gpg-interface: allow sign_buffer() to use default signing key

The `sign_commit_to_strbuf()` helper in "commit.c" provides fallback
logic to get the default configured signing key when a key is not
provided and handles generating the commit signature accordingly. This
signing operation is not really specific to commits as any arbitrary
buffer can be signed. Also, in a subsequent commit, this same logic is
reused by git-fast-import(1) when signing commits with invalid
signatures.

Remove the `sign_commit_to_strbuf()` helper from "commit.c" and extend
`sign_buffer()` in "gpg-interface.c" to support using the default key as
a fallback when the `SIGN_BUFFER_USE_DEFAULT_KEY` flag is provided. Call
sites are updated accordingly.

Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 5 insertions, 14 deletions

diff --git a/commit.c b/commit.c
index 0ffdd6679e..80d8d07875 100644
--- a/commit.c
+++ b/commit.c
@@ -1170,18 +1170,6 @@ int add_header_signature(struct strbuf *buf, struct strbuf *sig, const struct gi
 	return 0;
 }
 
-static int sign_commit_to_strbuf(struct strbuf *sig, struct strbuf *buf, const char *keyid)
-{
-	char *keyid_to_free = NULL;
-	int ret = 0;
-	if (!keyid || !*keyid)
-		keyid = keyid_to_free = get_signing_key();
-	if (sign_buffer(buf, sig, keyid))
-		ret = -1;
-	free(keyid_to_free);
-	return ret;
-}
-
 int parse_signed_commit(const struct commit *commit,
 			struct strbuf *payload, struct strbuf *signature,
 			const struct git_hash_algo *algop)
@@ -1759,7 +1747,8 @@ int commit_tree_extended(const char *msg, size_t msg_len,
 		oidcpy(&parent_buf[i++], &p->item->object.oid);
 
 	write_commit_tree(&buffer, msg, msg_len, tree, parent_buf, nparents, author, committer, extra);
-	if (sign_commit && sign_commit_to_strbuf(&sig, &buffer, sign_commit)) {
+	if (sign_commit && sign_buffer(&buffer, &sig, sign_commit,
+				       SIGN_BUFFER_USE_DEFAULT_KEY)) {
 		result = -1;
 		goto out;
 	}
@@ -1791,7 +1780,9 @@ int commit_tree_extended(const char *msg, size_t msg_len,
 		free_commit_extra_headers(compat_extra);
 		free(mapped_parents);
 
-		if (sign_commit && sign_commit_to_strbuf(&compat_sig, &compat_buffer, sign_commit)) {
+		if (sign_commit && sign_buffer(&compat_buffer, &compat_sig,
+					       sign_commit,
+					       SIGN_BUFFER_USE_DEFAULT_KEY)) {
 			result = -1;
 			goto out;
 		}