git_mkstemp_mode, xmkstemp_mode: variants of gitmkstemps with mode argument.
[gitweb.git] / git-rebase--interactive.sh
index 1ceb57ae8302dc3f0673779cf60f70df5c26a64d..3e4fd1456f1ebb4aabb61de6d7f13f820ae2abdc 100755 (executable)
@@ -27,23 +27,82 @@ 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)
+autosquash         move commits that begin with squash!/fixup! under -i
 "
 
 . git-sh-setup
 require_work_tree
 
 DOTEST="$GIT_DIR/rebase-merge"
+
+# 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 $DONE.
 TODO="$DOTEST"/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="$DOTEST"/done
+
+# The commit message that is planned to be used for any changes that
+# need to be committed following a user interaction.
 MSG="$DOTEST"/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 $COUNT is the number of commits whose messages have been
+# written to the file so far (including the initial "pick" commit).
+# Each time that a commit message is processed, this line is read and
+# updated.  It is deleted just before the combined commit is made.
 SQUASH_MSG="$DOTEST"/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="$DOTEST"/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
+# $UPSTREAM. They are not necessarily rewritten, but their children
+# might be.  This ensures that commits on merged, but otherwise
+# unrelated side branches are left alone. (Think "X" in the man page's
+# example.)
 REWRITTEN="$DOTEST"/rewritten
+
 DROPPED="$DOTEST"/dropped
+
+# A script to set the GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
+# GIT_AUTHOR_DATE that will be used for the commit that is currently
+# being rebased.
+AUTHOR_SCRIPT="$DOTEST"/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="$DOTEST"/amend
+
 PRESERVE_MERGES=
 STRATEGY=
 ONTO=
 VERBOSE=
 OK_TO_SKIP_PRE_REBASE=
+REBASE_ROOT=
+AUTOSQUASH=
 
 GIT_CHERRY_PICK_HELP="  After resolving the conflicts,
 mark the corrected paths with 'git add <paths>', and
@@ -68,6 +127,11 @@ output () {
        esac
 }
 
+# Output the commit message for the specified commit.
+commit_message () {
+       git cat-file commit "$1" | sed "1,/^$/d"
+}
+
 run_pre_rebase_hook () {
        if test -z "$OK_TO_SKIP_PRE_REBASE" &&
           test -x "$GIT_DIR/hooks/pre-rebase"
@@ -104,8 +168,8 @@ mark_action_done () {
        sed -e 1q < "$TODO" >> "$DONE"
        sed -e 1d < "$TODO" >> "$TODO".new
        mv -f "$TODO".new "$TODO"
-       count=$(grep -c '^[^#]' < "$DONE")
-       total=$(($count+$(grep -c '^[^#]' < "$TODO")))
+       count=$(sane_grep -c '^[^#]' < "$DONE")
+       total=$(($count+$(sane_grep -c '^[^#]' < "$TODO")))
        if test "$last_count" != "$count"
        then
                last_count=$count
@@ -127,10 +191,10 @@ make_patch () {
                echo "Root commit"
                ;;
        esac > "$DOTEST"/patch
-       test -f "$DOTEST"/message ||
-               git cat-file commit "$1" | sed "1,/^$/d" > "$DOTEST"/message
-       test -f "$DOTEST"/author-script ||
-               get_author_ident_from_commit "$1" > "$DOTEST"/author-script
+       test -f "$MSG" ||
+               commit_message "$1" > "$MSG"
+       test -f "$AUTHOR_SCRIPT" ||
+               get_author_ident_from_commit "$1" > "$AUTHOR_SCRIPT"
 }
 
 die_with_patch () {
@@ -145,7 +209,16 @@ die_abort () {
 }
 
 has_action () {
-       grep '^[^#]' "$1" >/dev/null
+       sane_grep '^[^#]' "$1" >/dev/null
+}
+
+# Run command with GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL, and
+# GIT_AUTHOR_DATE exported from the current environment.
+do_with_author () {
+       (
+               export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE
+               "$@"
+       )
 }
 
