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git-merge.sh
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git-merge.sh
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#!/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 $head |
cpio -0 -o >"$GIT_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
*,'')
# No common ancestors found. We need a real merge.
;;
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 "$1"
dropsave
exit 0
;;
1,?*"$LF"?*)
# We are not doing octopus and not fast forward. Need a
# real merge.
;;
1,*)
# We are not doing octopus, not fast forward, and have only
# one common. See if it is really trivial.
echo "Trying really trivial in-index merge..."
git-update-index --refresh 2>/dev/null
if git-read-tree --trivial -m -u $common $head "$1" &&
result_tree=$(git-write-tree)
then
echo "Wonderful."
result_commit=$(
echo "$merge_msg" |
git-commit-tree $result_tree -p HEAD -p "$1"
) || exit
git-update-ref HEAD $result_commit $head
summary $result_commit
dropsave
exit 0
fi
echo "Nope."
;;
*)
# An octopus. If we can reach all the remote we are up to date.
up_to_date=t
for remote
do
common_one=$(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"