filter-branch: Simplify parent computation.
[git/git.git] / git-filter-branch.sh
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1#!/bin/sh
2#
3# Rewrite revision history
4# Copyright (c) Petr Baudis, 2006
5# Minimal changes to "port" it to core-git (c) Johannes Schindelin, 2007
6#
7# Lets you rewrite GIT revision history by creating a new branch from
8# your current branch by applying custom filters on each revision.
9# Those filters can modify each tree (e.g. removing a file or running
10# a perl rewrite on all files) or information about each commit.
11# Otherwise, all information (including original commit times or merge
12# information) will be preserved.
13#
14# The command takes the new branch name as a mandatory argument and
15# the filters as optional arguments. If you specify no filters, the
16# commits will be recommitted without any changes, which would normally
17# have no effect and result with the new branch pointing to the same
18# branch as your current branch. (Nevertheless, this may be useful in
19# the future for compensating for some Git bugs or such, therefore
20# such a usage is permitted.)
21#
22# WARNING! The rewritten history will have different ids for all the
23# objects and will not converge with the original branch. You will not
24# be able to easily push and distribute the rewritten branch. Please do
25# not use this command if you do not know the full implications, and
26# avoid using it anyway - do not do what a simple single commit on top
27# of the current version would fix.
28#
29# Always verify that the rewritten version is correct before disposing
30# the original branch.
31#
32# Note that since this operation is extensively I/O expensive, it might
33# be a good idea to do it off-disk, e.g. on tmpfs. Reportedly the speedup
34# is very noticeable.
35#
36# OPTIONS
37# -------
38# -d TEMPDIR:: The path to the temporary tree used for rewriting
39# When applying a tree filter, the command needs to temporary
40# checkout the tree to some directory, which may consume
41# considerable space in case of large projects. By default it
42# does this in the '.git-rewrite/' directory but you can override
43# that choice by this parameter.
44#
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45# Filters
46# ~~~~~~~
47# The filters are applied in the order as listed below. The COMMAND
48# argument is always evaluated in shell using the 'eval' command.
49# The $GIT_COMMIT environment variable is permanently set to contain
50# the id of the commit being rewritten. The author/committer environment
51# variables are set before the first filter is run.
52#
53# A 'map' function is available that takes an "original sha1 id" argument
54# and outputs a "rewritten sha1 id" if the commit has been already
55# rewritten, fails otherwise; the 'map' function can return several
56# ids on separate lines if your commit filter emitted multiple commits
57# (see below).
58#
59# --env-filter COMMAND:: The filter for modifying environment
60# This is the filter for modifying the environment in which
61# the commit will be performed. Specifically, you might want
62# to rewrite the author/committer name/email/time environment
63# variables (see `git-commit` for details). Do not forget to
64# re-export the variables.
65#
66# --tree-filter COMMAND:: The filter for rewriting tree (and its contents)
67# This is the filter for rewriting the tree and its contents.
68# The COMMAND argument is evaluated in shell with the working
69# directory set to the root of the checked out tree. The new tree
70# is then used as-is (new files are auto-added, disappeared files
71# are auto-removed - .gitignore files nor any other ignore rules
72# HAVE NO EFFECT!).
73#
74# --index-filter COMMAND:: The filter for rewriting index
75# This is the filter for rewriting the Git's directory index.
76# It is similar to the tree filter but does not check out the
77# tree, which makes it much faster. However, you must use the
78# lowlevel Git index manipulation commands to do your work.
79#
80# --parent-filter COMMAND:: The filter for rewriting parents
81# This is the filter for rewriting the commit's parent list.
82# It will receive the parent string on stdin and shall output
83# the new parent string on stdout. The parent string is in
84# format accepted by `git-commit-tree`: empty for initial
85# commit, "-p parent" for a normal commit and "-p parent1
86# -p parent2 -p parent3 ..." for a merge commit.
87#
88# --msg-filter COMMAND:: The filter for rewriting commit message
89# This is the filter for rewriting the commit messages.
