# Copyright (c) Petr Baudis, 2006
# Minimal changes to "port" it to core-git (c) Johannes Schindelin, 2007
#
-# Lets you rewrite GIT revision history by creating a new branch from
-# your current branch by applying custom filters on each revision.
-# Those filters can modify each tree (e.g. removing a file or running
-# a perl rewrite on all files) or information about each commit.
-# Otherwise, all information (including original commit times or merge
-# information) will be preserved.
-#
-# The command takes the new branch name as a mandatory argument and
-# the filters as optional arguments. If you specify no filters, the
-# commits will be recommitted without any changes, which would normally
-# have no effect and result with the new branch pointing to the same
-# branch as your current branch. (Nevertheless, this may be useful in
-# the future for compensating for some Git bugs or such, therefore
-# such a usage is permitted.)
-#
-# WARNING! The rewritten history will have different ids for all the
-# objects and will not converge with the original branch. You will not
-# be able to easily push and distribute the rewritten branch. Please do
-# not use this command if you do not know the full implications, and
-# avoid using it anyway - do not do what a simple single commit on top
-# of the current version would fix.
-#
-# Always verify that the rewritten version is correct before disposing
-# the original branch.
-#
-# Note that since this operation is extensively I/O expensive, it might
-# be a good idea to do it off-disk, e.g. on tmpfs. Reportedly the speedup
-# is very noticeable.
-#
-# OPTIONS
-# -------
-# -d TEMPDIR:: The path to the temporary tree used for rewriting
-# When applying a tree filter, the command needs to temporary
-# checkout the tree to some directory, which may consume
-# considerable space in case of large projects. By default it
-# does this in the '.git-rewrite/' directory but you can override
-# that choice by this parameter.
-#
-# -r STARTREV:: The commit id to start the rewrite at
-# Normally, the command will rewrite the entire history. If you
-# pass this argument, though, this will be the first commit it
-# will rewrite and keep the previous commits intact.
-#
-# -k KEEPREV:: A commit id until which _not_ to rewrite history
-# If you pass this argument, this commit and all of its
-# predecessors are kept intact.
-#
-# Filters
-# ~~~~~~~
-# The filters are applied in the order as listed below. The COMMAND
-# argument is always evaluated in shell using the 'eval' command.
-# The $GIT_COMMIT environment variable is permanently set to contain
-# the id of the commit being rewritten. The author/committer environment
-# variables are set before the first filter is run.
-#
-# A 'map' function is available that takes an "original sha1 id" argument
-# and outputs a "rewritten sha1 id" if the commit has been already
-# rewritten, fails otherwise; the 'map' function can return several
-# ids on separate lines if your commit filter emitted multiple commits
-# (see below).
-#
-# --env-filter COMMAND:: The filter for modifying environment
-# This is the filter for modifying the environment in which
-# the commit will be performed. Specifically, you might want
-# to rewrite the author/committer name/email/time environment
-# variables (see `git-commit` for details). Do not forget to
-# re-export the variables.
-#
-# --tree-filter COMMAND:: The filter for rewriting tree (and its contents)
-# This is the filter for rewriting the tree and its contents.
-# The COMMAND argument is evaluated in shell with the working
-# directory set to the root of the checked out tree. The new tree
-# is then used as-is (new files are auto-added, disappeared files
-# are auto-removed - .gitignore files nor any other ignore rules
-# HAVE NO EFFECT!).
-#
-# --index-filter COMMAND:: The filter for rewriting index
-# This is the filter for rewriting the Git's directory index.
-# It is similar to the tree filter but does not check out the
-# tree, which makes it much faster. However, you must use the
-# lowlevel Git index manipulation commands to do your work.
-#
-# --parent-filter COMMAND:: The filter for rewriting parents
-# This is the filter for rewriting the commit's parent list.
-# It will receive the parent string on stdin and shall output
-# the new parent string on stdout. The parent string is in
-# format accepted by `git-commit-tree`: empty for initial
-# commit, "-p parent" for a normal commit and "-p parent1
-# -p parent2 -p parent3 ..." for a merge commit.
-#
-# --msg-filter COMMAND:: The filter for rewriting commit message
-# This is the filter for rewriting the commit messages.
-# The COMMAND argument is evaluated in shell with the original
-# commit message on standard input; its standard output is
-# is used as the new commit message.
