summaryrefslogtreecommitdiff
path: root/git-merge.sh
blob: 29e86c695320b3d575314bc7c0be9eea0fd1b04a (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
#!/bin/sh
#
# Copyright (c) 2005 Junio C Hamano
#

. git-sh-setup || die "Not a git archive"

LF='
'

usage () {
    die "git-merge [-n] [-s <strategy>]... <merge-message> <head> <remote>+"
}

# all_strategies='resolve recursive stupid octopus'

all_strategies='recursive octopus resolve stupid'
default_strategies='resolve octopus'
use_strategies=

dropsave() {
	rm -f -- "$GIT_DIR/MERGE_HEAD" "$GIT_DIR/MERGE_MSG" \
		 "$GIT_DIR/MERGE_SAVE" || exit 1
}

savestate() {
	# Stash away any local modifications.
	git-diff-index -r -z --name-only $head |
	cpio -0 -o >"$GIR_DIR/MERGE_SAVE"
}

restorestate() {
        if test -f "$GIT_DIR/MERGE_SAVE"
	then
		git reset --hard $head
		cpio -iuv <"$GIT_DIR/MERGE_SAVE"
		git-update-index --refresh >/dev/null
	fi
}

summary() {
	case "$no_summary" in
	'')
		git-diff-tree -p -M $head "$1" |
		git-apply --stat --summary
		;;
	esac
}

while case "$#" in 0) break ;; esac
do
	case "$1" in
	-n|--n|--no|--no-|--no-s|--no-su|--no-sum|--no-summ|\
		--no-summa|--no-summar|--no-summary)
		no_summary=t ;;
	-s=*|--s=*|--st=*|--str=*|--stra=*|--strat=*|--strate=*|\
		--strateg=*|--strategy=*|\
	-s|--s|--st|--str|--stra|--strat|--strate|--strateg|--strategy)
		case "$#,$1" in
		*,*=*)
			strategy=`expr "$1" : '-[^=]*=\(.*\)'` ;;
		1,*)
			usage ;;
		*)
			strategy="$2"
			shift ;;
		esac
		case " $all_strategies " in
		*" $strategy "*)
			use_strategies="$use_strategies$strategy " ;;
		*)
			die "available strategies are: $all_strategies" ;;
		esac
		;;
	-*)	usage ;;
	*)	break ;;
	esac
	shift
done

case "$use_strategies" in
'')
	use_strategies=$default_strategies
	;;
esac
test "$#" -le 2 && usage ;# we need at least two heads.

merge_msg="$1"
shift
head_arg="$1"
head=$(git-rev-parse --verify "$1"^0) || usage
shift

# All the rest are remote heads
for remote
do
	git-rev-parse --verify "$remote"^0 >/dev/null ||
	    die "$remote - not something we can merge"
done

common=$(git-show-branch --merge-base $head "$@")
echo "$head" >"$GIT_DIR/ORIG_HEAD"

case "$#,$common" in
*,'')
	die "Unable to find common commit between $head_arg and $*"
	;;
1,"$1")
	# If head can reach all the merge then we are up to date.
	# but first the most common case of merging one remote
	echo "Already up-to-date. Yeeah!"
	dropsave
	exit 0
	;;
1,"$head")
	# Again the most common case of merging one remote.
	echo "Updating from $head to $1."
	git-update-index --refresh 2>/dev/null
	git-read-tree -u -m $head "$1" &&
	new_head=$(git-rev-parse --verify "$1^0") &&
	git-update-ref HEAD "$new_head" "$head" || exit 1
	summary "$1"
	dropsave
	exit 0
	;;
1,*)
	# We are not doing octopus and not fast forward.  Need a
	# real merge.
	;;
*)
	# An octopus.  If we can reach all the remote we are up to date.
	up_to_date=t
	for remote
	do
		common_one=$(git-merge-base $head $remote)
		if test "$common_one" != "$remote"
		then
			up_to_date=f
			break
		fi
	done
	if test "$up_to_date" = t
	then
		echo "Already up-to-date. Yeeah!"
		dropsave
		exit 0
	fi
	;;
esac

# At this point, we need a real merge.  No matter what strategy
# we use, it would operate on the index, possibly affecting the
# working tree, and when resolved cleanly, have the desired tree
# in the index -- this means that the index must be in sync with
# the $head commit.  The strategies are responsible to ensure this.

case "$use_strategies" in
?*' '?*)
    # Stash away the local changes so that we can try more than one.
    savestate
    single_strategy=no
    ;;
*)
    rm -f "$GIT_DIR/MERGE_SAVE"
    single_strategy=yes
    ;;
esac

result_tree= best_cnt=-1 best_strategy= wt_strategy=
for strategy in $use_strategies
do
    test "$wt_strategy" = '' || {
	echo "Rewinding the tree to pristine..."
	restorestate
    }
    case "$single_strategy" in
    no)
	echo "Trying merge strategy $strategy..."
	;;
    esac

    # Remember which strategy left the state in the working tree
    wt_strategy=$strategy

    git-merge-$strategy $common -- "$head_arg" "$@" || {

	# The backend exits with 1 when conflicts are left to be resolved,
	# with 2 when it does not handle the given merge at all.

	exit=$?
	if test "$exit" -eq 1
	then
	    cnt=`{
		git-diff-files --name-only
		git-ls-files --unmerged
	    } | wc -l`
	    if test $best_cnt -le 0 -o $cnt -le $best_cnt
	    then
		best_strategy=$strategy
		best_cnt=$cnt
	    fi
	fi
	continue
    }

    # Automerge succeeded.
    result_tree=$(git-write-tree) && break
done

# If we have a resulting tree, that means the strategy module
# auto resolved the merge cleanly.
if test '' != "$result_tree"
then
    parents="-p $head"
    for remote
    do
        parents="$parents -p $remote"
    done
    result_commit=$(echo "$merge_msg" | git-commit-tree $result_tree $parents) || exit
    echo "Committed merge $result_commit, made by $wt_strategy."
    git-update-ref HEAD $result_commit $head
    summary $result_commit
    dropsave
    exit 0
fi

# Pick the result from the best strategy and have the user fix it up.
case "$best_strategy" in
'')
	restorestate
	die "No merge strategy handled the merge."
	;;
"$wt_strategy")
	# We already have its result in the working tree.
	;;
*)
	echo "Rewinding the tree to pristine..."
	restorestate
	echo "Using the $best_strategy to prepare resolving by hand."
	git-merge-$best_strategy $common -- "$head_arg" "$@"
	;;
esac
for remote
do
	echo $remote
done >"$GIT_DIR/MERGE_HEAD"
echo $merge_msg >"$GIT_DIR/MERGE_MSG"

die "Automatic merge failed; fix up by hand"