90# The COMMAND argument is evaluated in shell with the original
91# commit message on standard input; its standard output is
92# is used as the new commit message.
93#
94# --commit-filter COMMAND:: The filter for performing the commit
95# If this filter is passed, it will be called instead of the
96# `git-commit-tree` command, with those arguments:
97#
98# TREE_ID [-p PARENT_COMMIT_ID]...
99#
100# and the log message on stdin. The commit id is expected on
101# stdout. As a special extension, the commit filter may emit
102# multiple commit ids; in that case, all of them will be used
103# as parents instead of the original commit in further commits.
104#
105# --tag-name-filter COMMAND:: The filter for rewriting tag names.
106# If this filter is passed, it will be called for every tag ref
107# that points to a rewritten object (or to a tag object which
108# points to a rewritten object). The original tag name is passed
109# via standard input, and the new tag name is expected on standard
110# output.
111#
112# The original tags are not deleted, but can be overwritten;
113# use "--tag-name-filter=cat" to simply update the tags. In this
114# case, be very careful and make sure you have the old tags
115# backed up in case the conversion has run afoul.
116#
117# Note that there is currently no support for proper rewriting of
118# tag objects; in layman terms, if the tag has a message or signature
119# attached, the rewritten tag won't have it. Sorry. (It is by
120# definition impossible to preserve signatures at any rate, though.)
121#
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122# --subdirectory-filter DIRECTORY:: Only regard the history, as seen by
123# the given subdirectory. The result will contain that directory as
124# its project root.
125#
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126# EXAMPLE USAGE
127# -------------
128# Suppose you want to remove a file (containing confidential information
129# or copyright violation) from all commits:
130#
131# git-filter-branch --tree-filter 'rm filename' newbranch
132#
133# A significantly faster version:
134#
135# git-filter-branch --index-filter 'git-update-index --remove filename' newbranch
136#
137# Now, you will get the rewritten history saved in the branch 'newbranch'
138# (your current branch is left untouched).
139#
140# To "etch-graft" a commit to the revision history (set a commit to be
141# the parent of the current initial commit and propagate that):
142#
143# git-filter-branch --parent-filter sed\ 's/^$/-p graftcommitid/' newbranch
144#
145# (if the parent string is empty - therefore we are dealing with the
146# initial commit - add graftcommit as a parent). Note that this assumes
147# history with a single root (that is, no git-merge without common ancestors
148# happened). If this is not the case, use:
149#
150# git-filter-branch --parent-filter 'cat; [ "$GIT_COMMIT" = "COMMIT" ] && echo "-p GRAFTCOMMIT"' newbranch
151#
152# To remove commits authored by "Darl McBribe" from the history:
153#
154# git-filter-branch --commit-filter 'if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ]; then shift; while [ -n "$1" ]; do shift; echo "$1"; shift; done; else git-commit-tree "$@"; fi' newbranch
155#
156# (the shift magic first throws away the tree id and then the -p
157# parameters). Note that this handles merges properly! In case Darl
158# committed a merge between P1 and P2, it will be propagated properly
159# and all children of the merge will become merge commits with P1,P2
160# as their parents instead of the merge commit.
161#
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162# To restrict rewriting to only part of the history, specify a revision
163# range in addition to the new branch name. The new branch name will
164# point to the top-most revision that a 'git rev-list' of this range
165# will print.
