rebase: introduce the --rebase-merges option

[git] / git-rebase--interactive.sh

# This shell script fragment is sourced by git-rebase to implement
# its interactive mode.  "git rebase --interactive" makes it easy
# to fix up commits in the middle of a series and rearrange commits.
#
# Copyright (c) 2006 Johannes E. Schindelin
#
# The original idea comes from Eric W. Biederman, in
# https://public-inbox.org/git/m1odwkyuf5.fsf_-_@ebiederm.dsl.xmission.com/
#
# The file containing rebase commands, comments, and empty lines.
# This file is created by "git rebase -i" then edited by the user.  As
# the lines are processed, they are removed from the front of this
# file and written to the tail of $done.
todo="$state_dir"/git-rebase-todo

# The rebase command lines that have already been processed.  A line
# is moved here when it is first handled, before any associated user
# actions.
done="$state_dir"/done

# The commit message that is planned to be used for any changes that
# need to be committed following a user interaction.
msg="$state_dir"/message

# The file into which is accumulated the suggested commit message for
# squash/fixup commands.  When the first of a series of squash/fixups
# is seen, the file is created and the commit message from the
# previous commit and from the first squash/fixup commit are written
# to it.  The commit message for each subsequent squash/fixup commit
# is appended to the file as it is processed.
#
# The first line of the file is of the form
#     # This is a combination of $count commits.
# where $count is the number of commits whose messages have been
# written to the file so far (including the initial "pick" commit).
# Each time that a commit message is processed, this line is read and
# updated.  It is deleted just before the combined commit is made.
squash_msg="$state_dir"/message-squash

# If the current series of squash/fixups has not yet included a squash
# command, then this file exists and holds the commit message of the
# original "pick" commit.  (If the series ends without a "squash"
# command, then this can be used as the commit message of the combined
# commit without opening the editor.)
fixup_msg="$state_dir"/message-fixup

# $rewritten is the name of a directory containing files for each
# commit that is reachable by at least one merge base of $head and
# $upstream. They are not necessarily rewritten, but their children
# might be.  This ensures that commits on merged, but otherwise
# unrelated side branches are left alone. (Think "X" in the man page's
# example.)
rewritten="$state_dir"/rewritten

dropped="$state_dir"/dropped

end="$state_dir"/end
msgnum="$state_dir"/msgnum

# A script to set the GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
# GIT_AUTHOR_DATE that will be used for the commit that is currently
# being rebased.
author_script="$state_dir"/author-script

# When an "edit" rebase command is being processed, the SHA1 of the
# commit to be edited is recorded in this file.  When "git rebase
# --continue" is executed, if there are any staged changes then they
# will be amended to the HEAD commit, but only provided the HEAD
# commit is still the commit to be edited.  When any other rebase
# command is processed, this file is deleted.
amend="$state_dir"/amend

# For the post-rewrite hook, we make a list of rewritten commits and
# their new sha1s.  The rewritten-pending list keeps the sha1s of
# commits that have been processed, but not committed yet,
# e.g. because they are waiting for a 'squash' command.
rewritten_list="$state_dir"/rewritten-list
rewritten_pending="$state_dir"/rewritten-pending

# Work around Git for Windows' Bash whose "read" does not strip CRLF
# and leaves CR at the end instead.
cr=$(printf "\015")

strategy_args=${strategy:+--strategy=$strategy}
test -n "$strategy_opts" &&
eval '
        for strategy_opt in '"$strategy_opts"'
        do
                strategy_args="$strategy_args -X$(git rev-parse --sq-quote "${strategy_opt#--}")"
        done
'

GIT_CHERRY_PICK_HELP="$resolvemsg"
export GIT_CHERRY_PICK_HELP

comment_char=$(git config --get core.commentchar 2>/dev/null)
case "$comment_char" in
'' | auto)
        comment_char="#"
        ;;
?)
        ;;
*)
        comment_char=$(echo "$comment_char" | cut -c1)
        ;;
esac

warn () {
        printf '%s\n' "$*" >&2
}

# Output the commit message for the specified commit.
commit_message () {
        git cat-file commit "$1" | sed "1,/^$/d"
}

orig_reflog_action="$GIT_REFLOG_ACTION"

