Gerrit anti-unintended changes pre-push hook

pre-push

#!/bin/sh

# Git pre-push script to notify the user in case more than 1 commit is pushed.
# Handy when pushing to the gerrit review system where each commit will result
# in a change review. Pushing to or from an incorrect branch could result in a
# bunch of unintended change reviews to be created and/or changes dependent on
# unsubmitted changes.

remote="$1"
url="$2"

z40=0000000000000000000000000000000000000000

# GERRIT_MAX_PUSH can be configured, defaults to 1
GERRIT_MAX_PUSH="${GERRIT_MAX_PUSH:-1}"

while read local_ref local_sha remote_ref remote_sha
do
	if [ "$local_sha" = $z40 ]
	then
		# Handle delete
		:
	else
		# Check if remote_ref is for Gerrit.
		# Uses the "Remove Largest Prefix Pattern" sh parameter expansion to
		# return an empty string if remote_ref has the refs/for/* pattern.
		if [ -z ${remote_ref##refs/for/*} ]
		then
			echo "Creating or updating a Gerrit review. GERRIT_MAX_PUSH=$GERRIT_MAX_PUSH"
			# Get the name of the branch we are creating the review for
			branch=${remote_ref#refs/for/}
			# Count the amount of commits between the commit we are pushing and
			# $remote/$branch. Assumes $remote/$branch is up-to date.
			# Ignore error if $remote/$branch does not exists, let Gerrit handle
			# this
			count=`git rev-list --count "$remote/$branch".."$local_ref"` 2> /dev/null || count=1
			if [ $count -gt $GERRIT_MAX_PUSH ]
			then
				echo "Warning: Pushing $count commits to Gerrit might create $count reviews and/or create reviews dependent on other reviews"
				exec < /dev/tty # Enable reading
				read -p "Continue? (y/N): " yn
				exec <&- # Disable reading
				if [ $yn != "y" -a $yn != "Y" ]
				then
					echo >&2 "User aborted, not pushing"
					exit 1
				fi
				echo "Note: set GERRIT_MAX_PUSH to prevent this message"
			fi
		fi

	fi
done

exit 0