Merge branch 'tr/rebase-root'

* tr/rebase-root:
  rebase: update documentation for --root
  rebase -i: learn to rebase root commit
  rebase: learn to rebase root commit
  rebase -i: execute hook only after argument checking

4 files changed, 322 insertions, 52 deletions

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index c8ad86a56..3d6d429e5 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -8,10 +8,11 @@ git-rebase - Forward-port local commits to the updated upstream head
 SYNOPSIS
 --------
 [verse]
-'git rebase' [-i | --interactive] [-v | --verbose] [-m | --merge]
-	[-s <strategy> | --strategy=<strategy>] [--no-verify]
-	[-C<n>] [ --whitespace=<option>] [-p | --preserve-merges]
-	[--onto <newbase>] <upstream> [<branch>]
+'git rebase' [-i | --interactive] [options] [--onto <newbase>]
+	<upstream> [<branch>]
+'git rebase' [-i | --interactive] [options] --onto <newbase>
+	--root [<branch>]
+
 'git rebase' --continue | --skip | --abort
 
 DESCRIPTION
@@ -22,7 +23,8 @@ it remains on the current branch.
 
 All changes made by commits in the current branch but that are not
 in <upstream> are saved to a temporary area.  This is the same set
-of commits that would be shown by `git log <upstream>..HEAD`.
+of commits that would be shown by `git log <upstream>..HEAD` (or
+`git log HEAD`, if --root is specified).
 
 The current branch is reset to <upstream>, or <newbase> if the
 --onto option was supplied.  This has the exact same effect as
@@ -255,6 +257,15 @@ OPTIONS
 --preserve-merges::
 	Instead of ignoring merges, try to recreate them.
 
+--root::
+	Rebase all commits reachable from <branch>, instead of
+	limiting them with an <upstream>.  This allows you to rebase
+	the root commit(s) on a branch.  Must be used with --onto, and
+	will skip changes already contained in <newbase> (instead of
+	<upstream>).  When used together with --preserve-merges, 'all'
+	root commits will be rewritten to have <newbase> as parent
+	instead.
+
 include::merge-strategies.txt[]
 
 NOTES
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
index 8ed224481..21ac20c30 100755
--- a/git-rebase--interactive.sh
+++ b/git-rebase--interactive.sh
@@ -27,6 +27,7 @@ continue           continue rebasing process
 abort              abort rebasing process and restore original branch
 skip               skip current patch and continue rebasing process
 no-verify          override pre-rebase hook from stopping the operation
+root               rebase all reachable commmits up to the root(s)
 "
 
 . git-sh-setup
@@ -44,6 +45,7 @@ STRATEGY=
 ONTO=
 VERBOSE=
 OK_TO_SKIP_PRE_REBASE=
+REBASE_ROOT=
 
 GIT_CHERRY_PICK_HELP="  After resolving the conflicts,
 mark the corrected paths with 'git add <paths>', and
@@ -154,6 +156,11 @@ pick_one () {
 	output git rev-parse --verify $sha1 || die "Invalid commit name: $sha1"
 	test -d "$REWRITTEN" &&
 		pick_one_preserving_merges "$@" && return
+	if test ! -z "$REBASE_ROOT"
+	then
+		output git cherry-pick "$@"
+		return
+	fi
 	parent_sha1=$(git rev-parse --verify $sha1^) ||
 		die "Could not get the parent of $sha1"
 	current_sha1=$(git rev-parse --verify HEAD)
@@ -197,7 +204,11 @@ pick_one_preserving_merges () {
 