comment_for_reflog () {
        case "$orig_reflog_action" in
        ''|rebase*)
                GIT_REFLOG_ACTION="rebase -i ($1)"
                export GIT_REFLOG_ACTION
                ;;
        esac
}

last_count=
mark_action_done () {
        sed -e 1q < "$todo" >> "$done"
        sed -e 1d < "$todo" >> "$todo".new
        mv -f "$todo".new "$todo"
        new_count=$(( $(git stripspace --strip-comments <"$done" | wc -l) ))
        echo $new_count >"$msgnum"
        total=$(($new_count + $(git stripspace --strip-comments <"$todo" | wc -l)))
        echo $total >"$end"
        if test "$last_count" != "$new_count"
        then
                last_count=$new_count
                eval_gettext "Rebasing (\$new_count/\$total)"; printf "\r"
                test -z "$verbose" || echo
        fi
}

# Put the last action marked done at the beginning of the todo list
# again. If there has not been an action marked done yet, leave the list of
# items on the todo list unchanged.
reschedule_last_action () {
        tail -n 1 "$done" | cat - "$todo" >"$todo".new
        sed -e \$d <"$done" >"$done".new
        mv -f "$todo".new "$todo"
        mv -f "$done".new "$done"
}

append_todo_help () {
        gettext "
Commands:
p, pick <commit> = use commit
r, reword <commit> = use commit, but edit the commit message
e, edit <commit> = use commit, but stop for amending
s, squash <commit> = use commit, but meld into previous commit
f, fixup <commit> = like \"squash\", but discard this commit's log message
x, exec <commit> = run command (the rest of the line) using shell
d, drop <commit> = remove commit
l, label <label> = label current HEAD with a name
t, reset <label> = reset HEAD to a label
m, merge [-C <commit> | -c <commit>] <label> [# <oneline>]
.       create a merge commit using the original merge commit's
.       message (or the oneline, if no original merge commit was
.       specified). Use -c <commit> to reword the commit message.

These lines can be re-ordered; they are executed from top to bottom.
" | git stripspace --comment-lines >>"$todo"

        if test $(get_missing_commit_check_level) = error
        then
                gettext "
Do not remove any line. Use 'drop' explicitly to remove a commit.
" | git stripspace --comment-lines >>"$todo"
        else
                gettext "
If you remove a line here THAT COMMIT WILL BE LOST.
" | git stripspace --comment-lines >>"$todo"
        fi
}

make_patch () {
        sha1_and_parents="$(git rev-list --parents -1 "$1")"
        case "$sha1_and_parents" in
        ?*' '?*' '?*)
                git diff --cc $sha1_and_parents
                ;;
        ?*' '?*)
                git diff-tree -p "$1^!"
                ;;
        *)
                echo "Root commit"
                ;;
        esac > "$state_dir"/patch
        test -f "$msg" ||
                commit_message "$1" > "$msg"
        test -f "$author_script" ||
                get_author_ident_from_commit "$1" > "$author_script"
}

die_with_patch () {
        echo "$1" > "$state_dir"/stopped-sha
        git update-ref REBASE_HEAD "$1"
        make_patch "$1"
        die "$2"
}

exit_with_patch () {
        echo "$1" > "$state_dir"/stopped-sha
        git update-ref REBASE_HEAD "$1"
        make_patch $1
        git rev-parse --verify HEAD > "$amend"
        gpg_sign_opt_quoted=${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")}
        warn "$(eval_gettext "\
You can amend the commit now, with

        git commit --amend \$gpg_sign_opt_quoted

Once you are satisfied with your changes, run

        git rebase --continue")"
        warn
        exit $2
}

die_abort () {
        apply_autostash
        rm -rf "$state_dir"
        die "$1"
}

has_action () {
        test -n "$(git stripspace --strip-comments <"$1")"
}

is_empty_commit() {
        tree=$(git rev-parse -q --verify "$1"^{tree} 2>/dev/null) || {
                sha1=$1
                die "$(eval_gettext "\$sha1: not a commit that can be picked")"
        }
        ptree=$(git rev-parse -q --verify "$1"^^{tree} 2>/dev/null) ||
                ptree=4b825dc642cb6eb9a060e54bf8d69288fbee4904
        test "$tree" = "$ptree"
}

is_merge_commit()
{
        git rev-parse --verify --quiet "$1"^2 >/dev/null 2>&1
}

