subspace-enter

#!/bin/bash
set -euo pipefail

SUBSPACE_DIR="/subspace"


if [ "$EUID" -ne 0 ]; then
    echo "Entering a subspace requires superuser privileges."
    exit 1
fi


if [ $# -lt 1 ]; then
    echo "Usage: subspace-enter <subspace> [shell]" >&2
    echo "" >&2
    echo "Available subspaces:" >&2
    for d in "$SUBSPACE_DIR"/*/; do
        [ -d "$d/usr" ] && echo "  $(basename "$d")" >&2
    done
    exit 1
fi

subspace="$1"
root="$SUBSPACE_DIR/$subspace"

if [ ! -d "$root" ]; then
    echo "Error: Subspace '$subspace' not found at $root" >&2
    exit 1
fi

if [ $# -ge 2 ]; then
    shell="$2"
else
    for sh in /bin/bash /bin/sh /usr/bin/bash /usr/bin/sh /sbin/sh /bin/ash /usr/bin/ash; do
        if [ -L "$root/$sh" ] || [ -x "$root/$sh" ]; then
            shell="$sh"
            break
        fi
    done
fi

if [ -z "${shell:-}" ]; then
    echo "Error: No shell found in $subspace" >&2
    exit 1
fi

exec "$SUBSPACE_DIR/subspace-run" "$subspace" "$shell"