docs: Readme (#1358)

.github/dependabot.yml

@@ -1,4 +1,5 @@
 version: 2
+
 updates:
   - package-ecosystem: docker
     directory: /
@@ -6,9 +7,15 @@ updates:
       interval: weekly
     cooldown:
       default-days: 7
+
   - package-ecosystem: github-actions
     directory: /
     schedule:
       interval: weekly
     cooldown:
       default-days: 7
+    ignore:
+      - dependency-name: "*"
+        update-types:
+          - version-update:semver-minor
+          - version-update:semver-patch

.github/workflows/check.yml

@@ -27,7 +27,7 @@ jobs:
                 -e SC2153
           -
             name: Lint Dockerfile
-            uses: hadolint/hadolint-action@v3.3.0
+            uses: hadolint/hadolint-action@v3.4.0
             with:
               dockerfile: Dockerfile
               ignore: DL3008

Dockerfile

@@ -7,8 +7,9 @@ ARG TARGETARCH
 ARG TARGETPLATFORM
 
 ARG VERSION_ARG="0.0"
+ARG VERSION_WSD="0.4.2"
 ARG VERSION_CSTRUCT="4.7"
-ARG VERSION_PASST="2026_07_16"
+ARG VERSION_PASST="2026_07_28"
 
 ARG DEBCONF_NOWARNINGS="yes"
 ARG DEBIAN_FRONTEND="noninteractive"
@@ -29,10 +30,6 @@ RUN <<EOF
     procps \
     ipcalc \
     ethtool \
-    python3 \
-    python3-pip \
-    python3-msgpack \
-    python3-pysodium \
     xz-utils \
     iptables \
     iproute2 \
@@ -43,30 +40,29 @@ RUN <<EOF
     e2fsprogs \
     diffutils \
     qemu-utils \
-    websocketd \
     iputils-ping \
     inotify-tools \
     ca-certificates \
     netcat-openbsd \
-    qemu-system-x86
+    qemu-system-x86 \
+    python3 \
+    python3-pip \
+    python3-msgpack \
+    python3-pysodium
 
   # Install Passt package
   wget "https://github.com/qemus/passt/releases/download/v${VERSION_PASST}/passt_${VERSION_PASST}_${TARGETARCH}.deb" -O /tmp/passt.deb -q --timeout=10
   dpkg -i /tmp/passt.deb
 
+  # Install Websocketd package
+  wget "https://github.com/qemus/websocketd/releases/download/v${VERSION_WSD}/websocketd-${VERSION_WSD}_${TARGETARCH}.deb" -O /tmp/wsd.deb -q --timeout=10
+  dpkg -i /tmp/wsd.deb
+
   apt-get clean
 
   # Install Python dependencies
   pip3 install --no-cache-dir --break-system-packages --root-user-action=ignore "dissect.cstruct==$VERSION_CSTRUCT"
 
-  # Configure QEMU
-  mkdir -p /etc/qemu
-  echo "allow br0" > /etc/qemu/bridge.conf
-
-  # Configure nginx
-  unlink /etc/nginx/sites-enabled/default
-  sed -i 's/^worker_processes.*/worker_processes 1;/' /etc/nginx/nginx.conf
-
   # Set version file
   echo "$VERSION_ARG" > /etc/version
 

docs/environment.md

@@ -39,6 +39,7 @@ An empty default means the variable is unset and its value is determined automat
 | `DISK_DISCARD` | `unmap` | Discard/TRIM mode for the primary disk. |
 | `DISK_ROTATION` | `1` | Rotation rate reported to the guest. Use `1` to identify the disk as an SSD. |
 | `DISK_FLAGS` |  | Additional options used when creating `qcow2` disks. |
+| `DISK_OPTIONS` |  | Additional options appended to QEMU disk devices. |
 | `ALLOCATE` | `N` | Preallocates space for the data disks. |
 | `STORAGE` | `/storage` | Storage directory used for disks, settings, and downloads. |
 

readme.md

@@ -68,8 +68,8 @@ kubectl apply -f https://raw.githubusercontent.com/vdsm/virtual-dsm/refs/heads/m
 
 - Docker or Podman on a Linux host with KVM support.
 - Docker Desktop or Podman (Desktop) on Windows 11 with nested virtualization enabled.
-- At least 2 GB of available RAM.
-- At least 32 GB of free disk space.
+- At least 1 GB of available RAM.
+- At least 16 GB of free disk space.
 
 > [!NOTE]
 > Docker Desktop on Linux, macOS, and Windows 10 does not currently provide KVM access to containers and is therefore not supported.

src/check.sh

@@ -15,12 +15,16 @@ file="/run/shm/dsm.url"
 address="/run/shm/qemu.ip"
 gateway="/run/shm/qemu.gw"
 
-[ ! -s  "$file" ] && echo "DSM has not enabled networking yet..." && exit 1
+# dsm.url is written only after the guest agent reports both the DSM
+# address and its configured HTTP port.
+[ ! -s  "$file" ] && echo "DSM has not enabled networking yet..." && exit 0
 
 location=$(<"$file")
 
 if ! curl -m 20 -ILfSs "http://$location/" > /dev/null; then
 
+  # In DHCP mode the firewall must allow the container address; with port
+  # forwarding it must allow the internal gateway used to reach the guest.
   if enabled "$DHCP"; then
     ip=$(<"$address")
     echo "Failed to reach DSM at http://$location"

src/config.sh

@@ -6,6 +6,8 @@ DEV_OPTS=""
 
 configureProcessor() {
 
+  # Expose one thread per core in a single socket; DSM licensing and topology
+  # reporting are more predictable with this fixed layout.
   CPU_OPTS="-cpu $CPU_FLAGS"
   CPU_OPTS+=" -smp $CPU_CORES,sockets=1,dies=1,cores=$CPU_CORES,threads=1"
 
@@ -29,6 +31,8 @@ configureMonitor() {
 
 configureMachine() {
 
+  # Disable firmware and chipset features that Virtual DSM does not use and
+  # that can introduce extra devices or timing differences.
   MAC_OPTS="-machine type=$MACHINE,smm=off,usb=off"
   MAC_OPTS+=",vmport=off,dump-guest-core=off,hpet=off${KVM_OPTS}"
 
