Add configurable DOS drive volumes and tests

Dockerfile

@@ -36,9 +36,9 @@ RUN useradd -m -s /usr/local/bin/dos-shell dosuser && \
     mkdir -p /home/dosuser/.ssh && chown -R dosuser:dosuser /home/dosuser && \
     echo "dosuser:dosuser" | chpasswd
 
-# Create directories for allowed DOS files and the C: drive mount
+# Create directories for allowed DOS files, extra drives, and the C: drive mount
-RUN mkdir -p /opt/allowed_repo /cdrive /etc/dos_env /opt/svardos && \
+RUN mkdir -p /opt/allowed_repo /opt/dos_drives /cdrive /etc/dos_env /opt/svardos && \
-    chown -R dosuser:dosuser /opt/allowed_repo /cdrive
+    chown -R dosuser:dosuser /opt/allowed_repo /opt/dos_drives /cdrive
 
 # Download and stage SvarDOS base files
 ARG SVARDOS_IMG_URL

README.md

@@ -75,6 +75,7 @@ All persistent user data inside the guest lives under `/home/dosuser/.dosemu`, w
 - **`config/dos_allowed`** – list relative paths (from `allowed_repo/`) to permit when `DOS_ALLOW_MODE=list`. With `DOS_ALLOW_MODE=all` every file in the repo is staged.
 - **`dos_env/` templates** – place `AUTOEXEC.BAT` and/or `CONFIG.SYS` to control boot scripts.
 - **`dos_home/` volume** – bind-mounted to `/home/dosuser`; persists the DOS user profile, `.dosemu` state, SSH keys, etc.
+- **`dos_drives/` volume** – subdirectories named after drive letters (e.g. `F`, `G`) are exposed to DOS as additional drives. Letters `C`, `D`, and `E` are reserved by default (see `DOS_RESERVED_DRIVES` below); set that variable if you want to repurpose them.
 - **Pre-boot hook** – create an executable `dos_env/pre-boot.sh` (or point `DOS_PRE_BOOT_HOOK` at another path). It runs as `dosuser` immediately before dosemu starts, with helper environment variables (`C_DRIVE`, `DOSEMU_DIR`, `ALLOWED_REPO`, `SVARDOS_ROOT`, `SVARDOS_BASE`) so you can copy, delete, or patch files on the DOS drive.
 - **Forcing a reinstall** – set `DOS_FORCE_INSTALL=1` in the environment before logging in; the script re-seeds the drive from `/opt/svardos/base`.
 
@@ -88,6 +89,10 @@ allowed_repo/
 dos_home/
   .ssh/
     authorized_keys
+dos_drives/
+  F/
+    demos/
+      intro.exe
 dos_env/
   AUTOEXEC.BAT
   CONFIG.SYS
@@ -107,6 +112,10 @@ You can influence runtime behaviour with environment variables. Set them either
 | `DOS_TERMINAL_MODE`   | `auto`                                            | Determines whether `dosemu` launches with X11 (`-X`), terminal (`-td`) or `-dumb`.               |
 | `DOS_ENV_DIR`         | defaults to `/etc/dos_env`                       | Override if you mount templates somewhere else.                                                  |
 | `DOS_PRE_BOOT_HOOK`   | `${DOS_ENV_DIR}/pre-boot.sh`                     | Custom shell script to run (as `dosuser`) before launching dosemu. Must be executable.           |
+| `DOS_EXTRA_DRIVE_ROOT` | `/opt/dos_drives`                               | Override where `dos-shell` looks for extra drive directories (one per drive letter).             |
+| `DOS_RESERVED_DRIVES` | `CDE`                                            | Letters to leave untouched when mapping extra drives (remove or change to claim `D:`/`E:` etc.). |
+| `DOS_ALLOWED_REPO`    | `/opt/allowed_repo`                              | Alternate root for the allowed-repo staging area (useful in tests or custom mounts).             |
+| `DOS_ALLOWED_LIST`    | `/etc/dos_allowed`                               | Path to the allowlist file consumed when `DOS_ALLOW_MODE=list`.                                  |
 | `SVARDOS_ROOT`/`SVARDOS_BASE` | default `/opt/svardos`                   | Changes where the base image lives (mostly useful during debugging).                             |
 | `AO_DRIVER`           | auto-set to `null` when sound is muted            | You can override to force libao to a specific backend.                                           |
 

compose.yml

@@ -19,4 +19,5 @@ services:
       - ./config/dos_allowed:/etc/dos_allowed:ro
       - ./dos_env:/etc/dos_env
       - ./dos_home:/home/dosuser
+      - ./dos_drives:/opt/dos_drives
     restart: unless-stopped

