1 files changed, 94 insertions, 0 deletions
diff --git a/test/lint/git-subtree-check.sh b/test/lint/git-subtree-check.sh
new file mode 100755
index 0000000000..184951715e
--- /dev/null
+++ b/test/lint/git-subtree-check.sh
@@ -0,0 +1,94 @@
+#!/bin/sh
+# Copyright (c) 2015 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+DIR="$1"
+COMMIT="$2"
+if [ -z "$COMMIT" ]; then
+    COMMIT=HEAD
+fi
+
+# Taken from git-subtree (Copyright (C) 2009 Avery Pennarun <apenwarr@gmail.com>)
+find_latest_squash()
+{
+	dir="$1"
+	sq=
+	main=
+	sub=
+	git log --grep="^git-subtree-dir: $dir/*\$" \
+		--pretty=format:'START %H%n%s%n%n%b%nEND%n' "$COMMIT" |
+	while read a b _; do
+		case "$a" in
+			START) sq="$b" ;;
+			git-subtree-mainline:) main="$b" ;;
+			git-subtree-split:) sub="$b" ;;
+			END)
+				if [ -n "$sub" ]; then
+					if [ -n "$main" ]; then
+						# a rejoin commit?
+						# Pretend its sub was a squash.
+						sq="$sub"
+					fi
+					echo "$sq" "$sub"
+					break
+				fi
+				sq=
+				main=
+				sub=
+				;;
+		esac
+	done
+}
+
+# find latest subtree update
+latest_squash="$(find_latest_squash "$DIR")"
+if [ -z "$latest_squash" ]; then
+    echo "ERROR: $DIR is not a subtree" >&2
+    exit 2
+fi
+set $latest_squash
+old=$1
+rev=$2
+
+# get the tree in the current commit
+tree_actual=$(git ls-tree -d "$COMMIT" "$DIR" | head -n 1)
+if [ -z "$tree_actual" ]; then
+    echo "FAIL: subtree directory $DIR not found in $COMMIT" >&2
+    exit 1
+fi
+set $tree_actual
+tree_actual_type=$2
+tree_actual_tree=$3
+echo "$DIR in $COMMIT currently refers to $tree_actual_type $tree_actual_tree"
+if [ "d$tree_actual_type" != "dtree" ]; then
+    echo "FAIL: subtree directory $DIR is not a tree in $COMMIT" >&2
+    exit 1
+fi
+
+# get the tree at the time of the last subtree update
+tree_commit=$(git show -s --format="%T" $old)
+echo "$DIR in $COMMIT was last updated in commit $old (tree $tree_commit)"
+
+# ... and compare the actual tree with it
+if [ "$tree_actual_tree" != "$tree_commit" ]; then
+    git diff $tree_commit $tree_actual_tree >&2
+    echo "FAIL: subtree directory was touched without subtree merge" >&2
+    exit 1
+fi
+
+# get the tree in the subtree commit referred to
+if [ "d$(git cat-file -t $rev 2>/dev/null)" != dcommit ]; then
+    echo "subtree commit $rev unavailable: cannot compare" >&2
+    exit
+fi
+tree_subtree=$(git show -s --format="%T" $rev)
+echo "$DIR in $COMMIT was last updated to upstream commit $rev (tree $tree_subtree)"
+
+# ... and compare the actual tree with it
+if [ "$tree_actual_tree" != "$tree_subtree" ]; then
+    echo "FAIL: subtree update commit differs from upstream tree!" >&2
+    exit 1
+fi
+
+echo "GOOD"