@@ -37,9 +41,12 @@ configureMachine() {
 
 configureVirtioDevices() {
 
-  DEV_OPTS="-device virtio-balloon-pci,id=balloon0,bus=pcie.0,addr=0x4"
+  local bus
+  bus=$(getPciBus)
+
+  DEV_OPTS="-device virtio-balloon-pci,id=balloon0,bus=$bus,addr=0x4"
   DEV_OPTS+=" -object rng-random,id=objrng0,filename=/dev/urandom"
-  DEV_OPTS+=" -device virtio-rng-pci,rng=objrng0,id=rng0,bus=pcie.0,addr=0x1c"
+  DEV_OPTS+=" -device virtio-rng-pci,rng=objrng0,id=rng0,bus=$bus,addr=0x1c"
 
   return 0
 }
@@ -47,11 +54,15 @@ configureVirtioDevices() {
 buildArguments() {
 
   ARGS="$DEF_OPTS $CPU_OPTS $RAM_OPTS $MAC_OPTS $DISPLAY_OPTS $MON_OPTS $SERIAL_OPTS $NET_OPTS $DISK_OPTS $DEV_OPTS $ARGUMENTS"
+  # Collapse whitespace after optional argument groups are assembled so empty
+  # features cannot leave malformed spacing in the final QEMU command.
   ARGS=$(echo "$ARGS" | sed 's/\t/ /g' | tr -s ' ')
 
   return 0
 }
 
+finalizeMemory
+
 configureMemory
 configureMonitor
 configureMachine

src/disk.sh

@@ -7,6 +7,7 @@ set -Eeuo pipefail
 : "${DISK_FMT:="raw"}"            # Disk file format, 'raw' by default for best performance
 : "${DISK_TYPE:=""}"              # Device type to be used, "sata", "nvme", "blk" or "scsi"
 : "${DISK_FLAGS:=""}"             # Specifies the options for use with the qcow2 disk format
+: "${DISK_OPTIONS:=""}"           # Specifies additional options for the QEMU disk device
 : "${DISK_CACHE:="none"}"         # Caching mode, can be set to 'writeback' for better performance
 : "${DISK_DISCARD:="unmap"}"      # Controls whether unmap (TRIM) commands are passed to the host.
 : "${DISK_ROTATION:="1"}"         # Rotation rate, set to 1 for SSD storage and increase for HDD
@@ -16,6 +17,7 @@ DISK_IO=$(strip "$DISK_IO")
 DISK_FMT=$(strip "$DISK_FMT")
 DISK_TYPE=$(strip "$DISK_TYPE")
 DISK_FLAGS=$(strip "$DISK_FLAGS")
+DISK_OPTIONS=$(strip "$DISK_OPTIONS")
 DISK_CACHE=$(strip "$DISK_CACHE")
 DISK_DISCARD=$(strip "$DISK_DISCARD")
 DISK_ROTATION=$(strip "$DISK_ROTATION")
@@ -23,6 +25,8 @@ DISK_ROTATION=$(strip "$DISK_ROTATION")
 BOOT="$STORAGE/$BASE.boot.img"
 SYSTEM="$STORAGE/$BASE.system.img"
 
+# The boot and system images are installation artifacts, not optional data
+# disks, and must exist before any user storage is attached.
 [ ! -s "$BOOT" ] && error "Virtual DSM boot-image does not exist ($BOOT)" && exit 81
 [ ! -s "$SYSTEM" ] && error "Virtual DSM system-image does not exist ($SYSTEM)" && exit 82
 
@@ -125,6 +129,8 @@ allocateRaw() {
     return $?
   fi
 
+  # Prefer real allocation, retry with zero-range allocation where supported,
+  # and fall back to a sparse file when the host filesystem rejects both.
   fallocate -l "$dataSize" "$diskFile" &>/dev/null && return 0
   fallocate -l -x "$dataSize" "$diskFile" && return 0
   truncate -s "$dataSize" "$diskFile" || return 1
@@ -154,9 +160,11 @@ normalizeSize() {
   local diskDesc="$2"
   local dir="$3"
 
-  local gb free space
-  local dataSize spare=1073741824
+  local free dataSize
+  local spare=1073741824
 
+  # Dynamic sizes are resolved once from current free space. max reserves one
+  # GiB for host metadata and container activity; half uses half the space.
   if [[ "${diskSpace,,}" == "max" || "${diskSpace,,}" == "half" ]]; then
 
     free=$(df --output=avail -B 1 "$dir" | tail -n 1)
@@ -168,12 +176,12 @@ normalizeSize() {
     fi
 
     (( free < spare )) && free="$spare"
-    gb=$(( free / 1073741825 ))
+    local gb=$(( free / 1073741825 ))
     diskSpace="${gb}G"
 
   fi
 
-  space="${diskSpace// /}"
+  local space="${diskSpace// /}"
   [ -z "$space" ] && space="256G"
   [ -z "${space//[0-9. ]}" ] && space="${space}G"
   space=$(echo "${space^^}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
@@ -419,6 +427,8 @@ convertDisk() {
   if [[ "$destinationFmt" == "raw" ]]; then
     if ! disabled "$ALLOCATE"; then
 
+      # qemu-img may leave converted raw output sparse despite requested
+      # preallocation, so allocate its final length explicitly afterward.
       # Work around qemu-img bug
       if ! currentSize=$(stat -c%s "$tmpFile"); then
         error "Failed to determine converted image size: $tmpFile"
@@ -433,6 +443,8 @@ convertDisk() {
     fi
   fi
 
+  # Publish the converted image before deleting the original so a failed
+  # conversion or rename never destroys the only usable disk.
   if ! mv "$tmpFile" "$destinationFile"; then
     error "Failed to move converted $diskDesc image to $destinationFile."
     exit 79
@@ -477,6 +489,8 @@ checkFS () {
     warn "the filesystem of $base is FUSE, this extra layer will negatively affect performance!"
   fi
 
+  # Filesystems without O_DIRECT support require threaded I/O and writeback
+  # caching; native AIO with cache=none would fail at runtime.
   if ! supportsDirect "$fs"; then
     warn "the filesystem of $base is $fs, which does not support O_DIRECT mode, adjusting settings..."
   fi
@@ -504,9 +518,12 @@ createDevice () {
   local diskCache="$7"
   local diskSerial="$8"
   local diskSectors="$9"
-  local bus="${PCI_BUS:-pcie.0}"
 
-  [[ -z "${PCI_BUS:-}" && ( "${MACHINE,,}" == pc || "${MACHINE,,}" == pc-i440fx* ) ]] && bus="pci.0"
+  local bus
+  bus=$(getPciBus)
+
+  local options=""
+  [ -n "$DISK_OPTIONS" ] && options=",${DISK_OPTIONS#,}"
 