 	# rewrite parents; if none were rewritten, we can fast-forward.
 	new_parents=
-	pend=" $(git rev-list --parents -1 $sha1 | cut -d' ' -f2-)"
+	pend=" $(git rev-list --parents -1 $sha1 | cut -d' ' -s -f2-)"
+	if test "$pend" = " "
+	then
+		pend=" root"
+	fi
 	while [ "$pend" != "" ]
 	do
 		p=$(expr "$pend" : ' \([^ ]*\)')
@@ -227,7 +238,9 @@ pick_one_preserving_merges () {
 			if test -f "$DROPPED"/$p
 			then
 				fast_forward=f
-				pend=" $(cat "$DROPPED"/$p)$pend"
+				replacement="$(cat "$DROPPED"/$p)"
+				test -z "$replacement" && replacement=root
+				pend=" $replacement$pend"
 			else
 				new_parents="$new_parents $p"
 			fi
@@ -443,6 +456,7 @@ get_saved_options () {
 	test -d "$REWRITTEN" && PRESERVE_MERGES=t
 	test -f "$DOTEST"/strategy && STRATEGY="$(cat "$DOTEST"/strategy)"
 	test -f "$DOTEST"/verbose && VERBOSE=t
+	test ! -s "$DOTEST"/upstream && REBASE_ROOT=t
 }
 
 while test $# != 0
@@ -547,6 +561,9 @@ first and then run 'git rebase --continue' again."
 	-i)
 		# yeah, we know
 		;;
+	--root)
+		REBASE_ROOT=t
+		;;
 	--onto)
 		shift
 		ONTO=$(git rev-parse --verify "$1") ||
@@ -554,27 +571,36 @@ first and then run 'git rebase --continue' again."
 		;;
 	--)
 		shift
-		run_pre_rebase_hook ${1+"$@"}
-		test $# -eq 1 -o $# -eq 2 || usage
+		test ! -z "$REBASE_ROOT" -o $# -eq 1 -o $# -eq 2 || usage
 		test -d "$DOTEST" &&
 			die "Interactive rebase already started"
 
 		git var GIT_COMMITTER_IDENT >/dev/null ||
 			die "You need to set your committer info first"
 
+		if test -z "$REBASE_ROOT"
+		then
+			UPSTREAM_ARG="$1"
+			UPSTREAM=$(git rev-parse --verify "$1") || die "Invalid base"
+			test -z "$ONTO" && ONTO=$UPSTREAM
+			shift
+		else
+			UPSTREAM_ARG=--root
+			test -z "$ONTO" &&
+				die "You must specify --onto when using --root"
+		fi
+		run_pre_rebase_hook "$UPSTREAM_ARG" "$@"
+
 		comment_for_reflog start
 
 		require_clean_work_tree
 
-		UPSTREAM=$(git rev-parse --verify "$1") || die "Invalid base"
-		test -z "$ONTO" && ONTO=$UPSTREAM
-
-		if test ! -z "$2"
+		if test ! -z "$1"
 		then
-			output git show-ref --verify --quiet "refs/heads/$2" ||
-				die "Invalid branchname: $2"
-			output git checkout "$2" ||
-				die "Could not checkout $2"
+			output git show-ref --verify --quiet "refs/heads/$1" ||
+				die "Invalid branchname: $1"
+			output git checkout "$1" ||
+				die "Could not checkout $1"
 		fi
 
 		HEAD=$(git rev-parse --verify HEAD) || die "No HEAD?"
@@ -598,12 +624,19 @@ first and then run 'git rebase --continue' again."
 			# This ensures that commits on merged, but otherwise
 			# unrelated side branches are left alone. (Think "X"
 			# in the man page's example.)
-			mkdir "$REWRITTEN" &&
-			for c in $(git merge-base --all $HEAD $UPSTREAM)
-			do
-				echo $ONTO > "$REWRITTEN"/$c ||
+			if test -z "$REBASE_ROOT"
+			then
+				mkdir "$REWRITTEN" &&
+				for c in $(git merge-base --all $HEAD $UPSTREAM)
+				do
+					echo $ONTO > "$REWRITTEN"/$c ||
+						die "Could not init rewritten commits"
+				done
+			else
+				mkdir "$REWRITTEN" &&
+				echo $ONTO > "$REWRITTEN"/root ||
 					die "Could not init rewritten commits"
-			done
+			fi
 			# No cherry-pick because our first pass is to determine
 			# parents to rewrite and skipping dropped commits would
 			# prematurely end our probe
@@ -613,12 +646,21 @@ first and then run 'git rebase --continue' again."
 			MERGES_OPTION="--no-merges --cherry-pick"
 		fi
 
