contrib: resurrect scripted git-revert.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/contrib/examples/git-revert.sh b/contrib/examples/git-revert.sh
new file mode 100755 (executable)
index 0000000..49f0032
--- /dev/null
+++ b/contrib/examples/git-revert.sh
@@ -0,0 +1,197 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Linus Torvalds
+# Copyright (c) 2005 Junio C Hamano
+#
+
+case "$0" in
+*-revert* )
+       test -t 0 && edit=-e
+       replay=
+       me=revert
+       USAGE='[--edit | --no-edit] [-n] <commit-ish>' ;;
+*-cherry-pick* )
+       replay=t
+       edit=
+       me=cherry-pick
+       USAGE='[--edit] [-n] [-r] [-x] <commit-ish>'  ;;
+* )
+       echo >&2 "What are you talking about?"
+       exit 1 ;;
+esac
+
+SUBDIRECTORY_OK=Yes ;# we will cd up
+. git-sh-setup
+require_work_tree
+cd_to_toplevel
+
+no_commit=
+while case "$#" in 0) break ;; esac
+do
+       case "$1" in
+       -n|--n|--no|--no-|--no-c|--no-co|--no-com|--no-comm|\
+           --no-commi|--no-commit)
+               no_commit=t
+               ;;
+       -e|--e|--ed|--edi|--edit)
+               edit=-e
+               ;;
+       --n|--no|--no-|--no-e|--no-ed|--no-edi|--no-edit)
+               edit=
+               ;;
+       -r)
+               : no-op ;;
+       -x|--i-really-want-to-expose-my-private-commit-object-name)
+               replay=
+               ;;
+       -*)
+               usage
+               ;;
+       *)
+               break
+               ;;
+       esac
+       shift
+done
+
+set_reflog_action "$me"
+
+test "$me,$replay" = "revert,t" && usage
+
+case "$no_commit" in
+t)
+       # We do not intend to commit immediately.  We just want to
+       # merge the differences in.
+       head=$(git-write-tree) ||
+               die "Your index file is unmerged."
+       ;;
+*)
+       head=$(git-rev-parse --verify HEAD) ||
+               die "You do not have a valid HEAD"
+       files=$(git-diff-index --cached --name-only $head) || exit
+       if [ "$files" ]; then
+               die "Dirty index: cannot $me (dirty: $files)"
+       fi
+       ;;
+esac
+
+rev=$(git-rev-parse --verify "$@") &&
+commit=$(git-rev-parse --verify "$rev^0") ||
+       die "Not a single commit $@"
+prev=$(git-rev-parse --verify "$commit^1" 2>/dev/null) ||
+       die "Cannot run $me a root commit"
+git-rev-parse --verify "$commit^2" >/dev/null 2>&1 &&
+       die "Cannot run $me a multi-parent commit."
+
+encoding=$(git config i18n.commitencoding || echo UTF-8)
+
+# "commit" is an existing commit.  We would want to apply
+# the difference it introduces since its first parent "prev"
+# on top of the current HEAD if we are cherry-pick.  Or the
+# reverse of it if we are revert.
+
+case "$me" in
+revert)
+       git show -s --pretty=oneline --encoding="$encoding" $commit |
+       sed -e '
+               s/^[^ ]* /Revert "/
+               s/$/"/
+       '
+       echo
+       echo "This reverts commit $commit."
+       test "$rev" = "$commit" ||
+       echo "(original 'git revert' arguments: $@)"
+       base=$commit next=$prev
+       ;;
+
+cherry-pick)
+       pick_author_script='
+       /^author /{
+               s/'\''/'\''\\'\'\''/g
+               h
+               s/^author \([^<]*\) <[^>]*> .*$/\1/
+               s/'\''/'\''\'\'\''/g
+               s/.*/GIT_AUTHOR_NAME='\''&'\''/p
+
+               g
+               s/^author [^<]* <\([^>]*\)> .*$/\1/
+               s/'\''/'\''\'\'\''/g
+               s/.*/GIT_AUTHOR_EMAIL='\''&'\''/p
+
+               g
+               s/^author [^<]* <[^>]*> \(.*\)$/\1/
+               s/'\''/'\''\'\'\''/g
+               s/.*/GIT_AUTHOR_DATE='\''&'\''/p
+
+               q
+       }'
+
+       logmsg=`git show -s --pretty=raw --encoding="$encoding" "$commit"`
+       set_author_env=`echo "$logmsg" |
+       LANG=C LC_ALL=C sed -ne "$pick_author_script"`
+       eval "$set_author_env"
+       export GIT_AUTHOR_NAME
+       export GIT_AUTHOR_EMAIL
+       export GIT_AUTHOR_DATE
+
+       echo "$logmsg" |
+       sed -e '1,/^$/d' -e 's/^    //'
+       case "$replay" in
+       '')
+               echo "(cherry picked from commit $commit)"
+               test "$rev" = "$commit" ||
+               echo "(original 'git cherry-pick' arguments: $@)"
+               ;;
+       esac
+       base=$prev next=$commit
+       ;;
+
+esac >.msg
+
+eval GITHEAD_$head=HEAD
+eval GITHEAD_$next='`git show -s \
+       --pretty=oneline --encoding="$encoding" "$commit" |
+       sed -e "s/^[^ ]* //"`'
+export GITHEAD_$head GITHEAD_$next
+
+# This three way merge is an interesting one.  We are at
+# $head, and would want to apply the change between $commit
+# and $prev on top of us (when reverting), or the change between
+# $prev and $commit on top of us (when cherry-picking or replaying).
+
+git-merge-recursive $base -- $head $next &&
+result=$(git-write-tree 2>/dev/null) || {
+       mv -f .msg "$GIT_DIR/MERGE_MSG"
+       {
+           echo '
+Conflicts:
+'
+               git ls-files --unmerged |
+               sed -e 's/^[^   ]*      /       /' |
+               uniq
+       } >>"$GIT_DIR/MERGE_MSG"
+       echo >&2 "Automatic $me failed.  After resolving the conflicts,"
+       echo >&2 "mark the corrected paths with 'git-add <paths>'"
+       echo >&2 "and commit the result."
+       case "$me" in
+       cherry-pick)
+               echo >&2 "You may choose to use the following when making"
+               echo >&2 "the commit:"
+               echo >&2 "$set_author_env"
+       esac
+       exit 1
+}
+echo >&2 "Finished one $me."
+
+# If we are cherry-pick, and if the merge did not result in
+# hand-editing, we will hit this commit and inherit the original
+# author date and name.
+# If we are revert, or if our cherry-pick results in a hand merge,
+# we had better say that the current user is responsible for that.
+
+case "$no_commit" in
+'')
+       git-commit -n -F .msg $edit
+       rm -f .msg
+       ;;
+esac