git-filter-branch.sh

   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 #
  45 # -r STARTREV:: The commit id to start the rewrite at
  46 #       Normally, the command will rewrite the entire history. If you
  47 #       pass this argument, though, this will be the first commit it
  48 #       will rewrite and keep the previous commits intact.
  49 #
  50 # -k KEEPREV:: A commit id until which _not_ to rewrite history
  51 #       If you pass this argument, this commit and all of its
  52 #       predecessors are kept intact.
  53 #
  54 # Filters
  55 # ~~~~~~~
  56 # The filters are applied in the order as listed below. The COMMAND
  57 # argument is always evaluated in shell using the 'eval' command.
  58 # The $GIT_COMMIT environment variable is permanently set to contain
  59 # the id of the commit being rewritten. The author/committer environment
  60 # variables are set before the first filter is run.
  61 #
  62 # A 'map' function is available that takes an "original sha1 id" argument
  63 # and outputs a "rewritten sha1 id" if the commit has been already
  64 # rewritten, fails otherwise; the 'map' function can return several
  65 # ids on separate lines if your commit filter emitted multiple commits
  66 # (see below).
  67 #
  68 # --env-filter COMMAND:: The filter for modifying environment
  69 #       This is the filter for modifying the environment in which
  70 #       the commit will be performed. Specifically, you might want
  71 #       to rewrite the author/committer name/email/time environment
  72 #       variables (see `git-commit` for details). Do not forget to
  73 #       re-export the variables.
  74 #
  75 # --tree-filter COMMAND:: The filter for rewriting tree (and its contents)
  76 #       This is the filter for rewriting the tree and its contents.
  77 #       The COMMAND argument is evaluated in shell with the working
  78 #       directory set to the root of the checked out tree. The new tree
  79 #       is then used as-is (new files are auto-added, disappeared files
  80 #       are auto-removed - .gitignore files nor any other ignore rules
  81 #       HAVE NO EFFECT!).
  82 #
  83 # --index-filter COMMAND:: The filter for rewriting index
  84 #       This is the filter for rewriting the Git's directory index.
  85 #       It is similar to the tree filter but does not check out the
  86 #       tree, which makes it much faster. However, you must use the
  87 #       lowlevel Git index manipulation commands to do your work.
  88 #
  89 # --parent-filter COMMAND:: The filter for rewriting parents
  90 #       This is the filter for rewriting the commit's parent list.
  91 #       It will receive the parent string on stdin and shall output
  92 #       the new parent string on stdout. The parent string is in
  93 #       format accepted by `git-commit-tree`: empty for initial
  94 #       commit, "-p parent" for a normal commit and "-p parent1
  95 #       -p parent2 -p parent3 ..." for a merge commit.
  96 #
  97 # --msg-filter COMMAND:: The filter for rewriting commit message
  98 #       This is the filter for rewriting the commit messages.
  99 #       The COMMAND argument is evaluated in shell with the original
 100 #       commit message on standard input; its standard output is
 101 #       is used as the new commit message.
 102 #
 103 # --commit-filter COMMAND:: The filter for performing the commit
 104 #       If this filter is passed, it will be called instead of the
 105 #       `git-commit-tree` command, with those arguments:
 106 #
 107 #               TREE_ID [-p PARENT_COMMIT_ID]...
 108 #
 109 #       and the log message on stdin. The commit id is expected on
 110 #       stdout. As a special extension, the commit filter may emit
 111 #       multiple commit ids; in that case, all of them will be used
 112 #       as parents instead of the original commit in further commits.
 113 #
 114 # --tag-name-filter COMMAND:: The filter for rewriting tag names.
 115 #       If this filter is passed, it will be called for every tag ref
 116 #       that points to a rewritten object (or to a tag object which
 117 #       points to a rewritten object). The original tag name is passed
 118 #       via standard input, and the new tag name is expected on standard
 119 #       output.
 120 #
 121 #       The original tags are not deleted, but can be overwritten;
 122 #       use "--tag-name-filter=cat" to simply update the tags. In this
 123 #       case, be very careful and make sure you have the old tags
 124 #       backed up in case the conversion has run afoul.
 125 #
 126 #       Note that there is currently no support for proper rewriting of
 127 #       tag objects; in layman terms, if the tag has a message or signature
 128 #       attached, the rewritten tag won't have it. Sorry. (It is by
 129 #       definition impossible to preserve signatures at any rate, though.)
 130 #
 131 # EXAMPLE USAGE
 132 # -------------
 133 # Suppose you want to remove a file (containing confidential information
 134 # or copyright violation) from all commits:
 135 #
 136 #       git-filter-branch --tree-filter 'rm filename' newbranch
 137 #
 138 # A significantly faster version:
 139 #
 140 #       git-filter-branch --index-filter 'git-update-index --remove filename' newbranch
 141 #
 142 # Now, you will get the rewritten history saved in the branch 'newbranch'
 143 # (your current branch is left untouched).
