fetch-gerrit-change.sh

#!/bin/sh

# git config alias.lc='branch --list --remote --verbose c/*'
# git config alias.fc="!/path/to/this/script'
#
# Do "git fc <change id>" to get one change, the change will be put in remotes namespace c/. You can
# also do "git fc c/<change id>" if you copy paste the ref name. Do "git fc --all" to update all
# tracked gerrit changes.

fetch() {
	local id="$(echo "$1" | sed 's|^c/||')"

	case $id in
	*/*)
		change_id=${id%%/*}
		patchset_id=${id##*/}
		tryagain=f
		;;
	*)
		change_id=$id
		patchset_id="$(git config gerrit.c$change_id)"
		if [ -n "$patchset_id" ]; then
			patchset_id=$(($patchset_id+1))
		else
			patchset_id=1
		fi
		tryagain=t
		;;
	esac

	local hash=$(($change_id % 100))
	case $hash in
		[0-9]) hash="0$hash" ;;
	esac

	local last_good_patchset_id=
        echo -n "Updating c/$change_id ">&2
	while true; do
		refspec="refs/changes/$hash/$change_id/$patchset_id:refs/remotes/c/$change_id"
		git fetch -n origin +"$refspec" 2>/dev/null || break
		echo -n . >&2
		last_good_patchset_id=$patchset_id
		test $tryagain = f && break
		patchset_id=$((patchset_id+1))
	done
	if [ -n "$last_good_patchset_id" ]; then
		git config gerrit.c$change_id $last_good_patchset_id
		echo " --> $(git rev-list --oneline -1 refs/remotes/c/$change_id)" >&2
        else
	    echo >&2
	fi
}

if [ -z "$1" ]; then
	echo "Give me a change id!" >&2
	exit 1
fi

if [ "$1" = "--all" ]; then
	git branch --list --remote 'c/*' |
        	while read i; do fetch "$i"; done
else
	fetch "$1"
fi