# Run command with GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
# GIT_AUTHOR_DATE exported from the current environment.
do_with_author () {
        (
                export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE
                "$@"
        )
}

git_sequence_editor () {
        if test -z "$GIT_SEQUENCE_EDITOR"
        then
                GIT_SEQUENCE_EDITOR="$(git config sequence.editor)"
                if [ -z "$GIT_SEQUENCE_EDITOR" ]
                then
                        GIT_SEQUENCE_EDITOR="$(git var GIT_EDITOR)" || return $?
                fi
        fi

        eval "$GIT_SEQUENCE_EDITOR" '"$@"'
}

pick_one () {
        ff=--ff

        case "$1" in -n) sha1=$2; ff= ;; *) sha1=$1 ;; esac
        case "$force_rebase" in '') ;; ?*) ff= ;; esac
        output git rev-parse --verify $sha1 || die "$(eval_gettext "Invalid commit name: \$sha1")"

        if is_empty_commit "$sha1"
        then
                empty_args="--allow-empty"
        fi

        test -d "$rewritten" &&
                pick_one_preserving_merges "$@" && return
        output eval git cherry-pick $allow_rerere_autoupdate $allow_empty_message \
                        ${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
                        $signoff "$strategy_args" $empty_args $ff "$@"

        # If cherry-pick dies it leaves the to-be-picked commit unrecorded. Reschedule
        # previous task so this commit is not lost.
        ret=$?
        case "$ret" in [01]) ;; *) reschedule_last_action ;; esac
        return $ret
}

pick_one_preserving_merges () {
        fast_forward=t
        case "$1" in
        -n)
                fast_forward=f
                sha1=$2
                ;;
        *)
                sha1=$1
                ;;
        esac
        sha1=$(git rev-parse $sha1)

        if test -f "$state_dir"/current-commit && test "$fast_forward" = t
        then
                while read current_commit
                do
                        git rev-parse HEAD > "$rewritten"/$current_commit
                done <"$state_dir"/current-commit
                rm "$state_dir"/current-commit ||
                        die "$(gettext "Cannot write current commit's replacement sha1")"
        fi

        echo $sha1 >> "$state_dir"/current-commit

        # rewrite parents; if none were rewritten, we can fast-forward.
        new_parents=
        pend=" $(git rev-list --parents -1 $sha1 | cut -d' ' -s -f2-)"
        if test "$pend" = " "
        then
                pend=" root"
        fi
        while [ "$pend" != "" ]
        do
                p=$(expr "$pend" : ' \([^ ]*\)')
                pend="${pend# $p}"

                if test -f "$rewritten"/$p
                then
                        new_p=$(cat "$rewritten"/$p)

                        # If the todo reordered commits, and our parent is marked for
                        # rewriting, but hasn't been gotten to yet, assume the user meant to
                        # drop it on top of the current HEAD
                        if test -z "$new_p"
                        then
                                new_p=$(git rev-parse HEAD)
                        fi

                        test $p != $new_p && fast_forward=f
                        case "$new_parents" in
                        *$new_p*)
                                ;; # do nothing; that parent is already there
                        *)
                                new_parents="$new_parents $new_p"
                                ;;
                        esac
                else
                        if test -f "$dropped"/$p
                        then
                                fast_forward=f
                                replacement="$(cat "$dropped"/$p)"
                                test -z "$replacement" && replacement=root
                                pend=" $replacement$pend"
                        else
                                new_parents="$new_parents $p"
                        fi
                fi
        done
        case $fast_forward in
        t)
                output warn "$(eval_gettext "Fast-forward to \$sha1")"
                output git reset --hard $sha1 ||
                        die "$(eval_gettext "Cannot fast-forward to \$sha1")"
                ;;
        f)
                first_parent=$(expr "$new_parents" : ' \([^ ]*\)')

                if [ "$1" != "-n" ]
                then
                        # detach HEAD to current parent
                        output git checkout $first_parent 2> /dev/null ||
                                die "$(eval_gettext "Cannot move HEAD to \$first_parent")"
                fi

                case "$new_parents" in
                ' '*' '*)
                        test "a$1" = a-n && die "$(eval_gettext "Refusing to squash a merge: \$sha1")"

