On Fri, Sep 2, 2016 at 10:15 AM, Jonathan Tan <jonathantanmy@xxxxxxxxxx> wrote:
>
> + if (is_null_oid(&old_oid)) {
> + if (strcmp(name, "capabilities^{}"))
Its not the zero ID that is special, its the "capabilities^{}" name
that is special when its the first entry in the stream. In the wire
protocol a "x^{}" line is a modifier to a prior "x" line to add a
peeled object to the prior line. But if we see "^{}" on the first line
that is non-sense, there is no prior line to modify with this
identifier.
Further ^{} is used here because its invalid in a name. A server
really cannot have a reference that ends with the sequence ^{}. And a
server should not have a reference named "capabilities" without a
"refs/" prefix on it.
So the entire "capabilities^{}" on the first line is a bunch of
contradictions that violate a number of things about the protocol,
which is why clients should ignore it.
I think the test should be about:
!*list && !strcmp(name, "capabilities^{}")
> + warning("zero object ID received that is not accompanied by a "
> + "capability declaration, ignoring and continuing anyway");
Annoyingly a zero object ID is sort of possible; with a probability of
1/2^160 or something. Its just a very very unlikely value. Slightly
stronger to test against the known invalid name.