1#!/bin/bash
2#
3# git-subtree.sh: split/join git repositories in subdirectories of this one
4#
5# Copyright (C) 2009 Avery Pennarun <apenwarr@gmail.com>
6#
7if [ $# -eq 0 ]; then
8 set -- -h
9fi
10OPTS_SPEC="\
11git subtree add --prefix=<prefix> <commit>
12git subtree merge --prefix=<prefix> <commit>
13git subtree pull --prefix=<prefix> <repository> <refspec...>
14git subtree push --prefix=<prefix> <repository> <refspec...>
15git subtree split --prefix=<prefix> <commit...>
16--
17h,help show the help
18q quiet
19d show debug messages
20P,prefix= the name of the subdir to split out
21m,message= use the given message as the commit message for the merge commit
22 options for 'split'
23annotate= add a prefix to commit message of new commits
24b,branch= create a new branch from the split subtree
25ignore-joins ignore prior --rejoin commits
26onto= try connecting new tree to an existing one
27rejoin merge the new branch back into HEAD
28 options for 'add', 'merge', 'pull' and 'push'
29squash merge subtree changes as a single commit
30"
31eval "$(echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?)"
32
33PATH=$PATH:$(git --exec-path)
34. git-sh-setup
35
36require_work_tree
37
38quiet=
39branch=
40debug=
41command=
42onto=
43rejoin=
44ignore_joins=
45annotate=
46squash=
47message=
48
49debug()
50{
51 if [ -n "$debug" ]; then
52 echo "$@" >&2
53 fi
54}
55
56say()
57{
58 if [ -z "$quiet" ]; then
59 echo "$@" >&2
60 fi
61}
62
63assert()
64{
65 if "$@"; then
66 :
67 else
68 die "assertion failed: " "$@"
69 fi
70}
71
72
73#echo "Options: $*"
74
75while [ $# -gt 0 ]; do
76 opt="$1"
77 shift
78 case "$opt" in
79 -q) quiet=1 ;;
80 -d) debug=1 ;;
81 --annotate) annotate="$1"; shift ;;
82 --no-annotate) annotate= ;;
83 -b) branch="$1"; shift ;;
84 -P) prefix="$1"; shift ;;
85 -m) message="$1"; shift ;;
86 --no-prefix) prefix= ;;
87 --onto) onto="$1"; shift ;;
88 --no-onto) onto= ;;
89 --rejoin) rejoin=1 ;;
90 --no-rejoin) rejoin= ;;
91 --ignore-joins) ignore_joins=1 ;;
92 --no-ignore-joins) ignore_joins= ;;
93 --squash) squash=1 ;;
94 --no-squash) squash= ;;
95 --) break ;;
96 *) die "Unexpected option: $opt" ;;
97 esac
98done
99
100command="$1"
101shift
102case "$command" in
103 add|merge|pull) default= ;;
104 split|push) default="--default HEAD" ;;
105 *) die "Unknown command '$command'" ;;
106esac
107
108if [ -z "$prefix" ]; then
109 die "You must provide the --prefix option."
110fi
111
112case "$command" in
113 add) [ -e "$prefix" ] &&
114 die "prefix '$prefix' already exists." ;;
115 *) [ -e "$prefix" ] ||
116 die "'$prefix' does not exist; use 'git subtree add'" ;;
117esac
118
119dir="$(dirname "$prefix/.")"
120
121if [ "$command" != "pull" -a "$command" != "add" -a "$command" != "push" ]; then
122 revs=$(git rev-parse $default --revs-only "$@") || exit $?
123 dirs="$(git rev-parse --no-revs --no-flags "$@")" || exit $?
124 if [ -n "$dirs" ]; then
125 die "Error: Use --prefix instead of bare filenames."
