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rebase: learn to rebase root commit

Teach git-rebase a new option --root, which instructs it to rebase the
entire history leading up to <branch>.  This option must be used with
--onto <newbase>, and causes commits that already exist in <newbase>
to be skipped.  (Normal operation skips commits that already exist in
<upstream> instead.)

One possible use-case is with git-svn: suppose you start hacking
(perhaps offline) on a new project, but later notice you want to
commit this work to SVN.  You will have to rebase the entire history,
including the root commit, on a (possibly empty) commit coming from
git-svn, to establish a history connection.  This previously had to
be done by cherry-picking the root commit manually.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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1 parent d8fab02 commit 190f53232d1e92a57843df90e889bcfea39620d3 @trast trast committed with gitster Jan 5, 2009
Showing with 126 additions and 16 deletions.
  1. +40 −16 git-rebase.sh
  2. +86 −0 t/t3412-rebase-root.sh
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@@ -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 $1"
;;
+ --root)
+ rebase_root=t
+ ;;
-*)
usage
;;
@@ -344,34 +348,46 @@ case "$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)
# $orig_head -- commit object name of tip of the branch before rebasing
# $head_name -- refs/heads/<that-branch> or "detached HEAD"
switch_to=
case "$#" 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.$msgnum"
View
@@ -0,0 +1,86 @@
+#!/bin/sh
+
+test_description='git rebase --root
+
+Tests if git rebase --root --onto <newparent> can rebase the root commit.
+'
+. ./test-lib.sh
+
+test_expect_success 'prepare repository' '
+ echo 1 > A &&
+ git add A &&
+ git commit -m 1 &&
+ echo 2 > A &&
+ git add A &&
+ git commit -m 2 &&
+ git symbolic-ref HEAD refs/heads/other &&
+ rm .git/index &&
+ echo 3 > B &&
+ git add B &&
+ git commit -m 3 &&
+ echo 1 > A &&
+ git add A &&
+ git commit -m 1b &&
+ echo 4 > B &&
+ git add B &&
+ git commit -m 4
+'
+
+test_expect_success 'rebase --root expects --onto' '
+ test_must_fail git rebase --root
+'
+
+test_expect_success 'setup pre-rebase hook' '
+ mkdir -p .git/hooks &&
+ cat >.git/hooks/pre-rebase <<EOF &&
+#!$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 '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_done

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