1 files changed, 114 insertions, 0 deletions
diff --git a/git-merge-octopus.sh b/git-merge-octopus.sh
new file mode 100755
index 0000000000..645e1147dc
--- /dev/null
+++ b/git-merge-octopus.sh
@@ -0,0 +1,114 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+# Resolve two or more trees.
+#
+
+LF='
+'
+
+die () {
+    echo >&2 "$*"
+    exit 1
+}
+
+# The first parameters up to -- are merge bases; the rest are heads.
+bases= head= remotes= sep_seen=
+for arg
+do
+	case ",$sep_seen,$head,$arg," in
+	*,--,)
+		sep_seen=yes
+		;;
+	,yes,,*)
+		head=$arg
+		;;
+	,yes,*)
+		remotes="$remotes$arg "
+		;;
+	*)
+		bases="$bases$arg "
+		;;
+	esac
+done
+
+# Reject if this is not an Octopus -- resolve should be used instead.
+case "$remotes" in
+?*' '?*)
+	;;
+*)
+	exit 2 ;;
+esac
+
+# MRC is the current "merge reference commit"
+# MRT is the current "merge result tree"
+
+MRC=$head MSG= PARENT="-p $head"
+MRT=$(git write-tree)
+CNT=1 ;# counting our head
+NON_FF_MERGE=0
+OCTOPUS_FAILURE=0
+for SHA1 in $remotes
+do
+	case "$OCTOPUS_FAILURE" in
+	1)
+		# We allow only last one to have a hand-resolvable
+		# conflicts.  Last round failed and we still had
+		# a head to merge.
+		echo "Automated merge did not work."
+		echo "Should not be doing an Octopus."
+		exit 2
+	esac
+
+	common=$(git merge-base --all $MRC $SHA1) ||
+		die "Unable to find common commit with $SHA1"
+
+	case "$LF$common$LF" in
+	*"$LF$SHA1$LF"*)
+		echo "Already up-to-date with $SHA1"
+		continue
+		;;
+	esac
+
+	CNT=`expr $CNT + 1`
+	PARENT="$PARENT -p $SHA1"
+
+	if test "$common,$NON_FF_MERGE" = "$MRC,0"
+	then
+		# The first head being merged was a fast-forward.
+		# Advance MRC to the head being merged, and use that
+		# tree as the intermediate result of the merge.
+		# We still need to count this as part of the parent set.
+
+		echo "Fast forwarding to: $SHA1"
+		git read-tree -u -m $head $SHA1 || exit
+		MRC=$SHA1 MRT=$(git write-tree)
+		continue
+	fi
+
+	NON_FF_MERGE=1
+
+	echo "Trying simple merge with $SHA1"
+	git read-tree -u -m --aggressive  $common $MRT $SHA1 || exit 2
+	next=$(git write-tree 2>/dev/null)
+	if test $? -ne 0
+	then
+		echo "Simple merge did not work, trying automatic merge."
+		git-merge-index -o git-merge-one-file -a ||
+		OCTOPUS_FAILURE=1
+		next=$(git write-tree 2>/dev/null)
+	fi
+
+	# We have merged the other branch successfully.  Ideally
+	# we could implement OR'ed heads in merge-base, and keep
+	# a list of commits we have merged so far in MRC to feed
+	# them to merge-base, but we approximate it by keep using
+	# the current MRC.  We used to update it to $common, which
+	# was incorrectly doing AND'ed merge-base here, which was
+	# unneeded.
+
+	MRT=$next
+done
+
+exit "$OCTOPUS_FAILURE"