126 fi
127fi
128
129debug "command: {$command}"
130debug "quiet: {$quiet}"
131debug "revs: {$revs}"
132debug "dir: {$dir}"
133debug "opts: {$*}"
134debug
135
136cache_setup()
137{
138 cachedir="$GIT_DIR/subtree-cache/$$"
139 rm -rf "$cachedir" || die "Can't delete old cachedir: $cachedir"
140 mkdir -p "$cachedir" || die "Can't create new cachedir: $cachedir"
141 mkdir -p "$cachedir/notree" || die "Can't create new cachedir: $cachedir/notree"
142 debug "Using cachedir: $cachedir" >&2
143}
144
145cache_get()
146{
147 for oldrev in $*; do
148 if [ -r "$cachedir/$oldrev" ]; then
149 read newrev <"$cachedir/$oldrev"
150 echo $newrev
151 fi
152 done
153}
154
155cache_miss()
156{
157 for oldrev in $*; do
158 if [ ! -r "$cachedir/$oldrev" ]; then
159 echo $oldrev
160 fi
161 done
162}
163
164check_parents()
165{
166 missed=$(cache_miss $*)
167 for miss in $missed; do
168 if [ ! -r "$cachedir/notree/$miss" ]; then
169 debug " incorrect order: $miss"
170 fi
171 done
172}
173
174set_notree()
175{
176 echo "1" > "$cachedir/notree/$1"
177}
178
179cache_set()
180{
181 oldrev="$1"
182 newrev="$2"
183 if [ "$oldrev" != "latest_old" \
184 -a "$oldrev" != "latest_new" \
185 -a -e "$cachedir/$oldrev" ]; then
186 die "cache for $oldrev already exists!"
187 fi
188 echo "$newrev" >"$cachedir/$oldrev"
189}
190
191rev_exists()
192{
193 if git rev-parse "$1" >/dev/null 2>&1; then
194 return 0
195 else
196 return 1
197 fi
198}
199
200rev_is_descendant_of_branch()
201{
202 newrev="$1"
203 branch="$2"
204 branch_hash=$(git rev-parse $branch)
205 match=$(git rev-list -1 $branch_hash ^$newrev)
206
207 if [ -z "$match" ]; then
208 return 0
209 else
210 return 1
211 fi
212}
213
214# if a commit doesn't have a parent, this might not work. But we only want
215# to remove the parent from the rev-list, and since it doesn't exist, it won't
216# be there anyway, so do nothing in that case.
217try_remove_previous()
218{
219 if rev_exists "$1^"; then
220 echo "^$1^"
221 fi
222}
223
224find_latest_squash()
225{
226 debug "Looking for latest squash ($dir)..."
227 dir="$1"
228 sq=
229 main=
230 sub=
231 git log --grep="^git-subtree-dir: $dir/*\$" \
232 --pretty=format:'START %H%n%s%n%n%b%nEND%n' HEAD |
233 while read a b junk; do
234 debug "$a $b $junk"
235 debug "{{$sq/$main/$sub}}"
236 case "$a" in
237 START) sq="$b" ;;
238 git-subtree-mainline:) main="$b" ;;
239 git-subtree-split:) sub="$b" ;;
240 END)
241 if [ -n "$sub" ]; then
242 if [ -n "$main" ]; then
243 # a rejoin commit?
244 # Pretend its sub was a squash.
245 sq="$sub"
246 fi
247 debug "Squash found: $sq $sub"
248 echo "$sq" "$sub"
249 break
250 fi
251 sq=
252 main=
253 sub=
254 ;;
255 esac
256 done
257}
258
259find_existing_splits()
260{
261 debug "Looking for prior splits..."
