fast-import: refactor finalize_commit_buffer()

In a following commit we are going to finalize commit buffers with or
without signatures in order to check the signatures and possibly drop
them.

To do so easily and without duplication, let's refactor the current
code that finalizes commit buffers into a new finalize_commit_buffer()
function.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: chriscool

builtin/fast-import.c

@@ -2815,6 +2815,18 @@ static void import_one_signature(struct signature_data *sig_sha1,
 		die(_("parse_one_signature() returned unknown hash algo"));
 }
 
+static void finalize_commit_buffer(struct strbuf *new_data,
+				   struct signature_data *sig_sha1,
+				   struct signature_data *sig_sha256,
+				   struct strbuf *msg)
+{
+	add_gpgsig_to_commit(new_data, "gpgsig ", sig_sha1);
+	add_gpgsig_to_commit(new_data, "gpgsig-sha256 ", sig_sha256);
+
+	strbuf_addch(new_data, '\n');
+	strbuf_addbuf(new_data, msg);
+}
+
 static void parse_new_commit(const char *arg)
 {
 	static struct strbuf msg = STRBUF_INIT;
@@ -2950,11 +2962,8 @@ static void parse_new_commit(const char *arg)
 			"encoding %s\n",
 			encoding);
 
-	add_gpgsig_to_commit(&new_data, "gpgsig ", &sig_sha1);
-	add_gpgsig_to_commit(&new_data, "gpgsig-sha256 ", &sig_sha256);
+	finalize_commit_buffer(&new_data, &sig_sha1, &sig_sha256, &msg);
 
-	strbuf_addch(&new_data, '\n');
-	strbuf_addbuf(&new_data, &msg);
 	free(author);
 	free(committer);
 	free(encoding);