bindfs-idmap

#!/bin/bash

usage() {
	bin=$(basename $0)
	echo >&2 "Usage: $bin src-dir mountpoint [bindfs-opts]"
	echo >&2
	echo >&2 "Convenience wrapper for: bindfs --map=... --create-for-user=... --create-for-group=..."
	echo >&2 "uid of the src-dir owner will be mapped to mountpoint owner,"
	echo >&2 " and anything created in mountpoint will be done as src-dir owner/group."
	exit ${1:-0}
}
[[ "$#" -lt 2 || "$1" = -h || "$1" = --help ]] && usage

src=$(realpath "$1") dst=$(realpath "$2")
read uid_src gid_src < <(stat --format='%u %g' "$src")
read uid_dst gid_dst < <(stat --format='%u %g' "$dst")
shift; shift

exec bindfs --map="$uid_src"/"$uid_dst" \
	--create-for-user="$uid_src" --create-for-group="$gid_src" \
	"$@" "$src" "$dst"