#!/bin/sh

# SPDX-License-Identifier: GPL-2.0-or-later

# A hook script to prevent pushing unsuitable commits to the master branch.
# Unsuitable commits are commits that contain a local changelog below a '---'
# line. The criteria may get extended later.
#
# Information about the commits which are being pushed is supplied as lines to
# the standard input in the form:
#
#   <local ref> <local sha1> <remote ref> <remote sha1>

z40=0000000000000000000000000000000000000000

while read -r local_ref local_sha remote_ref remote_sha
do
	if [ "$remote_ref" != refs/heads/master ]
	then
		continue
	fi

	# The remote master branch should never get deleted by this push, so we
	# can assume that local_sha is not 0's. We may however be creating the
	# remote branch, when pushing to a new empty repository for instance.
	if [ "$remote_sha" = $z40 ]
	then
		# New branch, examine all commits
		range="$local_sha"
	else
		# Update to existing branch, examine new commits
		range="$remote_sha..$local_sha"
	fi

	# Find invalid commits.
	commit=$(git rev-list -n 1 --grep '^---' "$range")
	if [ -n "$commit" ]
	then
		echo >&2 "Found local changelog in $local_ref, not pushing"
		echo >&2 "Check commit $commit"
		exit 1
	fi
done

exit 0