Add git-mergetool to run an appropriate merge conflict resolution program

The git-mergetool program can be used to automatically run an appropriate
merge resolution program to resolve merge conflicts.  It will automatically
run one of kdiff3, tkdiff, meld, xxdiff, or emacs emerge programs.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 352 insertions, 0 deletions

diff --git a/git-mergetool.sh b/git-mergetool.sh
new file mode 100755
index 000000000..52386a544
--- /dev/null
+++ b/git-mergetool.sh
@@ -0,0 +1,352 @@
+#!/bin/sh
+#
+# This program resolves merge conflicts in git
+#
+# Copyright (c) 2006 Theodore Y. Ts'o
+#
+# This file is licensed under the GPL v2, or a later version
+# at the discretion of Junio C Hammano.
+#
+
+USAGE='[--tool=tool] [file to merge] ...'
+SUBDIRECTORY_OK=Yes
+. git-sh-setup
+require_work_tree
+
+# Returns true if the mode reflects a symlink
+function is_symlink () {
+    test "$1" = 120000
+}
+
+function local_present () {
+    test -n "$local_mode"
+}
+
+function remote_present () {
+    test -n "$remote_mode"
+}
+
+function base_present () {
+    test -n "$base_mode"
+}
+
+cleanup_temp_files () {
+    if test "$1" = --save-backup ; then
+	mv -- "$BACKUP" "$path.orig"
+	rm -f -- "$LOCAL" "$REMOTE" "$BASE"
+    else
+	rm -f -- "$LOCAL" "$REMOTE" "$BASE" "$BACKUP"
+    fi
+}
+
+function describe_file () {
+    mode="$1"
+    branch="$2"
+    file="$3"
+
+    echo -n "    "
+    if test -z "$mode"; then
+	echo -n "'$path' was deleted"
+    elif is_symlink "$mode" ; then
+	echo -n "'$path' is a symlink containing '"
+	cat "$file"
+	echo -n "'"
+    else
+	if base_present; then
+	    echo -n "'$path' was created"
+	else
+	    echo -n "'$path' was modified"
+	fi
+    fi
+    echo " in the $branch branch"
+}
+
+
+resolve_symlink_merge () {
+    while /bin/true; do
+	echo -n "Use (r)emote or (l)ocal, or (a)bort? "
+	read ans
+	case "$ans" in
+	    [lL]*)
+		git-checkout-index -f --stage=2 -- "$path"
+		git-add -- "$path"
+		cleanup_temp_files --save-backup
+		return
+		;;
+	   [rR]*)
+		git-checkout-index -f --stage=3 -- "$path"
+		git-add -- "$path"
+		cleanup_temp_files --save-backup
+		return
+		;;
+	    [qQ]*)
+		exit 1
+		;;
+	    esac
+	done
+}
+
+resolve_deleted_merge () {
+    while /bin/true; do
+	echo -n "Use (m)odified or (d)eleted file, or (a)bort? "
+	read ans
+	case "$ans" in
+	    [mM]*)
+		git-add -- "$path"
+		cleanup_temp_files --save-backup
+		return
+		;;
+	   [dD]*)
+		git-rm -- "$path"
+		cleanup_temp_files
+		return
+		;;
+	    [qQ]*)
+		exit 1
+		;;
+	    esac
+	done
+}
+
+merge_file () {
+    path="$1"
+
+    if test ! -f "$path" ; then
+	echo "$path: file not found"
+	exit 1
+    fi
+
+    f=`git-ls-files -u -- "$path"`
+    if test -z "$f" ; then
+	echo "$path: file does not need merging"
+	exit 1
+    fi
+
+    BACKUP="$path.BACKUP.$$"
+    LOCAL="$path.LOCAL.$$"
+    REMOTE="$path.REMOTE.$$"
+    BASE="$path.BASE.$$"
+
+    mv -- "$path" "$BACKUP"
+    cp -- "$BACKUP" "$path"