 pick_one () {
@@ -154,14 +227,18 @@ pick_one () {
        output git rev-parse --verify $sha1 || die "Invalid commit name: $sha1"
        test -d "$REWRITTEN" &&
                pick_one_preserving_merges "$@" && return
+       if test -n "$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)
-       if test "$no_ff$current_sha1" = "$parent_sha1"; then
+       if test -z "$no_ff" && test "$current_sha1" = "$parent_sha1"
+       then
                output git reset --hard $sha1
-               test "a$1" = a-n && output git reset --soft $current_sha1
-               sha1=$(git rev-parse --short $sha1)
-               output warn Fast forward to $sha1
+               output warn Fast-forward to $(git rev-parse --short $sha1)
        else
                output git cherry-pick "$@"
        fi
@@ -197,7 +274,11 @@ 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 +308,9 @@ 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
@@ -235,9 +318,9 @@ pick_one_preserving_merges () {
        done
        case $fast_forward in
        t)
-               output warn "Fast forward to $sha1"
+               output warn "Fast-forward to $sha1"
                output git reset --hard $sha1 ||
-                       die "Cannot fast forward to $sha1"
+                       die "Cannot fast-forward to $sha1"
                ;;
        f)
                first_parent=$(expr "$new_parents" : ' \([^ ]*\)')
@@ -256,14 +339,11 @@ pick_one_preserving_merges () {
                        # redo merge
                        author_script=$(get_author_ident_from_commit $sha1)
                        eval "$author_script"
-                       msg="$(git cat-file commit $sha1 | sed -e '1,/^$/d')"
+                       msg="$(commit_message $sha1)"
                        # No point in merging the first parent, that's HEAD
                        new_parents=${new_parents# $first_parent}
-                       if ! GIT_AUTHOR_NAME="$GIT_AUTHOR_NAME" \
-                               GIT_AUTHOR_EMAIL="$GIT_AUTHOR_EMAIL" \
-                               GIT_AUTHOR_DATE="$GIT_AUTHOR_DATE" \
-                               output git merge $STRATEGY -m "$msg" \
-                                       $new_parents
+                       if ! do_with_author output \
+                               git merge $STRATEGY -m "$msg" $new_parents
                        then
                                printf "%s\n" "$msg" > "$GIT_DIR"/MERGE_MSG
                                die_with_patch $sha1 "Error redoing merge $sha1"
@@ -287,34 +367,66 @@ nth_string () {
        esac
 }
 
-make_squash_message () {
+update_squash_messages () {
        if test -f "$SQUASH_MSG"; then
-               COUNT=$(($(sed -n "s/^# This is [^0-9]*\([1-9][0-9]*\).*/\1/p" \
-                       < "$SQUASH_MSG" | sed -ne '$p')+1))
-               echo "# This is a combination of $COUNT commits."
-               sed -e 1d -e '2,/^./{
-                       /^$/d
-               }' <"$SQUASH_MSG"
+               mv "$SQUASH_MSG" "$SQUASH_MSG".bak || exit
+               COUNT=$(($(sed -n \
+                       -e "1s/^# This is a combination of \(.*\) commits\./\1/p" \
+                       -e "q" < "$SQUASH_MSG".bak)+1))
+               {
+                       echo "# This is a combination of $COUNT commits."
+                       sed -e 1d -e '2,/^./{
+                               /^$/d
+                       }' <"$SQUASH_MSG".bak
+               } >"$SQUASH_MSG"
        else
+               commit_message HEAD > "$FIXUP_MSG" || die "Cannot write $FIXUP_MSG"
                COUNT=2
-               echo "# This is a combination of two commits."
-               echo "# The first commit's message is:"
-               echo
-               git cat-file commit HEAD | sed -e '1,/^$/d'
+               {
+                       echo "# This is a combination of 2 commits."
+                       echo "# The first commit's message is:"
+                       echo
+                       cat "$FIXUP_MSG"
+               } >"$SQUASH_MSG"
        fi
-       echo
-       echo "# This is the $(nth_string $COUNT) commit message:"
-       echo
-       git cat-file commit $1 | sed -e '1,/^$/d'
+       case $1 in
+       squash)
+               rm -f "$FIXUP_MSG"
+               echo
+               echo "# This is the $(nth_string $COUNT) commit message:"
+               echo
+               commit_message $2
+               ;;
+       fixup)
+               echo
+               echo "# The $(nth_string $COUNT) commit message will be skipped:"
+               echo
+               commit_message $2 | sed -e 's/^/#       /'
+               ;;
+       esac >>"$SQUASH_MSG"
 }
 
 peek_next_command () {
-       sed -n "1s/ .*$//p" < "$TODO"
+       sed -n -e "/^#/d" -e '/^$/d' -e "s/ .*//p" -e "q" < "$TODO"
+}
+
+# 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() {
+       mv "$SQUASH_MSG" "$MSG" || exit
+       rm -f "$FIXUP_MSG"
+       cp "$MSG" "$GIT_DIR"/MERGE_MSG || exit
+       warn
+       warn "Could not apply $1... $2"
+       die_with_patch $1 ""
 }
 