   local bootIndex=""
   local diskId="data$diskIndex"
@@ -520,29 +537,29 @@ createDevice () {
       ;;
     "usb" )
       result+=",if=none \
-      -device usb-storage,drive=${diskId}${bootIndex}${diskSerial}${diskSectors}"
+      -device usb-storage,drive=${diskId}${bootIndex}${diskSerial}${diskSectors}${options}"
       echo "$result"
       ;;
     "nvme" )
       result+=",if=none \
-      -device nvme,drive=${diskId}${bootIndex},serial=deadbeaf${diskIndex}${diskSerial}${diskSectors}"
+      -device nvme,drive=${diskId}${bootIndex},serial=deadbeaf${diskIndex}${diskSerial}${diskSectors}${options}"
       echo "$result"
       ;;
     "ide" | "sata" )
       result+=",if=none \
       -device ich9-ahci,id=ahci${diskIndex},addr=$diskAddress \
-      -device ide-hd,drive=${diskId},bus=ahci$diskIndex.0,rotation_rate=$DISK_ROTATION${bootIndex}${diskSerial}${diskSectors}"
+      -device ide-hd,drive=${diskId},bus=ahci$diskIndex.0,rotation_rate=$DISK_ROTATION${bootIndex}${diskSerial}${diskSectors}${options}"
       echo "$result"
       ;;
     "blk" | "virtio-blk" )
       result+=",if=none \
-      -device virtio-blk-pci,drive=${diskId},bus=$bus,addr=$diskAddress,iothread=io2${bootIndex}${diskSerial}${diskSectors}"
+      -device virtio-blk-pci,drive=${diskId},bus=$bus,addr=$diskAddress,iothread=io2${bootIndex}${diskSerial}${diskSectors}${options}"
       echo "$result"
       ;;
     "scsi" | "virtio-scsi" )
       result+=",if=none \
       -device virtio-scsi-pci,id=${diskId}b,bus=$bus,addr=$diskAddress,iothread=io2,hotplug=off \
-      -device scsi-hd,drive=${diskId},bus=${diskId}b.0,channel=0,scsi-id=0,lun=0,rotation_rate=$DISK_ROTATION${bootIndex}${diskSerial}${diskSectors}"
+      -device scsi-hd,drive=${diskId},bus=${diskId}b.0,channel=0,scsi-id=0,lun=0,rotation_rate=$DISK_ROTATION${bootIndex}${diskSerial}${diskSectors}${options}"
       echo "$result"
       ;;
   esac
@@ -554,6 +571,8 @@ finishDisks () {
 
   case "${DISK_TYPE,,}" in
     "blk" | "scsi" | "virtio-blk" | "virtio-scsi" )
+      # VirtIO block and SCSI devices share one dedicated I/O thread, which
+      # must be declared exactly once regardless of disk count.
       [[ "$DISK_OPTS" != *" -object iothread,id=io2"* ]] && DISK_OPTS+=" -object iothread,id=io2" ;;
   esac
 
@@ -573,13 +592,12 @@ addDisk () {
   local diskCache="$9"
 
   local fs dir used space
-  local diskExt diskFile
-  local dataSize missing
+  local diskExt dataSize
   local available currentSize
-  local previousExt previousFmt
+  local previousExt
 
   diskExt=$(fmt2ext "$diskFmt")
-  diskFile="$diskBase.$diskExt"
+  local diskFile="$diskBase.$diskExt"
 
   dir=$(dirname "$diskFile")
   [ ! -d "$dir" ] && return 0
@@ -587,7 +605,11 @@ addDisk () {
   space=$(normalizeSize "$diskSpace" "$diskDesc" "$dir")
   dataSize=$(numfmt --from=iec "$space")
 
-  fs=$(stat -f -c %T "$dir")
+  if ! fs=$(stat -f -c %T "$dir"); then
+    error "Failed to determine filesystem type of \"$dir\" !"
+    return 1
+  fi
+
   checkFS "$fs" "$diskFile" "$diskDesc" || exit $?
 
   if ! supportsDirect "$fs"; then
@@ -595,23 +617,26 @@ addDisk () {
     diskCache="writeback"
   fi
 
-  if [ ! -s "$diskFile" ] ; then
+  if [ ! -f "$diskFile" ] || [ ! -s "$diskFile" ]; then
 
     if [[ "${diskFmt,,}" != "raw" ]]; then
-      previousFmt="raw"
+      local previousFmt="raw"
     else
-      previousFmt="qcow2"
+      local previousFmt="qcow2"
     fi
 
     previousExt=$(fmt2ext "$previousFmt")
 
-    if [ -s "$diskBase.$previousExt" ] ; then
+    # Treat a disk in the other supported format as the same logical disk and
+    # convert it automatically instead of creating an empty replacement.
+    if [ -f "$diskBase.$previousExt" ] &&
+      [ -s "$diskBase.$previousExt" ]; then
       convertDisk "$diskBase.$previousExt" "$previousFmt" "$diskFile" "$diskFmt" "$diskBase" "$diskDesc" "$fs" || exit $?
     fi
 
   fi
 
-  if [ -s "$diskFile" ]; then
+  if [ -f "$diskFile" ] && [ -s "$diskFile" ]; then
 
     currentSize=$(getSize "$diskFile") || exit 71
 
@@ -636,23 +661,25 @@ addDisk () {
 
   fi
 
+  # Sparse disks can promise more guest capacity than the host can currently
+  # satisfy, so report the future shortfall without blocking startup.
   if [ -f "$diskFile" ] && disabled "$ALLOCATE"; then
 
     currentSize=$(getSize "$diskFile") || exit 73
     used=$(du -sB 1 "$diskFile" | cut -f1)
     available=$(df --output=avail -B 1 "$dir" | tail -n 1)
-    missing=$(( currentSize - used - available ))
+    local missing=$(( currentSize - used - available ))
     (( missing < 0 )) && missing=0
 
     if (( missing > 0 )); then
 
-      local gb base msg
+      local gb base
 
       gb=$(formatBytes "$available")
       base=$(baseDir "$dir")
       missing=$(formatBytes "$missing")
       currentSize=$(formatBytes "$currentSize")
-      msg="The virtual size of the ${diskDesc,,} is $currentSize"
+      local msg="The virtual size of the ${diskDesc,,} is $currentSize"
 
       if [ -n "$used" ] && [[ "$used" != "0" ]]; then
         used=$(formatBytes "$used")
@@ -690,6 +717,8 @@ addDevice () {
   [ -z "$diskDev" ] && return 0
   [ ! -b "$diskDev" ] && error "Device $diskDev cannot be found! Please add it to the 'devices' section of your compose file." && exit 55
 
+  # DSM may reject whole-disk passthrough when QEMU is given explicit sector
+  # geometry; partitions need it to preserve non-512-byte host geometry.
   # Only detect and apply sector sizes for partitions, not whole disks.
   # Whole disk passthrough with explicit sector sizes causes DSM not to recognize the disk.
   if [[ "$devType" == "part" ]]; then
@@ -767,6 +796,11 @@ if [[ "$DISK_FLAGS" =~ [[:space:]] ]]; then
   exit 78
 fi
 
+if [[ "$DISK_OPTIONS" =~ [[:space:]] ]]; then
+  error "Invalid DISK_OPTIONS value '$DISK_OPTIONS', spaces are not allowed."
+  exit 78
+fi
+
 if [ -z "$ALLOCATE" ]; then
   ALLOCATE="N"
 fi
@@ -779,6 +813,8 @@ else
   DISK_ALLOC="preallocation=falloc"
 fi
 
+# Reserve the first two boot indexes and PCI addresses for the managed boot
+# and system images; user disks begin at index 3.
 DISK_OPTS+=$(createDevice "$BOOT" "$DISK_TYPE" "1" "0xa" "raw" "$DISK_IO" "$DISK_CACHE" "" "")
 DISK_OPTS+=$(createDevice "$SYSTEM" "$DISK_TYPE" "2" "0xb" "raw" "$DISK_IO" "$DISK_CACHE" "" "")
 