                        # redo merge
                        author_script_content=$(get_author_ident_from_commit $sha1)
                        eval "$author_script_content"
                        msg_content="$(commit_message $sha1)"
                        # No point in merging the first parent, that's HEAD
                        new_parents=${new_parents# $first_parent}
                        merge_args="--no-log --no-ff"
                        if ! do_with_author output eval \
                                git merge ${gpg_sign_opt:+$(git rev-parse \
                                        --sq-quote "$gpg_sign_opt")} \
                                $allow_rerere_autoupdate "$merge_args" \
                                "$strategy_args" \
                                -m "$(git rev-parse --sq-quote "$msg_content")" \
                                "$new_parents"
                        then
                                printf "%s\n" "$msg_content" > "$GIT_DIR"/MERGE_MSG
                                die_with_patch $sha1 "$(eval_gettext "Error redoing merge \$sha1")"
                        fi
                        echo "$sha1 $(git rev-parse HEAD^0)" >> "$rewritten_list"
                        ;;
                *)
                        output eval git cherry-pick $allow_rerere_autoupdate \
                                $allow_empty_message \
                                ${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")} \
                                "$strategy_args" "$@" ||
                                die_with_patch $sha1 "$(eval_gettext "Could not pick \$sha1")"
                        ;;
                esac
                ;;
        esac
}

this_nth_commit_message () {
        n=$1
        eval_gettext "This is the commit message #\${n}:"
}

skip_nth_commit_message () {
        n=$1
        eval_gettext "The commit message #\${n} will be skipped:"
}

update_squash_messages () {
        if test -f "$squash_msg"; then
                mv "$squash_msg" "$squash_msg".bak || exit
                count=$(($(sed -n \
                        -e "1s/^$comment_char[^0-9]*\([0-9][0-9]*\).*/\1/p" \
                        -e "q" < "$squash_msg".bak)+1))
                {
                        printf '%s\n' "$comment_char $(eval_ngettext \
                                "This is a combination of \$count commit." \
                                "This is a combination of \$count commits." \
                                $count)"
                        sed -e 1d -e '2,/^./{
                                /^$/d
                        }' <"$squash_msg".bak
                } >"$squash_msg"
        else
                commit_message HEAD >"$fixup_msg" ||
                die "$(eval_gettext "Cannot write \$fixup_msg")"
                count=2
                {
                        printf '%s\n' "$comment_char $(gettext "This is a combination of 2 commits.")"
                        printf '%s\n' "$comment_char $(gettext "This is the 1st commit message:")"
                        echo
                        cat "$fixup_msg"
                } >"$squash_msg"
        fi
        case $1 in
        squash)
                rm -f "$fixup_msg"
                echo
                printf '%s\n' "$comment_char $(this_nth_commit_message $count)"
                echo
                commit_message $2
                ;;
        fixup)
                echo
                printf '%s\n' "$comment_char $(skip_nth_commit_message $count)"
                echo
                # Change the space after the comment character to TAB:
                commit_message $2 | git stripspace --comment-lines | sed -e 's/ /       /'
                ;;
        esac >>"$squash_msg"
}

peek_next_command () {
        git stripspace --strip-comments <"$todo" | sed -n -e 's/ .*//p' -e q
}

# A squash/fixup has failed.  Prepare the long version of the squash
# commit message, then die_with_patch.  This code path requires the
# user to edit the combined commit message for all commits that have
# been squashed/fixedup so far.  So also erase the old squash
# messages, effectively causing the combined commit to be used as the
# new basis for any further squash/fixups.  Args: sha1 rest
die_failed_squash() {
        sha1=$1
        rest=$2
        mv "$squash_msg" "$msg" || exit
        rm -f "$fixup_msg"
        cp "$msg" "$GIT_DIR"/MERGE_MSG || exit
        warn
        warn "$(eval_gettext "Could not apply \$sha1... \$rest")"
        die_with_patch $sha1 ""
}

flush_rewritten_pending() {
        test -s "$rewritten_pending" || return
        newsha1="$(git rev-parse HEAD^0)"
        sed "s/$/ $newsha1/" < "$rewritten_pending" >> "$rewritten_list"
        rm -f "$rewritten_pending"
}