dos_drives/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

scripts/dos-shell

@@ -4,8 +4,10 @@
 
 set -euo pipefail
 
-ALLOWED_LIST="/etc/dos_allowed"
+ALLOWED_LIST="${DOS_ALLOWED_LIST:-/etc/dos_allowed}"
-ALLOWED_REPO="/opt/allowed_repo"
+ALLOWED_REPO="${DOS_ALLOWED_REPO:-/opt/allowed_repo}"
+EXTRA_DRIVE_ROOT="${DOS_EXTRA_DRIVE_ROOT:-/opt/dos_drives}"
+RESERVED_DRIVES_RAW="${DOS_RESERVED_DRIVES:-CDE}"
 ENV_DIR="/etc/dos_env"
 AUTOEXEC_TEMPLATE="${ENV_DIR}/AUTOEXEC.BAT"
 CONFIG_TEMPLATE="${ENV_DIR}/CONFIG.SYS"
@@ -113,6 +115,8 @@ detect_dosemu_args() {
   esac
 }
 allowed_entries=()
+extra_drive_logs=()
+declare -A reserved_letters=()
 
 mkdir -p "${DOSEMU_DIR}" "${C_DRIVE}"
 if [ "$(id -u)" -eq 0 ] && [ ! -d "${ENV_DIR}" ]; then
@@ -140,6 +144,19 @@ reset_drive_c() {
   echo "SvarDOS base staged to ${C_DRIVE}"
 }
 
+normalise_reserved_drives() {
+  local raw="$1"
+  local cleaned="${raw//[^[:alpha:]]/}"
+  local i letter
+  for ((i=0; i<${#cleaned}; i++)); do
+    letter="${cleaned:i:1}"
+    letter="${letter,,}"
+    reserved_letters["${letter}"]=1
+  done
+}
+
+normalise_reserved_drives "${RESERVED_DRIVES_RAW}"
+
 sync_allowed_content() {
   allowed_entries=()
   local mode="${ALLOW_MODE}"
@@ -179,6 +196,70 @@ sync_allowed_content() {
   done
 }
 
+sync_extra_drives() {
+  extra_drive_logs=()
+  local root="${EXTRA_DRIVE_ROOT}"
+  local -A seen_letters=()
+
+  if [ -d "${root}" ]; then
+    shopt -s nullglob
+    local entry base letter letter_lower letter_upper dest
+    for entry in "${root}"/*; do
+      if [ ! -d "$entry" ]; then
+        continue
+      fi
+      base="$(basename "$entry")"
+      case "$base" in
+        [A-Za-z]|[A-Za-z]:)
+          letter="${base:0:1}"
+          ;;
+        *)
+          continue
+          ;;
+      esac
+      letter_lower="${letter,,}"
+      letter_upper="${letter^^}"
+      if [ -n "${reserved_letters[${letter_lower}]+x}" ]; then
+        echo "dos-shell: skipping extra drive '${base}' (${letter_upper}: is reserved)" >&2
+        continue
+      fi
+      dest="${DOSEMU_DIR}/drive_${letter_lower}"
+      if [ -e "${dest}" ] && [ ! -L "${dest}" ]; then
+        echo "dos-shell: cannot map ${letter_upper}: - ${dest} already exists and is not a symlink" >&2
+        continue
+      fi
+      if ! ln -sfn "$entry" "$dest"; then
+        echo "dos-shell: failed to link ${letter_upper}: to ${entry}" >&2
+        continue
+      fi
+      seen_letters["${letter_lower}"]=1
+      extra_drive_logs+=("${letter_upper}: ${entry}")
+    done
+    shopt -u nullglob
+  fi
+
+  shopt -s nullglob
+  local link base letter target
+  for link in "${DOSEMU_DIR}"/drive_[[:lower:]]; do
+    [ -L "$link" ] || continue
+    base="$(basename "$link")"
+    letter="${base#drive_}"
+    if [ -z "$letter" ] || [ "$letter" = "c" ]; then
+      continue
+    fi
+    if [ -n "${seen_letters[$letter]+x}" ]; then
+      continue
+    fi
+    target="$(readlink "$link")"
+    case "$target" in
+      "${EXTRA_DRIVE_ROOT}"/*)
+        rm -f "$link"
+        ;;
+    esac
+  done
+  shopt -u nullglob
+}
+
 apply_templates() {
   if [ -f "${AUTOEXEC_TEMPLATE}" ]; then
     cp "${AUTOEXEC_TEMPLATE}" "${C_DRIVE}/AUTOEXEC.BAT"
@@ -364,6 +445,7 @@ else
 fi
 
 sync_allowed_content
+sync_extra_drives
 apply_templates
 run_pre_boot_hook
 write_autoconfig
@@ -381,6 +463,13 @@ elif [ "${#allowed_entries[@]}" -gt 0 ]; then
   done
 fi
 