-		SHORTUPSTREAM=$(git rev-parse --short $UPSTREAM)
 		SHORTHEAD=$(git rev-parse --short $HEAD)
 		SHORTONTO=$(git rev-parse --short $ONTO)
+		if test -z "$REBASE_ROOT"
+			# this is now equivalent to ! -z "$UPSTREAM"
+		then
+			SHORTUPSTREAM=$(git rev-parse --short $UPSTREAM)
+			REVISIONS=$UPSTREAM...$HEAD
+			SHORTREVISIONS=$SHORTUPSTREAM..$SHORTHEAD
+		else
+			REVISIONS=$ONTO...$HEAD
+			SHORTREVISIONS=$SHORTHEAD
+		fi
 		git rev-list $MERGES_OPTION --pretty=oneline --abbrev-commit \
 			--abbrev=7 --reverse --left-right --topo-order \
-			$UPSTREAM...$HEAD | \
+			$REVISIONS | \
 			sed -n "s/^>//p" | while read shortsha1 rest
 		do
 			if test t != "$PRESERVE_MERGES"
@@ -626,14 +668,19 @@ first and then run 'git rebase --continue' again."
 				echo "pick $shortsha1 $rest" >> "$TODO"
 			else
 				sha1=$(git rev-parse $shortsha1)
-				preserve=t
-				for p in $(git rev-list --parents -1 $sha1 | cut -d' ' -f2-)
-				do
-					if test -f "$REWRITTEN"/$p -a \( $p != $UPSTREAM -o $sha1 = $first_after_upstream \)
-					then
-						preserve=f
-					fi
-				done
+				if test -z "$REBASE_ROOT"
+				then
+					preserve=t
+					for p in $(git rev-list --parents -1 $sha1 | cut -d' ' -s -f2-)
+					do
+						if test -f "$REWRITTEN"/$p -a \( $p != $UPSTREAM -o $sha1 = $first_after_upstream \)
+						then
+							preserve=f
+						fi
+					done
+				else
+					preserve=f
+				fi
 				if test f = "$preserve"
 				then
 					touch "$REWRITTEN"/$sha1
@@ -647,11 +694,11 @@ first and then run 'git rebase --continue' again."
 		then
 			mkdir "$DROPPED"
 			# Save all non-cherry-picked changes
-			git rev-list $UPSTREAM...$HEAD --left-right --cherry-pick | \
+			git rev-list $REVISIONS --left-right --cherry-pick | \
 				sed -n "s/^>//p" > "$DOTEST"/not-cherry-picks
 			# Now all commits and note which ones are missing in
 			# not-cherry-picks and hence being dropped
-			git rev-list $UPSTREAM..$HEAD |
+			git rev-list $REVISIONS |
 			while read rev
 			do
 				if test -f "$REWRITTEN"/$rev -a "$(grep "$rev" "$DOTEST"/not-cherry-picks)" = ""
@@ -660,17 +707,18 @@ first and then run 'git rebase --continue' again."
 					# not worthwhile, we don't want to track its multiple heads,
 					# just the history of its first-parent for others that will
 					# be rebasing on top of it
-					git rev-list --parents -1 $rev | cut -d' ' -f2 > "$DROPPED"/$rev
+					git rev-list --parents -1 $rev | cut -d' ' -s -f2 > "$DROPPED"/$rev
 					short=$(git rev-list -1 --abbrev-commit --abbrev=7 $rev)
 					grep -v "^[a-z][a-z]* $short" <"$TODO" > "${TODO}2" ; mv "${TODO}2" "$TODO"
 					rm "$REWRITTEN"/$rev
 				fi
 			done
 		fi
+
 		test -s "$TODO" || echo noop >> "$TODO"
 		cat >> "$TODO" << EOF
 
