Re: [PATCH] upload-pack.c: treat want-ref relative to namespace

[Kim Altintop <kim@eagain.st>]

On Fri Jul 30, 2021 at 8:57 PM CEST, Junio C Hamano wrote:
>
> Kim Altintop <kim@eagain.st> writes:
[..]
> > Also check if the wanted ref is hidden via 'hideRefs', and respond with
> > an error otherwise. It was previously possible to request any ref, but
> > note that this is still the case unless 'hideRefs' is in effect.
[..]
> Nicely described. I have a question on the last sentence, though.
> Do you mean that any ref can be requested when a namespace is in
> use, as long as 'hideRefs' is not in effect? What does "any ref"
> exactly mean---even thouse outside the given namespace (and if so
> how?)

Thank you. It seems like I got confused for a moment when writing the commit
message. It's not possible to get a ref outside the namespace anymore. I removed
that sentence.

> > +test_expect_success 'setup namespaced repo' '
> > +	(
> > +		git init -b main "$REPO" &&
> > +		cd "$REPO" &&
> > +		test_commit a &&
> > +		test_commit b &&
> > +		git checkout a &&
> > +		test_commit c &&
> > +		git checkout a &&
> > +		test_commit d &&
> > +		git update-ref refs/heads/ns-no b &&
> > +		git update-ref refs/namespaces/ns/refs/heads/ns-yes c &&
> > +		git update-ref refs/namespaces/ns/refs/heads/hidden d
> > +	) &&
> > +    git -C "$REPO" config uploadpack.allowRefInWant true &&
> > +    git -C "$REPO" config transfer.hideRefs refs/heads/hidden
> > +'
>
> I wonder why the last two are outside the subshell? IOW, you could
> have configured the newly created repository while you were still in
> there.

To be honest, I don't know. I did that because the other repo setups in that
file follow the same pattern, I suppose that qualifies as "cargo culting". Happy
to remove the subshell, unless others point out that there is some specific
reason for it.

> Unless you mean to make all subsequent tests to be done inside the
> 'ns' namespace, and even when you do, you do not want to do this
> in order to keep each test as independent as possible (iow, make
> some of them skippable without affecting the later tests). Run the
> final test in a subshell, e.g.
>
> oid=$(git -C "$REPO" rev-parse c) &&
> test-tool pkt-line pack >in <<-EOF &&
> ...
> EOF
>
> (
> export GIT_NAMESPACE=ns &&
> test-tool ... >out <in
> ) &&
> check_output
>
> or if the command you want to run with a custom environment variable
> is a single external executable like this case, do
>
> oid=$(git -C "$REPO" rev-parse c) &&
> test-tool pkt-line pack >in <<-EOF &&
> ...
> EOF
> GIT_NAMESPACE=ns test-tool ... >out <in &&
> check_output
>
> That way, the environment will be kept clean without GIT_NAMESPACE
> outside the invocation of test-tool.
>
> Note that you cannot use this technique directly with test_must_fail
> which is *not* an external executable but is a shell function.
>
> test_must_fail env GIT_NAMESPACE=ns test-tool ...
>
> would be the way to write a step that must fail.


Ah thanks! I had tried

...
GIT_NAMESPACE=ns test-tool ... >out <in


but the linter complained about this without giving a hint as to what the fix
would be. It turns out that "env" works, ie.

...
env GIT_NAMESPACE=ns test-tool ...
test_must_fail env GIT_NAMESPACE=ns test-tool ...


>
> > diff --git a/upload-pack.c b/upload-pack.c
> > index 297b76fcb4..008ac75125 100644
> > --- a/upload-pack.c
> > +++ b/upload-pack.c
> > @@ -1417,21 +1417,24 @@ static int parse_want_ref(struct packet_writer *writer, const char *line,
> >  			  struct string_list *wanted_refs,
> >  			  struct object_array *want_obj)
> >  {
> > -	const char *arg;
> > +	const char *refname_nons;
> >  	if (skip_prefix(line, "want-ref ", &arg)) {
>
> Don't you receive the result in refname_nons here, as arg is no
> longer there?

Ouch. Will fix.

>
> >  		struct object_id oid;
> >  		struct string_list_item *item;
> >  		struct object *o;
> > +		struct strbuf refname = STRBUF_INIT;
> >
> > -		if (read_ref(arg, &oid)) {
> > -			packet_writer_error(writer, "unknown ref %s", arg);
> > -			die("unknown ref %s", arg);
> > +		strbuf_addf(&refname, "%s%s", get_git_namespace(), refname_nons);
> > +		if (ref_is_hidden(refname_nons, refname.buf) ||
> > +		    read_ref(refname.buf, &oid)) {
> > +			packet_writer_error(writer, "unknown ref %s", refname_nons);
> > +			die("unknown ref %s", refname.buf);
> >  		}
>
> OK. Assuming that it makes sense for the hideRefs mechanism to kick
> in here (which I would prefer to hear from others who've worked with
> this code, say Jonathan Tan?), the updated code makes sense.

I have also updated the code for the v2 to use refname_nons for any die() calls,
as I realised that this may be transmitted to the client via sideband (is that
correct?).