+#!/bin/sh
+# git-difftool-helper is a GIT_EXTERNAL_DIFF-compatible diff tool launcher.
+# It supports kdiff3, tkdiff, xxdiff, meld, opendiff, emerge, ecmerge,
+# vimdiff, gvimdiff, and custom user-configurable tools.
+# This script is typically launched by using the 'git difftool'
+# convenience command.
+#
+# Copyright (c) 2009 David Aguilar
+
+# Set GIT_DIFFTOOL_NO_PROMPT to bypass the per-file prompt.
+should_prompt () {
+ ! test -n "$GIT_DIFFTOOL_NO_PROMPT"
+}
+
+# Should we keep the backup .orig file?
+keep_backup_mode="$(git config --bool merge.keepBackup || echo true)"
+keep_backup () {
+ test "$keep_backup_mode" = "true"
+}
+
+# This function manages the backup .orig file.
+# A backup $MERGED.orig file is created if changes are detected.
+cleanup_temp_files () {
+ if test -n "$MERGED"; then
+ if keep_backup && test "$MERGED" -nt "$BACKUP"; then
+ test -f "$BACKUP" && mv -- "$BACKUP" "$MERGED.orig"
+ else
+ rm -f -- "$BACKUP"
+ fi
+ fi
+}
+
+# This is called when users Ctrl-C out of git-difftool-helper
+sigint_handler () {
+ echo
+ cleanup_temp_files
+ exit 1
+}
+
+# This function prepares temporary files and launches the appropriate
+# merge tool.
+launch_merge_tool () {
+ # Merged is the filename as it appears in the work tree
+ # Local is the contents of a/filename
+ # Remote is the contents of b/filename
+ # Custom merge tool commands might use $BASE so we provide it
+ MERGED="$1"
+ LOCAL="$2"
+ REMOTE="$3"
+ BASE="$1"
+ ext="$$$(expr "$MERGED" : '.*\(\.[^/]*\)$')"
+ BACKUP="$MERGED.BACKUP.$ext"
+
+ # Create and ensure that we clean up $BACKUP
+ test -f "$MERGED" && cp -- "$MERGED" "$BACKUP"
+ trap sigint_handler SIGINT
+
+ # $LOCAL and $REMOTE are temporary files so prompt
+ # the user with the real $MERGED name before launching $merge_tool.
+ if should_prompt; then
+ printf "\nViewing: '$MERGED'\n"
+ printf "Hit return to launch '%s': " "$merge_tool"
+ read ans
+ fi
+
+ # Run the appropriate merge tool command
+ case "$merge_tool" in
+ kdiff3)
+ basename=$(basename "$MERGED")
+ "$merge_tool_path" --auto \
+ --L1 "$basename (A)" \
+ --L2 "$basename (B)" \
+ -o "$MERGED" "$LOCAL" "$REMOTE" \
+ > /dev/null 2>&1
+ ;;
+
+ tkdiff)
+ "$merge_tool_path" -o "$MERGED" "$LOCAL" "$REMOTE"
+ ;;
+
+ meld|vimdiff)
+ "$merge_tool_path" "$LOCAL" "$REMOTE"
+ ;;
+
+ gvimdiff)
+ "$merge_tool_path" -f "$LOCAL" "$REMOTE"
+ ;;
+
+ xxdiff)
+ "$merge_tool_path" \
+ -X \
+ -R 'Accel.SaveAsMerged: "Ctrl-S"' \
+ -R 'Accel.Search: "Ctrl+F"' \
+ -R 'Accel.SearchForward: "Ctrl-G"' \
+ --merged-file "$MERGED" \
+ "$LOCAL" "$REMOTE"
+ ;;
+
+ opendiff)
+ "$merge_tool_path" "$LOCAL" "$REMOTE" \
+ -merge "$MERGED" | cat
+ ;;
+
+ ecmerge)
+ "$merge_tool_path" "$LOCAL" "$REMOTE" \
+ --default --mode=merge2 --to="$MERGED"
+ ;;
+
+ emerge)
+ "$merge_tool_path" -f emerge-files-command \
+ "$LOCAL" "$REMOTE" "$(basename "$MERGED")"
+ ;;
+
+ *)
+ if test -n "$merge_tool_cmd"; then
+ ( eval $merge_tool_cmd )
+ fi
+ ;;
+ esac
+
+ cleanup_temp_files
+}
+
+# Verifies that mergetool.<tool>.cmd exists
+valid_custom_tool() {
+ merge_tool_cmd="$(git config mergetool.$1.cmd)"
+ test -n "$merge_tool_cmd"
+}
+
+# Verifies that the chosen merge tool is properly setup.
