#!/usr/bin/env bash
# Execute ARM userspace with no host binfmt registration or physical USB access.
source "$(dirname -- "${BASH_SOURCE[0]}")/lib.sh"
(( $# >= 2 )) || die 'Usage: tools/in-rootfs ROOT [--direct] COMMAND [ARGUMENT...]'
root=$(realpath -e -- "$1")
shift
[[ -x $root/usr/bin/bash ]] || die 'Not an assembled FDS rootfs'
check_void_pin
"$FDS_ROOT/tools/verify-elf" "$FDS_VOID/masterdir-x86_64/usr/bin/qemu-aarch64" x86_64 static >/dev/null
# The target is the actual kernel-visible root. Linux 6.7+ gives this new user
# namespace its own binfmt registry; host registration is never changed.
# The native loader and tools are read-only temporary mounts, absent from tar.
host=/tmp/fds-build-host
runner=("$host/usr/lib/ld-linux-x86-64.so.2" --library-path "$host/usr/lib"
    "$host/usr/bin/bash" /tmp/fds-rootfs-namespace)
capabilities=(--cap-add CAP_SYS_ADMIN --cap-add CAP_SETPCAP)
# A single ELF needs no child-exec handler.
if [[ ${1:-} == --direct ]]; then
    shift
    (( $# > 0 )) || die 'Missing command after --direct'
    runner=("$host/usr/bin/qemu-aarch64")
    capabilities=()
fi
exec bwrap --unshare-user --uid 0 --gid 0 --cap-add CAP_SETFCAP "${capabilities[@]}" --unshare-pid \
    --bind "$root" / --dev /dev --proc /proc --tmpfs /tmp --tmpfs /run \
    --ro-bind "$FDS_VOID/masterdir-x86_64" "$host" \
    --ro-bind "$FDS_ROOT/tools/finalize-rootfs" /tmp/fds-finalize \
    --ro-bind "$FDS_ROOT/tools/rootfs-namespace" /tmp/fds-rootfs-namespace \
    --chdir / --clearenv --setenv PATH /usr/bin:/bin \
    --setenv HOME /root \
    --setenv XBPS_ARCH aarch64 --setenv LC_ALL C "${runner[@]}" "$@"