summaryrefslogtreecommitdiff
path: root/contrib/subtree/git-subtree.sh
blob: d1ed7f9a6ce016c9fca2189c6c4f94b510c0b124 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
#!/bin/sh
#
# git-subtree.sh: split/join git repositories in subdirectories of this one
#
# Copyright (C) 2009 Avery Pennarun <apenwarr@gmail.com>
#
 
OPTS_SPEC="\
git subtree add   --prefix=<prefix> <commit>
git subtree add   --prefix=<prefix> <repository> <ref>
git subtree merge --prefix=<prefix> <commit>
git subtree pull  --prefix=<prefix> <repository> <ref>
git subtree push  --prefix=<prefix> <repository> <ref>
git subtree split --prefix=<prefix> <commit>
--
h,help        show the help
q             quiet
d             show debug messages
P,prefix=     the name of the subdir to split out
m,message=    use the given message as the commit message for the merge commit
 options for 'split'
annotate=     add a prefix to commit message of new commits
b,branch=     create a new branch from the split subtree
ignore-joins  ignore prior --rejoin commits
onto=         try connecting new tree to an existing one
rejoin        merge the new branch back into HEAD
 options for 'add', 'merge', and 'pull'
squash        merge subtree changes as a single commit
"
 
PATH=$PATH:$(git --exec-path)
 
quiet=
branch=
debug=
command=
onto=
rejoin=
ignore_joins=
annotate=
squash=
message=
prefix=
 
debug () {
	if test -n "$debug"
	then
		printf "%s\n" "$*" >&2
	fi
}
 
say () {
	if test -z "$quiet"
	then
		printf "%s\n" "$*" >&2
	fi
}
 
progress () {
	if test -z "$quiet"
	then
		printf "%s\r" "$*" >&2
	fi
}
 
assert () {
	if ! "$@"
	then
		die "assertion failed: " "$@"
	fi
}
 
ensure_single_rev () {
	if test $# -ne 1
	then
		die "You must provide exactly one revision.  Got: '$@'"
	fi
}
 
main () {
	if test $# -eq 0
	then
		set -- -h
	fi
	eval "$(echo "$OPTS_SPEC" | git rev-parse --parseopt -- "$@" || echo exit $?)"
	. git-sh-setup
	require_work_tree
 
	while test $# -gt 0
	do
		opt="$1"
		shift
 
		case "$opt" in
		-q)
			quiet=1
			;;
		-d)
			debug=1
			;;
		--annotate)
			annotate="$1"
			shift
			;;
		--no-annotate)
			annotate=
			;;
		-b)
			branch="$1"
			shift
			;;
		-P)
			prefix="${1%/}"
			shift
			;;
		-m)
			message="$1"
			shift
			;;
		--no-prefix)
			prefix=
			;;
		--onto)
			onto="$1"
			shift
			;;
		--no-onto)
			onto=
			;;
		--rejoin)
			rejoin=1
			;;
		--no-rejoin)
			rejoin=
			;;
		--ignore-joins)
			ignore_joins=1
			;;
		--no-ignore-joins)
			ignore_joins=
			;;
		--squash)
			squash=1
			;;
		--no-squash)
			squash=
			;;
		--)
			break
			;;
		*)
			die "Unexpected option: $opt"
			;;
		esac
	done
 
	command="$1"
	shift
 
	case "$command" in
	add|merge|pull)
		default=
		;;
	split|push)
		default="--default HEAD"
		;;
	*)
		die "Unknown command '$command'"
		;;
	esac
 
	if test -z "$prefix"
	then
		die "You must provide the --prefix option."
	fi
 
	case "$command" in
	add)
		test -e "$prefix" &&
			die "prefix '$prefix' already exists."
		;;
	*)
		test -e "$prefix" ||
			die "'$prefix' does not exist; use 'git subtree add'"
		;;
	esac
 
	dir="$(dirname "$prefix/.")"
 
	if test "$command" != "pull" &&
			test "$command" != "add" &&
			test "$command" != "push"
	then
		revs=$(git rev-parse $default --revs-only "$@") || exit $?
		dirs=$(git rev-parse --no-revs --no-flags "$@") || exit $?
		ensure_single_rev $revs
		if test -n "$dirs"
		then
			die "Error: Use --prefix instead of bare filenames."
		fi
	fi
 
	debug "command: {$command}"
	debug "quiet: {$quiet}"
	debug "revs: {$revs}"
	debug "dir: {$dir}"
	debug "opts: {$*}"
	debug
 