 do_next () {
-       rm -f "$DOTEST"/message "$DOTEST"/author-script \
-               "$DOTEST"/amend || exit
+       rm -f "$MSG" "$AUTHOR_SCRIPT" "$AMEND" || exit
        read command sha1 rest < "$TODO"
        case "$command" in
        '#'*|''|noop)
@@ -327,6 +439,14 @@ do_next () {
                pick_one $sha1 ||
                        die_with_patch $sha1 "Could not apply $sha1... $rest"
                ;;
+       reword|r)
+               comment_for_reflog reword
+
+               mark_action_done
+               pick_one $sha1 ||
+                       die_with_patch $sha1 "Could not apply $sha1... $rest"
+               git commit --amend
+               ;;
        edit|e)
                comment_for_reflog edit
 
@@ -334,7 +454,7 @@ do_next () {
                pick_one $sha1 ||
                        die_with_patch $sha1 "Could not apply $sha1... $rest"
                make_patch $sha1
-               git rev-parse --verify HEAD > "$DOTEST"/amend
+               git rev-parse --verify HEAD > "$AMEND"
                warn "Stopped at $sha1... $rest"
                warn "You can amend the commit now, with"
                warn
@@ -346,56 +466,58 @@ do_next () {
                warn
                exit 0
                ;;
-       squash|s)
-               comment_for_reflog squash
+       squash|s|fixup|f)
+               case "$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 "Cannot 'squash' without a previous commit"
+                       die "Cannot '$squash_style' without a previous commit"
 
                mark_action_done
-               make_squash_message $sha1 > "$MSG"
-               failed=f
+               update_squash_messages $squash_style $sha1
                author_script=$(get_author_ident_from_commit HEAD)
+               echo "$author_script" > "$AUTHOR_SCRIPT"
+               eval "$author_script"
                output git reset --soft HEAD^
-               pick_one -n $sha1 || failed=t
+               pick_one -n $sha1 || die_failed_squash $sha1 "$rest"
                case "$(peek_next_command)" in
-               squash|s)
-                       USE_OUTPUT=output
-                       MSG_OPT=-F
-                       EDIT_OR_FILE="$MSG"
-                       cp "$MSG" "$SQUASH_MSG"
+               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 --no-verify -F "$SQUASH_MSG" ||
+                               die_failed_squash $sha1 "$rest"
                        ;;
                *)
-                       USE_OUTPUT=
-                       MSG_OPT=
-                       EDIT_OR_FILE=-e
-                       rm -f "$SQUASH_MSG" || exit
-                       cp "$MSG" "$GIT_DIR"/SQUASH_MSG
-                       rm -f "$GIT_DIR"/MERGE_MSG || exit
+                       # This is the final command of this squash/fixup group
+                       if test -f "$FIXUP_MSG"
+                       then
+                               do_with_author git commit --no-verify -F "$FIXUP_MSG" ||
+                                       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 --no-verify -e ||
+                                       die_failed_squash $sha1 "$rest"
+                       fi
+                       rm -f "$SQUASH_MSG" "$FIXUP_MSG"
                        ;;
                esac
-               echo "$author_script" > "$DOTEST"/author-script
-               if test $failed = f
-               then
-                       # This is like --amend, but with a different message
-                       eval "$author_script"
-                       GIT_AUTHOR_NAME="$GIT_AUTHOR_NAME" \
-                       GIT_AUTHOR_EMAIL="$GIT_AUTHOR_EMAIL" \
-                       GIT_AUTHOR_DATE="$GIT_AUTHOR_DATE" \
-                       $USE_OUTPUT git commit --no-verify \
-                               $MSG_OPT "$EDIT_OR_FILE" || failed=t
-               fi
-               if test $failed = t
-               then
-                       cp "$MSG" "$GIT_DIR"/MERGE_MSG
-                       warn
-                       warn "Could not apply $sha1... $rest"
-                       die_with_patch $sha1 ""
-               fi
                ;;
        *)
                warn "Unknown command: $command $sha1 $rest"
-               die_with_patch $sha1 "Please fix this in the file $TODO."
+               if git rev-parse --verify -q "$sha1" >/dev/null
+               then
+                       die_with_patch $sha1 "Please fix this in the file $TODO."
+               else
+                       die "Please fix this in the file $TODO."
+               fi
                ;;
        esac
        test -s "$TODO" && return
@@ -407,7 +529,7 @@ do_next () {
        NEWHEAD=$(git rev-parse HEAD) &&
        case $HEADNAME in
        refs/*)
-               message="$GIT_REFLOG_ACTION: $HEADNAME onto $SHORTONTO)" &&
+               message="$GIT_REFLOG_ACTION: $HEADNAME onto $SHORTONTO" &&
                git update-ref -m "$message" $HEADNAME $NEWHEAD $OLDHEAD &&
                git symbolic-ref HEAD $HEADNAME
                ;;
@@ -429,6 +551,30 @@ do_rest () {
        done
 }
 
