object-store.h: move for_each_alternate_ref() from transport.h

There's nothing inherently transport-related about enumerating the
alternate ref tips. The code has lived in transport.[ch] because the
only use so far had been advertising available tips during transport.
But it could be used for more, and a future patch will teach rev-list to
access these refs.

Let's move it alongside the other alt-odb code, declaring it in
object-store.h with the implementation in sha1-file.c.

This lets us drop the inclusion of transport.h from receive-pack, which
perhaps shows how it was misplaced (though receive-pack is about
transporting objects, transport.h is mostly about the client side).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 97 insertions, 0 deletions

diff --git a/sha1-file.c b/sha1-file.c
index ed5c50d..ccd5bf3 100644
--- a/sha1-file.c
+++ b/sha1-file.c
@@ -743,6 +743,103 @@ out:
 	return ref_git;
 }
 
+static void fill_alternate_refs_command(struct child_process *cmd,
+					const char *repo_path)
+{
+	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)");
+
+		if (!git_config_get_value("core.alternateRefsPrefixes", &value)) {
+			argv_array_push(&cmd->args, "--");
+			argv_array_split(&cmd->args, value);
+		}
+	}
+
+	cmd->env = local_repo_env;
+	cmd->out = -1;
+}
+
+static void read_alternate_refs(const char *path,
+				alternate_ref_fn *cb,
+				void *data)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+	struct strbuf line = STRBUF_INIT;
+	FILE *fh;
+
+	fill_alternate_refs_command(&cmd, path);
+
+	if (start_command(&cmd))
+		return;
+
+	fh = xfdopen(cmd.out, "r");
+	while (strbuf_getline_lf(&line, fh) != EOF) {
+		struct object_id oid;
+		const char *p;
+
+		if (parse_oid_hex(line.buf, &oid, &p) || *p) {
+			warning(_("invalid line while parsing alternate refs: %s"),
+				line.buf);
+			break;
+		}
+
+		cb(&oid, data);
+	}
+
+	fclose(fh);
+	finish_command(&cmd);
+}
+
+struct alternate_refs_data {
+	alternate_ref_fn *fn;
+	void *data;
+};
+
+static int refs_from_alternate_cb(struct object_directory *e,
+				  void *data)
+{
+	struct strbuf path = STRBUF_INIT;
+	size_t base_len;
+	struct alternate_refs_data *cb = data;
+
+	if (!strbuf_realpath(&path, e->path, 0))
+		goto out;
+	if (!strbuf_strip_suffix(&path, "/objects"))
+		goto out;
+	base_len = path.len;
+
+	/* Is this a git repository with refs? */
+	strbuf_addstr(&path, "/refs");
+	if (!is_directory(path.buf))
+		goto out;
+	strbuf_setlen(&path, base_len);
+
+	read_alternate_refs(path.buf, cb->fn, cb->data);
+
+out:
+	strbuf_release(&path);
+	return 0;
+}
+
+void for_each_alternate_ref(alternate_ref_fn fn, void *data)
+{
+	struct alternate_refs_data cb;
+	cb.fn = fn;
+	cb.data = data;
+	foreach_alt_odb(refs_from_alternate_cb, &cb);
+}
+
 int foreach_alt_odb(alt_odb_fn fn, void *cb)
 {
 	struct object_directory *ent;