git/git-rebase.sh
Thomas Rast 190f53232d 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>
2009-01-11 23:03:36 -08:00

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#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano.
#
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>
It then attempts to create a new commit for each commit from the original
<branch> that does not exist in the <upstream> branch.
It is possible that a merge failure will prevent this process from being
completely automatic. You will have to resolve any such merge failure
and run git rebase --continue. Another option is to bypass the commit
that caused the merge failure with git rebase --skip. To restore the
original <branch> and remove the .git/rebase-apply working files, use the
command git rebase --abort instead.
Note that if <branch> is not specified on the command line, the
currently checked out branch is used.
Example: git-rebase master~1 topic
A---B---C topic A'\''--B'\''--C'\'' topic
/ --> /
D---E---F---G master D---E---F---G master
'
SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
. git-sh-setup
set_reflog_action rebase
require_work_tree
cd_to_toplevel
OK_TO_SKIP_PRE_REBASE=
RESOLVEMSG="
When you have resolved this problem run \"git rebase --continue\".
If you would prefer to skip this patch, instead run \"git rebase --skip\".
To restore the original branch and stop rebasing run \"git rebase --abort\".
"
unset newbase
strategy=recursive
do_merge=
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"
test -d "$dotest" || die "$dotest directory does not exist"
unmerged=$(git ls-files -u)
if test -n "$unmerged"
then
echo "You still have unmerged paths in your index"
echo "did you forget to use git add?"
die "$RESOLVEMSG"
fi
cmt=`cat "$dotest/current"`
if ! git diff-index --quiet --ignore-submodules HEAD --
then
if ! git commit --no-verify -C "$cmt"
then
echo "Commit failed, please do not call \"git commit\""
echo "directly, but instead do one of the following: "
die "$RESOLVEMSG"
fi
printf "Committed: %0${prec}d " $msgnum
else
printf "Already applied: %0${prec}d " $msgnum
fi
git rev-list --pretty=oneline -1 "$cmt" | sed -e 's/^[^ ]* //'
prev_head=`git rev-parse HEAD^0`
# save the resulting commit so we can read-tree on it later
echo "$prev_head" > "$dotest/prev_head"
# onto the next patch:
msgnum=$(($msgnum + 1))
echo "$msgnum" >"$dotest/msgnum"
}
call_merge () {
cmt="$(cat "$dotest/cmt.$1")"
echo "$cmt" > "$dotest/current"
hd=$(git rev-parse --verify HEAD)
cmt_name=$(git symbolic-ref HEAD 2> /dev/null || echo HEAD)
msgnum=$(cat "$dotest/msgnum")
end=$(cat "$dotest/end")
eval GITHEAD_$cmt='"${cmt_name##refs/heads/}~$(($end - $msgnum))"'
eval GITHEAD_$hd='$(cat "$dotest/onto_name")'
export GITHEAD_$cmt GITHEAD_$hd
git-merge-$strategy "$cmt^" -- "$hd" "$cmt"
rv=$?
case "$rv" in
0)
unset GITHEAD_$cmt GITHEAD_$hd
return
;;
1)
git rerere
die "$RESOLVEMSG"
;;
2)
echo "Strategy: $rv $strategy failed, try another" 1>&2
die "$RESOLVEMSG"
;;
*)
die "Unknown exit code ($rv) from command:" \
"git-merge-$strategy $cmt^ -- HEAD $cmt"
;;
esac
}
move_to_original_branch () {
test -z "$head_name" &&
head_name="$(cat "$dotest"/head-name)" &&
onto="$(cat "$dotest"/onto)" &&
orig_head="$(cat "$dotest"/orig-head)"
case "$head_name" in
refs/*)
message="rebase finished: $head_name onto $onto"
git update-ref -m "$message" \
$head_name $(git rev-parse HEAD) $orig_head &&
git symbolic-ref HEAD $head_name ||
die "Could not move back to $head_name"
;;
esac
}
finish_rb_merge () {
move_to_original_branch
rm -r "$dotest"
echo "All done."
