no URL"));
 	transport = transport_get(_remote, _remote->url[0]);
 	transport_connect(transport, "git-upload-archive", exec, fd);