166#
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167# Consider this history:
168#
169# D--E--F--G--H
170# / /
171# A--B-----C
172#
2766ce28 173# To rewrite commits D,E,F,G,H, use:
6f6826c5 174#
2766ce28 175# git-filter-branch ... new-H C..H
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176#
177# To rewrite commits E,F,G,H, use one of these:
178#
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179# git-filter-branch ... new-H C..H --not D
180# git-filter-branch ... new-H D..H --not C
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181
182# Testsuite: TODO
183
184set -e
185
2766ce28 186USAGE="git-filter-branch [-d TEMPDIR] [FILTERS] DESTBRANCH [REV-RANGE]"
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187. git-sh-setup
188
189map()
190{
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191 # if it was not rewritten, take the original
192 test -r "$workdir/../map/$1" || echo "$1"
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193 cat "$workdir/../map/$1"
194}
195
196# When piped a commit, output a script to set the ident of either
197# "author" or "committer
198
199set_ident () {
200 lid="$(echo "$1" | tr "A-Z" "a-z")"
201 uid="$(echo "$1" | tr "a-z" "A-Z")"
202 pick_id_script='
203 /^'$lid' /{
204 s/'\''/'\''\\'\'\''/g
205 h
206 s/^'$lid' \([^<]*\) <[^>]*> .*$/\1/
207 s/'\''/'\''\'\'\''/g
208 s/.*/export GIT_'$uid'_NAME='\''&'\''/p
209
210 g
211 s/^'$lid' [^<]* <\([^>]*\)> .*$/\1/
212 s/'\''/'\''\'\'\''/g
213 s/.*/export GIT_'$uid'_EMAIL='\''&'\''/p
214
215 g
216 s/^'$lid' [^<]* <[^>]*> \(.*\)$/\1/
217 s/'\''/'\''\'\'\''/g
218 s/.*/export GIT_'$uid'_DATE='\''&'\''/p
219
220 q
221 }
222 '
223
224 LANG=C LC_ALL=C sed -ne "$pick_id_script"
225 # Ensure non-empty id name.
226 echo "[ -n \"\$GIT_${uid}_NAME\" ] || export GIT_${uid}_NAME=\"\${GIT_${uid}_EMAIL%%@*}\""
227}
228
6f6826c5 229tempdir=.git-rewrite
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230filter_env=
231filter_tree=
232filter_index=
233filter_parent=
234filter_msg=cat
235filter_commit='git-commit-tree "$@"'
236filter_tag_name=
685ef546 237filter_subdir=
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238while case "$#" in 0) usage;; esac
239do
240 case "$1" in
241 --)
242 shift
243 break
244 ;;
245 -*)
246 ;;
247 *)
248 break;
249 esac
250
251 # all switches take one argument
252 ARG="$1"
253 case "$#" in 1) usage ;; esac
254 shift
255 OPTARG="$1"
256 shift
257
258 case "$ARG" in
259 -d)
260 tempdir="$OPTARG"
261 ;;
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262 --env-filter)
263 filter_env="$OPTARG"
264 ;;
265 --tree-filter)
266 filter_tree="$OPTARG"
267 ;;
268 --index-filter)
269 filter_index="$OPTARG"
270 ;;
271 --parent-filter)
272 filter_parent="$OPTARG"
273 ;;
274 --msg-filter)
275 filter_msg="$OPTARG"
276 ;;
277 --commit-filter)
278 filter_commit="$OPTARG"
279 ;;
280 --tag-name-filter)
281 filter_tag_name="$OPTARG"
282 ;;
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283 --subdirectory-filter)
284 filter_subdir="$OPTARG"
285 ;;
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286 *)
287 usage
288 ;;
289 esac
290done
291
292dstbranch="$1"
2766ce28 293shift
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294test -n "$dstbranch" || die "missing branch name"
295git-show-ref "refs/heads/$dstbranch" 2> /dev/null &&
296 die "branch $dstbranch already exists"
297
298test ! -e "$tempdir" || die "$tempdir already exists, please remove it"
299mkdir -p "$tempdir/t"
300cd "$tempdir/t"
301workdir="$(pwd)"
302
303case "$GIT_DIR" in
304/*)
305 ;;
306*)
307 export GIT_DIR="$(pwd)/../../$GIT_DIR"
308 ;;
309esac
310
311export GIT_INDEX_FILE="$(pwd)/../index"
312git-read-tree # seed the index file
313
314ret=0
315
316
317mkdir ../map # map old->new commit ids for rewriting parents
318
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319case "$filter_subdir" in
320"")
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321 git-rev-list --reverse --topo-order --default HEAD \