262 dir="$1"
263 revs="$2"
264 main=
265 sub=
266 git log --grep="^git-subtree-dir: $dir/*\$" \
267 --pretty=format:'START %H%n%s%n%n%b%nEND%n' $revs |
268 while read a b junk; do
269 case "$a" in
270 START) sq="$b" ;;
271 git-subtree-mainline:) main="$b" ;;
272 git-subtree-split:) sub="$b" ;;
273 END)
274 debug " Main is: '$main'"
275 if [ -z "$main" -a -n "$sub" ]; then
276 # squash commits refer to a subtree
277 debug " Squash: $sq from $sub"
278 cache_set "$sq" "$sub"
279 fi
280 if [ -n "$main" -a -n "$sub" ]; then
281 debug " Prior: $main -> $sub"
282 cache_set $main $sub
283 cache_set $sub $sub
284 try_remove_previous "$main"
285 try_remove_previous "$sub"
286 fi
287 main=
288 sub=
289 ;;
290 esac
291 done
292}
293
294copy_commit()
295{
296 # We're going to set some environment vars here, so
297 # do it in a subshell to get rid of them safely later
298 debug copy_commit "{$1}" "{$2}" "{$3}"
299 git log -1 --pretty=format:'%an%n%ae%n%ad%n%cn%n%ce%n%cd%n%s%n%n%b' "$1" |
300 (
301 read GIT_AUTHOR_NAME
302 read GIT_AUTHOR_EMAIL
303 read GIT_AUTHOR_DATE
304 read GIT_COMMITTER_NAME
305 read GIT_COMMITTER_EMAIL
306 read GIT_COMMITTER_DATE
307 export GIT_AUTHOR_NAME \
308 GIT_AUTHOR_EMAIL \
309 GIT_AUTHOR_DATE \
310 GIT_COMMITTER_NAME \
311 GIT_COMMITTER_EMAIL \
312 GIT_COMMITTER_DATE
313 (echo -n "$annotate"; cat ) |
314 git commit-tree "$2" $3 # reads the rest of stdin
315 ) || die "Can't copy commit $1"
316}
317
318add_msg()
319{
320 dir="$1"
321 latest_old="$2"
322 latest_new="$3"
323 if [ -n "$message" ]; then
324 commit_message="$message"
325 else
326 commit_message="Add '$dir/' from commit '$latest_new'"
327 fi
328 cat <<-EOF
329 $commit_message
330
331 git-subtree-dir: $dir
332 git-subtree-mainline: $latest_old
333 git-subtree-split: $latest_new
334 EOF
335}
336
337add_squashed_msg()
338{
339 if [ -n "$message" ]; then
340 echo "$message"
341 else
342 echo "Merge commit '$1' as '$2'"
343 fi
344}
345
346rejoin_msg()
347{
348 dir="$1"
349 latest_old="$2"
350 latest_new="$3"
351 if [ -n "$message" ]; then
352 commit_message="$message"
353 else
354 commit_message="Split '$dir/' into commit '$latest_new'"
355 fi
356 cat <<-EOF
357 $commit_message
358
359 git-subtree-dir: $dir
360 git-subtree-mainline: $latest_old
361 git-subtree-split: $latest_new
362 EOF
363}
364
365squash_msg()
366{
367 dir="$1"
368 oldsub="$2"
369 newsub="$3"
370 newsub_short=$(git rev-parse --short "$newsub")
371
372 if [ -n "$oldsub" ]; then
373 oldsub_short=$(git rev-parse --short "$oldsub")
374 echo "Squashed '$dir/' changes from $oldsub_short..$newsub_short"
375 echo
376 git log --pretty=tformat:'%h %s' "$oldsub..$newsub"
377 git log --pretty=tformat:'REVERT: %h %s' "$newsub..$oldsub"
378 else
379 echo "Squashed '$dir/' content from commit $newsub_short"
380 fi
381
382 echo
383 echo "git-subtree-dir: $dir"
384 echo "git-subtree-split: $newsub"
385}
386
387toptree_for_commit()
388{
389 commit="$1"
390 git log -1 --pretty=format:'%T' "$commit" -- || exit $?
391}
392
393subtree_for_commit()
394{
395 commit="$1"
396 dir="$2"
397 git ls-tree "$commit" -- "$dir" |
398 while read mode type tree name; do
399 assert [ "$name" = "$dir" ]
400 assert [ "$type" = "tree" -o "$type" = "commit" ]
401 echo $tree
402 break
403 done
404}
405
406tree_changed()
407{
408 tree=$1
409 shift
410 if [ $# -ne 1 ]; then
411 return 0 # weird parents, consider it changed
412 else
413 ptree=$(toptree_for_commit $1)
414 if [ "$ptree" != "$tree" ]; then
415 return 0 # changed
416 else
417 return 1 # not changed
418 fi
419 fi
420}
421
422new_squash_commit()
423{
424 old="$1"
425 oldsub="$2"
426 newsub="$3"
427 tree=$(toptree_for_commit $newsub) || exit $?
428 if [ -n "$old" ]; then
429 squash_msg "$dir" "$oldsub" "$newsub" |
430 git commit-tree "$tree" -p "$old" || exit $?
431 else
432 squash_msg "$dir" "" "$newsub" |
433 git commit-tree "$tree" || exit $?