-#
-# --commit-filter COMMAND:: The filter for performing the commit
-# If this filter is passed, it will be called instead of the
-# `git-commit-tree` command, with those arguments:
-#
-# TREE_ID [-p PARENT_COMMIT_ID]...
-#
-# and the log message on stdin. The commit id is expected on
-# stdout. As a special extension, the commit filter may emit
-# multiple commit ids; in that case, all of them will be used
-# as parents instead of the original commit in further commits.
-#
-# --tag-name-filter COMMAND:: The filter for rewriting tag names.
-# If this filter is passed, it will be called for every tag ref
-# that points to a rewritten object (or to a tag object which
-# points to a rewritten object). The original tag name is passed
-# via standard input, and the new tag name is expected on standard
-# output.
-#
-# The original tags are not deleted, but can be overwritten;
-# use "--tag-name-filter=cat" to simply update the tags. In this
-# case, be very careful and make sure you have the old tags
-# backed up in case the conversion has run afoul.
-#
-# Note that there is currently no support for proper rewriting of
-# tag objects; in layman terms, if the tag has a message or signature
-# attached, the rewritten tag won't have it. Sorry. (It is by
-# definition impossible to preserve signatures at any rate, though.)
-#
-# EXAMPLE USAGE
-# -------------
-# Suppose you want to remove a file (containing confidential information
-# or copyright violation) from all commits:
-#
-# git-filter-branch --tree-filter 'rm filename' newbranch
-#
-# A significantly faster version:
-#
-# git-filter-branch --index-filter 'git-update-index --remove filename' newbranch
-#
-# Now, you will get the rewritten history saved in the branch 'newbranch'
-# (your current branch is left untouched).
-#
-# To "etch-graft" a commit to the revision history (set a commit to be
-# the parent of the current initial commit and propagate that):
-#
-# git-filter-branch --parent-filter sed\ 's/^$/-p graftcommitid/' newbranch
-#
-# (if the parent string is empty - therefore we are dealing with the
-# initial commit - add graftcommit as a parent). Note that this assumes
-# history with a single root (that is, no git-merge without common ancestors
-# happened). If this is not the case, use:
-#
-# git-filter-branch --parent-filter 'cat; [ "$GIT_COMMIT" = "COMMIT" ] && echo "-p GRAFTCOMMIT"' newbranch
-#
-# To remove commits authored by "Darl McBribe" from the history:
-#
-# git-filter-branch --commit-filter 'if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ]; then shift; while [ -n "$1" ]; do shift; echo "$1"; shift; done; else git-commit-tree "$@"; fi' newbranch
-#
-# (the shift magic first throws away the tree id and then the -p
-# parameters). Note that this handles merges properly! In case Darl
-# committed a merge between P1 and P2, it will be propagated properly
-# and all children of the merge will become merge commits with P1,P2
-# as their parents instead of the merge commit.
-#
-# To restrict rewriting to only part of the history, use -r or -k or both.
-# Consider this history:
-#
-# D--E--F--G--H
-# / /
-# A--B-----C
-#
-# To rewrite only commits F,G,H, use:
-#
-# git-filter-branch -r F ...
-#
-# To rewrite commits E,F,G,H, use one of these:
-#
-# git-filter-branch -r E -k C ...
-# git-filter-branch -k D -k C ...
-
-# Testsuite: TODO
+# Lets you rewrite the revision history of the current branch, creating
+# a new branch. You can specify a number of filters to modify the commits,
+# files and trees.