	"cmd_$command" "$@"
}
 
cache_setup () {
	cachedir="$GIT_DIR/subtree-cache/$$"
	rm -rf "$cachedir" ||
		die "Can't delete old cachedir: $cachedir"
	mkdir -p "$cachedir" ||
		die "Can't create new cachedir: $cachedir"
	mkdir -p "$cachedir/notree" ||
		die "Can't create new cachedir: $cachedir/notree"
	debug "Using cachedir: $cachedir" >&2
}
 
cache_get () {
	for oldrev in "$@"
	do
		if test -r "$cachedir/$oldrev"
		then
			read newrev <"$cachedir/$oldrev"
			echo $newrev
		fi
	done
}
 
cache_miss () {
	for oldrev in "$@"
	do
		if ! test -r "$cachedir/$oldrev"
		then
			echo $oldrev
		fi
	done
}
 
check_parents () {
	missed=$(cache_miss "$1")
	local indent=$(($2 + 1))
	for miss in $missed
	do
		if ! test -r "$cachedir/notree/$miss"
		then
			debug "  incorrect order: $miss"
			process_split_commit "$miss" "" "$indent"
		fi
	done
}
 
set_notree () {
	echo "1" > "$cachedir/notree/$1"
}
 
cache_set () {
	oldrev="$1"
	newrev="$2"
	if test "$oldrev" != "latest_old" &&
		test "$oldrev" != "latest_new" &&
		test -e "$cachedir/$oldrev"
	then
		die "cache for $oldrev already exists!"
	fi
	echo "$newrev" >"$cachedir/$oldrev"
}
 
rev_exists () {
	if git rev-parse "$1" >/dev/null 2>&1
	then
		return 0
	else
		return 1
	fi
}
 
rev_is_descendant_of_branch () {
	newrev="$1"
	branch="$2"
	branch_hash=$(git rev-parse "$branch")
	match=$(git rev-list -1 "$branch_hash" "^$newrev")
 
	if test -z "$match"
	then
		return 0
	else
		return 1
	fi
}
 
# if a commit doesn't have a parent, this might not work.  But we only want
# to remove the parent from the rev-list, and since it doesn't exist, it won't
# be there anyway, so do nothing in that case.
try_remove_previous () {
	if rev_exists "$1^"
	then
		echo "^$1^"
	fi
}
 
find_latest_squash () {
	debug "Looking for latest squash ($dir)..."
	dir="$1"
	sq=
	main=
	sub=
	git log --grep="^git-subtree-dir: $dir/*\$" \
		--no-show-signature --pretty=format:'START %H%n%s%n%n%b%nEND%n' HEAD |
	while read a b junk
	do
		debug "$a $b $junk"
		debug "{{$sq/$main/$sub}}"
		case "$a" in
		START)
			sq="$b"
			;;
		git-subtree-mainline:)
			main="$b"
			;;
		git-subtree-split:)
			sub="$(git rev-parse "$b^0")" ||
			die "could not rev-parse split hash $b from commit $sq"
			;;
		END)
			if test -n "$sub"
			then
				if test -n "$main"
				then
					# a rejoin commit?
					# Pretend its sub was a squash.
					sq="$sub"
				fi
				debug "Squash found: $sq $sub"
				echo "$sq" "$sub"
				break
			fi
			sq=
			main=
			sub=
			;;
		esac
	done
}
 
find_existing_splits () {
	debug "Looking for prior splits..."
	dir="$1"
	revs="$2"
	main=
	sub=
	local grep_format="^git-subtree-dir: $dir/*\$"
	if test -n "$ignore_joins"
	then
		grep_format="^Add '$dir/' from commit '"
	fi
	git log --grep="$grep_format" \
		--no-show-signature --pretty=format:'START %H%n%s%n%n%b%nEND%n' $revs |
	while read a b junk
	do
		case "$a" in
		START)
			sq="$b"
			;;
		git-subtree-mainline:)
			main="$b"
			;;
		git-subtree-split:)
			sub="$(git rev-parse "$b^0")" ||
			die "could not rev-parse split hash $b from commit $sq"
			;;
		END)
			debug "  Main is: '$main'"
			if test -z "$main" -a -n "$sub"
			then
				# squash commits refer to a subtree
				debug "  Squash: $sq from $sub"
				cache_set "$sq" "$sub"
			fi
			if test -n "$main" -a -n "$sub"
			then
				debug "  Prior: $main -> $sub"
				cache_set $main $sub
				cache_set $sub $sub
				try_remove_previous "$main"
				try_remove_previous "$sub"
			fi
			main=
			sub=
			;;
		esac
	done
}
 