+# Built-in merge tools are always valid.
+valid_tool() {
+ case "$1" in
+ kdiff3 | tkdiff | xxdiff | meld | opendiff | emerge | vimdiff | gvimdiff | ecmerge)
+ ;; # happy
+ *)
+ if ! valid_custom_tool "$1"
+ then
+ return 1
+ fi
+ ;;
+ esac
+}
+
+# Sets up the merge_tool_path variable.
+# This handles the mergetool.<tool>.path configuration.
+init_merge_tool_path() {
+ merge_tool_path=$(git config mergetool."$1".path)
+ if test -z "$merge_tool_path"; then
+ case "$1" in
+ emerge)
+ merge_tool_path=emacs
+ ;;
+ *)
+ merge_tool_path="$1"
+ ;;
+ esac
+ fi
+}
+
+# Allow the GIT_MERGE_TOOL variable to provide a default value
+test -n "$GIT_MERGE_TOOL" && merge_tool="$GIT_MERGE_TOOL"
+
+# If not merge tool was specified then use the merge.tool
+# configuration variable. If that's invalid then reset merge_tool.
+if test -z "$merge_tool"; then
+ merge_tool=$(git config merge.tool)
+ if test -n "$merge_tool" && ! valid_tool "$merge_tool"; then
+ echo >&2 "git config option merge.tool set to unknown tool: $merge_tool"
+ echo >&2 "Resetting to default..."
+ unset merge_tool
+ fi
+fi
+
+# Try to guess an appropriate merge tool if no tool has been set.
+if test -z "$merge_tool"; then
+
+ # We have a $DISPLAY so try some common UNIX merge tools
+ if test -n "$DISPLAY"; then
+ merge_tool_candidates="kdiff3 tkdiff xxdiff meld gvimdiff"
+ # If gnome then prefer meld
+ if test -n "$GNOME_DESKTOP_SESSION_ID"; then
+ merge_tool_candidates="meld $merge_tool_candidates"
+ fi
+ # If KDE then prefer kdiff3
+ if test "$KDE_FULL_SESSION" = "true"; then
+ merge_tool_candidates="kdiff3 $merge_tool_candidates"
+ fi
+ fi
+
+ # $EDITOR is emacs so add emerge as a candidate
+ if echo "${VISUAL:-$EDITOR}" | grep 'emacs' > /dev/null 2>&1; then
+ merge_tool_candidates="$merge_tool_candidates emerge"
+ fi
+
+ # $EDITOR is vim so add vimdiff as a candidate
+ if echo "${VISUAL:-$EDITOR}" | grep 'vim' > /dev/null 2>&1; then
+ merge_tool_candidates="$merge_tool_candidates vimdiff"
+ fi
+
+ merge_tool_candidates="$merge_tool_candidates opendiff emerge vimdiff"
+ echo "merge tool candidates: $merge_tool_candidates"
+
+ # Loop over each candidate and stop when a valid merge tool is found.
+ for i in $merge_tool_candidates
+ do
+ init_merge_tool_path $i
+ if type "$merge_tool_path" > /dev/null 2>&1; then
+ merge_tool=$i
+ break
+ fi
+ done
+
+ if test -z "$merge_tool" ; then
+ echo "No known merge resolution program available."
+ exit 1
+ fi
+
+else
+ # A merge tool has been set, so verify that it's valid.
+ if ! valid_tool "$merge_tool"; then
+ echo >&2 "Unknown merge tool $merge_tool"
+ exit 1
+ fi
+
+ init_merge_tool_path "$merge_tool"
+
+ if test -z "$merge_tool_cmd" && ! type "$merge_tool_path" > /dev/null 2>&1; then
+ echo "The merge tool $merge_tool is not available as '$merge_tool_path'"
+ exit 1
+ fi
+fi
+
+
+# Launch the merge tool on each path provided by 'git diff'
+while test $# -gt 6
+do
+ launch_merge_tool "$1" "$2" "$5"
+ shift 7
+done