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connect: advertized capability is not a ref

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When cloning an empty repository served by standard git, "git clone" produces
the following reassuring message:

	$ git clone git://localhost/tmp/empty
	Cloning into 'empty'...
	warning: You appear to have cloned an empty repository.
	Checking connectivity... done.

Meanwhile when cloning an empty repository served by JGit, the output is more
haphazard:

	$ git clone git://localhost/tmp/empty
	Cloning into 'empty'...
	Checking connectivity... done.
	warning: remote HEAD refers to nonexistent ref, unable to checkout.

This is a common command to run immediately after creating a remote repository
as preparation for adding content to populate it and pushing. The warning is
confusing and needlessly worrying.

The cause is that, since v3.1.0.201309270735-rc1~22 (Advertise capabilities
with no refs in upload service., 2013-08-08), JGit's ref advertisement includes
a ref named capabilities^{} to advertise its capabilities on, while git's ref
advertisement is empty in this case. This allows the client to learn about the
server's capabilities and is needed, for example, for fetch-by-sha1 to work
when no refs are advertised.

This also affects "ls-remote". For example, against an empty repository served
by JGit:

	$ git ls-remote git://localhost/tmp/empty
	0000000000000000000000000000000000000000        capabilities^{}

Git advertises the same capabilities^{} ref in its ref advertisement for push
but since it never did so for fetch, the client didn't need to handle this
case.  Handle it.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Helped-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jonathan Tan
2016-09-09 10:36:30 -07:00
committed by Junio C Hamano
parent 55e4f9365a
commit eb398797cd
2 changed files with 54 additions and 0 deletions
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14
connect.c
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@ -123,6 +123,7 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
* response does not necessarily mean an ACL problem, though.
*/
int saw_response;
int got_dummy_ref_with_capabilities_declaration = 0;
*list = NULL;
for (saw_response = 0; ; saw_response = 1) {
@ -172,8 +173,21 @@ struct ref **get_remote_heads(int in, char *src_buf, size_t src_len,
continue;
}
if (!strcmp(name, "capabilities^{}")) {
if (saw_response)
die("protocol error: unexpected capabilities^{}");
if (got_dummy_ref_with_capabilities_declaration)
die("protocol error: multiple capabilities^{}");
got_dummy_ref_with_capabilities_declaration = 1;
continue;
}
if (!check_ref(name, flags))
continue;
if (got_dummy_ref_with_capabilities_declaration)
die("protocol error: unexpected ref after capabilities^{}");
ref = alloc_ref(buffer + GIT_SHA1_HEXSZ + 1);
oidcpy(&ref->old_oid, &old_oid);
*list = ref;