@@ -818,6 +854,8 @@ DISK_DEVICES=( "$DEVICE" "$DEVICE2" "$DEVICE3" "$DEVICE4" )
 DISK_INDEXES=( "3" "4" "5" "6" )
 DISK_ADDRESSES=( "0xc" "0xd" "0xe" "0xf" )
 
+# A passed-through block device takes precedence over the image-file slot
+# with the same number.
 for i in "${!DISK_FILES[@]}"; do
 
   if [ -n "${DISK_DEVICES[i]}" ]; then

src/display.sh

@@ -17,8 +17,12 @@ RENDERNODE=$(strip "$RENDERNODE")
 
 CPU_VENDOR=$(lscpu | awk '/Vendor ID/{print $3}')
 
+# The accelerated Intel render-node path is restricted to x86 Intel hosts;
+# other platforms retain the normal QEMU display backend.
 if ! enabled "$GPU" || isAmdCpu || [[ "$ARCH" != "amd64" ]]; then
 
+  # A disabled frontend also removes the emulated VGA device to keep the guest
+  # hardware layout headless.
   [[ "${DISPLAY,,}" == "none" ]] && VGA="none"
 
   if enabled "$LOSSY" && [[ "${DISPLAY,,}" == vnc=* ]]; then
@@ -40,6 +44,8 @@ DISPLAY_OPTS+=" -vga $VGA"
 [ ! -d /dev/dri ] && mkdir -m 755 /dev/dri
 
 # Extract the card number from the render node
+# Linux renderD128 corresponds to card0; derive both device minors because
+# container device bindings may expose only the render node.
 CARD_NUMBER=$(echo "$RENDERNODE" | grep -oP '(?<=renderD)\d+')
 CARD_DEVICE="/dev/dri/card$((CARD_NUMBER - 128))"
 
@@ -59,6 +65,8 @@ if [ ! -c "$RENDERNODE" ] || [ ! -r "$RENDERNODE" ] || [ ! -w "$RENDERNODE" ]; t
   warn "render device '${RENDERNODE}' is unavailable or inaccessible."
 fi
 
+# Install acceleration packages lazily so non-GPU deployments keep the base
+# image small and do not require OpenGL modules.
 addPackage "xserver-xorg-video-intel" "Intel GPU drivers"
 addPackage "qemu-system-modules-opengl" "OpenGL module"
 

src/entry.sh

@@ -9,7 +9,8 @@ cd /run
 
 . start.sh      # Startup hook
 . utils.sh      # Load functions
-. reset.sh      # Initialize system
+. init.sh       # Initialize system
+. memory.sh     # Check memory
 . server.sh     # Start webserver
 . install.sh    # Run installation
 . disk.sh       # Initialize disks
@@ -18,7 +19,6 @@ cd /run
 . proc.sh       # Initialize processor
 . serial.sh     # Initialize serialport
 . power.sh      # Configure shutdown
-. memory.sh     # Check available memory
 . config.sh     # Configure arguments
 . finish.sh     # Finish initialization
 

src/finish.sh

@@ -2,7 +2,10 @@
 set -Eeuo pipefail
 
 if enabled "$DEBUG"; then
-  printf "QEMU arguments:\n\n%s\n\n" "${ARGS// -/$'\n-'}"
+  printf "QEMU arguments:\n\n    %s\n\n" "${ARGS// -/$'\n    -'}"
 fi
 
+# Must always remain the very last command
+enableTrap
+
 return 0

src/init.sh

@@ -41,8 +41,10 @@ detectEngine() {
 
 detectRootless() {
 
-  local uid_map=""
+  local uid_map
 
+  # A full identity UID map indicates a rootful container; any remapping is
+  # treated as rootless even though the process itself runs as UID 0.
   uid_map=$(awk '{$1=$1; print}' /proc/self/uid_map 2>/dev/null || true)
 
   if [[ "$uid_map" == "0 0 4294967295" ]]; then
@@ -58,8 +60,6 @@ checkPrivileged() {
 
   local cap_bnd
   local last_cap
-  local max_cap
-
   # Get the capability bounding set
   cap_bnd=$(grep '^CapBnd:' /proc/$$/status | awk '{print $2}')
   cap_bnd=$(printf "%d" "0x${cap_bnd}")
@@ -68,7 +68,9 @@ checkPrivileged() {
   last_cap=$(cat /proc/sys/kernel/cap_last_cap)
 
   # Calculate the maximum capability value
-  max_cap=$(((1 << (last_cap + 1)) - 1))
+  # Compare the bounding set with every capability supported by this kernel;
+  # checking only a few known capabilities would misclassify newer kernels.
+  local max_cap=$(((1 << (last_cap + 1)) - 1))
 
   if [ "$cap_bnd" -eq "$max_cap" ]; then
     PRIVILEGED="Y"
@@ -77,15 +79,15 @@ checkPrivileged() {
   return 0
 }
 
-normalizeCpuCores() {
+checkCores() {
 
   CPU_CORES=$(strip "$CPU_CORES")
   [ -z "$CPU_CORES" ] && CPU_CORES=2
   [[ "${CPU_CORES,,}" == "max" ]] && CPU_CORES="$CORES"
   [[ "${CPU_CORES,,}" == "half" ]] && CPU_CORES=$(( CORES / 2 ))
   [ -z "${CPU_CORES##*[!0-9]*}" ] && error "Invalid amount of CPU_CORES: $CPU_CORES" && exit 15
-
   [ "$CPU_CORES" -lt "1" ] && CPU_CORES=1
+
   if [ "$CPU_CORES" -gt "$CORES" ]; then
     warn "The amount for CPU_CORES (${CPU_CORES}) exceeds the amount of logical cores available (${CORES}) and will be limited."
     CPU_CORES="$CORES"
@@ -94,6 +96,20 @@ normalizeCpuCores() {
   return 0
 }
 
+checkSockets() {
+
+  local lscpu_out
+  lscpu_out=$(lscpu 2>/dev/null || true)
+
+  if grep -qi "socket(s)" <<< "$lscpu_out"; then
+    SOCKETS=$(grep -m 1 -i 'socket(s)' <<< "$lscpu_out" | awk '{print $2}')
+    [ -z "${SOCKETS##*[!0-9]*}" ] && SOCKETS=1
+    [ "$SOCKETS" -lt "1" ] && SOCKETS=1
+  fi
+
+  return 0
+}
+
 checkStorage() {
 
   # Check system
@@ -103,6 +119,8 @@ checkStorage() {
   if [ ! -d "/dev/shm" ]; then
     error "Directory /dev/shm not found!" && exit 14
   else
+    # Keep runtime sockets and PID files on shared memory even on images where
+    # /run/shm is absent but /dev/shm is available.
     [ ! -d "$QEMU_DIR" ] && ln -s /dev/shm "$QEMU_DIR"
   fi
 
@@ -111,7 +129,9 @@ checkStorage() {
   # Check folder
 
   if [[ "${STORAGE,,}" != "/storage" ]]; then
-    mkdir -p "$STORAGE"
+    if ! mkdir -p -- "$STORAGE"; then
+      error "Cannot create storage folder ($STORAGE)!" && exit 13
+    fi
   fi
 
   if [ ! -d "$STORAGE" ]; then
@@ -127,11 +147,9 @@ checkStorage() {
   return 0
 }
 
