Add GIT_EDITOR environment and core.editor configuration variables

These variables let you specify an editor that will be launched in
preference to the EDITOR and VISUAL environment variables. The order
of preference is GIT_EDITOR, core.editor, EDITOR, VISUAL.

[jc: added a test and config variable documentation]

Signed-off-by: Adam Roben <aroben@apple.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -281,6 +281,14 @@ core.excludesfile::
 	of files which are not meant to be tracked.  See
 	gitlink:gitignore[5].
 
+core.editor::
+	Commands such as `commit` and `tag` that lets you edit
+	messages by lauching an editor uses the value of this
+	variable when it is set, and the environment variable
+	`GIT_EDITOR` is not set.  The order of preference is
+	`GIT_EDITOR` environment, `core.editor`, `EDITOR` and
+	`VISUAL` environment variables and then finally `vi`.
+
 core.pager::
 	The command that git will use to paginate output.  Can be overridden
 	with the `GIT_PAGER` environment variable.

Documentation/git-commit.txt

@@ -244,10 +244,12 @@ on the Subject: line and the rest of the commit in the body.
 
 include::i18n.txt[]
 
-ENVIRONMENT VARIABLES
----------------------
-The command specified by either the VISUAL or EDITOR environment
-variables is used to edit the commit log message.
+ENVIRONMENT AND CONFIGURATION VARIABLES
+---------------------------------------
+The editor used to edit the commit log message will be chosen from the
+GIT_EDITOR environment variable, the core.editor configuration variable, the
+VISUAL environment variable, or the EDITOR environment variable (in that
+order).
 
 HOOKS
 -----

Documentation/git-send-email.txt

@@ -44,8 +44,8 @@ The --cc option must be repeated for each user you want on the cc list.
 	value; if that is unspecified, default to --chain-reply-to.
 
 --compose::
-	Use $EDITOR to edit an introductory message for the
-	patch series.
+	Use $GIT_EDITOR, core.editor, $VISUAL, or $EDITOR to edit an
+	introductory message for the patch series.
 
 --from::
 	Specify the sender of the emails.  This will default to

git-am.sh

@@ -364,7 +364,7 @@ do
 		[yY]*) action=yes ;;
 		[aA]*) action=yes interactive= ;;
 		[nN]*) action=skip ;;
-		[eE]*) "${VISUAL:-${EDITOR:-vi}}" "$dotest/final-commit"
+		[eE]*) git_editor "$dotest/final-commit"
 		       action=again ;;
 		[vV]*) action=again
 		       LESS=-S ${PAGER:-less} "$dotest/patch" ;;

git-commit.sh

@@ -544,18 +544,9 @@ fi
 
 case "$no_edit" in
 '')
-	case "${VISUAL:-$EDITOR},$TERM" in
-	,dumb)
-		echo >&2 "Terminal is dumb but no VISUAL nor EDITOR defined."
-		echo >&2 "Please supply the commit log message using either"
-		echo >&2 "-m or -F option.  A boilerplate log message has"
-		echo >&2 "been prepared in $GIT_DIR/COMMIT_EDITMSG"
-		exit 1
-		;;
-	esac
 	git-var GIT_AUTHOR_IDENT > /dev/null  || die
 	git-var GIT_COMMITTER_IDENT > /dev/null  || die
-	${VISUAL:-${EDITOR:-vi}} "$GIT_DIR/COMMIT_EDITMSG"
+	git_editor "$GIT_DIR/COMMIT_EDITMSG"
 	;;
 esac
 

git-rebase--interactive.sh

@@ -414,7 +414,7 @@ EOF
 			die_abort "Nothing to do"
 
 		cp "$TODO" "$TODO".backup
-		${VISUAL:-${EDITOR:-vi}} "$TODO" ||
+		git_editor "$TODO" ||
 			die "Could not execute editor"
 
 		test -z "$(grep -ve '^$' -e '^#' < $TODO)" &&

git-send-email.perl

@@ -49,8 +49,8 @@ sub usage {
    --bcc          Specify a list of email addresses that should be Bcc:
 		  on all the emails.
 
-   --compose      Use \$EDITOR to edit an introductory message for the
-                  patch series.
+   --compose      Use \$GIT_EDITOR, core.editor, \$EDITOR, or \$VISUAL to edit
+		  an introductory message for the patch series.
 