record_in_rewritten() {
        oldsha1="$(git rev-parse $1)"
        echo "$oldsha1" >> "$rewritten_pending"

        case "$(peek_next_command)" in
        squash|s|fixup|f)
                ;;
        *)
                flush_rewritten_pending
                ;;
        esac
}

do_pick () {
        sha1=$1
        rest=$2
        if test "$(git rev-parse HEAD)" = "$squash_onto"
        then
                # Set the correct commit message and author info on the
                # sentinel root before cherry-picking the original changes
                # without committing (-n).  Finally, update the sentinel again
                # to include these changes.  If the cherry-pick results in a
                # conflict, this means our behaviour is similar to a standard
                # failed cherry-pick during rebase, with a dirty index to
                # resolve before manually running git commit --amend then git
                # rebase --continue.
                git commit --allow-empty --allow-empty-message --amend \
                           --no-post-rewrite -n -q -C $sha1 $signoff &&
                        pick_one -n $sha1 &&
                        git commit --allow-empty --allow-empty-message \
                                   --amend --no-post-rewrite -n -q -C $sha1 $signoff \
                                   ${gpg_sign_opt:+"$gpg_sign_opt"} ||
                                   die_with_patch $sha1 "$(eval_gettext "Could not apply \$sha1... \$rest")"
        else
                pick_one $sha1 ||
                        die_with_patch $sha1 "$(eval_gettext "Could not apply \$sha1... \$rest")"
        fi
}

do_next () {
        rm -f "$msg" "$author_script" "$amend" "$state_dir"/stopped-sha || exit
        read -r command sha1 rest < "$todo"
        case "$command" in
        "$comment_char"*|''|noop|drop|d)
                mark_action_done
                ;;
        "$cr")
                # Work around CR left by "read" (e.g. with Git for Windows' Bash).
                mark_action_done
                ;;
        pick|p)
                comment_for_reflog pick

                mark_action_done
                do_pick $sha1 "$rest"
                record_in_rewritten $sha1
                ;;
        reword|r)
                comment_for_reflog reword

                mark_action_done
                do_pick $sha1 "$rest"
                git commit --amend --no-post-rewrite ${gpg_sign_opt:+"$gpg_sign_opt"} \
                        $allow_empty_message || {
                        warn "$(eval_gettext "\
Could not amend commit after successfully picking \$sha1... \$rest
This is most likely due to an empty commit message, or the pre-commit hook
failed. If the pre-commit hook failed, you may need to resolve the issue before
you are able to reword the commit.")"
                        exit_with_patch $sha1 1
                }
                record_in_rewritten $sha1
                ;;
        edit|e)
                comment_for_reflog edit

                mark_action_done
                do_pick $sha1 "$rest"
                sha1_abbrev=$(git rev-parse --short $sha1)
                warn "$(eval_gettext "Stopped at \$sha1_abbrev... \$rest")"
                exit_with_patch $sha1 0
                ;;
        squash|s|fixup|f)
                case "$command" in
                squash|s)
                        squash_style=squash
                        ;;
                fixup|f)
                        squash_style=fixup
                        ;;
                esac
                comment_for_reflog $squash_style

                test -f "$done" && has_action "$done" ||
                        die "$(eval_gettext "Cannot '\$squash_style' without a previous commit")"

                mark_action_done
                update_squash_messages $squash_style $sha1
                author_script_content=$(get_author_ident_from_commit HEAD)
                echo "$author_script_content" > "$author_script"
                eval "$author_script_content"
                if ! pick_one -n $sha1
                then
                        git rev-parse --verify HEAD >"$amend"
                        die_failed_squash $sha1 "$rest"
                fi
                case "$(peek_next_command)" in
                squash|s|fixup|f)
                        # This is an intermediate commit; its message will only be
                        # used in case of trouble.  So use the long version:
                        do_with_author output git commit --amend --no-verify -F "$squash_msg" \
                                ${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
                                die_failed_squash $sha1 "$rest"
                        ;;
                *)
                        # This is the final command of this squash/fixup group
                        if test -f "$fixup_msg"
                        then
                                do_with_author git commit --amend --no-verify -F "$fixup_msg" \
                                        ${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
                                        die_failed_squash $sha1 "$rest"
                        else
                                cp "$squash_msg" "$GIT_DIR"/SQUASH_MSG || exit
                                rm -f "$GIT_DIR"/MERGE_MSG
                                do_with_author git commit --amend --no-verify -F "$GIT_DIR"/SQUASH_MSG -e \
                                        ${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
                                        die_failed_squash $sha1 "$rest"
                        fi
                        rm -f "$squash_msg" "$fixup_msg"
                        ;;
                esac
                record_in_rewritten $sha1
                ;;
        x|"exec")
                read -r command rest < "$todo"
                mark_action_done
                eval_gettextln "Executing: \$rest"
                "${SHELL:-@SHELL_PATH@}" -c "$rest" # Actual execution
                status=$?
                # Run in subshell because require_clean_work_tree can die.
                dirty=f
                (require_clean_work_tree "rebase" 2>/dev/null) || dirty=t
                if test "$status" -ne 0
                then
                        warn "$(eval_gettext "Execution failed: \$rest")"
                        test "$dirty" = f ||
                                warn "$(gettext "and made changes to the index and/or the working tree")"