322 --parents "$@"
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323 ;;
324*)
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325 git-rev-list --reverse --topo-order --default HEAD \
326 --parents "$@" -- "$filter_subdir"
685ef546 327esac > ../revs
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328commits=$(cat ../revs | wc -l | tr -d " ")
329
330test $commits -eq 0 && die "Found nothing to rewrite"
331
332i=0
813b4734 333while read commit parents; do
c12764b8 334 i=$(($i+1))
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335 printf "$commit ($i/$commits) "
336
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337 case "$filter_subdir" in
338 "")
339 git-read-tree -i -m $commit
340 ;;
341 *)
342 git-read-tree -i -m $commit:"$filter_subdir"
343 esac
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344
345 export GIT_COMMIT=$commit
346 git-cat-file commit "$commit" >../commit
347
348 eval "$(set_ident AUTHOR <../commit)"
349 eval "$(set_ident COMMITTER <../commit)"
350d8575 350 eval "$filter_env" < /dev/null
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351
352 if [ "$filter_tree" ]; then
353 git-checkout-index -f -u -a
354 # files that $commit removed are now still in the working tree;
355 # remove them, else they would be added again
356 git-ls-files -z --others | xargs -0 rm -f
350d8575 357 eval "$filter_tree" < /dev/null
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358 git-diff-index -r $commit | cut -f 2- | tr '\n' '\0' | \
359 xargs -0 git-update-index --add --replace --remove
360 git-ls-files -z --others | \
361 xargs -0 git-update-index --add --replace --remove
362 fi
363
350d8575 364 eval "$filter_index" < /dev/null
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365
366 parentstr=
813b4734 367 for parent in $parents; do
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368 for reparent in $(map "$parent"); do
369 parentstr="$parentstr -p $reparent"
370 done
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371 done
372 if [ "$filter_parent" ]; then
373 parentstr="$(echo "$parentstr" | eval "$filter_parent")"
374 fi
375
376 sed -e '1,/^$/d' <../commit | \
377 eval "$filter_msg" | \
378 sh -c "$filter_commit" git-commit-tree $(git-write-tree) $parentstr | \
379 tee ../map/$commit
380done <../revs
381
813b4734 382src_head=$(tail -n 1 ../revs | sed -e 's/ .*//')
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383target_head=$(head -n 1 ../map/$src_head)
384case "$target_head" in
385'')
386 echo Nothing rewritten
387 ;;
388*)
389 git-update-ref refs/heads/"$dstbranch" $target_head
390 if [ $(cat ../map/$src_head | wc -l) -gt 1 ]; then
391 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 $dstbranch head but you will need to resolve the situation now (probably by manually merging the other commits). These are all the commits:" >&2
392 sed 's/^/ /' ../map/$src_head >&2
393 ret=1
394 fi
395 ;;
396esac
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397
398if [ "$filter_tag_name" ]; then
399 git-for-each-ref --format='%(objectname) %(objecttype) %(refname)' refs/tags |
400 while read sha1 type ref; do
401 ref="${ref#refs/tags/}"
402 # XXX: Rewrite tagged trees as well?
403 if [ "$type" != "commit" -a "$type" != "tag" ]; then
404 continue;
405 fi
406
407 if [ "$type" = "tag" ]; then
408 # Dereference to a commit
409 sha1t="$sha1"
410 sha1="$(git-rev-parse "$sha1"^{commit} 2>/dev/null)" || continue
411 fi
412
413 [ -f "../map/$sha1" ] || continue
414 new_sha1="$(cat "../map/$sha1")"
415 export GIT_COMMIT="$sha1"
416 new_ref="$(echo "$ref" | eval "$filter_tag_name")"
417
418 echo "$ref -> $new_ref ($sha1 -> $new_sha1)"
419
420 if [ "$type" = "tag" ]; then
421 # Warn that we are not rewriting the tag object itself.
422 warn "unreferencing tag object $sha1t"
423 fi
424
425 git-update-ref "refs/tags/$new_ref" "$new_sha1"
426 done
427fi
428
429cd ../..
430rm -rf "$tempdir"
431echo "Rewritten history saved to the $dstbranch branch"
432
433exit $ret