 144 #
 145 # To "etch-graft" a commit to the revision history (set a commit to be
 146 # the parent of the current initial commit and propagate that):
 147 #
 148 #       git-filter-branch --parent-filter sed\ 's/^$/-p graftcommitid/' newbranch
 149 #
 150 # (if the parent string is empty - therefore we are dealing with the
 151 # initial commit - add graftcommit as a parent). Note that this assumes
 152 # history with a single root (that is, no git-merge without common ancestors
 153 # happened). If this is not the case, use:
 154 #
 155 #       git-filter-branch --parent-filter 'cat; [ "$GIT_COMMIT" = "COMMIT" ] && echo "-p GRAFTCOMMIT"' newbranch
 156 #
 157 # To remove commits authored by "Darl McBribe" from the history:
 158 #
 159 #       git-filter-branch --commit-filter 'if [ "$GIT_AUTHOR_NAME" = "Darl McBribe" ]; then shift; while [ -n "$1" ]; do shift; echo "$1"; shift; done; else git-commit-tree "$@"; fi' newbranch
 160 #
 161 # (the shift magic first throws away the tree id and then the -p
 162 # parameters). Note that this handles merges properly! In case Darl
 163 # committed a merge between P1 and P2, it will be propagated properly
 164 # and all children of the merge will become merge commits with P1,P2
 165 # as their parents instead of the merge commit.
 166 #
 167 # To restrict rewriting to only part of the history, use -r or -k or both.
 168 # Consider this history:
 169 #
 170 #            D--E--F--G--H
 171 #           /     /
 172 #       A--B-----C
 173 #
 174 # To rewrite only commits F,G,H, use:
 175 #
 176 #       git-filter-branch -r F ...
 177 #
 178 # To rewrite commits E,F,G,H, use one of these:
 179 #
 180 #       git-filter-branch -r E -k C ...
 181 #       git-filter-branch -k D -k C ...
 182
 183 # Testsuite: TODO
 184
 185 set -e
 186
 187 USAGE="git-filter-branch [-d TEMPDIR] [-r STARTREV]... [-k KEEPREV]... [-s SRCBRANCH] [FILTERS] DESTBRANCH"
 188 . git-sh-setup
 189
 190 map()
 191 {
 192         [ -r "$workdir/../map/$1" ] || return 1
 193         cat "$workdir/../map/$1"
 194 }
 195
 196 # When piped a commit, output a script to set the ident of either
 197 # "author" or "committer
 198
 199 set_ident () {
 200         lid="$(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
 229 # list all parent's object names for a given commit
 230 get_parents () {
 231         git-rev-list -1 --parents "$1" | sed "s/^[0-9a-f]*//"
 232 }
 233
 234 tempdir=.git-rewrite
 235 unchanged=" "
 236 filter_env=
 237 filter_tree=
 238 filter_index=
 239 filter_parent=
 240 filter_msg=cat
 241 filter_commit='git-commit-tree "$@"'
 242 filter_tag_name=
 243 srcbranch=HEAD
 244 while case "$#" in 0) usage;; esac
 245 do
 246         case "$1" in
 247         --)
 248                 shift
 249                 break
 250                 ;;
 251         -*)
 252                 ;;
 253         *)
 254                 break;
 255         esac
 256
 257         # all switches take one argument
 258         ARG="$1"
 259         case "$#" in 1) usage ;; esac
 260         shift
 261         OPTARG="$1"
 262         shift
 263
 264         case "$ARG" in
 265         -d)
 266                 tempdir="$OPTARG"
 267                 ;;
 268         -r)
 269                 unchanged="$(get_parents "$OPTARG") $unchanged"
 270                 ;;
 271         -k)
 272                 unchanged="$(git-rev-parse "$OPTARG"^{commit}) $unchanged"
 273                 ;;
 274         --env-filter)
 275                 filter_env="$OPTARG"
 276                 ;;
 277         --tree-filter)
 278                 filter_tree="$OPTARG"
 279                 ;;
 280         --index-filter)
 281                 filter_index="$OPTARG"
 282                 ;;
 283         --parent-filter)
 284                 filter_parent="$OPTARG"
 285                 ;;
 286         --msg-filter)
 287                 filter_msg="$OPTARG"
 288                 ;;
 289         --commit-filter)
 290                 filter_commit="$OPTARG"
 291                 ;;
 292         --tag-name-filter)
 293                 filter_tag_name="$OPTARG"
 294                 ;;
 295         -s)
 296                 srcbranch="$OPTARG"
 297                 ;;
 298         *)
 299                 usage
 300                 ;;
 301         esac
 302 done
 303
 304 dstbranch="$1"
 305 test -n "$dstbranch" || die "missing branch name"
 306 git-show-ref "refs/heads/$dstbranch" 2> /dev/null &&
 307         die "branch $dstbranch already exists"
 308
 309 test ! -e "$tempdir" || die "$tempdir already exists, please remove it"
 310 mkdir -p "$tempdir/t"
 311 cd "$tempdir/t"
