path: root/transport.c
diff options
authorTaylor Blau <>2018-10-08 18:09:28 (GMT)
committerJunio C Hamano <>2018-10-09 05:30:03 (GMT)
commit89284c1d6ca03480a93f9d95a2460a09390f3c40 (patch)
treedeb7abeff37672387a43a0f188c699e89cbca55b /transport.c
parent1e5f31d444436cfab1b1aef3026ffbd925f5a818 (diff)
transport.c: introduce core.alternateRefsCommand
When in a repository containing one or more alternates, Git would sometimes like to list references from those alternates. For example, 'git receive-pack' lists the "tips" pointed to by references in those alternates as special ".have" references. Listing ".have" references is designed to make pushing changes from upstream to a fork a lightweight operation, by advertising to the pusher that the fork already has the objects (via its alternate). Thus, the client can avoid sending them. However, when the alternate (upstream, in the previous example) has a pathologically large number of references, the initial advertisement is too expensive. In fact, it can dominate any such optimization where the pusher avoids sending certain objects. Introduce "core.alternateRefsCommand" in order to provide a facility to limit or filter alternate references. This can be used, for example, to filter out references the alternate does not wish to send (for space concerns, or otherwise) during the initial advertisement. Let the repository that has alternates configure this command to avoid trusting the alternate to provide us a safe command to run in the shell. To find the alternate, pass its absolute path as the first argument. Signed-off-by: Taylor Blau <> Acked-by: Jeff King <> Signed-off-by: Junio C Hamano <>
Diffstat (limited to 'transport.c')
1 files changed, 15 insertions, 4 deletions
diff --git a/transport.c b/transport.c
index 25d8ea7..19baec7 100644
--- a/transport.c
+++ b/transport.c
@@ -1328,10 +1328,21 @@ literal_copy:
static void fill_alternate_refs_command(struct child_process *cmd,
const char *repo_path)
- cmd->git_cmd = 1;
- argv_array_pushf(&cmd->args, "--git-dir=%s", repo_path);
- argv_array_push(&cmd->args, "for-each-ref");
- argv_array_push(&cmd->args, "--format=%(objectname)");
+ const char *value;
+ if (!git_config_get_value("core.alternateRefsCommand", &value)) {
+ cmd->use_shell = 1;
+ argv_array_push(&cmd->args, value);
+ argv_array_push(&cmd->args, repo_path);
+ } else {
+ cmd->git_cmd = 1;
+ argv_array_pushf(&cmd->args, "--git-dir=%s", repo_path);
+ argv_array_push(&cmd->args, "for-each-ref");
+ argv_array_push(&cmd->args, "--format=%(objectname)");
+ }
cmd->env = local_repo_env;
cmd->out = -1;