set -e
-USAGE="git-filter-branch [-d TEMPDIR] [-r STARTREV]... [-k KEEPREV]... [-s SRCBRANCH] [FILTERS] DESTBRANCH"
+USAGE="git-filter-branch [-d TEMPDIR] [FILTERS] DESTBRANCH [REV-RANGE]"
. git-sh-setup
+warn () {
+ echo "$*" >&2
+}
+
map()
{
- [ -r "$workdir/../map/$1" ] || return 1
- cat "$workdir/../map/$1"
+ # if it was not rewritten, take the original
+ if test -r "$workdir/../map/$1"
+ then
+ cat "$workdir/../map/$1"
+ else
+ echo "$1"
+ fi
+}
+
+# override die(): this version puts in an extra line break, so that
+# the progress is still visible
+
+die()
+{
+ echo >&2
+ echo "$*" >&2
+ exit 1
}
# When piped a commit, output a script to set the ident of either
echo "[ -n \"\$GIT_${uid}_NAME\" ] || export GIT_${uid}_NAME=\"\${GIT_${uid}_EMAIL%%@*}\""
}
-# list all parent's object names for a given commit
-get_parents () {
- git-rev-list -1 --parents "$1" | sed "s/^[0-9a-f]*//"
-}
-
tempdir=.git-rewrite
-unchanged=" "
filter_env=
filter_tree=
filter_index=
filter_parent=
filter_msg=cat
-filter_commit='git-commit-tree "$@"'
+filter_commit='git commit-tree "$@"'
filter_tag_name=
-srcbranch=HEAD
+filter_subdir=
while case "$#" in 0) usage;; esac
do
case "$1" in
-d)
tempdir="$OPTARG"
;;
- -r)
- unchanged="$(get_parents "$OPTARG") $unchanged"
- ;;
- -k)
- unchanged="$(git-rev-parse "$OPTARG"^{commit}) $unchanged"
- ;;
--env-filter)
filter_env="$OPTARG"
;;
--tag-name-filter)
filter_tag_name="$OPTARG"
;;
- -s)
- srcbranch="$OPTARG"
+ --subdirectory-filter)
+ filter_subdir="$OPTARG"
;;
*)
usage
done
dstbranch="$1"
+shift
test -n "$dstbranch" || die "missing branch name"
-git-show-ref "refs/heads/$dstbranch" 2> /dev/null &&
+git show-ref "refs/heads/$dstbranch" 2> /dev/null &&
die "branch $dstbranch already exists"
test ! -e "$tempdir" || die "$tempdir already exists, please remove it"
/*)
;;
*)
- export GIT_DIR="$(pwd)/../../$GIT_DIR"
+ GIT_DIR="$(pwd)/../../$GIT_DIR"
;;
esac
+export GIT_DIR GIT_WORK_TREE=.
export GIT_INDEX_FILE="$(pwd)/../index"
-git-read-tree # seed the index file
+git read-tree # seed the index file
ret=0
mkdir ../map # map old->new commit ids for rewriting parents
-# seed with identity mappings for the parents where we start off
-for commit in $unchanged; do
- echo $commit > ../map/$commit
-done
-
-git-rev-list --reverse --topo-order $srcbranch --not $unchanged >../revs
+case "$filter_subdir" in
+"")
+ git rev-list --reverse --topo-order --default HEAD \
+ --parents "$@"
+ ;;
+*)
+ git rev-list --reverse --topo-order --default HEAD \
+ --parents --full-history "$@" -- "$filter_subdir"
+esac > ../revs
commits=$(cat ../revs | wc -l | tr -d " ")
test $commits -eq 0 && die "Found nothing to rewrite"
i=0
-while read commit; do
- i=$((i+1))
- printf "$commit ($i/$commits) "
+while read commit parents; do
+ i=$(($i+1))
+ printf "\rRewrite $commit ($i/$commits)"
- git-read-tree -i -m $commit
+ case "$filter_subdir" in
+ "")
+ git read-tree -i -m $commit
+ ;;
+ *)
+ git read-tree -i -m $commit:"$filter_subdir"
+ esac
export GIT_COMMIT=$commit
- git-cat-file commit "$commit" >../commit
+ git cat-file commit "$commit" >../commit
- eval "$(set_ident AUTHOR <../commit)"
- eval "$(set_ident COMMITTER <../commit)"
- eval "$filter_env"
+ eval "$(set_ident AUTHOR <../commit)" ||
+ die "setting author failed for commit $commit"
+ eval "$(set_ident COMMITTER <../commit)" ||
+ die "setting committer failed for commit $commit"
+ eval "$filter_env" < /dev/null ||
+ die "env filter failed: $filter_env"
if [ "$filter_tree" ]; then
- git-checkout-index -f -u -a
+ git checkout-index -f -u -a
# files that $commit removed are now still in the working tree;
# remove them, else they would be added again
- git-ls-files -z --others | xargs -0 rm -f
- eval "$filter_tree"
- git-diff-index -r $commit | cut -f 2- | tr '\n' '\0' | \