                        warn "$(gettext "\
You can fix the problem, and then run

        git rebase --continue")"
                        warn
                        if test $status -eq 127         # command not found
                        then
                                status=1
                        fi
                        exit "$status"
                elif test "$dirty" = t
                then
                        # TRANSLATORS: after these lines is a command to be issued by the user
                        warn "$(eval_gettext "\
Execution succeeded: \$rest
but left changes to the index and/or the working tree
Commit or stash your changes, and then run

        git rebase --continue")"
                        warn
                        exit 1
                fi
                ;;
        *)
                warn "$(eval_gettext "Unknown command: \$command \$sha1 \$rest")"
                fixtodo="$(gettext "Please fix this using 'git rebase --edit-todo'.")"
                if git rev-parse --verify -q "$sha1" >/dev/null
                then
                        die_with_patch $sha1 "$fixtodo"
                else
                        die "$fixtodo"
                fi
                ;;
        esac
        test -s "$todo" && return

        comment_for_reflog finish &&
        newhead=$(git rev-parse HEAD) &&
        case $head_name in
        refs/*)
                message="$GIT_REFLOG_ACTION: $head_name onto $onto" &&
                git update-ref -m "$message" $head_name $newhead $orig_head &&
                git symbolic-ref \
                  -m "$GIT_REFLOG_ACTION: returning to $head_name" \
                  HEAD $head_name
                ;;
        esac && {
                test ! -f "$state_dir"/verbose ||
                        git diff-tree --stat $orig_head..HEAD
        } &&
        {
                test -s "$rewritten_list" &&
                git notes copy --for-rewrite=rebase < "$rewritten_list" ||
                true # we don't care if this copying failed
        } &&
        hook="$(git rev-parse --git-path hooks/post-rewrite)"
        if test -x "$hook" && test -s "$rewritten_list"; then
                "$hook" rebase < "$rewritten_list"
                true # we don't care if this hook failed
        fi &&
                warn "$(eval_gettext "Successfully rebased and updated \$head_name.")"

        return 1 # not failure; just to break the do_rest loop
}

# can only return 0, when the infinite loop breaks
do_rest () {
        while :
        do
                do_next || break
        done
}

expand_todo_ids() {
        git rebase--helper --expand-ids
}

collapse_todo_ids() {
        git rebase--helper --shorten-ids
}

# Switch to the branch in $into and notify it in the reflog
checkout_onto () {
        GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $onto_name"
        output git checkout $onto || die_abort "$(gettext "could not detach HEAD")"
        git update-ref ORIG_HEAD $orig_head
}

get_missing_commit_check_level () {
        check_level=$(git config --get rebase.missingCommitsCheck)
        check_level=${check_level:-ignore}
        # Don't be case sensitive
        printf '%s' "$check_level" | tr 'A-Z' 'a-z'
}

# Initiate an action. If the cannot be any
# further action it  may exec a command
# or exit and not return.
#
# TODO: Consider a cleaner return model so it
# never exits and always return 0 if process
# is complete.
#
# Parameter 1 is the action to initiate.
#
# Returns 0 if the action was able to complete
# and if 1 if further processing is required.
initiate_action () {
        case "$1" in
        continue)
                if test ! -d "$rewritten"
                then
                        exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
                                --continue
                fi
                # do we have anything to commit?
                if git diff-index --cached --quiet HEAD --
                then
                        # Nothing to commit -- skip this commit

