+static void strbuf_addstr_or_null(struct strbuf *sb, const char *s)
+{
+ if (s)
+ strbuf_addstr(sb, s);
+}
+
+struct expand_path_context {
+ const char *directory;
+};
+
+static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
+{
+ struct expand_path_context *context = ctx;
+
+ switch (placeholder[0]) {
+ case 'H':
+ strbuf_addstr_or_null(sb, hostname);
+ return 1;
+ case 'C':
+ if (placeholder[1] == 'H') {
+ strbuf_addstr_or_null(sb, get_canon_hostname());
+ return 2;
+ }
+ break;
+ case 'I':
+ if (placeholder[1] == 'P') {
+ strbuf_addstr_or_null(sb, get_ip_address());
+ return 2;
+ }
+ break;
+ case 'P':
+ strbuf_addstr_or_null(sb, tcp_port);
+ return 1;
+ case 'D':
+ strbuf_addstr(sb, context->directory);
+ return 1;
+ }
+ return 0;
+}
+