+if [ "${#extra_drive_logs[@]}" -gt 0 ]; then
+  echo "Additional DOS drives mapped:"
+  for mapping in "${extra_drive_logs[@]}"; do
+    echo "  ${mapping}"
+  done
+fi
+
 if [ "$(id -u)" -eq 0 ]; then
   exec runuser -u "${DOS_USER}" -- dosemu "${DOSEMU_ARGS[@]}"
 else

tests/run-dos-shell-tests.sh

@@ -0,0 +1,134 @@
+#!/bin/bash
+set -euo pipefail
+
+ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+DOS_SHELL="${ROOT_DIR}/scripts/dos-shell"
+
+if [ ! -x "${DOS_SHELL}" ]; then
+  echo "dos-shell not found or not executable at ${DOS_SHELL}" >&2
+  exit 1
+fi
+
+tmp_root="$(mktemp -d)"
+cleanup() {
+  rm -rf "${tmp_root}"
+}
+trap cleanup EXIT
+
+stub_bin="${tmp_root}/bin"
+mkdir -p "${stub_bin}"
+
+cat > "${stub_bin}/dosemu" <<'EOF'
+#!/bin/sh
+echo "dosemu stub invoked with: $*" >&2
+exit 0
+EOF
+chmod +x "${stub_bin}/dosemu"
+
+run_case() {
+  local name="$1"
+  local allow_mode="$2"
+  local reserved="$3"
+  local expected_files="$4"
+  shift 4
+  local asserts=("$@")
+
+  local case_dir="${tmp_root}/${name}"
+  local home_dir="${case_dir}/home"
+  local base_dir="${case_dir}/svardos_base"
+  local allowed_repo="${case_dir}/allowed_repo"
+  local allow_list="${case_dir}/allowed_list"
+  local extra_root="${case_dir}/extra_drives"
+
+  mkdir -p "${home_dir}" "${base_dir}" "${allowed_repo}" "${extra_root}"
+
+  # Populate minimal base image
+  echo "base-${name}" > "${base_dir}/BASE.TXT"
+
+  # Populate allowed repo fixtures
+  echo "common-${name}" > "${allowed_repo}/common.txt"
+  mkdir -p "${allowed_repo}/subdir"
+  echo "sub-${name}" > "${allowed_repo}/subdir/sub.txt"
+  echo "denied-${name}" > "${allowed_repo}/denied.txt"
+
+  # Prepare allow list (filled later per mode)
+  : > "${allow_list}"
+
+  # Create extra drive scaffolding
+  mkdir -p "${extra_root}/F"
+  echo "driveF-${name}" > "${extra_root}/F/file.txt"
+  mkdir -p "${extra_root}/D"
+  echo "driveD-${name}" > "${extra_root}/D/file.txt"
+
+  # Additional file for list mode
+  if [ "${allow_mode}" = "list" ]; then
+    {
+      echo "common.txt"
+      echo "subdir/sub.txt"
+    } > "${allow_list}"
+  fi
+
+  # Expected files in C: after sync
+  IFS=',' read -ra expected_array <<< "${expected_files}"
+
+  (
+    export PATH="${stub_bin}:${PATH}"
+    export HOME="${home_dir}"
+    export SVARDOS_ROOT="${case_dir}/svardos_root"
+    export SVARDOS_BASE="${base_dir}"
+    export DOS_FORCE_INSTALL=1
+    export DOS_ALLOW_MODE="${allow_mode}"
+    export DOS_EXTRA_DRIVE_ROOT="${extra_root}"
+    export DOS_RESERVED_DRIVES="${reserved}"
+    export DOS_ALLOWED_REPO="${allowed_repo}"
+    export DOS_ALLOWED_LIST="${allow_list}"
+    "${DOS_SHELL}" >/dev/null
+  )
+
+  local c_drive="${home_dir}/.dosemu/drive_c"
+
+  for rel_path in "${expected_array[@]}"; do
+    if [ ! -f "${c_drive}/${rel_path}" ]; then
+      echo "[${name}] expected file missing in C: ${rel_path}" >&2
+      exit 1
+    fi
+  done
+
+  for assert in "${asserts[@]}"; do
+    case "${assert}" in
+      expect_symlink:*)
+        local letter="${assert#expect_symlink:}"
+        local link="${home_dir}/.dosemu/drive_${letter,,}"
+        if [ ! -L "${link}" ]; then
+          echo "[${name}] expected symlink for drive ${letter^^}: not found" >&2
+          exit 1
+        fi
+        ;;
+      expect_absent:*)
+        local letter="${assert#expect_absent:}"
+        local link="${home_dir}/.dosemu/drive_${letter,,}"
+        if [ -e "${link}" ]; then
+          echo "[${name}] expected drive ${letter^^}: to be absent, found $(ls -ld "${link}")" >&2
+          exit 1
+        fi
+        ;;
+      expect_no_file:*)
+        local rel="${assert#expect_no_file:}"
+        if [ -e "${c_drive}/${rel}" ]; then
+          echo "[${name}] unexpected file present in C: ${rel}" >&2
+          exit 1
+        fi
+        ;;
+    esac
+  done
+
+  echo "[${name}] OK"
+}
+
+run_case "allow-all" "all" "CDE" "BASE.TXT,common.txt,subdir/sub.txt,denied.txt" \
+  "expect_symlink:f" "expect_absent:d"
+
+run_case "allow-list-reserved-override" "list" "C" "BASE.TXT,common.txt,subdir/sub.txt" \
+  "expect_symlink:f" "expect_symlink:d" "expect_no_file:denied.txt"
+
+echo "All tests passed."