                        test ! -f "$GIT_DIR"/CHERRY_PICK_HEAD ||
                        rm "$GIT_DIR"/CHERRY_PICK_HEAD ||
                        die "$(gettext "Could not remove CHERRY_PICK_HEAD")"
                else
                        if ! test -f "$author_script"
                        then
                                gpg_sign_opt_quoted=${gpg_sign_opt:+$(git rev-parse --sq-quote "$gpg_sign_opt")}
                                die "$(eval_gettext "\
You have staged changes in your working tree.
If these changes are meant to be
squashed into the previous commit, run:

  git commit --amend \$gpg_sign_opt_quoted

If they are meant to go into a new commit, run:

  git commit \$gpg_sign_opt_quoted

In both cases, once you're done, continue with:

  git rebase --continue
")"
                        fi
                        . "$author_script" ||
                                die "$(gettext "Error trying to find the author identity to amend commit")"
                        if test -f "$amend"
                        then
                                current_head=$(git rev-parse --verify HEAD)
                                test "$current_head" = $(cat "$amend") ||
                                die "$(gettext "\
You have uncommitted changes in your working tree. Please commit them
first and then run 'git rebase --continue' again.")"
                                do_with_author git commit --amend --no-verify -F "$msg" -e \
                                        ${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
                                        die "$(gettext "Could not commit staged changes.")"
                        else
                                do_with_author git commit --no-verify -F "$msg" -e \
                                        ${gpg_sign_opt:+"$gpg_sign_opt"} $allow_empty_message ||
                                        die "$(gettext "Could not commit staged changes.")"
                        fi
                fi

                if test -r "$state_dir"/stopped-sha
                then
                        record_in_rewritten "$(cat "$state_dir"/stopped-sha)"
                fi

                require_clean_work_tree "rebase"
                do_rest
                return 0
                ;;
        skip)
                git rerere clear

                if test ! -d "$rewritten"
                then
                        exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
                                --continue
                fi
                do_rest
                return 0
                ;;
        edit-todo)
                git stripspace --strip-comments <"$todo" >"$todo".new
                mv -f "$todo".new "$todo"
                collapse_todo_ids
                append_todo_help
                gettext "
You are editing the todo file of an ongoing interactive rebase.
To continue rebase after editing, run:
    git rebase --continue

" | git stripspace --comment-lines >>"$todo"

                git_sequence_editor "$todo" ||
                        die "$(gettext "Could not execute editor")"
                expand_todo_ids

                exit
                ;;
        show-current-patch)
                exec git show REBASE_HEAD --
                ;;
        *)
                return 1 # continue
                ;;
        esac
}

setup_reflog_action () {
        comment_for_reflog start

        if test ! -z "$switch_to"
        then
                GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION: checkout $switch_to"
                output git checkout "$switch_to" -- ||
                        die "$(eval_gettext "Could not checkout \$switch_to")"

                comment_for_reflog start
        fi
}

init_basic_state () {
        orig_head=$(git rev-parse --verify HEAD) || die "$(gettext "No HEAD?")"
        mkdir -p "$state_dir" || die "$(eval_gettext "Could not create temporary \$state_dir")"
        rm -f "$(git rev-parse --git-path REBASE_HEAD)"

        : > "$state_dir"/interactive || die "$(gettext "Could not mark as interactive")"
        write_basic_state
}

init_revisions_and_shortrevisions () {
        shorthead=$(git rev-parse --short $orig_head)
        shortonto=$(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...$orig_head
                shortrevisions=$shortupstream..$shorthead
        else
                revisions=$onto...$orig_head
                shortrevisions=$shorthead
        fi
}

complete_action() {
        test -s "$todo" || echo noop >> "$todo"
        test -z "$autosquash" || git rebase--helper --rearrange-squash || exit
        test -n "$cmd" && git rebase--helper --add-exec-commands "$cmd"

        todocount=$(git stripspace --strip-comments <"$todo" | wc -l)
        todocount=${todocount##* }

cat >>"$todo" <<EOF

$comment_char $(eval_ngettext \
        "Rebase \$shortrevisions onto \$shortonto (\$todocount command)" \
        "Rebase \$shortrevisions onto \$shortonto (\$todocount commands)" \
        "$todocount")
EOF
        append_todo_help
        gettext "
        However, if you remove everything, the rebase will be aborted.