-checkFilesystem() {
+checkHost() {
 
   # Check filesystem
-  FS=$(stat -f -c %T "$STORAGE")
-
   if [[ "${FS,,}" == "ecryptfs" || "${FS,,}" == "tmpfs" ]]; then
     DISK_IO="threads"
     DISK_CACHE="writeback"
@@ -140,91 +158,6 @@ checkFilesystem() {
   return 0
 }
 
-finiteMemoryLimit() {
-
-  local limit="$1"
-  local sentinel="4611686018427387904"
-  local i=0
-  local left=""
-  local right=""
-
-  [[ "$limit" =~ ^[0-9]+$ ]] || return 1
-
-  (( ${#limit} < ${#sentinel} )) && return 0
-  (( ${#limit} > ${#sentinel} )) && return 1
-
-  for (( i=0; i<${#sentinel}; i++ )); do
-    left="${limit:i:1}"
-    right="${sentinel:i:1}"
-
-    (( left < right )) && return 0
-    (( left > right )) && return 1
-  done
-
-  return 1
-}
-
-getMemoryInfo() {
-
-  local host_total=""
-  local host_avail=""
-  local limit=""
-  local current=""
-  local available=""
-
-  host_total=$(free -b | awk '/^Mem:/ {print $2; exit}')
-  host_avail=$(free -b | awk '/^Mem:/ {print $7; exit}')
-
-  RAM_TOTAL="$host_total"
-  RAM_AVAIL="$host_avail"
-
-  if [ -r /sys/fs/cgroup/memory.max ] && [ -r /sys/fs/cgroup/memory.current ]; then
-    limit=$(< /sys/fs/cgroup/memory.max)
-    current=$(< /sys/fs/cgroup/memory.current)
-  elif [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ] && [ -r /sys/fs/cgroup/memory/memory.usage_in_bytes ]; then
-    limit=$(< /sys/fs/cgroup/memory/memory.limit_in_bytes)
-    current=$(< /sys/fs/cgroup/memory/memory.usage_in_bytes)
-  fi
-
-  if finiteMemoryLimit "$limit" && [[ "$current" =~ ^[0-9]+$ ]]; then
-    (( limit < RAM_TOTAL )) && RAM_TOTAL="$limit"
-
-    available=$(( limit - current ))
-    (( available < 0 )) && available=0
-    (( available < RAM_AVAIL )) && RAM_AVAIL="$available"
-  fi
-
-  return 0
-}
-
-normalizeRamSize() {
-
-  # Read host and container memory limits.
-  getMemoryInfo
-
-  RAM_SPARE=500000000
-  RAM_MINIMUM=136314880
-
-  RAM_SIZE=$(strip "$RAM_SIZE")
-  RAM_SIZE="${RAM_SIZE// /}"
-  [ -z "$RAM_SIZE" ] && RAM_SIZE="2G"
-
-  if [[ "${RAM_SIZE,,}" != "max" && "${RAM_SIZE,,}" != "half" ]]; then
-
-    if [ -z "${RAM_SIZE//[0-9. ]}" ]; then
-      [ "${RAM_SIZE%%.*}" -lt "130" ] && RAM_SIZE="${RAM_SIZE}G" || RAM_SIZE="${RAM_SIZE}M"
-    fi
-
-    RAM_SIZE=$(echo "${RAM_SIZE^^}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
-    ! numfmt --from=iec "$RAM_SIZE" &>/dev/null && error "Invalid RAM_SIZE: $RAM_SIZE" && exit 16
-    wanted=$(numfmt --from=iec "$RAM_SIZE")
-    [ "$wanted" -lt "$RAM_MINIMUM" ] && error "RAM_SIZE is too low: $RAM_SIZE" && exit 16
-
-  fi
-
-  return 0
-}
-
 checkKvm() {
 
   # Check KVM support
@@ -238,6 +171,8 @@ checkKvm() {
   if disabled "$KVM"; then
     warn "KVM acceleration is disabled, this will cause the machine to run about 10 times slower!"
   else
+    # KVM accelerates only matching host and guest instruction sets; cross-
+    # architecture execution must fall back to software emulation.
     if [[ "${ARCH,,}" != "$TARGET" ]]; then
       KVM="N"
       warn "your CPU architecture is ${ARCH^^} and cannot provide KVM acceleration for ${PLATFORM^^} instructions, so the machine will run about 10 times slower."
@@ -261,7 +196,7 @@ checkKvm() {
           fi
           if ! grep -qw "sse4_2" <<< "$flags"; then
             error "Your CPU does not have the SSE4 instruction set that Virtual DSM requires!"
-            ! enabled "$DEBUG" && exit 88
+            enabled "$DEBUG" || exit 88
           fi
         fi
       fi
@@ -282,7 +217,7 @@ checkKvm() {
             error "KVM acceleration is not available $KVM_ERR, this will cause the machine to run about 10 times slower."
             error "See the FAQ for possible causes, or disable acceleration by adding the \"KVM=N\" variable (not recommended)." ;;
         esac
-        ! enabled "$DEBUG" && exit 88
+        enabled "$DEBUG" || exit 88
       fi
     fi
 
@@ -295,6 +230,7 @@ checkKvm() {
 TZ=$(strip "$TZ")
 STORAGE=$(strip "$STORAGE")
 COUNTRY=$(strip "$COUNTRY")
+MACHINE=$(strip "${MACHINE,,}")
 DISK_SIZE=$(strip "$DISK_SIZE")
 
 # Helper variables
@@ -322,22 +258,17 @@ SOCKETS=1
 CPU=$(cpu)
 SYS=$(uname -r)
 ARCH=$(dpkg --print-architecture)
-IFS=. read -r KERNEL MINOR _ <<< "$SYS"
 CORES=$(grep -c '^processor' /proc/cpuinfo)
+IFS=. read -r KERNEL MINOR _ <<< "$SYS"
 
-if grep -qi "socket(s)" <<< "$(lscpu)"; then
-  SOCKETS=$(lscpu | grep -m 1 -i 'socket(s)' | awk '{print $2}')
-  [ -z "${SOCKETS##*[!0-9]*}" ] && SOCKETS=1
-  [ "$SOCKETS" -lt "1" ] && SOCKETS=1
-fi
-
-normalizeCpuCores
+checkSockets
+checkCores
 checkStorage
-checkFilesystem
-normalizeRamSize
+getMemoryInfo
 
 # Print system info
 SYS="${SYS/-generic/}"
+FS=$(stat -f -c %T "$STORAGE")
 FS="${FS/UNKNOWN //}"
 FS="${FS/ext2\/ext3/ext4}"
 FS=$(echo "$FS" | sed 's/[)(]//g')
@@ -349,8 +280,11 @@ TOTAL_MEM=$(formatBytes "$RAM_TOTAL" "up")
 echo "❯ CPU: ${CPU} | RAM: ${AVAIL_MEM/ GB/}/$TOTAL_MEM | DISK: $SPACE_GB (${FS}) | KERNEL: ${SYS}"
 echo
 
+checkHost
 checkKvm
 
+# Runtime state is intentionally discarded at each container start; persistent
+# machine and disk identity lives under STORAGE instead.
 # Cleanup files
 rm -f "$QEMU_DIR"/dsm.url
 rm -f "$QEMU_DIR"/{qemu.*,*.{pid,sock,pipe}}

src/install.sh

@@ -3,6 +3,8 @@ set -Eeuo pipefail
 
 : "${URL:=""}"    # URL of the PAT file to be downloaded.
 