434 fi
435}
436
437copy_or_skip()
438{
439 rev="$1"
440 tree="$2"
441 newparents="$3"
442 assert [ -n "$tree" ]
443
444 identical=
445 nonidentical=
446 p=
447 gotparents=
448 for parent in $newparents; do
449 ptree=$(toptree_for_commit $parent) || exit $?
450 [ -z "$ptree" ] && continue
451 if [ "$ptree" = "$tree" ]; then
452 # an identical parent could be used in place of this rev.
453 identical="$parent"
454 else
455 nonidentical="$parent"
456 fi
457
458 # sometimes both old parents map to the same newparent;
459 # eliminate duplicates
460 is_new=1
461 for gp in $gotparents; do
462 if [ "$gp" = "$parent" ]; then
463 is_new=
464 break
465 fi
466 done
467 if [ -n "$is_new" ]; then
468 gotparents="$gotparents $parent"
469 p="$p -p $parent"
470 fi
471 done
472
473 if [ -n "$identical" ]; then
474 echo $identical
475 else
476 copy_commit $rev $tree "$p" || exit $?
477 fi
478}
479
480ensure_clean()
481{
482 if ! git diff-index HEAD --exit-code --quiet 2>&1; then
483 die "Working tree has modifications. Cannot add."
484 fi
485 if ! git diff-index --cached HEAD --exit-code --quiet 2>&1; then
486 die "Index has modifications. Cannot add."
487 fi
488}
489
490cmd_add()
491{
492 if [ -e "$dir" ]; then
493 die "'$dir' already exists. Cannot add."
494 fi
495
496 ensure_clean
497
498 if [ $# -eq 1 ]; then
499 "cmd_add_commit" "$@"
500 elif [ $# -eq 2 ]; then
501 "cmd_add_repository" "$@"
502 else
503 say "error: parameters were '$@'"
504 die "Provide either a refspec or a repository and refspec."
505 fi
506}
507
508cmd_add_repository()
509{
510 echo "git fetch" "$@"
511 repository=$1
512 refspec=$2
513 git fetch "$@" || exit $?
514 revs=FETCH_HEAD
515 set -- $revs
516 cmd_add_commit "$@"
517}
518
519cmd_add_commit()
520{
521 revs=$(git rev-parse $default --revs-only "$@") || exit $?
522 set -- $revs
523 rev="$1"
524
525 debug "Adding $dir as '$rev'..."
526 git read-tree --prefix="$dir" $rev || exit $?
527 git checkout -- "$dir" || exit $?
528 tree=$(git write-tree) || exit $?
529
530 headrev=$(git rev-parse HEAD) || exit $?
531 if [ -n "$headrev" -a "$headrev" != "$rev" ]; then
532 headp="-p $headrev"
533 else
534 headp=
535 fi
536
537 if [ -n "$squash" ]; then
538 rev=$(new_squash_commit "" "" "$rev") || exit $?
539 commit=$(add_squashed_msg "$rev" "$dir" |
540 git commit-tree $tree $headp -p "$rev") || exit $?
541 else
542 commit=$(add_msg "$dir" "$headrev" "$rev" |
543 git commit-tree $tree $headp -p "$rev") || exit $?
544 fi
545 git reset "$commit" || exit $?
546
547 say "Added dir '$dir'"
548}
549
550cmd_split()
551{
552 debug "Splitting $dir..."
553 cache_setup || exit $?
554
555 if [ -n "$onto" ]; then
556 debug "Reading history for --onto=$onto..."
557 git rev-list $onto |
558 while read rev; do
559 # the 'onto' history is already just the subdir, so
560 # any parent we find there can be used verbatim
561 debug " cache: $rev"
562 cache_set $rev $rev
563 done
564 fi
565
566 if [ -n "$ignore_joins" ]; then
567 unrevs=
568 else
569 unrevs="$(find_existing_splits "$dir" "$revs")"
570 fi
571
572 # We can't restrict rev-list to only $dir here, because some of our
573 # parents have the $dir contents the root, and those won't match.