+
+    base_mode=`git ls-files -u -- "$path" | awk '{if ($3==1) print $1;}'`
+    local_mode=`git ls-files -u -- "$path" | awk '{if ($3==2) print $1;}'`
+    remote_mode=`git ls-files -u -- "$path" | awk '{if ($3==3) print $1;}'`
+
+    base_present   && git cat-file blob ":1:$path" > "$BASE" 2>/dev/null
+    local_present  && git cat-file blob ":2:$path" > "$LOCAL" 2>/dev/null
+    remote_present && git cat-file blob ":3:$path" > "$REMOTE" 2>/dev/null
+
+    if test -z "$local_mode" -o -z "$remote_mode"; then
+	echo "Deleted merge conflict for $path:"
+	describe_file "$local_mode" "local" "$LOCAL"
+	describe_file "$remote_mode" "remote" "$REMOTE"
+	resolve_deleted_merge
+	return
+    fi
+
+    if is_symlink "$local_mode" || is_symlink "$remote_mode"; then
+	echo "Symlink merge conflict for $path:"
+	describe_file "$local_mode" "local" "$LOCAL"
+	describe_file "$remote_mode" "remote" "$REMOTE"
+	resolve_symlink_merge
+	return
+    fi
+
+    echo "Normal merge conflict for $path:"
+    describe_file "$local_mode" "local" "$LOCAL"
+    describe_file "$remote_mode" "remote" "$REMOTE"
+    echo -n "Hit return to start merge resolution tool ($merge_tool): "
+    read ans
+
+    case "$merge_tool" in
+	kdiff3)
+	    if base_present ; then
+		(kdiff3 --auto --L1 "$path (Base)" -L2 "$path (Local)" --L3 "$path (Remote)" \
+		    -o "$path" -- "$BASE" "$LOCAL" "$REMOTE" > /dev/null 2>&1)
+	    else
+		(kdiff3 --auto -L1 "$path (Local)" --L2 "$path (Remote)" \
+		    -o "$path" -- "$LOCAL" "$REMOTE" > /dev/null 2>&1)
+	    fi
+	    status=$?
+	    if test "$status" -eq 0; then
+		rm "$BACKUP"
+	    fi
+	    ;;
+	tkdiff)
+	    if base_present ; then
+		tkdiff -a "$BASE" -o "$path" -- "$LOCAL" "$REMOTE"
+	    else
+		tkdiff -o "$path" -- "$LOCAL" "$REMOTE"
+	    fi
+	    status=$?
+	    if test "$status" -eq 0; then
+		mv -- "$BACKUP" "$path.orig"
+	    fi
+	    ;;
+	meld)
+	    touch "$BACKUP"
+	    meld -- "$LOCAL" "$path" "$REMOTE"
+	    if test "$path" -nt "$BACKUP" ; then
+		status=0;
+	    else
+		while true; do
+		    echo "$path seems unchanged."
+		    echo -n "Was the merge successful? [y/n] "
+		    read answer < /dev/tty
+		    case "$answer" in
+			y*|Y*) status=0; break ;;
+			n*|N*) status=1; break ;;
+		    esac
+		done
+	    fi
+	    if test "$status" -eq 0; then
+		mv -- "$BACKUP" "$path.orig"
+	    fi
+	    ;;
+	xxdiff)
+	    touch "$BACKUP"
+	    if base_present ; then
+		xxdiff -X --show-merged-pane \
+		    -R 'Accel.SaveAsMerged: "Ctrl-S"' \
+		    -R 'Accel.Search: "Ctrl+F"' \
+		    -R 'Accel.SearchForward: "Ctrl-G"' \
+		    --merged-file "$path" -- "$LOCAL" "$BASE" "$REMOTE"
+	    else
+		xxdiff -X --show-merged-pane \
+		    -R 'Accel.SaveAsMerged: "Ctrl-S"' \
+		    -R 'Accel.Search: "Ctrl+F"' \
+		    -R 'Accel.SearchForward: "Ctrl-G"' \
+		    --merged-file "$path" -- "$LOCAL" "$REMOTE"
+	    fi
+	    if test "$path" -nt "$BACKUP" ; then
+		status=0;
+	    else
+		while true; do
+		    echo "$path seems unchanged."
