Add a pre-commit hook that checks for whitespace errors

Signed-off-by: Benjamin C Meyer <ben@meyerhome.net>

diff --git a/contrib/pre-commit/whitespace b/contrib/pre-commit/whitespace
new file mode 100755 (executable)
index 0000000..ee588cc
--- /dev/null
+++ b/contrib/pre-commit/whitespace
@@ -0,0 +1,20 @@
+#!/bin/bash -e
+
+function run_test {
+    if git rev-parse --verify HEAD >/dev/null 2>&1 ; then
+        head="HEAD"
+    else
+        # First commit, use an empty tree
+        head="4b825dc642cb6eb9a060e54bf8d69288fbee4904"
+    fi
+    git diff-index --check --cached "${head}" --
+}
+
+case "${1}" in
+    --about )
+        echo "Check for introduced trailing whitespace or an indent that uses a space before a tab."
+        ;;
+    * )
+        run_test
+        ;;
+esac