copy_commit () {
	# We're going to set some environment vars here, so
	# do it in a subshell to get rid of them safely later
	debug copy_commit "{$1}" "{$2}" "{$3}"
	git log -1 --no-show-signature --pretty=format:'%an%n%ae%n%aD%n%cn%n%ce%n%cD%n%B' "$1" |
	(
		read GIT_AUTHOR_NAME
		read GIT_AUTHOR_EMAIL
		read GIT_AUTHOR_DATE
		read GIT_COMMITTER_NAME
		read GIT_COMMITTER_EMAIL
		read GIT_COMMITTER_DATE
		export  GIT_AUTHOR_NAME \
			GIT_AUTHOR_EMAIL \
			GIT_AUTHOR_DATE \
			GIT_COMMITTER_NAME \
			GIT_COMMITTER_EMAIL \
			GIT_COMMITTER_DATE
		(
			printf "%s" "$annotate"
			cat
		) |
		git commit-tree "$2" $3  # reads the rest of stdin
	) || die "Can't copy commit $1"
}
 
add_msg () {
	dir="$1"
	latest_old="$2"
	latest_new="$3"
	if test -n "$message"
	then
		commit_message="$message"
	else
		commit_message="Add '$dir/' from commit '$latest_new'"
	fi
	cat <<-EOF
		$commit_message
 
		git-subtree-dir: $dir
		git-subtree-mainline: $latest_old
		git-subtree-split: $latest_new
	EOF
}
 
add_squashed_msg () {
	if test -n "$message"
	then
		echo "$message"
	else
		echo "Merge commit '$1' as '$2'"
	fi
}
 
rejoin_msg () {
	dir="$1"
	latest_old="$2"
	latest_new="$3"
	if test -n "$message"
	then
		commit_message="$message"
	else
		commit_message="Split '$dir/' into commit '$latest_new'"
	fi
	cat <<-EOF
		$commit_message
 
		git-subtree-dir: $dir
		git-subtree-mainline: $latest_old
		git-subtree-split: $latest_new
	EOF
}
 
squash_msg () {
	dir="$1"
	oldsub="$2"
	newsub="$3"
	newsub_short=$(git rev-parse --short "$newsub")
 
	if test -n "$oldsub"
	then
		oldsub_short=$(git rev-parse --short "$oldsub")
		echo "Squashed '$dir/' changes from $oldsub_short..$newsub_short"
		echo
		git log --no-show-signature --pretty=tformat:'%h %s' "$oldsub..$newsub"
		git log --no-show-signature --pretty=tformat:'REVERT: %h %s' "$newsub..$oldsub"
	else
		echo "Squashed '$dir/' content from commit $newsub_short"
	fi
 
	echo
	echo "git-subtree-dir: $dir"
	echo "git-subtree-split: $newsub"
}
 
toptree_for_commit () {
	commit="$1"
	git rev-parse --verify "$commit^{tree}" || exit $?
}
 
subtree_for_commit () {
	commit="$1"
	dir="$2"
	git ls-tree "$commit" -- "$dir" |
	while read mode type tree name
	do
		assert test "$name" = "$dir"
		assert test "$type" = "tree" -o "$type" = "commit"
		test "$type" = "commit" && continue  # ignore submodules
		echo $tree
		break
	done
}
 
tree_changed () {
	tree=$1
	shift
	if test $# -ne 1
	then
		return 0   # weird parents, consider it changed
	else
		ptree=$(toptree_for_commit $1)
		if test "$ptree" != "$tree"
		then
			return 0   # changed
		else
			return 1   # not changed
		fi
	fi
}
 
new_squash_commit () {
	old="$1"
	oldsub="$2"
	newsub="$3"
	tree=$(toptree_for_commit $newsub) || exit $?
	if test -n "$old"
	then
		squash_msg "$dir" "$oldsub" "$newsub" |
		git commit-tree "$tree" -p "$old" || exit $?
	else
		squash_msg "$dir" "" "$newsub" |
		git commit-tree "$tree" || exit $?
	fi
}
 
copy_or_skip () {
	rev="$1"
	tree="$2"
	newparents="$3"
	assert test -n "$tree"
 
	identical=
	nonidentical=
	p=
	gotparents=
	copycommit=
	for parent in $newparents
	do
		ptree=$(toptree_for_commit $parent) || exit $?
		test -z "$ptree" && continue
		if test "$ptree" = "$tree"
		then
			# an identical parent could be used in place of this rev.
			if test -n "$identical"
			then
				# if a previous identical parent was found, check whether
				# one is already an ancestor of the other
				mergebase=$(git merge-base $identical $parent)
				if test "$identical" = "$mergebase"
				then
					# current identical commit is an ancestor of parent
					identical="$parent"
				elif test "$parent" != "$mergebase"
				then
					# no common history; commit must be copied
					copycommit=1
				fi
			else
				# first identical parent detected
				identical="$parent"
			fi
		else
			nonidentical="$parent"
		fi
 