+		    echo -n "Was the merge successful? [y/n] "
+		    read answer < /dev/tty
+		    case "$answer" in
+			y*|Y*) status=0; break ;;
+			n*|N*) status=1; break ;;
+		    esac
+		done
+	    fi
+	    if test "$status" -eq 0; then
+		mv -- "$BACKUP" "$path.orig"
+	    fi
+	    ;;
+	emerge)
+	    if base_present ; then
+		emacs -f emerge-files-with-ancestor-command "$LOCAL" "$REMOTE" "$BASE" "$path"
+	    else
+		emacs -f emerge-files-command "$LOCAL" "$REMOTE" "$path"
+	    fi
+	    status=$?
+	    if test "$status" -eq 0; then
+		mv -- "$BACKUP" "$path.orig"
+	    fi
+	    ;;
+    esac
+    if test "$status" -ne 0; then
+	echo "merge of $path failed" 1>&2
+	mv -- "$BACKUP" "$path"
+	exit 1
+    fi
+    git add -- "$path"
+    cleanup_temp_files
+}
+
+while case $# in 0) break ;; esac
+do
+    case "$1" in
+	-t|--tool*)
+	    case "$#,$1" in
+		*,*=*)
+		    merge_tool=`expr "z$1" : 'z-[^=]*=\(.*\)'`
+		    ;;
+		1,*)
+		    usage ;;
+		*)
+		    merge_tool="$2"
+		    shift ;;
+	    esac
+	    ;;
+	--)
+	    break
+	    ;;
+	-*)
+	    usage
+	    ;;
+	*)
+	    break
+	    ;;
+    esac
+    shift
+done
+
+if test -z "$merge_tool"; then
+    merge_tool=`git-config merge.tool`
+    if test $merge_tool = kdiff3 -o $merge_tool = tkdiff -o \
+	$merge_tool = xxdiff -o $merge_tool = meld ; then
+	unset merge_tool
+    fi
+fi
+
+if test -z "$merge_tool" ; then
+    if type kdiff3 >/dev/null 2>&1 && test -n "$DISPLAY"; then
+	merge_tool="kdiff3";
+    elif type tkdiff >/dev/null 2>&1 && test -n "$DISPLAY"; then
+	merge_tool=tkdiff
+    elif type xxdiff >/dev/null 2>&1 && test -n "$DISPLAY"; then
+	merge_tool=xxdiff
+    elif type meld >/dev/null 2>&1 && test -n "$DISPLAY"; then
+	merge_tool=meld
+    elif type emacs >/dev/null 2>&1; then
+	merge_tool=emerge
+    else
+	echo "No available merge resolution programs available."
+	exit 1
+    fi
+fi
+
+case "$merge_tool" in
+    kdiff3|tkdiff|meld|xxdiff)
+	if ! type "$merge_tool" > /dev/null 2>&1; then
+	    echo "The merge tool $merge_tool is not available"
+	    exit 1
+	fi
+	;;
+    emerge)
+	if ! type "emacs" > /dev/null 2>&1; then
+	    echo "Emacs is not available"
+	    exit 1
+	fi
+	;;
+    *)
+	echo "Unknown merge tool: $merge_tool"
+	exit 1
+	;;
+esac
+
+if test $# -eq 0 ; then
+	files=`git ls-files -u | sed -e 's/^[^	]*	//' | sort -u`
+	if test -z "$files" ; then
+		echo "No files need merging"
+		exit 0
+	fi
+	echo Merging the files: $files
+	git ls-files -u | sed -e 's/^[^	]*	//' | sort -u | while read i
+	do
+		echo ""
+		merge_file "$i" < /dev/tty > /dev/tty
+	done
+else
+	while test $# -gt 0; do
+		echo ""
+		merge_file "$1"
+		shift
+	done
+fi
+exit 0