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transport: list refs before fetch if necessary 

The built-in bundle transport and the transport helper interface do not
work when transport_fetch_refs() is called immediately after transport
creation. This will be needed in a subsequent patch, so fix this.

Evidence: fetch_refs_from_bundle() relies on data->header being
initialized in get_refs_from_bundle(), and fetch() in transport-helper.c
relies on either data->fetch or data->import being set by get_helper(),
but neither transport_helper_init() nor fetch() calls get_helper().

Up until the introduction of the partial clone feature, this has not
been a problem, because transport_fetch_refs() is always called after
transport_get_remote_refs(). With the introduction of the partial clone
feature, which involves calling transport_fetch_refs() (to fetch objects
by their OIDs) without transport_get_remote_refs(), this is still not a
problem, but only coincidentally - we do not support partially cloning a
bundle, and as for cloning using a transport-helper-using protocol, it
so happens that before transport_fetch_refs() is called, fetch_refs() in
fetch-object.c calls transport_set_option(), which means that the
aforementioned get_helper() is invoked through set_helper_option() in
transport-helper.c.

This could be fixed by fixing the transports themselves, but it doesn't
seem like a good idea to me to open up previously untested code paths;
also, there may be transport helpers in the wild that assume that "list"
is always called before "fetch". Instead, fix this by having
transport_fetch_refs() call transport_get_remote_refs() to ensure that
the latter is always called at least once, unless the transport
explicitly states that it supports fetching without listing refs.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Jonathan Tan 2018-09-27 12:24:06 -07:00 committed by Junio C Hamano
parent 0177565148
commit 6ab4055775
3 changed files with 19 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
transport-helper.c
View File

@ -1105,6 +1105,7 @@ static struct ref *get_refs_list(struct transport *transport, int for_push,
}
static struct transport_vtable vtable = {
0,
set_helper_option,
get_refs_list,
fetch,

6
transport-internal.h
View File

@ -6,6 +6,12 @@ struct transport;
struct argv_array;
struct transport_vtable {
/**
* This transport supports the fetch() function being called
* without get_refs_list() first being called.
*/
unsigned fetch_without_list : 1;
/**
* Returns 0 if successful, positive if the option is not
* recognized or is inapplicable, and negative if the option

12
transport.c
View File

@ -733,6 +733,7 @@ static int disconnect_git(struct transport *transport)
}
static struct transport_vtable taken_over_vtable = {
1,
NULL,
get_refs_via_connect,
fetch_refs_via_pack,
@ -882,6 +883,7 @@ void transport_check_allowed(const char *type)
}
static struct transport_vtable bundle_vtable = {
0,
NULL,
get_refs_from_bundle,
fetch_refs_from_bundle,
@ -891,6 +893,7 @@ static struct transport_vtable bundle_vtable = {
};
static struct transport_vtable builtin_smart_vtable = {
1,
NULL,
get_refs_via_connect,
fetch_refs_via_pack,
@ -1254,6 +1257,15 @@ int transport_fetch_refs(struct transport *transport, struct ref *refs)
struct ref **heads = NULL;
struct ref *rm;
if (!transport->vtable->fetch_without_list)
/*
* Some transports (e.g. the built-in bundle transport and the
* transport helper interface) do not work when fetching is
* done immediately after transport creation. List the remote
* refs anyway (if not already listed) as a workaround.
*/
transport_get_remote_refs(transport, NULL);
for (rm = refs; rm; rm = rm->next) {
nr_refs++;
if (rm->peer_ref &&