+# skip picking commits whose parents are unchanged
+skip_unnecessary_picks () {
+       fd=3
+       while read command sha1 rest
+       do
+               # fd=3 means we skip the command
+               case "$fd,$command,$(git rev-parse --verify --quiet $sha1^)" in
+               3,pick,"$ONTO"*|3,p,"$ONTO"*)
+                       # pick a commit whose parent is current $ONTO -> skip
+                       ONTO=$sha1
+                       ;;
+               3,#*|3,,*)
+                       # copy comments
+                       ;;
+               *)
+                       fd=1
+                       ;;
+               esac
+               echo "$command${sha1:+ }$sha1${rest:+ }$rest" >&$fd
+       done <"$TODO" >"$TODO.new" 3>>"$DONE" &&
+       mv -f "$TODO".new "$TODO" ||
+       die "Could not skip unnecessary pick commands"
+}
+
 # check if no other options are set
 is_standalone () {
        test $# -eq 2 -a "$2" = '--' &&
@@ -442,6 +588,57 @@ get_saved_options () {
        test -d "$REWRITTEN" && PRESERVE_MERGES=t
        test -f "$DOTEST"/strategy && STRATEGY="$(cat "$DOTEST"/strategy)"
        test -f "$DOTEST"/verbose && VERBOSE=t
+       test -f "$DOTEST"/rebase-root && REBASE_ROOT=t
+}
+
+# Rearrange the todo list that has both "pick sha1 msg" and
+# "pick sha1 fixup!/squash! msg" appears in it so that the latter
+# comes immediately after the former, and change "pick" to
+# "fixup"/"squash".
+rearrange_squash () {
+       sed -n -e 's/^pick \([0-9a-f]*\) \(squash\)! /\1 \2 /p' \
+               -e 's/^pick \([0-9a-f]*\) \(fixup\)! /\1 \2 /p' \
+               "$1" >"$1.sq"
+       test -s "$1.sq" || return
+
+       used=
+       while read pick sha1 message
+       do
+               case " $used" in
+               *" $sha1 "*) continue ;;
+               esac
+               echo "$pick $sha1 $message"
+               while read squash action msg
+               do
+                       case "$message" in
+                       "$msg"*)
+                               echo "$action $squash $action! $msg"
+                               used="$used$squash "
+                               ;;
+                       esac
+               done <"$1.sq"
+       done >"$1.rearranged" <"$1"
+       cat "$1.rearranged" >"$1"
+       rm -f "$1.sq" "$1.rearranged"
+}
+
+LF='
+'
+parse_onto () {
+       case "$1" in
+       *...*)
+               if      left=${1%...*} right=${1#*...} &&
+                       onto=$(git merge-base --all ${left:-HEAD} ${right:-HEAD})
+               then
+                       case "$onto" in
+                       ?*"$LF"?* | '')
+                               exit 1 ;;
+                       esac
+                       echo "$onto"
+                       exit 0
+               fi
+       esac
+       git rev-parse --verify "$1^0"
 }
 