574 # (and rev-list --follow doesn't seem to solve this)
575 grl='git rev-list --topo-order --reverse --parents $revs $unrevs'
576 revmax=$(eval "$grl" | wc -l)
577 revcount=0
578 createcount=0
579 eval "$grl" |
580 while read rev parents; do
581 revcount=$(($revcount + 1))
582 say -n "$revcount/$revmax ($createcount)
"
583 debug "Processing commit: $rev"
584 exists=$(cache_get $rev)
585 if [ -n "$exists" ]; then
586 debug " prior: $exists"
587 continue
588 fi
589 createcount=$(($createcount + 1))
590 debug " parents: $parents"
591 newparents=$(cache_get $parents)
592 debug " newparents: $newparents"
593
594 tree=$(subtree_for_commit $rev "$dir")
595 debug " tree is: $tree"
596
597 check_parents $parents
598
599 # ugly. is there no better way to tell if this is a subtree
600 # vs. a mainline commit? Does it matter?
601 if [ -z $tree ]; then
602 set_notree $rev
603 if [ -n "$newparents" ]; then
604 cache_set $rev $rev
605 fi
606 continue
607 fi
608
609 newrev=$(copy_or_skip "$rev" "$tree" "$newparents") || exit $?
610 debug " newrev is: $newrev"
611 cache_set $rev $newrev
612 cache_set latest_new $newrev
613 cache_set latest_old $rev
614 done || exit $?
615 latest_new=$(cache_get latest_new)
616 if [ -z "$latest_new" ]; then
617 die "No new revisions were found"
618 fi
619
620 if [ -n "$rejoin" ]; then
621 debug "Merging split branch into HEAD..."
622 latest_old=$(cache_get latest_old)
623 git merge -s ours \
624 -m "$(rejoin_msg $dir $latest_old $latest_new)" \
625 $latest_new >&2 || exit $?
626 fi
627 if [ -n "$branch" ]; then
628 if rev_exists "refs/heads/$branch"; then
629 if ! rev_is_descendant_of_branch $latest_new $branch; then
630 die "Branch '$branch' is not an ancestor of commit '$latest_new'."
631 fi
632 action='Updated'
633 else
634 action='Created'
635 fi
636 git update-ref -m 'subtree split' "refs/heads/$branch" $latest_new || exit $?
637 say "$action branch '$branch'"
638 fi
639 echo $latest_new
640 exit 0
641}
642
643cmd_merge()
644{
645 revs=$(git rev-parse $default --revs-only "$@") || exit $?
646 ensure_clean
647
648 set -- $revs
649 if [ $# -ne 1 ]; then
650 die "You must provide exactly one revision. Got: '$revs'"
651 fi
652 rev="$1"
653
654 if [ -n "$squash" ]; then
655 first_split="$(find_latest_squash "$dir")"
656 if [ -z "$first_split" ]; then
657 die "Can't squash-merge: '$dir' was never added."
658 fi
659 set $first_split
660 old=$1
661 sub=$2
662 if [ "$sub" = "$rev" ]; then
663 say "Subtree is already at commit $rev."
664 exit 0
665 fi
666 new=$(new_squash_commit "$old" "$sub" "$rev") || exit $?
667 debug "New squash commit: $new"
668 rev="$new"
669 fi
670
671 version=$(git version)
672 if [ "$version" \< "git version 1.7" ]; then
673 if [ -n "$message" ]; then
674 git merge -s subtree --message="$message" $rev
675 else
676 git merge -s subtree $rev
677 fi
678 else
679 if [ -n "$message" ]; then
680 git merge -Xsubtree="$prefix" --message="$message" $rev
681 else
682 git merge -Xsubtree="$prefix" $rev
683 fi
684 fi
685}
686
687cmd_pull()
688{
689 ensure_clean
690 git fetch "$@" || exit $?
691 revs=FETCH_HEAD
692 set -- $revs
693 cmd_merge "$@"
694}
695
696cmd_push()
697{
698 if [ $# -ne 2 ]; then
699 die "You must provide <repository> <refspec>"
700 fi
701 if [ -e "$dir" ]; then
702 repository=$1
703 refspec=$2
704 echo "git push using: " $repository $refspec
705 git push $repository $(git subtree split --prefix=$prefix):refs/heads/$refspec
706 else
707 die "'$dir' must already exist. Try 'git subtree add'."
708 fi
709}
710
711"cmd_$command" "$@"