    --subject      Specify the initial "Subject:" line.
                   Only necessary if --compose is also set.  If --compose
@@ -341,8 +341,7 @@ sub expand_aliases {
 EOT
 	close(C);
 
-	my $editor = $ENV{EDITOR};
-	$editor = 'vi' unless defined $editor;
+	my $editor = $ENV{GIT_EDITOR} || $repo->config("core.editor") || $ENV{VISUAL} || $ENV{EDITOR} || "vi";
 	system($editor, $compose_filename);
 
 	open(C2,">",$compose_filename . ".final")

git-sh-setup.sh

@@ -28,6 +28,21 @@ set_reflog_action() {
 	fi
 }
 
+git_editor() {
+	GIT_EDITOR=${GIT_EDITOR:-$(git config core.editor || echo ${VISUAL:-${EDITOR}})}
+	case "$GIT_EDITOR,$TERM" in
+	,dumb)
+		echo >&2 "No editor specified in GIT_EDITOR, core.editor, VISUAL,"
+		echo >&2 "or EDITOR. Tried to fall back to vi but terminal is dumb."
+		echo >&2 "Please set one of these variables to an appropriate"
+		echo >&2 "editor or run $0 with options that will not cause an"
+		echo >&2 "editor to be invoked (e.g., -m or -F for git-commit)."
+		exit 1
+		;;
+	esac
+	"${GIT_EDITOR:-vi}" "$1"
+}
+
 is_bare_repository () {
 	git rev-parse --is-bare-repository
 }

git-tag.sh

@@ -177,7 +177,7 @@ if [ "$annotate" ]; then
         ( echo "#"
           echo "# Write a tag message"
           echo "#" ) > "$GIT_DIR"/TAG_EDITMSG
-        ${VISUAL:-${EDITOR:-vi}} "$GIT_DIR"/TAG_EDITMSG || exit
+        git_editor "$GIT_DIR"/TAG_EDITMSG || exit
     else
         printf '%s\n' "$message" >"$GIT_DIR"/TAG_EDITMSG
     fi

t/t7005-editor.sh

@@ -0,0 +1,91 @@
+#!/bin/sh
+
+test_description='GIT_EDITOR, core.editor, and stuff'
+
+. ./test-lib.sh
+
+for i in GIT_EDITOR core_editor EDITOR VISUAL vi
+do
+	cat >e-$i.sh <<-EOF
+	echo "Edited by $i" >"\$1"
+	EOF
+	chmod +x e-$i.sh
+done
+unset vi
+mv e-vi.sh vi
+PATH=".:$PATH"
+unset EDITOR VISUAL GIT_EDITOR
+
+test_expect_success setup '
+
+	msg="Hand edited" &&
+	echo "$msg" >expect &&
+	git add vi &&
+	test_tick &&
+	git commit -m "$msg" &&
+	git show -s --pretty=oneline |
+	sed -e "s/^[0-9a-f]* //" >actual &&
+	diff actual expect
+
+'
+
+TERM=dumb
+export TERM
+test_expect_success 'dumb should error out when falling back on vi' '
+
+	if git commit --amend
+	then
+		echo "Oops?"
+		exit 1
+	else
+		: happy
+	fi
+'
+
+TERM=vt100
+export TERM
+for i in vi EDITOR VISUAL core_editor GIT_EDITOR
+do
+	echo "Edited by $i" >expect
+	unset EDITOR VISUAL GIT_EDITOR
+	git config --unset-all core.editor
+	case "$i" in
+	core_editor)
+		git config core.editor ./e-core_editor.sh
+		;;
+	[A-Z]*)
+		eval "$i=./e-$i.sh"
+		export $i
+		;;
+	esac
+	test_expect_success "Using $i" '
+		git commit --amend &&
+		git show -s --pretty=oneline |
+		sed -e "s/^[0-9a-f]* //" >actual &&
+		diff actual expect
+	'
+done
+
+unset EDITOR VISUAL GIT_EDITOR
+git config --unset-all core.editor
+for i in vi EDITOR VISUAL core_editor GIT_EDITOR
+do
+	echo "Edited by $i" >expect
+	case "$i" in
+	core_editor)
+		git config core.editor ./e-core_editor.sh
+		;;
+	[A-Z]*)
+		eval "$i=./e-$i.sh"
+		export $i
+		;;
+	esac
+	test_expect_success "Using $i (override)" '
+		git commit --amend &&
+		git show -s --pretty=oneline |
+		sed -e "s/^[0-9a-f]* //" >actual &&
+		diff actual expect
+	'
+done
+
+test_done