-# Rebase $SHORTUPSTREAM..$SHORTHEAD onto $SHORTONTO
+# Rebase $SHORTREVISIONS onto $SHORTONTO
 #
 # Commands:
 #  p, pick = use commit
diff --git a/git-rebase.sh b/git-rebase.sh
index ebd4df3a0..6d3eddbad 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -3,7 +3,7 @@
 # Copyright (c) 2005 Junio C Hamano.
 #
 
-USAGE='[--interactive | -i] [-v] [--onto <newbase>] <upstream> [<branch>]'
+USAGE='[--interactive | -i] [-v] [--onto <newbase>] [<upstream>|--root] [<branch>]'
 LONG_USAGE='git-rebase replaces <branch> with a new branch of the
 same name.  When the --onto option is provided the new branch starts
 out with a HEAD equal to <newbase>, otherwise it is equal to <upstream>
@@ -47,6 +47,7 @@ dotest="$GIT_DIR"/rebase-merge
 prec=4
 verbose=
 git_am_opt=
+rebase_root=
 
 continue_merge () {
 	test -n "$prev_head" || die "prev_head must be defined"
@@ -297,6 +298,9 @@ do
 	-C*)
 		git_am_opt="$git_am_opt $1"
 		;;
+	--root)
+		rebase_root=t
+		;;
 	-*)
 		usage
 		;;
@@ -344,17 +348,29 @@ case "$diff" in
 	;;
 esac
 
-# The upstream head must be given.  Make sure it is valid.
-upstream_name="$1"
-upstream=`git rev-parse --verify "${upstream_name}^0"` ||
-    die "invalid upstream $upstream_name"
+if test -z "$rebase_root"
+then
+	# The upstream head must be given.  Make sure it is valid.
+	upstream_name="$1"
+	shift
+	upstream=`git rev-parse --verify "${upstream_name}^0"` ||
+	die "invalid upstream $upstream_name"
+	unset root_flag
+	upstream_arg="$upstream_name"
+else
+	test -z "$newbase" && die "--root must be used with --onto"
+	unset upstream_name
+	unset upstream
+	root_flag="--root"
+	upstream_arg="$root_flag"
+fi
 
 # Make sure the branch to rebase onto is valid.
 onto_name=${newbase-"$upstream_name"}
 onto=$(git rev-parse --verify "${onto_name}^0") || exit
 
 # If a hook exists, give it a chance to interrupt
-run_pre_rebase_hook ${1+"$@"}
+run_pre_rebase_hook "$upstream_arg" "$@"
 
 # If the branch to rebase is given, that is the branch we will rebase
 # $branch_name -- branch being rebased, or HEAD (already detached)
@@ -362,16 +378,16 @@ run_pre_rebase_hook ${1+"$@"}
 # $head_name -- refs/heads/<that-branch> or "detached HEAD"
 switch_to=
 case "$#" in
-2)
+1)
 	# Is it "rebase other $branchname" or "rebase other $commit"?
-	branch_name="$2"
-	switch_to="$2"
+	branch_name="$1"
+	switch_to="$1"
 
-	if git show-ref --verify --quiet -- "refs/heads/$2" &&
-	   branch=$(git rev-parse -q --verify "refs/heads/$2")
+	if git show-ref --verify --quiet -- "refs/heads/$1" &&
+	   branch=$(git rev-parse -q --verify "refs/heads/$1")
 	then
-		head_name="refs/heads/$2"
-	elif branch=$(git rev-parse -q --verify "$2")
+		head_name="refs/heads/$1"
+	elif branch=$(git rev-parse -q --verify "$1")
 	then
 		head_name="detached HEAD"
 	else
@@ -393,7 +409,8 @@ case "$#" in
 esac
 orig_head=$branch
 