+# Persist the exact PAT base name so future starts reopen the matching boot,
+# system, and cached installation files.
 if [ -f "$STORAGE/dsm.ver" ]; then
   BASE=$(<"$STORAGE/dsm.ver")
   BASE="${BASE//[![:print:]]/}"
@@ -16,6 +18,8 @@ FN="boot.pat"
 DIR=$(find / -maxdepth 1 -type d -iname "$FN" -print -quit)
 [ ! -d "$DIR" ] && DIR=$(find "$STORAGE" -maxdepth 1 -type d -iname "$FN" -print -quit)
 
+# A boot.pat directory bind represents already extracted boot and system
+# images and therefore takes precedence over PAT file or URL discovery.
 if [ -d "$DIR" ]; then
   BASE="DSM_VirtualDSM" && URL="file://$DIR"
   if [[ ! -s "$STORAGE/$BASE.boot.img" || ! -s "$STORAGE/$BASE.system.img" ]]; then
@@ -29,6 +33,8 @@ FILE=$(find / -maxdepth 1 -type f -iname "$FN" -print -quit)
 
 URL=$(strip "$URL")
 
+# Derive a filesystem-safe identity from the URL only when no local boot.pat
+# source was supplied; preserve an existing system image identity if present.
 if [ -n "$URL" ] && [ ! -s "$FILE" ] && [ ! -d "$DIR" ]; then
   BASE=$(basename "$URL" .pat)
   if [ ! -s "$STORAGE/$BASE.system.img" ]; then
@@ -42,6 +48,8 @@ if [ -n "$URL" ] && [ ! -s "$FILE" ] && [ ! -d "$DIR" ]; then
   fi
 fi
 
+# A complete matching image pair is the installation marker; the cached PAT
+# itself is optional after installation.
 if [[ -s "$STORAGE/$BASE.boot.img" && -s "$STORAGE/$BASE.system.img" ]]; then
   return 0  # Previous installation found
 fi
@@ -55,6 +63,8 @@ DL_GLOBAL="https://global.synologydownload.com/download/DSM"
 [[ "${URL,,}" == *"cndl.synology"* ]] && DL="$DL_CHINA"
 [[ "${URL,,}" == *"global.synology"* ]] && DL="$DL_GLOBAL"
 
+# Honor an explicitly selected Synology mirror first, otherwise choose the
+# China or global endpoint from the detected country.
 if [ -z "$DL" ]; then
   [ -z "$COUNTRY" ] && setCountry
   [ -z "$COUNTRY" ] && info "Warning: could not detect country to select mirror!"
@@ -98,6 +108,8 @@ if [[ "${FS,,}" == "fat"* || "${FS,,}" == "vfat"* || "${FS,,}" == "msdos"* ]]; t
   error "Unable to install on $FS filesystems, please use a different filesystem for /storage." && exit 61
 fi
 
+# Extract beside storage on Unix filesystems to avoid container-space limits;
+# use /tmp for filesystems that cannot safely host the installer workspace.
 if [[ "${FS,,}" != "exfat"* && "${FS,,}" != "ntfs"* && "${FS,,}" != "unknown"* ]]; then
   TMP="$STORAGE/tmp"
   rm -rf "$TMP"
@@ -206,6 +218,8 @@ fi
 
 SIZE=$(stat -c%s "$PAT")
 
+# Full Virtual DSM PAT files are substantially larger than update packs;
+# reject undersized inputs before attempting destructive image preparation.
 if ((SIZE<250000000)); then
   error "The specified PAT file is probably an update pack as it's too small." && exit 62
 fi
@@ -213,6 +227,8 @@ fi
 MSG="Extracting installation image..."
 info "Install: $MSG" && html "$MSG"
 
+# Newer PAT files are normal tar archives; older encrypted/proprietary forms
+# require the bundled extractor as a compatibility fallback.
 if { tar tf "$PAT"; } >/dev/null 2>&1; then
 
   tar xpf "$PAT" -C "$TMP/."
@@ -231,6 +247,8 @@ fi
 MSG="Preparing system partition..."
 info "Install: $MSG" && html "$MSG"
 
+# The PAT boot archive becomes the persistent QEMU boot disk after its
+# companion system partition has been assembled.
 BOOT=$(find "$TMP" -name "*.bin.zip" -print -quit)
 [ -z "$BOOT" ] && error "The PAT file contains no boot image." && exit 67
 [ ! -s "$BOOT" ] && error "The PAT boot image archive is empty." && exit 67
@@ -254,7 +272,7 @@ if ! touch "$SYSTEM"; then
   error "Could not create file $SYSTEM for the system disk." && exit 98
 fi
 
-! setOwner "$SYSTEM" && warn "failed to set the owner for \"$SYSTEM\" !"
+setOwner "$SYSTEM" || warn "failed to set the owner for \"$SYSTEM\" !"
 
 if [[ "${FS,,}" == "btrfs" ]]; then
   { chattr +C "$SYSTEM"; } || :
@@ -273,6 +291,8 @@ if ! fallocate -l "$SYSTEM_SIZE" "$SYSTEM" &>/dev/null; then
   fi
 fi
 
+# Recreate Synology's expected DOS partition layout inside the fixed 10 GiB
+# system image before populating the ext4 root partition.
 PART="$TMP/partition.fdisk"
 
 {
@@ -320,6 +340,8 @@ OFFSET="1048576"    # 2048 * 512
 NUMBLOCKS="2097152" # (16777216 * 512) / 4096
 MSG="Installing system partition..."
 
+# Build the ext4 filesystem directly from the extracted tree under fakeroot,
+# preserving archive ownership without mounting a loop device.
 fakeroot -- bash -c "set -Eeu;\
   [ -s $HDP.txz ] && tar xpfJ $HDP.txz --absolute-names -C $MOUNT/;\
   [ -s $IDB.txz ] && tar xpfJ $IDB.txz --absolute-names -C $INDEX_DB/;\
@@ -329,8 +351,10 @@ fakeroot -- bash -c "set -Eeu;\
 
 rm -rf "$MOUNT"
 echo "$BASE" > "$STORAGE/dsm.ver"
-! setOwner "$STORAGE/dsm.ver" && warn "failed to set the owner for \"$STORAGE/dsm.ver\" !"
+setOwner "$STORAGE/dsm.ver" || warn "failed to set the owner for \"$STORAGE/dsm.ver\" !"
 
