Merge pull request #112 from github/prcv-block-direct-pushes

add script to restrict changes on default branch to PRs

Author: cjs

pre-receive-hooks/restrict-master-to-gui-merges.sh

@@ -0,0 +1,18 @@
+#!/bin/bash
+#
+# This hook restricts changes on the default branch to those made with the GUI Pull Request Merge button, or the Pull Request Merge API.
+#
+DEFAULT_BRANCH=$(git symbolic-ref HEAD)
+while read -r oldrev newrev refname; do
+  if [[ "${refname}" != "${DEFAULT_BRANCH:=refs/heads/master}" ]]; then
+    exit 0
+  else
+    if [[ "${GITHUB_VIA}" != 'pull request merge button' && \
+          "${GITHUB_VIA}" != 'pull request merge api' ]]; then
+      echo "Changes to the default branch must be made by Pull Request. Direct pushes, edits, or merges are not allowed."
+      exit 1
+    else
+      exit 0
+    fi
+  fi
+done