[PATCH 1/2] subtree: support GPG commit signing

["Jacques Vidrine via GitGitGadget" <gitgitgadget@gmail.com>]

From: Jacques Vidrine <t@fboundp.com>

Add support for -S/--gpg-sign/--no-gpg-sign command line options
and commit.gpgsign configuration. These are passed to invocations
of `git commit-tree`.

Signed-off-by: Allen Reese <java.allen@apple.com>
Signed-off-by: Jacques Vidrine <t@fboundp.com>
---
 contrib/subtree/git-subtree.sh  | 24 +++++++++++++++++++-----
 contrib/subtree/git-subtree.txt |  9 +++++++++
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 10c9c87839a..553b4391deb 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@ -46,6 +46,8 @@ rejoin        merge the new branch back into HEAD
  options for 'add' and 'merge' (also: 'pull', 'split --rejoin', and 'push --rejoin')
 squash        merge subtree changes as a single commit
 m,message=    use the given message as the commit message for the merge commit
+S,gpg-sign?   GPG-sign commits, optionally specifying keyid.
+no-gpg-sign   Disable GPG commit signing.
 "
 
 indent=0
@@ -165,6 +167,7 @@ main () {
 	arg_quiet=
 	arg_debug=
 	arg_prefix=
+	arg_gpgsign=
 	arg_split_branch=
 	arg_split_onto=
 	arg_split_ignore_joins=
@@ -240,6 +243,9 @@ main () {
 			test -n "$allow_addmerge" || die_incompatible_opt "$opt" "$arg_command"
 			arg_addmerge_squash=
 			;;
+		-S*|--gpg-sign=*|--no-gpg-sign)
+			arg_gpgsign="${opt}"
+			;;
 		--)
 			break
 			;;
@@ -268,6 +274,12 @@ main () {
 
 	dir="$(dirname "$arg_prefix/.")"
 
+	if test -z "$arg_gpgsign" &&
+		git config --bool commit.gpgsign >/dev/null
+	then
+		arg_gpgsign="-S"
+	fi
+
 	debug "command: {$arg_command}"
 	debug "quiet: {$arg_quiet}"
 	debug "dir: {$dir}"
@@ -534,7 +546,7 @@ copy_commit () {
 			printf "%s" "$arg_split_annotate"
 			cat
 		) |
-		git commit-tree "$2" $3  # reads the rest of stdin
+		git commit-tree $arg_gpgsign "$2" $3  # reads the rest of stdin
 	) || die "fatal: can't copy commit $1"
 }
 
@@ -674,10 +686,10 @@ new_squash_commit () {
 	if test -n "$old"
 	then
 		squash_msg "$dir" "$oldsub" "$newsub" |
-		git commit-tree "$tree" -p "$old" || exit $?
+		git commit-tree $arg_gpgsign "$tree" -p "$old" || exit $?
 	else
 		squash_msg "$dir" "" "$newsub" |
-		git commit-tree "$tree" || exit $?
+		git commit-tree $arg_gpgsign "$tree" || exit $?
 	fi
 }
 
@@ -900,11 +912,13 @@ cmd_add_commit () {
 	then
 		rev=$(new_squash_commit "" "" "$rev") || exit $?
 		commit=$(add_squashed_msg "$rev" "$dir" |
-			git commit-tree "$tree" $headp -p "$rev") || exit $?
+			git commit-tree $arg_gpgsign "$tree" \
+			$headp -p "$rev") || exit $?
 	else
 		revp=$(peel_committish "$rev") || exit $?
 		commit=$(add_msg "$dir" $headrev "$rev" |
-			git commit-tree "$tree" $headp -p "$revp") || exit $?
+			git commit-tree $arg_gpgsign "$tree" \
+			$headp -p "$revp") || exit $?
 	fi
 	git reset "$commit" || exit $?
 
diff --git a/contrib/subtree/git-subtree.txt b/contrib/subtree/git-subtree.txt
index 004abf415b8..fa54541b288 100644
--- a/contrib/subtree/git-subtree.txt
+++ b/contrib/subtree/git-subtree.txt
@@ -185,6 +185,15 @@ subproject.
 --message=<message>::
 	Specify <message> as the commit message for the merge commit.
 
+-S[<keyid>]::
+--gpg-sign[=<keyid>]::
+--no-gpg-sign::
+	GPG-sign commits. The `keyid` argument is optional and
+	defaults to the committer identity; if specified, it must be
+	stuck to the option without a space. `--no-gpg-sign` is useful to
+	countermand both `commit.gpgSign` configuration variable, and
+	earlier `--gpg-sign`.
+
 OPTIONS FOR 'split' (ALSO: 'push')
 ----------------------------------
 These options for 'split' may also be given to 'push' (which wraps
-- 
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