builtin/receive-pack: use check_signature from gpg-interface

The combination of verify_signed_buffer followed by parse_gpg_output is
available as check_signature. Use that instead of implementing it again.

Signed-off-by: Henning Schild <henning.schild@siemens.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/receive-pack.c

@@ -629,8 +629,6 @@ static void prepare_push_cert_sha1(struct child_process *proc)
 		return;
 
 	if (!already_done) {
-		struct strbuf gpg_output = STRBUF_INIT;
-		struct strbuf gpg_status = STRBUF_INIT;
 		int bogs /* beginning_of_gpg_sig */;
 
 		already_done = 1;
@@ -639,22 +637,11 @@ static void prepare_push_cert_sha1(struct child_process *proc)
 			oidclr(&push_cert_oid);
 
 		memset(&sigcheck, '\0', sizeof(sigcheck));
-		sigcheck.result = 'N';
 
 		bogs = parse_signature(push_cert.buf, push_cert.len);
-		if (verify_signed_buffer(push_cert.buf, bogs,
-					 push_cert.buf + bogs, push_cert.len - bogs,
-					 &gpg_output, &gpg_status) < 0) {
-			; /* error running gpg */
-		} else {
-			sigcheck.payload = push_cert.buf;
-			sigcheck.gpg_output = gpg_output.buf;
-			sigcheck.gpg_status = gpg_status.buf;
-			parse_gpg_output(&sigcheck);
-		}
+		check_signature(push_cert.buf, bogs, push_cert.buf + bogs,
+				push_cert.len - bogs, &sigcheck);
 
-		strbuf_release(&gpg_output);
-		strbuf_release(&gpg_status);
 		nonce_status = check_nonce(push_cert.buf, bogs);
 	}
 	if (!is_null_oid(&push_cert_oid)) {