+# Do not keep a second copy when the source PAT already lives in storage;
+# downloaded or externally mounted sources are cached for later reuse.
 if [[ "$URL" == "file://$STORAGE/$BASE.pat" ]]; then
   rm -f "$PAT"
 else
@@ -338,11 +362,11 @@ else
 fi
 
 if [ -f "$STORAGE/$BASE.pat" ]; then
-  ! setOwner "$STORAGE/$BASE.pat" && warn "failed to set the owner for \"$STORAGE/$BASE.pat\" !"
+  setOwner "$STORAGE/$BASE.pat" || warn "failed to set the owner for \"$STORAGE/$BASE.pat\" !"
 fi
 
 mv -f "$BOOT" "$STORAGE/$BASE.boot.img"
-! setOwner "$STORAGE/$BASE.boot.img" && warn "failed to set the owner for \"$STORAGE/$BASE.boot.img\" !"
+setOwner "$STORAGE/$BASE.boot.img" || warn "failed to set the owner for \"$STORAGE/$BASE.boot.img\" !"
 
 rm -rf "$TMP"
 

src/memory.sh

@@ -1,78 +1,144 @@
 #!/usr/bin/env bash
 set -Eeuo pipefail
 
-msg="Checking memory..."
-enabled "$DEBUG" && echo "$msg"
+normalizeMemory() {
+
+  local wanted
+
+  RAM_SPARE=500000000
+  RAM_MINIMUM="${RAM_MINIMUM:-1073741824}"
+
+  RAM_MINIMUM=$(strip "$RAM_MINIMUM")
+  RAM_MINIMUM="${RAM_MINIMUM// /}"
+  RAM_MINIMUM=$(echo "${RAM_MINIMUM^^}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
+  numfmt --from=iec "$RAM_MINIMUM" &>/dev/null || {
+    error "Invalid RAM_MINIMUM: $RAM_MINIMUM"
+    exit 16
+  }
+  RAM_MINIMUM=$(numfmt --from=iec "$RAM_MINIMUM")
+
+  RAM_SIZE=$(strip "$RAM_SIZE")
+  RAM_SIZE="${RAM_SIZE// /}"
+  [ -z "$RAM_SIZE" ] && RAM_SIZE="2G"
+
+  if [[ "${RAM_SIZE,,}" != "max" && "${RAM_SIZE,,}" != "half" ]]; then
+
+    # Bare values below 130 are interpreted as GiB for convenience; larger bare
+    # values are treated as MiB to preserve historical configurations.
+    if [ -z "${RAM_SIZE//[0-9. ]}" ]; then
+      [ "${RAM_SIZE%%.*}" -lt "130" ] && RAM_SIZE="${RAM_SIZE}G" || RAM_SIZE="${RAM_SIZE}M"
+    fi
+
+    RAM_SIZE=$(echo "${RAM_SIZE^^}" | sed 's/MB/M/g;s/GB/G/g;s/TB/T/g')
+    numfmt --from=iec "$RAM_SIZE" &>/dev/null || {
+      error "Invalid RAM_SIZE: $RAM_SIZE"
+      exit 16
+    }
+
+    wanted=$(numfmt --from=iec "$RAM_SIZE")
+
+    if [ "$wanted" -lt "$RAM_MINIMUM" ]; then
+      error "$(app) requires at least $(formatBytes "$RAM_MINIMUM") of RAM, but RAM_SIZE is set to $(formatBytes "$wanted")."
+      exit 16
+    fi
+
+    # QEMU requires a whole-number memory value, so convert decimal sizes to MiB.
+    if [[ "$RAM_SIZE" == *.* ]]; then
+      RAM_SIZE="$(( wanted / 1048576 ))M"
+    fi
+
+  fi
 
-app() {
-  echo "Virtual DSM"
   return 0
 }
 
 checkConfiguredMemory() {
 
+  local final="$1"
+
   if disabled "$RAM_CHECK" || [[ "${RAM_SIZE,,}" == "max" || "${RAM_SIZE,,}" == "half" ]]; then
     return 0
   fi
 
-  local wanted msg avail_mem
+  local wanted avail_mem
   wanted=$(numfmt --from=iec "$RAM_SIZE")
   avail_mem=$(formatBytes "$RAM_AVAIL")
 
   if (( (wanted + RAM_SPARE) > RAM_AVAIL )); then
-    msg="Your configured RAM_SIZE of ${RAM_SIZE/G/ GB} is too high for the $avail_mem of free memory available,"
+
+    local msg="Your configured RAM_SIZE of ${RAM_SIZE/G/ GB} is too high for the $avail_mem of free memory available,"
+
+    # ZFS ARC can release cached memory under pressure, so this free-memory
+    # heuristic remains informational instead of rewriting RAM_SIZE.
     if [[ "${FS,,}" == "zfs" ]]; then
-      info "$msg but since ZFS is active this will be ignored."
+
+      enabled "$final" && info "$msg but since ZFS is active this will be ignored."
+
     else
+
       RAM_SIZE="max"
-      warn "$msg it will automatically be adjusted to a lower amount."
+      RAM_WARNING="$msg it will automatically be adjusted to a lower amount."
+
     fi
+
   else
+
     if (( (wanted + (RAM_SPARE * 3)) > RAM_AVAIL )); then
-      msg="your configured RAM_SIZE of ${RAM_SIZE/G/ GB} is very close to the $avail_mem of free memory available,"
+
+      local msg="your configured RAM_SIZE of ${RAM_SIZE/G/ GB} is very close to the $avail_mem of free memory available,"
+
       if [[ "${FS,,}" == "zfs" ]]; then
-        info "$msg but since ZFS is active this will be ignored."
+        enabled "$final" && info "$msg but since ZFS is active this will be ignored."
       else
-        warn "$msg please consider a lower amount."
+        enabled "$final" && warn "$msg please consider a lower amount."
       fi
+
     fi
+
   fi
 
   return 0
 }
 
 configureHalfMemory() {
-  local wanted
 
   if [[ "${RAM_SIZE,,}" != "half" ]]; then
     return 0
   fi
 
   if (( (RAM_AVAIL / 2) > RAM_SPARE )); then
-    wanted=$(( (RAM_AVAIL / 2) / 1048577 ))
-    RAM_SIZE="${wanted}M"
-    info "Allocated $wanted MB of RAM for $(app)."
+
+    local wanted=$(( RAM_AVAIL / 2 ))
+
+    # Divide by one byte more than a MiB to round down
+    local target=$(( wanted / 1048577 ))
+    RAM_SIZE="${target}M"
+    RAM_ALLOCATION="$wanted"
+
   else
+
     RAM_SIZE="max"
+
   fi
 
   return 0
 }
 
 configureMaxMemory() {
-  local wanted
 
   if [[ "${RAM_SIZE,,}" != "max" ]]; then
     return 0
   fi
 
+  # max keeps a host reserve when possible, but on very small systems falls back
+  # to half the available memory to avoid starving the container.
   if (( RAM_AVAIL < (RAM_SPARE * 2) )); then
 
