profile-stack.sh

#!/usr/bin/env bash
#

set -e

PROFILE_PATH="$1"
: "${REPO:=${2:-/var/db/repos/gentoo}}"
if [[ ! $PROFILE_PATH =~ ^/ ]]; then
	PROFILE_PATH="${REPO%%/}/profiles/${PROFILE_PATH}"
fi
if [[ ! -d "$PROFILE_PATH" ]] || [[ ! -x "$PROFILE_PATH" ]]; then
	echo "'$PROFILE_PATH' is not a directory!" >&2
	echo " or cannot execute!" >&2
	exit 1
fi

declare -a PROFILE_STACK

push_to_stack() {
	local p="$1" pa

	pushd "$p" >/dev/null
	trap '
	PROFILE_STACK+=( "$(pwd)" )
	popd >/dev/null
	' RETURN

	pa="$(pwd)/parent"
	if [[ -f "$pa" ]]; then
		while read -r line; do
			push_to_stack "$line"
		done < <(cat "$pa")
	fi
}

push_to_stack "$PROFILE_PATH"

echo $'\n'"Priority decreases from top to bottom:"$'\n'

for (( i=$((${#PROFILE_STACK[@]}-1)); i>=0; i-- )); do
	echo "${PROFILE_STACK[i]}"
done