[RFC/PATCH v4 31/49] external-odb: add external_odb_get_capabilities()

@@ -66,6 +66,14 @@ static int external_odb_config(const char *var, const char *value, void *data)
 	return 0;
 }
 
+static void external_odb_get_capabilities(void)
+{
+	struct odb_helper *o;
+
+	for (o = helpers; o; o = o->next)
+		odb_helper_get_capabilities(o);
+}
+
 static void external_odb_init(void)
 {
 	static int initialized;

@@ -75,6 +83,8 @@ static void external_odb_init(void)
 	initialized = 1;
 
 	git_config(external_odb_config, NULL);
+
+	external_odb_get_capabilities();
 }
 
 const char *external_odb_root(void)

@@ -94,9 +104,12 @@ int external_odb_has_object(const unsigned char *sha1)
 
 	external_odb_init();
 
-	for (o = helpers; o; o = o->next)
+	for (o = helpers; o; o = o->next) {
+		if (!(o->supported_capabilities & ODB_HELPER_CAP_HAVE))
+			return 1;
 		if (odb_helper_has_object(o, sha1))
 			return 1;
+	}
 	return 0;
 }
 

@@ -260,6 +260,29 @@ static int odb_helper_finish(struct odb_helper *o,
 	return 0;
 }
 
+int odb_helper_get_capabilities(struct odb_helper *o)
+{
+	struct odb_helper_cmd cmd;
+	FILE *fh;
+	struct strbuf line = STRBUF_INIT;
+
+	if (!o->script_mode)
+		return 0;
+
+	if (odb_helper_start(o, &cmd, 0, "get_cap") < 0)
+		return -1;
+
+	fh = xfdopen(cmd.child.out, "r");
+	while (strbuf_getline(&line, fh) != EOF)
+		parse_capabilities(line.buf, &o->supported_capabilities, o->name);
+
+	strbuf_release(&line);
+	fclose(fh);
+	odb_helper_finish(o, &cmd);
+
+	return 0;
+}
+
 static int parse_object_line(struct odb_helper_object *o, const char *line)
 {
 	char *end;

@@ -33,6 +33,7 @@ struct odb_helper {
 };
 
 struct odb_helper *odb_helper_new(const char *name, int namelen);
+int odb_helper_get_capabilities(struct odb_helper *o);
 int odb_helper_has_object(struct odb_helper *o, const unsigned char *sha1);
 int odb_helper_fetch_object(struct odb_helper *o, const unsigned char *sha1,
 			    int fd);