svarbox/scripts/dos-shell
2025-10-18 11:47:07 +03:00

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#!/bin/bash
# /usr/local/bin/dos-shell
# 1) reset C: drive contents to only the allowed files
# 2) launch dosemu with /cdrive mounted as C:
set -euo pipefail
ALLOWED_LIST="/etc/dos_allowed"
ALLOWED_REPO="/opt/allowed_repo" # repository of allowed DOS files stored in container
C_DRIVE="/cdrive"
ENV_DIR="/etc/dos_env"
AUTOEXEC_TEMPLATE="${ENV_DIR}/AUTOEXEC.BAT"
CONFIG_TEMPLATE="${ENV_DIR}/CONFIG.SYS"
SVARDOS_BASE="/opt/svardos/base"
ALLOW_MODE="${DOS_ALLOW_MODE:-all}" # default to exposing everything from the repo
if [ "$(id -u)" -eq 0 ] && [ ! -d "${ENV_DIR}" ]; then
mkdir -p "${ENV_DIR}"
fi
# clear C: drive to ensure only allowed programs are present
rm -rf "${C_DRIVE:?}/"*
mkdir -p "${C_DRIVE}"
# Seed the C: drive with the SvarDOS base image
if [ -e "${SVARDOS_BASE}/COMMAND.COM" ] || [ -e "${SVARDOS_BASE}/command.com" ]; then
cp -a "${SVARDOS_BASE}/." "${C_DRIVE}/"
else
echo "SvarDOS base not found in ${SVARDOS_BASE}. Aborting." >&2
exit 1
fi
# Sync additional DOS files into the C: drive
allowed_entries=()
case "${ALLOW_MODE}" in
all)
if [ -d "${ALLOWED_REPO}" ] && [ "$(ls -A "${ALLOWED_REPO}")" ]; then
cp -a "${ALLOWED_REPO}/." "${C_DRIVE}/"
fi
;;
list|allowlist)
;;
*)
echo "Unknown DOS_ALLOW_MODE '${ALLOW_MODE}', falling back to allowlist mode." >&2
ALLOW_MODE="list"
;;
esac
if [ "${ALLOW_MODE}" != "all" ]; then
if [ -f "${ALLOWED_LIST}" ]; then
while IFS= read -r line || [ -n "$line" ]; do
# trim whitespace
line="$(printf '%s' "$line" | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//')"
# skip blank/comment lines
case "$line" in
''|\#*) continue ;;
esac
allowed_entries+=("$line")
done < "${ALLOWED_LIST}"
fi
for entry in "${allowed_entries[@]}"; do
src="${ALLOWED_REPO}/${entry}"
if [ -e "$src" ]; then
dst_dir="$(dirname "${entry}")"
mkdir -p "${C_DRIVE}/${dst_dir}"
cp -a "$src" "${C_DRIVE}/${dst_dir}/"
else
echo "Warning: allowed file not found: $src" >&2
fi
done
fi
# Optional: create an AUTOEXEC.BAT and CONFIG.SYS or other DOS boot files
autoexec_path="${C_DRIVE}/AUTOEXEC.BAT"
config_path="${C_DRIVE}/CONFIG.SYS"
if [ -f "${AUTOEXEC_TEMPLATE}" ]; then
cp "${AUTOEXEC_TEMPLATE}" "${autoexec_path}"
else
cat > "${autoexec_path}" <<'EOF'
@echo off
prompt [DOS]$P$G
echo Welcome to the containerized DOS environment.
EOF
fi
if [ "${ALLOW_MODE}" = "all" ]; then
printf 'echo All repository programs are currently enabled.\r\n' >> "${autoexec_path}"
elif [ ${#allowed_entries[@]} -gt 0 ]; then
{
printf 'echo Allowed programs:\r\n'
for entry in "${allowed_entries[@]}"; do
dos_entry="${entry//\//\\}"
printf 'echo %s\r\n' "${dos_entry}"
done
} >> "${autoexec_path}"
else
{
printf 'echo No extra programs are currently enabled.\r\n'
} >> "${autoexec_path}"
fi
if [ -f "${CONFIG_TEMPLATE}" ]; then
cp "${CONFIG_TEMPLATE}" "${config_path}"
fi
# Drop privileges to dosuser if we were run as root (ssh will run as the user)
# but in case sshd runs ForceCommand as root, we switch.
if [ "$(id -u)" -eq 0 ]; then
exec runuser -u dosuser -- dosemu -quiet -K "${C_DRIVE}"
else
# running as the user already
exec dosemu -quiet -K "${C_DRIVE}"
fi