        " | git stripspace --comment-lines >>"$todo"

        if test -z "$keep_empty"
        then
                printf '%s\n' "$comment_char $(gettext "Note that empty commits are commented out")" >>"$todo"
        fi


        has_action "$todo" ||
                return 2

        cp "$todo" "$todo".backup
        collapse_todo_ids
        git_sequence_editor "$todo" ||
                die_abort "$(gettext "Could not execute editor")"

        has_action "$todo" ||
                return 2

        git rebase--helper --check-todo-list || {
                ret=$?
                checkout_onto
                exit $ret
        }

        expand_todo_ids

        test -d "$rewritten" || test -n "$force_rebase" ||
        onto="$(git rebase--helper --skip-unnecessary-picks)" ||
        die "Could not skip unnecessary pick commands"

        checkout_onto
        if test -z "$rebase_root" && test ! -d "$rewritten"
        then
                require_clean_work_tree "rebase"
                exec git rebase--helper ${force_rebase:+--no-ff} $allow_empty_message \
                        --continue
        fi
        do_rest
}

git_rebase__interactive () {
        initiate_action "$action"
        ret=$?
        if test $ret = 0; then
                return 0
        fi

        setup_reflog_action
        init_basic_state

        init_revisions_and_shortrevisions

        git rebase--helper --make-script ${keep_empty:+--keep-empty} \
                ${rebase_merges:+--rebase-merges} \
                $revisions ${restrict_revision+^$restrict_revision} >"$todo" ||
        die "$(gettext "Could not generate todo list")"

        complete_action
}

git_rebase__interactive__preserve_merges () {
        initiate_action "$action"
        ret=$?
        if test $ret = 0; then
                return 0
        fi

        setup_reflog_action
        init_basic_state

        if test -z "$rebase_root"
        then
                mkdir "$rewritten" &&
                for c in $(git merge-base --all $orig_head $upstream)
                do
                        echo $onto > "$rewritten"/$c ||
                                die "$(gettext "Could not init rewritten commits")"
                done
        else
                mkdir "$rewritten" &&
                echo $onto > "$rewritten"/root ||
                        die "$(gettext "Could not init rewritten commits")"
        fi

        init_revisions_and_shortrevisions

        format=$(git config --get rebase.instructionFormat)
        # the 'rev-list .. | sed' requires %m to parse; the instruction requires %H to parse
        git rev-list --format="%m%H ${format:-%s}" \
                --reverse --left-right --topo-order \
                $revisions ${restrict_revision+^$restrict_revision} | \
                sed -n "s/^>//p" |
        while read -r sha1 rest
        do
                if test -z "$keep_empty" && is_empty_commit $sha1 && ! is_merge_commit $sha1
                then
                        comment_out="$comment_char "
                else
                        comment_out=
                fi

                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"/$p
                                then
                                        preserve=f
                                fi
                        done
                else
                        preserve=f
                fi
                if test f = "$preserve"
                then
                        touch "$rewritten"/$sha1
                        printf '%s\n' "${comment_out}pick $sha1 $rest" >>"$todo"
                fi
        done

        # Watch for commits that been dropped by --cherry-pick
        mkdir "$dropped"
        # Save all non-cherry-picked changes
        git rev-list $revisions --left-right --cherry-pick | \
                sed -n "s/^>//p" > "$state_dir"/not-cherry-picks
        # Now all commits and note which ones are missing in
        # not-cherry-picks and hence being dropped
        git rev-list $revisions |
        while read rev
        do
                if test -f "$rewritten"/$rev &&
                   ! sane_grep "$rev" "$state_dir"/not-cherry-picks >/dev/null
                then
                        # Use -f2 because if rev-list is telling us this commit is
                        # 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 $rev | cut -d' ' -s -f2 > "$dropped"/$rev
                        sha1=$(git rev-list -1 $rev)
                        sane_grep -v "^[a-z][a-z]* $sha1" <"$todo" > "${todo}2" ; mv "${todo}2" "$todo"
                        rm "$rewritten"/$rev
                fi
        done

        complete_action
}