}
is_interactive () {
while test $# != 0
do
case "$1" in
-i|--interactive)
interactive_rebase=explicit
break
;;
-p|--preserve-merges)
interactive_rebase=implied
;;
esac
shift
done
if [ "$interactive_rebase" = implied ]; then
GIT_EDITOR=:
export GIT_EDITOR
fi
test -n "$interactive_rebase" || test -f "$dotest"/interactive
}
run_pre_rebase_hook () {
if test -z "$OK_TO_SKIP_PRE_REBASE" &&
test -x "$GIT_DIR/hooks/pre-rebase"
then
"$GIT_DIR/hooks/pre-rebase" ${1+"$@"} || {
echo >&2 "The pre-rebase hook refused to rebase."
exit 1
}
fi
}
test -f "$GIT_DIR"/rebase-apply/applying &&
die 'It looks like git-am is in progress. Cannot rebase.'
is_interactive "$@" && exec git-rebase--interactive "$@"
if test $# -eq 0
then
test -d "$dotest" -o -d "$GIT_DIR"/rebase-apply || usage
test -d "$dotest" -o -f "$GIT_DIR"/rebase-apply/rebasing &&
die 'A rebase is in progress, try --continue, --skip or --abort.'
die "No arguments given and $GIT_DIR/rebase-apply already exists."
fi
while test $# != 0
do
case "$1" in
--no-verify)
OK_TO_SKIP_PRE_REBASE=yes
;;
--continue)
test -d "$dotest" -o -d "$GIT_DIR"/rebase-apply ||
die "No rebase in progress?"
git diff-files --quiet --ignore-submodules || {
echo "You must edit all merge conflicts and then"
echo "mark them as resolved using git add"
exit 1
}
if test -d "$dotest"
then
prev_head=$(cat "$dotest/prev_head")
end=$(cat "$dotest/end")
msgnum=$(cat "$dotest/msgnum")
onto=$(cat "$dotest/onto")
continue_merge
while test "$msgnum" -le "$end"
do
call_merge "$msgnum"
continue_merge
done
finish_rb_merge
exit
fi
head_name=$(cat "$GIT_DIR"/rebase-apply/head-name) &&
onto=$(cat "$GIT_DIR"/rebase-apply/onto) &&
orig_head=$(cat "$GIT_DIR"/rebase-apply/orig-head) &&
git am --resolved --3way --resolvemsg="$RESOLVEMSG" &&
move_to_original_branch
exit
;;
--skip)
test -d "$dotest" -o -d "$GIT_DIR"/rebase-apply ||
die "No rebase in progress?"
git reset --hard HEAD || exit $?
if test -d "$dotest"
then
git rerere clear
prev_head=$(cat "$dotest/prev_head")
end=$(cat "$dotest/end")
msgnum=$(cat "$dotest/msgnum")
msgnum=$(($msgnum + 1))
onto=$(cat "$dotest/onto")
while test "$msgnum" -le "$end"
do
call_merge "$msgnum"
continue_merge
done
finish_rb_merge
exit
fi
head_name=$(cat "$GIT_DIR"/rebase-apply/head-name) &&
onto=$(cat "$GIT_DIR"/rebase-apply/onto) &&
orig_head=$(cat "$GIT_DIR"/rebase-apply/orig-head) &&
git am -3 --skip --resolvemsg="$RESOLVEMSG" &&
move_to_original_branch
exit
;;
--abort)
test -d "$dotest" -o -d "$GIT_DIR"/rebase-apply ||
die "No rebase in progress?"
git rerere clear
if test -d "$dotest"
then
move_to_original_branch
else
dotest="$GIT_DIR"/rebase-apply
move_to_original_branch
fi
git reset --hard $(cat "$dotest/orig-head")
rm -r "$dotest"
exit
;;
--onto)
test 2 -le "$#" || usage
newbase="$2"
shift
;;
-M|-m|--m|--me|--mer|--merg|--merge)
do_merge=t
;;
-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
--strateg=*|--strategy=*|\
-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
case "$#,$1" in
*,*=*)
strategy=`expr "z$1" : 'z-[^=]*=\(.*\)'` ;;
1,*)
usage ;;
*)
strategy="$2"
shift ;;
esac
do_merge=t
;;
-v|--verbose)
verbose=t
;;
--whitespace=*)
git_am_opt="$git_am_opt $1"
;;
-C*)
git_am_opt="$git_am_opt $1"
;;
--root)
rebase_root=t
;;
-*)
usage
;;
*)
break
;;
esac
shift
done
# Make sure we do not have $GIT_DIR/rebase-apply
if test -z "$do_merge"
then
if mkdir "$GIT_DIR"/rebase-apply 2>/dev/null
then
rmdir "$GIT_DIR"/rebase-apply
else
echo >&2 '
It seems that I cannot create a rebase-apply directory, and
I wonder if you are in the middle of patch application or another
rebase. If that is not the case, please
rm -fr '"$GIT_DIR"'/rebase-apply
and run me again. I am stopping in case you still have something
valuable there.'