		# sometimes both old parents map to the same newparent;
		# eliminate duplicates
		is_new=1
		for gp in $gotparents
		do
			if test "$gp" = "$parent"
			then
				is_new=
				break
			fi
		done
		if test -n "$is_new"
		then
			gotparents="$gotparents $parent"
			p="$p -p $parent"
		fi
	done
 
	if test -n "$identical" && test -n "$nonidentical"
	then
		extras=$(git rev-list --count $identical..$nonidentical)
		if test "$extras" -ne 0
		then
			# we need to preserve history along the other branch
			copycommit=1
		fi
	fi
	if test -n "$identical" && test -z "$copycommit"
	then
		echo $identical
	else
		copy_commit "$rev" "$tree" "$p" || exit $?
	fi
}
 
ensure_clean () {
	if ! git diff-index HEAD --exit-code --quiet 2>&1
	then
		die "Working tree has modifications.  Cannot add."
	fi
	if ! git diff-index --cached HEAD --exit-code --quiet 2>&1
	then
		die "Index has modifications.  Cannot add."
	fi
}
 
ensure_valid_ref_format () {
	git check-ref-format "refs/heads/$1" ||
		die "'$1' does not look like a ref"
}
 
process_split_commit () {
	local rev="$1"
	local parents="$2"
	local indent=$3
 
	if test $indent -eq 0
	then
		revcount=$(($revcount + 1))
	else
		# processing commit without normal parent information;
		# fetch from repo
		parents=$(git rev-parse "$rev^@")
		extracount=$(($extracount + 1))
	fi
 
	progress "$revcount/$revmax ($createcount) [$extracount]"
 
	debug "Processing commit: $rev"
	exists=$(cache_get "$rev")
	if test -n "$exists"
	then
		debug "  prior: $exists"
		return
	fi
	createcount=$(($createcount + 1))
	debug "  parents: $parents"
	check_parents "$parents" "$indent"
	newparents=$(cache_get $parents)
	debug "  newparents: $newparents"
 
	tree=$(subtree_for_commit "$rev" "$dir")
	debug "  tree is: $tree"
 
	# ugly.  is there no better way to tell if this is a subtree
	# vs. a mainline commit?  Does it matter?
	if test -z "$tree"
	then
		set_notree "$rev"
		if test -n "$newparents"
		then
			cache_set "$rev" "$rev"
		fi
		return
	fi
 
	newrev=$(copy_or_skip "$rev" "$tree" "$newparents") || exit $?
	debug "  newrev is: $newrev"
	cache_set "$rev" "$newrev"
	cache_set latest_new "$newrev"
	cache_set latest_old "$rev"
}
 
cmd_add () {
	if test -e "$dir"
	then
		die "'$dir' already exists.  Cannot add."
	fi
 
	ensure_clean
 
	if test $# -eq 1
	then
		git rev-parse -q --verify "$1^{commit}" >/dev/null ||
			die "'$1' does not refer to a commit"
 
		cmd_add_commit "$@"
 
	elif test $# -eq 2
	then
		# Technically we could accept a refspec here but we're
		# just going to turn around and add FETCH_HEAD under the
		# specified directory.  Allowing a refspec might be
		# misleading because we won't do anything with any other
		# branches fetched via the refspec.
		ensure_valid_ref_format "$2"
 
		cmd_add_repository "$@"
	else
		say "error: parameters were '$@'"
		die "Provide either a commit or a repository and commit."
	fi
}
 
cmd_add_repository () {
	echo "git fetch" "$@"
	repository=$1
	refspec=$2
	git fetch "$@" || exit $?
	revs=FETCH_HEAD
	set -- $revs
	cmd_add_commit "$@"
}
 
cmd_add_commit () {
	rev=$(git rev-parse $default --revs-only "$@") || exit $?
	ensure_single_rev $rev
 
	debug "Adding $dir as '$rev'..."
	git read-tree --prefix="$dir" $rev || exit $?
	git checkout -- "$dir" || exit $?
	tree=$(git write-tree) || exit $?
 
