[PATCH] commit: Add commit.signoff configuration option

[Chris Down <chris@chrisdown.name>]

Introduce a new `commit.signoff` config variable that mirrors the
behavior of the -s/--signoff flag.

We already have prior art in format-patch with `format.signoff`; this
brings parity for those who don’t use a patch-based workflow but still
rely on signoffs.

Right now people who have to do this regularly often alias commit to
`commit --signoff` in their shell, which is less than ideal -- this
config option avoids having to do that.

Signed-off-by: Chris Down <chris@chrisdown.name>
---
 Documentation/signoff-option.adoc         |  4 ++++
 builtin/commit.c                          |  4 ++++
 t/t7500-commit-template-squash-signoff.sh | 10 ++++++++++
 3 files changed, 18 insertions(+)

diff --git a/Documentation/signoff-option.adoc b/Documentation/signoff-option.adoc
index cddfb225d1..0055874e84 100644
--- a/Documentation/signoff-option.adoc
+++ b/Documentation/signoff-option.adoc
@@ -13,6 +13,10 @@ endif::git-commit[]
 	Linux kernel and Git projects.)  Consult the documentation or
 	leadership of the project to which you're contributing to
 	understand how the signoffs are used in that project.
+ifdef::git-commit[]
+	The `commit.signoff` configuration variable may also be used to imply
+	`--signoff`.
+endif::git-commit[]
 +
 The `--no-signoff` option can be used to countermand an earlier `--signoff`
 option on the command line.
diff --git a/builtin/commit.c b/builtin/commit.c
index 66bd91fd52..da98895438 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1670,6 +1670,10 @@ static int git_commit_config(const char *k, const char *v,
 							       &is_bool);
 		return 0;
 	}
+	if (!strcmp(k, "commit.signoff")) {
+		signoff = git_config_bool(k, v);
+		return 0;
+	}
 
 	return git_status_config(k, v, ctx, s);
 }
diff --git a/t/t7500-commit-template-squash-signoff.sh b/t/t7500-commit-template-squash-signoff.sh
index 4dca8d97a7..03c20dcb1d 100755
--- a/t/t7500-commit-template-squash-signoff.sh
+++ b/t/t7500-commit-template-squash-signoff.sh
@@ -181,6 +181,16 @@ test_expect_success '--signoff' '
 	test_cmp expect output
 '
 
+test_expect_success 'config commit.signoff implies signoff' '
+	git config commit.signoff true &&
+	echo "871119" >> bar &&
+	git add bar &&
+	echo "zort" | git commit -F - bar &&
+	git cat-file commit HEAD | sed "1,/^\$/d" > output &&
+	test_cmp expect output &&
+	git config --unset commit.signoff
+'
+
 test_expect_success 'commit message from file (1)' '
 	mkdir subdir &&
 	echo "Log in top directory" >log &&
-- 
2.49.0