exit 1
fi
else
if test -d "$dotest"
then
die "previous rebase directory $dotest still exists." \
'Try git rebase (--continue | --abort | --skip)'
fi
fi
# The tree must be really really clean.
if ! git update-index --ignore-submodules --refresh; then
echo >&2 "cannot rebase: you have unstaged changes"
exit 1
fi
diff=$(git diff-index --cached --name-status -r --ignore-submodules HEAD --)
case "$diff" in
?*) echo >&2 "cannot rebase: your index contains uncommitted changes"
echo >&2 "$diff"
exit 1
;;
esac
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 "$upstream_arg" "$@"
# 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
1)
# Is it "rebase other $branchname" or "rebase other $commit"?
branch_name="$1"
switch_to="$1"
if git show-ref --verify --quiet -- "refs/heads/$1" &&
branch=$(git rev-parse -q --verify "refs/heads/$1")
then
head_name="refs/heads/$1"
elif branch=$(git rev-parse -q --verify "$1")
then
head_name="detached HEAD"
else
usage
fi
;;
*)
# Do not need to switch branches, we are already on it.
if branch_name=`git symbolic-ref -q HEAD`
then
head_name=$branch_name
branch_name=`expr "z$branch_name" : 'zrefs/heads/\(.*\)'`
else
head_name="detached HEAD"
branch_name=HEAD ;# detached
fi
branch=$(git rev-parse --verify "${branch_name}^0") || exit
;;
esac
orig_head=$branch
# 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 $onto with linear history,
# but this should be done only when upstream and onto are the same.
mb=$(git merge-base "$onto" "$branch")
if test "$upstream" = "$onto" && test "$mb" = "$onto" &&
# linear history?
! (git rev-list --parents "$onto".."$branch" | grep " .* ") > /dev/null
then
# Lazily switch to the target branch if needed...
test -z "$switch_to" || git checkout "$switch_to"
echo >&2 "Current branch $branch_name is up to date."
exit 0
fi
if test -n "$verbose"
then
echo "Changes from $mb to $onto:"
# We want color (if set), but no pager
GIT_PAGER='' git diff --stat --summary "$mb" "$onto"
fi
# Detach HEAD and reset the tree
echo "First, rewinding head to replay your work on top of it..."
git checkout -q "$onto^0" || die "could not detach HEAD"
git update-ref ORIG_HEAD $branch
# If the $onto is a proper descendant of the tip of the branch, then
# we just fast forwarded.
if test "$mb" = "$branch"
then
echo >&2 "Fast-forwarded $branch_name to $onto_name."
move_to_original_branch
exit 0
fi
if test -n "$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 \
$root_flag "$revisions" |
git am $git_am_opt --rebasing --resolvemsg="$RESOLVEMSG" &&
move_to_original_branch
ret=$?
test 0 != $ret -a -d "$GIT_DIR"/rebase-apply &&
echo $head_name > "$GIT_DIR"/rebase-apply/head-name &&
echo $onto > "$GIT_DIR"/rebase-apply/onto &&
echo $orig_head > "$GIT_DIR"/rebase-apply/orig-head
exit $ret
fi
# start doing a rebase with git-merge
# this is rename-aware if the recursive (default) strategy is used
mkdir -p "$dotest"
echo "$onto" > "$dotest/onto"
echo "$onto_name" > "$dotest/onto_name"
prev_head=$orig_head
echo "$prev_head" > "$dotest/prev_head"
echo "$orig_head" > "$dotest/orig-head"
echo "$head_name" > "$dotest/head-name"
msgnum=0
for cmt in `git rev-list --reverse --no-merges "$revisions"`
do
msgnum=$(($msgnum + 1))
echo "$cmt" > "$dotest/cmt.$msgnum"
done
echo 1 >"$dotest/msgnum"
echo $msgnum >"$dotest/end"
end=$msgnum
msgnum=1
while test "$msgnum" -le "$end"
do
call_merge "$msgnum"
continue_merge
done
finish_rb_merge