 while test $# != 0
@@ -471,21 +668,20 @@ do
                then
                        : Nothing to commit -- skip this
                else
-                       . "$DOTEST"/author-script ||
+                       . "$AUTHOR_SCRIPT" ||
                                die "Cannot find the author identity"
                        amend=
-                       if test -f "$DOTEST"/amend
+                       if test -f "$AMEND"
                        then
                                amend=$(git rev-parse --verify HEAD)
-                               test "$amend" = $(cat "$DOTEST"/amend) ||
+                               test "$amend" = $(cat "$AMEND") ||
                                die "\
 You have uncommitted changes in your working tree. Please, commit them
 first and then run 'git rebase --continue' again."
                                git reset --soft HEAD^ ||
                                die "Cannot rewind the HEAD"
                        fi
-                       export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL GIT_AUTHOR_DATE &&
-                       git commit --no-verify -F "$DOTEST"/message -e || {
+                       do_with_author git commit --no-verify -F "$MSG" -e || {
                                test -n "$amend" && git reset --soft $amend
                                die "Could not commit staged changes."
                        }
@@ -546,34 +742,51 @@ first and then run 'git rebase --continue' again."
        -i)
                # yeah, we know
                ;;
+       --root)
+               REBASE_ROOT=t
+               ;;
+       --autosquash)
+               AUTOSQUASH=t
+               ;;
        --onto)
                shift
-               ONTO=$(git rev-parse --verify "$1") ||
+               ONTO=$(parse_onto "$1") ||
                        die "Does not point to a valid commit: $1"
                ;;
        --)
                shift
-               run_pre_rebase_hook ${1+"$@"}
-               test $# -eq 1 -o $# -eq 2 || usage
+               test -z "$REBASE_ROOT" -a $# -ge 1 -a $# -le 2 ||
+               test ! -z "$REBASE_ROOT" -a $# -le 1 || usage
                test -d "$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=$UPSTREAM
+                       shift
+               else
+                       UPSTREAM=
+                       UPSTREAM_ARG=--root
+                       test -z "$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=$(git rev-parse --verify HEAD) || die "No HEAD?"
@@ -584,25 +797,30 @@ first and then run 'git rebase --continue' again."
                        echo "detached HEAD" > "$DOTEST"/head-name
 
                echo $HEAD > "$DOTEST"/head
-               echo $UPSTREAM > "$DOTEST"/upstream
+               case "$REBASE_ROOT" in
+               '')
+                       rm -f "$DOTEST"/rebase-root ;;
+               *)
+                       : >"$DOTEST"/rebase-root ;;
+               esac
                echo $ONTO > "$DOTEST"/onto
                test -z "$STRATEGY" || echo "$STRATEGY" > "$DOTEST"/strategy
                test t = "$VERBOSE" && : > "$DOTEST"/verbose
                if test t = "$PRESERVE_MERGES"
                then
-                       # $REWRITTEN contains files for each commit that is
-                       # reachable by at least one merge base of $HEAD and
-                       # $UPSTREAM. They are not necessarily rewritten, but
-                       # their children might be.
-                       # This ensures that commits on merged, but otherwise
-                       # unrelated side branches are left alone. (Think "X"
-                       # in the man page's example.)
-                       mkdir "$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
@@ -612,12 +830,21 @@ 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"
@@ -625,14 +852,19 @@ 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 \( $p != $ONTO -o $sha1 = $first_after_upstream \)
+                                               then
+                                                       preserve=f
+                                               fi
+                                       done
+                               else
+                                       preserve=f
+                               fi
                                if test f = "$preserve"
                                then
                                        touch "$REWRITTEN"/$sha1
@@ -646,35 +878,39 @@ first and then run 'git rebase --continue' again."
                then
                        mkdir "$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)" = ""
+                               if test -f "$REWRITTEN"/$rev -a "$(sane_grep "$rev" "$DOTEST"/not-cherry-picks)" = ""
                                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 $rev | cut -d' ' -f2 > "$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"
+                                       sane_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 >> "$TODO"
+               test -n "$AUTOSQUASH" && rearrange_squash "$TODO"
                cat >> "$TODO" << EOF
 
-# Rebase $SHORTUPSTREAM..$SHORTHEAD onto $SHORTONTO
+# Rebase $SHORTREVISIONS onto $SHORTONTO
 #
 # Commands:
 #  p, pick = use commit
+#  r, reword = use commit, but edit the commit message
 #  e, edit = use commit, but stop for amending
 #  s, squash = use commit, but meld into previous commit
+#  f, fixup = like "squash", but discard this commit's log message
 #
 # If you remove a line here THAT COMMIT WILL BE LOST.
 # However, if you remove everything, the rebase will be aborted.
@@ -686,11 +922,13 @@ EOF
 
                cp "$TODO" "$TODO".backup
                git_editor "$TODO" ||
-                       die "Could not execute editor"
+                       die_abort "Could not execute editor"
 
                has_action "$TODO" ||
                        die_abort "Nothing to do"
 
+               test -d "$REWRITTEN" || skip_unnecessary_picks
+
                git update-ref ORIG_HEAD $HEAD
                output git checkout $ONTO && do_rest
                ;;