	headrev=$(git rev-parse HEAD) || exit $?
	if test -n "$headrev" && test "$headrev" != "$rev"
	then
		headp="-p $headrev"
	else
		headp=
	fi
 
	if test -n "$squash"
	then
		rev=$(new_squash_commit "" "" "$rev") || exit $?
		commit=$(add_squashed_msg "$rev" "$dir" |
			git commit-tree "$tree" $headp -p "$rev") || exit $?
	else
		revp=$(peel_committish "$rev") &&
		commit=$(add_msg "$dir" $headrev "$rev" |
			git commit-tree "$tree" $headp -p "$revp") || exit $?
	fi
	git reset "$commit" || exit $?
 
	say "Added dir '$dir'"
}
 
cmd_split () {
	debug "Splitting $dir..."
	cache_setup || exit $?
 
	if test -n "$onto"
	then
		debug "Reading history for --onto=$onto..."
		git rev-list $onto |
		while read rev
		do
			# the 'onto' history is already just the subdir, so
			# any parent we find there can be used verbatim
			debug "  cache: $rev"
			cache_set "$rev" "$rev"
		done
	fi
 
	unrevs="$(find_existing_splits "$dir" "$revs")"
 
	# We can't restrict rev-list to only $dir here, because some of our
	# parents have the $dir contents the root, and those won't match.
	# (and rev-list --follow doesn't seem to solve this)
	grl='git rev-list --topo-order --reverse --parents $revs $unrevs'
	revmax=$(eval "$grl" | wc -l)
	revcount=0
	createcount=0
	extracount=0
	eval "$grl" |
	while read rev parents
	do
		process_split_commit "$rev" "$parents" 0
	done || exit $?
 
	latest_new=$(cache_get latest_new)
	if test -z "$latest_new"
	then
		die "No new revisions were found"
	fi
 
	if test -n "$rejoin"
	then
		debug "Merging split branch into HEAD..."
		latest_old=$(cache_get latest_old)
		git merge -s ours \
			--allow-unrelated-histories \
			-m "$(rejoin_msg "$dir" "$latest_old" "$latest_new")" \
			"$latest_new" >&2 || exit $?
	fi
	if test -n "$branch"
	then
		if rev_exists "refs/heads/$branch"
		then
			if ! rev_is_descendant_of_branch "$latest_new" "$branch"
			then
				die "Branch '$branch' is not an ancestor of commit '$latest_new'."
			fi
			action='Updated'
		else
			action='Created'
		fi
		git update-ref -m 'subtree split' \
			"refs/heads/$branch" "$latest_new" || exit $?
		say "$action branch '$branch'"
	fi
	echo "$latest_new"
	exit 0
}
 
cmd_merge () {
	rev=$(git rev-parse $default --revs-only "$@") || exit $?
	ensure_single_rev $rev
	ensure_clean
 
	if test -n "$squash"
	then
		first_split="$(find_latest_squash "$dir")"
		if test -z "$first_split"
		then
			die "Can't squash-merge: '$dir' was never added."
		fi
		set $first_split
		old=$1
		sub=$2
		if test "$sub" = "$rev"
		then
			say "Subtree is already at commit $rev."
			exit 0
		fi
		new=$(new_squash_commit "$old" "$sub" "$rev") || exit $?
		debug "New squash commit: $new"
		rev="$new"
	fi
 
	version=$(git version)
	if test "$version" \< "git version 1.7"
	then
		if test -n "$message"
		then
			git merge -s subtree --message="$message" "$rev"
		else
			git merge -s subtree "$rev"
		fi
	else
		if test -n "$message"
		then
			git merge -Xsubtree="$prefix" \
				--message="$message" "$rev"
		else
			git merge -Xsubtree="$prefix" $rev
		fi
	fi
}
 
cmd_pull () {
	if test $# -ne 2
	then
		die "You must provide <repository> <ref>"
	fi
	ensure_clean
	ensure_valid_ref_format "$2"
	git fetch "$@" || exit $?
	revs=FETCH_HEAD
	set -- $revs
	cmd_merge "$@"
}
 
cmd_push () {
	if test $# -ne 2
	then
		die "You must provide <repository> <ref>"
	fi
	ensure_valid_ref_format "$2"
	if test -e "$dir"
	then
		repository=$1
		refspec=$2
		echo "git push using: " "$repository" "$refspec"
		localrev=$(git subtree split --prefix="$prefix") || die
		git push "$repository" "$localrev":"refs/heads/$refspec"
	else
		die "'$dir' must already exist. Try 'git subtree add'."
	fi
}
 
main "$@"