pacdiff: Add option to use sudo/sudoedit to manage files

This allows the user to run their diff program as their own user instead
of root. The advantage of this approach is that they can use their own
configuration for the editor or even use a GUI merge program such as
meld.
Signed-off-by: Daniel Parks <danielrparks@gmail.com>
Signed-off-by: Daniel M. Capella <polyzen@archlinux.org>

src/pacdiff.sh.in

@@ -30,6 +30,7 @@ diffsearchpath=${DIFFSEARCHPATH:-/etc}
 mergeprog=${MERGEPROG:-'diff3 -m'}
 cachedir=
 USE_COLOR='y'
+SUDO=''
 declare -a oldsaves
 declare -i USE_FIND=0 USE_LOCATE=0 USE_PACDB=0 OUTPUTONLY=0
 
@@ -59,6 +60,7 @@ General Options:
   --nocolor           remove colors from output
   -c/--cachedir <dir> scan "dir" for 3-way merge base candidates.
                       (default: read from @sysconfdir@/pacman.conf)
+  -s/--sudo         use sudo to merge/remove files
 
 Environment Variables:
   DIFFPROG          override the merge program: (default: 'vim -d')
@@ -115,15 +117,20 @@ merge_file() {
 	fi
 
 	basename="$(basename "$file")"
-	base="$(mktemp --tmpdir "$basename.base.XXX")"
-	merged="$(mktemp --tmpdir "$basename.merged.XXX")"
+	tempdir="$($SUDO mktemp -d --tmpdir "pacdiff-merge-$basename.XXX")"
+	base="$($SUDO mktemp "$tempdir"/"$basename.base.XXX")"
+	merged="$($SUDO mktemp "$tempdir"/"$basename.merged.XXX")"
 
-	tar -xOf "$base_tar" "${file#/}" >"$base"
-	if $mergeprog "$file" "$base" "$pacfile" >"$merged"; then
+	tar -xOf "$base_tar" "${file#/}" | $SUDO tee "$base" > /dev/null
+	if $SUDO $mergeprog "$file" "$base" "$pacfile" | $SUDO tee "$merged" > /dev/null; then
 		msg2 "Merged without conflicts."
 	fi
 
-	$diffprog "$file" "$merged"
+	if [[ -n "$SUDO" ]]; then
+		SUDO_EDITOR="$diffprog" sudoedit "$file" "$merged"
+	else
+		$diffprog "$file" "$merged"
+	fi
 
 	while :; do
 		ask "Would you like to use the results of the merge? [y/n] "
@@ -136,11 +143,11 @@ merge_file() {
 		esac
 	done
 
-	if ! cp -v "$merged" "$file"; then
+	if ! $SUDO cp -v "$merged" "$file"; then
 		warning "Unable to write merged file to %s. Merged file is preserved at %s" "$file" "$merged"
 		return 1
 	fi
-	rm -v "$pacfile" "$base" "$merged"
+	$SUDO rm -rv "$pacfile" "$tempdir"
 	return 0
 }
 
@@ -177,6 +184,8 @@ while [[ -n "$1" ]]; do
 			USE_COLOR='n';;
 		-c|--cachedir)
 			cachedir="$2"; shift;;
+		-s|--sudo)
+			SUDO=sudo;;
 		-V|--version)
 			version; exit 0;;
 		-h|--help)
@@ -243,26 +252,30 @@ while IFS= read -u 3 -r -d '' pacfile; do
 	msg "%s file found for %s" "$file_type" "$file"
 	if [ ! -f "$file" ]; then
 		warning "$file does not exist"
-		rm -iv "$pacfile"
+		$SUDO rm -iv "$pacfile"
 		continue
 	fi
 
 	if cmp -s "$pacfile" "$file"; then
 		msg2 "Files are identical, removing..."
-		rm -v "$pacfile"
+		$SUDO rm -v "$pacfile"
 	else
 		while :; do
 			ask "(V)iew, (M)erge, (S)kip, (R)emove %s, (O)verwrite with %s, (Q)uit: [v/m/s/r/o/q] " "$file_type" "$file_type"
 			read c || break
 			case $c in
 				q|Q) exit 0;;
-				r|R) rm -v "$pacfile"; break ;;
-				o|O) mv -v "$pacfile" "$file"; break ;;
+				r|R) $SUDO rm -v "$pacfile"; break ;;
+				o|O) $SUDO mv -v "$pacfile" "$file"; break ;;
 				v|V)
-					$diffprog "$pacfile" "$file"
+					if [[ -n "$SUDO" ]]; then
+						SUDO_EDITOR="$diffprog" sudoedit "$pacfile" "$file"
+					else
+						$diffprog "$pacfile" "$file"
+					fi
 					if cmp -s "$pacfile" "$file"; then
 						msg2 "Files are identical, removing..."
-						rm -v "$pacfile"
+						$SUDO rm -v "$pacfile"
 						break
 					fi ;;
 				m|M)