[PATCH v2 1/2] replay: allow callers to sign commits

[Souma <git@5ouma.me>]

The replay machinery creates commits directly through
`commit_tree_extended()`, but callers cannot currently request
signatures. Commands that replay rewritten history consequently cannot
carry their signing policy through to descendant commits.

Add `sign_commit` to `replay_revisions_options` and thread it through
commit creation. `NULL` preserves the existing unsigned behavior, an
empty string selects the default signing key, and a non-empty string
selects an explicit key. Existing callers zero-initialize the options
structure, so their behavior is unchanged.

Signed-off-by: Souma <git@5ouma.me>
---
 replay.c | 13 ++++++++-----
 replay.h |  6 ++++++
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/replay.c b/replay.c
index aac9178875..19a6402bf0 100644
--- a/replay.c
+++ b/replay.c
@@ -81,13 +81,13 @@ static struct commit *create_commit(struct repository *repo,
 				    struct tree *tree,
 				    struct commit *based_on,
 				    struct commit *parent,
-				    enum replay_mode mode)
+				    enum replay_mode mode,
+				    const char *sign_commit)
 {
 	struct object_id ret;
 	struct object *obj = NULL;
 	struct commit_list *parents = NULL;
 	char *author = NULL;
-	char *sign_commit = NULL; /* FIXME: cli users might want to sign again */
 	struct commit_extra_header *extra = NULL;
 	struct strbuf msg = STRBUF_INIT;
 	const char *out_enc = get_commit_output_encoding();
@@ -270,7 +270,8 @@ static struct commit *pick_regular_commit(struct repository *repo,
 					  struct merge_options *merge_opt,
 					  struct merge_result *result,
 					  enum replay_mode mode,
-					  enum replay_empty_commit_action empty)
+					  enum replay_empty_commit_action empty,
+					  const char *sign_commit)
 {
 	struct commit *base, *replayed_base;
 	struct tree *pickme_tree, *base_tree, *replayed_base_tree;
@@ -341,7 +342,8 @@ static struct commit *pick_regular_commit(struct repository *repo,
 		}
 	}
 
-	return create_commit(repo, result->tree, pickme, replayed_base, mode);
+	return create_commit(repo, result->tree, pickme, replayed_base, mode,
+			     sign_commit);
 }
 
 void replay_result_release(struct replay_result *result)
@@ -431,7 +433,8 @@ int replay_revisions(struct rev_info *revs,
 
 		last_commit = pick_regular_commit(revs->repo, commit, replayed_commits,
 						  mode == REPLAY_MODE_REVERT ? last_commit : onto,
-						  &merge_opt, &result, mode, opts->empty);
+						  &merge_opt, &result, mode, opts->empty,
+						  opts->sign_commit);
 		if (!last_commit)
 			break;
 
diff --git a/replay.h b/replay.h
index 491db145e3..6ed0608911 100644
--- a/replay.h
+++ b/replay.h
@@ -57,6 +57,12 @@ struct replay_revisions_options {
 	 */
 	int contained;
 
+	/*
+	 * Key used to sign newly-created commits. An empty string requests the
+	 * default configured signing key, and NULL disables signing.
+	 */
+	const char *sign_commit;
+
 	/*
 	 * Controls what to do when a replayed commit becomes empty.
 	 * Defaults to REPLAY_EMPTY_COMMIT_DROP.
-- 
2.55.0