-# Now we are rebasing commits $upstream..$branch on top of $onto
+# Now we are rebasing commits $upstream..$branch (or with --root,
+# everything leading up to $branch) on top of $onto
 
 # Check if we are already based on $onto with linear history,
 # but this should be done only when upstream and onto are the same.
@@ -429,10 +446,17 @@ then
 	exit 0
 fi
 
+if test -n "$rebase_root"
+then
+	revisions="$onto..$orig_head"
+else
+	revisions="$upstream..$orig_head"
+fi
+
 if test -z "$do_merge"
 then
 	git format-patch -k --stdout --full-index --ignore-if-in-upstream \
-		"$upstream..$orig_head" |
+		$root_flag "$revisions" |
 	git am $git_am_opt --rebasing --resolvemsg="$RESOLVEMSG" &&
 	move_to_original_branch
 	ret=$?
@@ -455,7 +479,7 @@ echo "$orig_head" > "$dotest/orig-head"
 echo "$head_name" > "$dotest/head-name"
 
 msgnum=0
-for cmt in `git rev-list --reverse --no-merges "$upstream..$orig_head"`
+for cmt in `git rev-list --reverse --no-merges "$revisions"`
 do
 	msgnum=$(($msgnum + 1))
 	echo "$cmt" > "$dotest/cmt.$msgnum"
diff --git a/t/t3412-rebase-root.sh b/t/t3412-rebase-root.sh
new file mode 100755
index 000000000..635958026
--- /dev/null
+++ b/t/t3412-rebase-root.sh
@@ -0,0 +1,187 @@
+#!/bin/sh
+
+test_description='git rebase --root
+
+Tests if git rebase --root --onto <newparent> can rebase the root commit.
+'
+. ./test-lib.sh
+
+test_expect_success 'prepare repository' '
+	echo 1 > A &&
+	git add A &&
+	git commit -m 1 &&
+	echo 2 > A &&
+	git add A &&
+	git commit -m 2 &&
+	git symbolic-ref HEAD refs/heads/other &&
+	rm .git/index &&
+	echo 3 > B &&
+	git add B &&
+	git commit -m 3 &&
+	echo 1 > A &&
+	git add A &&
+	git commit -m 1b &&
+	echo 4 > B &&
+	git add B &&
+	git commit -m 4
+'
+
+test_expect_success 'rebase --root expects --onto' '
+	test_must_fail git rebase --root
+'
+
+test_expect_success 'setup pre-rebase hook' '
+	mkdir -p .git/hooks &&
+	cat >.git/hooks/pre-rebase <<EOF &&
+#!$SHELL_PATH
+echo "\$1,\$2" >.git/PRE-REBASE-INPUT
+EOF
+	chmod +x .git/hooks/pre-rebase
+'
+cat > expect <<EOF
+4
+3
+2
+1
+EOF
+
+test_expect_success 'rebase --root --onto <newbase>' '
+	git checkout -b work &&
+	git rebase --root --onto master &&
+	git log --pretty=tformat:"%s" > rebased &&
+	test_cmp expect rebased
+'
+
+test_expect_success 'pre-rebase got correct input (1)' '
+	test "z$(cat .git/PRE-REBASE-INPUT)" = z--root,
+'
+
+test_expect_success 'rebase --root --onto <newbase> <branch>' '
+	git branch work2 other &&
+	git rebase --root --onto master work2 &&
+	git log --pretty=tformat:"%s" > rebased2 &&
+	test_cmp expect rebased2
+'
+
+test_expect_success 'pre-rebase got correct input (2)' '
+	test "z$(cat .git/PRE-REBASE-INPUT)" = z--root,work2
+'
+
+test_expect_success 'rebase -i --root --onto <newbase>' '
+	git checkout -b work3 other &&
+	GIT_EDITOR=: git rebase -i --root --onto master &&