- xargs -0 git-update-index --add --replace --remove
- git-ls-files -z --others | \
- xargs -0 git-update-index --add --replace --remove
+ git ls-files -z --others | xargs -0 rm -f
+ eval "$filter_tree" < /dev/null ||
+ die "tree filter failed: $filter_tree"
+
+ git diff-index -r $commit | cut -f 2- | tr '\n' '\0' | \
+ xargs -0 git update-index --add --replace --remove
+ git ls-files -z --others | \
+ xargs -0 git update-index --add --replace --remove
fi
- eval "$filter_index"
+ eval "$filter_index" < /dev/null ||
+ die "index filter failed: $filter_index"
parentstr=
- for parent in $(get_parents $commit); do
- if [ -r "../map/$parent" ]; then
- for reparent in $(cat "../map/$parent"); do
- parentstr="$parentstr -p $reparent"
- done
- else
- die "assertion failed: parent $parent for commit $commit not found in rewritten ones"
- fi
+ for parent in $parents; do
+ for reparent in $(map "$parent"); do
+ parentstr="$parentstr -p $reparent"
+ done
done
if [ "$filter_parent" ]; then
- parentstr="$(echo "$parentstr" | eval "$filter_parent")"
+ parentstr="$(echo "$parentstr" | eval "$filter_parent")" ||
+ die "parent filter failed: $filter_parent"
fi
sed -e '1,/^$/d' <../commit | \
- eval "$filter_msg" | \
- sh -c "$filter_commit" git-commit-tree $(git-write-tree) $parentstr | \
- tee ../map/$commit
+ eval "$filter_msg" > ../message ||
+ die "msg filter failed: $filter_msg"
+ sh -c "$filter_commit" "git commit-tree" \
+ $(git write-tree) $parentstr < ../message > ../map/$commit
done <../revs
-git-update-ref refs/heads/"$dstbranch" $(head -n 1 ../map/$(tail -n 1 ../revs))
-if [ "$(cat ../map/$(tail -n 1 ../revs) | wc -l)" -gt 1 ]; then
- echo "WARNING: Your commit filter caused the head commit to expand to several rewritten commits. Only the first such commit was recorded as the current $dstbranch head but you will need to resolve the situation now (probably by manually merging the other commits). These are all the commits:" >&2
- sed 's/^/ /' ../map/$(tail -n 1 ../revs) >&2
- ret=1
-fi
+src_head=$(tail -n 1 ../revs | sed -e 's/ .*//')
+target_head=$(head -n 1 ../map/$src_head)
+case "$target_head" in
+'')
+ echo Nothing rewritten
+ ;;
+*)
+ git update-ref refs/heads/"$dstbranch" $target_head
+ if [ $(cat ../map/$src_head | wc -l) -gt 1 ]; then
+ echo "WARNING: Your commit filter caused the head commit to expand to several rewritten commits. Only the first such commit was recorded as the current $dstbranch head but you will need to resolve the situation now (probably by manually merging the other commits). These are all the commits:" >&2
+ sed 's/^/ /' ../map/$src_head >&2
+ ret=1
+ fi
+ ;;
+esac
if [ "$filter_tag_name" ]; then
- git-for-each-ref --format='%(objectname) %(objecttype) %(refname)' refs/tags |
+ git for-each-ref --format='%(objectname) %(objecttype) %(refname)' refs/tags |
while read sha1 type ref; do
ref="${ref#refs/tags/}"
# XXX: Rewrite tagged trees as well?
if [ "$type" = "tag" ]; then
# Dereference to a commit
sha1t="$sha1"
- sha1="$(git-rev-parse "$sha1"^{commit} 2>/dev/null)" || continue
+ sha1="$(git rev-parse "$sha1"^{commit} 2>/dev/null)" || continue
fi
[ -f "../map/$sha1" ] || continue
new_sha1="$(cat "../map/$sha1")"
export GIT_COMMIT="$sha1"
- new_ref="$(echo "$ref" | eval "$filter_tag_name")"
+ new_ref="$(echo "$ref" | eval "$filter_tag_name")" ||
+ die "tag name filter failed: $filter_tag_name"
echo "$ref -> $new_ref ($sha1 -> $new_sha1)"
warn "unreferencing tag object $sha1t"
fi
- git-update-ref "refs/tags/$new_ref" "$new_sha1"
+ git update-ref "refs/tags/$new_ref" "$new_sha1"
done
fi
cd ../..
rm -rf "$tempdir"
-echo "Rewritten history saved to the $dstbranch branch"
+printf "\nRewritten history saved to the $dstbranch branch\n"
exit $ret