Add clean.requireForce option, and add -f option to git-clean to override it

Add a new configuration option clean.requireForce.  If set, git-clean will
refuse to run, unless forced with the new -f option, or not acting due to -n.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/config.txt

@@ -300,6 +300,10 @@ branch.<name>.merge::
 	branch.<name>.merge to the desired branch, and use the special setting
 	`.` (a period) for branch.<name>.remote.
 
+clean.requireForce::
+	A boolean to make git-clean do nothing unless given -f or -n.  Defaults
+	to false.
+
 color.branch::
 	A boolean to enable/disable color in the output of
 	gitlink:git-branch[1]. May be set to `true` (or `always`),

Documentation/git-clean.txt

@@ -8,7 +8,7 @@ git-clean - Remove untracked files from the working tree
 SYNOPSIS
 --------
 [verse]
-'git-clean' [-d] [-n] [-q] [-x | -X] [--] <paths>...
+'git-clean' [-d] [-f] [-n] [-q] [-x | -X] [--] <paths>...
 
 DESCRIPTION
 -----------
@@ -25,6 +25,10 @@ OPTIONS
 -d::
 	Remove untracked directories in addition to untracked files.
 
+-f::
+	If the git configuration specifies clean.forceRequire as true,
+	git-clean will refuse to run unless given -f or -n.
+
 -n::
 	Don't actually remove anything, just show what would be done.
 

contrib/completion/git-completion.bash

@@ -790,6 +790,7 @@ _git_config ()
 		core.legacyHeaders
 		core.packedGitWindowSize
 		core.packedGitLimit
+		clean.requireForce
 		color.branch
 		color.branch.current
 		color.branch.local

git-clean.sh

@@ -3,9 +3,10 @@
 # Copyright (c) 2005-2006 Pavel Roskin
 #
 
-USAGE="[-d] [-n] [-q] [-x | -X] [--] <paths>..."
+USAGE="[-d] [-f] [-n] [-q] [-x | -X] [--] <paths>..."
 LONG_USAGE='Clean untracked files from the working directory
 	-d	remove directories as well
+	-f	override clean.requireForce and clean anyway
 	-n 	don'\''t remove anything, just show what would be done
 	-q	be quiet, only report errors
 	-x	remove ignored files as well
@@ -19,6 +20,7 @@ require_work_tree
 ignored=
 ignoredonly=
 cleandir=
+disabled="`git-config --bool clean.requireForce`"
 rmf="rm -f --"
 rmrf="rm -rf --"
 rm_refuse="echo Not removing"
@@ -30,7 +32,11 @@ do
 	-d)
 		cleandir=1
 		;;
+	-f)
+		disabled=
+		;;
 	-n)
+		disabled=
 		rmf="echo Would remove"
 		rmrf="echo Would remove"
 		rm_refuse="echo Would not remove"
@@ -58,6 +64,11 @@ do
 	shift
 done
 
+if [ "$disabled" = true ]; then
+	echo "clean.requireForce set and -n or -f not given; refusing to clean"
+	exit 1
+fi
+
 case "$ignored,$ignoredonly" in
 	1,1) usage;;
 esac