 312 workdir="$(pwd)"
 313
 314 case "$GIT_DIR" in
 315 /*)
 316         ;;
 317 *)
 318         export GIT_DIR="$(pwd)/../../$GIT_DIR"
 319         ;;
 320 esac
 321
 322 export GIT_INDEX_FILE="$(pwd)/../index"
 323 git-read-tree # seed the index file
 324
 325 ret=0
 326
 327
 328 mkdir ../map # map old->new commit ids for rewriting parents
 329
 330 # seed with identity mappings for the parents where we start off
 331 for commit in $unchanged; do
 332         echo $commit > ../map/$commit
 333 done
 334
 335 git-rev-list --reverse --topo-order $srcbranch --not $unchanged >../revs
 336 commits=$(cat ../revs | wc -l | tr -d " ")
 337
 338 test $commits -eq 0 && die "Found nothing to rewrite"
 339
 340 i=0
 341 while read commit; do
 342         i=$((i+1))
 343         printf "$commit ($i/$commits) "
 344
 345         git-read-tree -i -m $commit
 346
 347         export GIT_COMMIT=$commit
 348         git-cat-file commit "$commit" >../commit
 349
 350         eval "$(set_ident AUTHOR <../commit)"
 351         eval "$(set_ident COMMITTER <../commit)"
 352         eval "$filter_env" < /dev/null
 353
 354         if [ "$filter_tree" ]; then
 355                 git-checkout-index -f -u -a
 356                 # files that $commit removed are now still in the working tree;
 357                 # remove them, else they would be added again
 358                 git-ls-files -z --others | xargs -0 rm -f
 359                 eval "$filter_tree" < /dev/null
 360                 git-diff-index -r $commit | cut -f 2- | tr '\n' '\0' | \
 361                         xargs -0 git-update-index --add --replace --remove
 362                 git-ls-files -z --others | \
 363                         xargs -0 git-update-index --add --replace --remove
 364         fi
 365
 366         eval "$filter_index" < /dev/null
 367
 368         parentstr=
 369         for parent in $(get_parents $commit); do
 370                 if [ -r "../map/$parent" ]; then
 371                         for reparent in $(cat "../map/$parent"); do
 372                                 parentstr="$parentstr -p $reparent"
 373                         done
 374                 else
 375                         die "assertion failed: parent $parent for commit $commit not found in rewritten ones"
 376                 fi
 377         done
 378         if [ "$filter_parent" ]; then
 379                 parentstr="$(echo "$parentstr" | eval "$filter_parent")"
 380         fi
 381
 382         sed -e '1,/^$/d' <../commit | \
 383                 eval "$filter_msg" | \
 384                 sh -c "$filter_commit" git-commit-tree $(git-write-tree) $parentstr | \
 385                 tee ../map/$commit
 386 done <../revs
 387
 388 git-update-ref refs/heads/"$dstbranch" $(head -n 1 ../map/$(tail -n 1 ../revs))
 389 if [ "$(cat ../map/$(tail -n 1 ../revs) | wc -l)" -gt 1 ]; then
 390         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 $dstbranch head but you will need to resolve the situation now (probably by manually merging the other commits). These are all the commits:" >&2
 391         sed 's/^/       /' ../map/$(tail -n 1 ../revs) >&2
 392         ret=1
 393 fi
 394
 395 if [ "$filter_tag_name" ]; then
 396         git-for-each-ref --format='%(objectname) %(objecttype) %(refname)' refs/tags |
 397         while read sha1 type ref; do
 398                 ref="${ref#refs/tags/}"
 399                 # XXX: Rewrite tagged trees as well?
 400                 if [ "$type" != "commit" -a "$type" != "tag" ]; then
 401                         continue;
 402                 fi
 403
 404                 if [ "$type" = "tag" ]; then
 405                         # Dereference to a commit
 406                         sha1t="$sha1"
 407                         sha1="$(git-rev-parse "$sha1"^{commit} 2>/dev/null)" || continue
 408                 fi
 409
 410                 [ -f "../map/$sha1" ] || continue
 411                 new_sha1="$(cat "../map/$sha1")"
 412                 export GIT_COMMIT="$sha1"
 413                 new_ref="$(echo "$ref" | eval "$filter_tag_name")"
 414
 415                 echo "$ref -> $new_ref ($sha1 -> $new_sha1)"
 416
 417                 if [ "$type" = "tag" ]; then
 418                         # Warn that we are not rewriting the tag object itself.
 419                         warn "unreferencing tag object $sha1t"
 420                 fi
 421
 422                 git-update-ref "refs/tags/$new_ref" "$new_sha1"
 423         done
 424 fi
 425
 426 cd ../..
 427 rm -rf "$tempdir"
 428 echo "Rewritten history saved to the $dstbranch branch"
 429
 430 exit $ret