[PATCH 1/1] commit: make the sign-off trailer configurable

[Hans Jerry Illikainen <hji@dyntopia.com>]

The commit builtin did not previously have a configuration option to
enable the 'Signed-off-by' trailer by default.

For some use-cases (namely, when the user doesn't always have the right
to contribute patches to a project) it makes sense to make it a
conscientious decision to add the signoff trailer.  However, others'
might always have the right to ship patches -- in which case it makes
sense to have an option to add the trailer by default for projects that
require it.

This patch introduces a commit.signOff configuration option that
determine whether the trailer should be added for commits.  It can be
overridden with the --(no-)signoff command-line option.

Signed-off-by: Hans Jerry Illikainen <hji@dyntopia.com>
---
 Documentation/config/commit.txt |  8 ++++++++
 Documentation/git-commit.txt    |  4 ++++
 builtin/commit.c                |  4 ++++
 t/t7502-commit-porcelain.sh     | 36 +++++++++++++++++++++++++++++++++
 4 files changed, 52 insertions(+)

diff --git a/Documentation/config/commit.txt b/Documentation/config/commit.txt
index 2c95573930..6ebfe384ac 100644
--- a/Documentation/config/commit.txt
+++ b/Documentation/config/commit.txt
@@ -15,6 +15,14 @@ commit.gpgSign::
 	convenient to use an agent to avoid typing your GPG passphrase
 	several times.
 
+commit.signOff::
+	A boolean to specify whether commits should enable the
+	`-s/--signoff` option by default.  *Note:* Adding the
+	Signed-off-by: line to a commit message should be a conscious
+	act and means that you certify you have the rights to submit the
+	work under the same open source license.  Please see the
+	'SubmittingPatches' document for further discussion.
+
 commit.status::
 	A boolean to enable/disable inclusion of status information in the
 	commit message template when using an editor to prepare the commit
diff --git a/Documentation/git-commit.txt b/Documentation/git-commit.txt
index ced5a9beab..61a362770d 100644
--- a/Documentation/git-commit.txt
+++ b/Documentation/git-commit.txt
@@ -165,12 +165,16 @@ The `-m` option is mutually exclusive with `-c`, `-C`, and `-F`.
 
 -s::
 --signoff::
+--no-signoff::
 	Add Signed-off-by line by the committer at the end of the commit
 	log message.  The meaning of a signoff depends on the project,
 	but it typically certifies that committer has
 	the rights to submit this work under the same license and
 	agrees to a Developer Certificate of Origin
 	(see http://developercertificate.org/ for more information).
+	This option can be enabled by default with the `commit.signOff`
+	configuration option, in which case it can be disabled
+	temporarily with `--no-signoff`.
 
 -n::
 --no-verify::
diff --git a/builtin/commit.c b/builtin/commit.c
index c70ad01cc9..497e29c58c 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -1474,6 +1474,10 @@ static int git_commit_config(const char *k, const char *v, void *cb)
 		sign_commit = git_config_bool(k, v) ? "" : NULL;
 		return 0;
 	}
+	if (!strcmp(k, "commit.signoff")) {
+		signoff = git_config_bool(k, v);
+		return 0;
+	}
 	if (!strcmp(k, "commit.verbose")) {
 		int is_bool;
 		config_commit_verbose = git_config_bool_or_int(k, v, &is_bool);
diff --git a/t/t7502-commit-porcelain.sh b/t/t7502-commit-porcelain.sh
index 14c92e4c25..7510325698 100755
--- a/t/t7502-commit-porcelain.sh
+++ b/t/t7502-commit-porcelain.sh
@@ -151,6 +151,42 @@ test_expect_success 'sign off' '
 
 '
 
+test_expect_success 'commit.signOff=true' '
+	test_config commit.signOff true &&
+	echo 1 >>positive &&
+	git add positive &&
+	git commit -m "thank you" &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -ne "s/Signed-off-by: //p" commit.msg >actual &&
+	git var GIT_COMMITTER_IDENT >ident &&
+	sed -e "s/>.*/>/" ident >expected &&
+	test_cmp expected actual
+'
+
+test_expect_success 'commit.signOff=true and --no-signoff' '
+	test_config commit.signOff true &&
+	echo 2 >>positive &&
+	git add positive &&
+	git commit --no-signoff -m "thank you" &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -ne "s/Signed-off-by: //p" commit.msg >actual &&
+	git var GIT_COMMITTER_IDENT >ident &&
+	sed -e "s/>.*/>/" ident >expected &&
+	! test_cmp expected actual
+'
+
+test_expect_success 'commit.signOff=false and --signoff' '
+	test_config commit.signOff false &&
+	echo 1 >>positive &&
+	git add positive &&
+	git commit --signoff -m "thank you" &&
+	git cat-file commit HEAD >commit.msg &&
+	sed -ne "s/Signed-off-by: //p" commit.msg >actual &&
+	git var GIT_COMMITTER_IDENT >ident &&
+	sed -e "s/>.*/>/" ident >expected &&
+	test_cmp expected actual
+'
+
 test_expect_success 'multiple -m' '
 
 	>negative &&
-- 
2.25.0.rc1.298.g45d5f025e1