+	git log --pretty=tformat:"%s" > rebased3 &&
+	test_cmp expect rebased3
+'
+
+test_expect_success 'pre-rebase got correct input (3)' '
+	test "z$(cat .git/PRE-REBASE-INPUT)" = z--root,
+'
+
+test_expect_success 'rebase -i --root --onto <newbase> <branch>' '
+	git branch work4 other &&
+	GIT_EDITOR=: git rebase -i --root --onto master work4 &&
+	git log --pretty=tformat:"%s" > rebased4 &&
+	test_cmp expect rebased4
+'
+
+test_expect_success 'pre-rebase got correct input (4)' '
+	test "z$(cat .git/PRE-REBASE-INPUT)" = z--root,work4
+'
+
+test_expect_success 'rebase -i -p with linear history' '
+	git checkout -b work5 other &&
+	GIT_EDITOR=: git rebase -i -p --root --onto master &&
+	git log --pretty=tformat:"%s" > rebased5 &&
+	test_cmp expect rebased5
+'
+
+test_expect_success 'pre-rebase got correct input (5)' '
+	test "z$(cat .git/PRE-REBASE-INPUT)" = z--root,
+'
+
+test_expect_success 'set up merge history' '
+	git checkout other^ &&
+	git checkout -b side &&
+	echo 5 > C &&
+	git add C &&
+	git commit -m 5 &&
+	git checkout other &&
+	git merge side
+'
+
+sed 's/#/ /g' > expect-side <<'EOF'
+*   Merge branch 'side' into other
+|\##
+| * 5
+* | 4
+|/##
+* 3
+* 2
+* 1
+EOF
+
+test_expect_success 'rebase -i -p with merge' '
+	git checkout -b work6 other &&
+	GIT_EDITOR=: git rebase -i -p --root --onto master &&
+	git log --graph --topo-order --pretty=tformat:"%s" > rebased6 &&
+	test_cmp expect-side rebased6
+'
+
+test_expect_success 'set up second root and merge' '
+	git symbolic-ref HEAD refs/heads/third &&
+	rm .git/index &&
+	rm A B C &&
+	echo 6 > D &&
+	git add D &&
+	git commit -m 6 &&
+	git checkout other &&
+	git merge third
+'
+
+sed 's/#/ /g' > expect-third <<'EOF'
+*   Merge branch 'third' into other
+|\##
+| * 6
+* |   Merge branch 'side' into other
+|\ \##
+| * | 5
+* | | 4
+|/ /##
+* | 3
+|/##
+* 2
+* 1
+EOF
+
+test_expect_success 'rebase -i -p with two roots' '
+	git checkout -b work7 other &&
+	GIT_EDITOR=: git rebase -i -p --root --onto master &&
+	git log --graph --topo-order --pretty=tformat:"%s" > rebased7 &&
+	test_cmp expect-third rebased7
+'
+
+test_expect_success 'setup pre-rebase hook that fails' '
+	mkdir -p .git/hooks &&
+	cat >.git/hooks/pre-rebase <<EOF &&
+#!$SHELL_PATH
+false
+EOF
+	chmod +x .git/hooks/pre-rebase
+'
+
+test_expect_success 'pre-rebase hook stops rebase' '
+	git checkout -b stops1 other &&
+	GIT_EDITOR=: test_must_fail git rebase --root --onto master &&
+	test "z$(git symbolic-ref HEAD)" = zrefs/heads/stops1
+	test 0 = $(git rev-list other...stops1 | wc -l)
+'
+
+test_expect_success 'pre-rebase hook stops rebase -i' '
+	git checkout -b stops2 other &&
+	GIT_EDITOR=: test_must_fail git rebase --root --onto master &&
+	test "z$(git symbolic-ref HEAD)" = zrefs/heads/stops2
+	test 0 = $(git rev-list other...stops2 | wc -l)
+'
+
+test_done