-    wanted=$(( RAM_AVAIL / 2 ))
+    local wanted=$(( RAM_AVAIL / 2 ))
 
   else
 
-    wanted=$(( RAM_AVAIL - (RAM_SPARE * 3) ))
+    local wanted=$(( RAM_AVAIL - (RAM_SPARE * 3) ))
 
     if (( wanted < (RAM_SPARE * 6) )); then
       wanted=$(( RAM_AVAIL - RAM_SPARE ))
@@ -80,33 +146,90 @@ configureMaxMemory() {
 
   fi
 
-  wanted=$(( wanted / 1048577 ))
-  RAM_SIZE="${wanted}M"
+  # Divide by one byte more than a MiB to round down
+  local target=$(( wanted / 1048577 ))
+  RAM_SIZE="${target}M"
+  RAM_ALLOCATION="$wanted"
 
-  info "Allocated $wanted MB of RAM for $(app)."
+  return 0
+}
+
+showMemoryLimitHint() {
+
+  local kernel
+  kernel=$(uname -r)
+
+  if [[ "${kernel,,}" == *-wsl2* ]]; then
+    echo
+    info "Docker Desktop (WSL2) is detected, follow these instructions:"
+    info ""
+    info "Increase the memory limit in \"%UserProfile%\\.wslconfig\" by setting \"memory=<size>\" under \"[wsl2]\"."
+    info "Then run \"wsl --shutdown\" in PowerShell and restart Docker Desktop for the new limit to take effect."
+    echo
+  fi
 
   return 0
 }
 
 checkMinimumMemory() {
-  local wanted
 
+  local wanted
   wanted=$(numfmt --from=iec "$RAM_SIZE")
 
   if [ "$wanted" -lt "$RAM_MINIMUM" ]; then
-    wanted=$(( wanted / 1048577 ))
-    error "Not enough memory available, there is only $wanted MB left!"
+
+    error "$(app) requires at least $(formatBytes "$RAM_MINIMUM") of RAM, but only $(formatBytes "$wanted") can be allocated."
+
+    showMemoryLimitHint
+
     exit 16
   fi
 
   return 0
 }
 
-getMemoryInfo
+checkMemoryAllocation() {
 
-checkConfiguredMemory
-configureHalfMemory
-configureMaxMemory
-checkMinimumMemory
+  local final="${1:-N}"
+  local configured
+
+  normalizeMemory
+  configured="$RAM_SIZE"
+
+  RAM_WARNING=""
+  RAM_ALLOCATION=""
+
+  getMemoryInfo
+  checkConfiguredMemory "$final"
+
+  configureHalfMemory
+  configureMaxMemory
+  checkMinimumMemory
+
+  if enabled "$final"; then
+    [ -n "$RAM_WARNING" ] && warn "$RAM_WARNING"
+    [ -n "$RAM_ALLOCATION" ] && info "Allocated $(formatBytes "$RAM_ALLOCATION") of RAM for $(app)."
+  else
+    RAM_SIZE="$configured"
+  fi
+
+  return 0
+}
+
+checkMemoryRequirement() {
+
+  checkMemoryAllocation "N"
+
+  return 0
+}
+
+finalizeMemory() {
+
+  checkMemoryAllocation "Y"
+
+  return 0
+}
+
+checkMemoryRequirement
 
 return 0

src/network.sh

@@ -84,8 +84,7 @@ getMTU() {
 
 minMTU() {
 
-  local mtu=""
-  local min=""
+  local mtu min=""
 
   for mtu in "$@"; do
     [[ -z "$mtu" || "$mtu" == "0" ]] && continue
@@ -124,7 +123,7 @@ gatewayMAC() {
 maskToCIDR() {
 
   local mask="$1"
-  local prefix=""
+  local prefix
 
   if ! command -v ipcalc > /dev/null 2>&1; then
     error "Required command 'ipcalc' is not installed!"
@@ -154,7 +153,7 @@ maskToCIDR() {
 networkCIDR() {
 
   local ip="$1"
-  local network=""
+  local network
 
   network=$(ipcalc -n -b "$ip/$MASK" 2>/dev/null | awk '
     /^Network:/ {
@@ -172,6 +171,37 @@ networkCIDR() {
   return 0
 }
 
+upstreamIP() {
+
+  local subnet="$1"
+  local guest="$2"
+  local gateway="$3"
+  local broadcast candidate last
+
+  broadcast=$(ipcalc -n -b "$subnet" 2>/dev/null | awk '
+    /^Broadcast:/ {
+      print $2
+      exit
+    }
+  ')
+
+  if [[ ! "$broadcast" =~ ^([0-9]{1,3}\.){3}[0-9]{1,3}$ ]]; then
+    return 1
+  fi
+
+  last="${broadcast##*.}"
+
+  for (( last--; last>=2; last-- )); do
+    candidate="${broadcast%.*}.$last"
+    [[ "$candidate" == "$guest" || "$candidate" == "$gateway" ]] && continue
+
+    echo "$candidate"
+    return 0
+  done
+
+  return 1
+}
+
 detectInterface() {
 
   if [ -n "$DEV" ]; then
@@ -207,16 +237,23 @@ formatAddress() {
   return 0
 }
 
+defaultGateway() {
+
+  ip -4 route list default dev "$1" 2>/dev/null |
+    awk '$1 == "default" { for (i = 1; i < NF; i++) if ($i == "via") { print $(i + 1); exit } }' || :
+
+  return 0
+}
+
 detectAddresses() {
 
-  GATEWAY=$(ip route list dev "$DEV" | awk ' /^default/ {print $3}' | head -n 1)
+  GATEWAY=$(defaultGateway "$DEV")
   { UPLINK=$(ip address show dev "$DEV" | grep inet | awk '/inet / { print $2 }' | cut -f1 -d/ | head -n 1); } 2>/dev/null || :
 
   IP6=""
 
   if [ -f /proc/net/if_inet6 ] && [[ "$(cat /proc/sys/net/ipv6/conf/all/disable_ipv6 2>/dev/null)" != "1" ]]; then
-    local rc=0
-    { IP6=$(ip -6 addr show dev "$DEV" scope global up); rc=$?; } 2>/dev/null || :
+    { IP6=$(ip -6 addr show dev "$DEV" scope global up); local rc=$?; } 2>/dev/null || :
     (( rc != 0 )) && IP6=""
     [ -n "$IP6" ] && IP6=$(echo "$IP6" | sed -e's/^.*inet6 \([^ ]*\)\/.*$/\1/;t;d' | head -n 1)
   fi
@@ -226,7 +263,7 @@ detectAddresses() {
 
 detectAdapter() {
 
-  local result=""
+  local result
 
   NIC=""
   BUS=""
@@ -252,7 +289,7 @@ detectAdapter() {
 
 containerID() {
 
-  local id=""
+  local id
 
   id=$(hostname -s 2>/dev/null || true)
 
@@ -260,7 +297,7 @@ containerID() {
     id=$(< /etc/machine-id)
   fi
 
-  if [ -z "$id" ] && [ -s /proc/sys/kernel/random/boot_id ]; then
+  if [ -z "$id" ] && [ -r /proc/sys/kernel/random/boot_id ]; then
     id=$(< /proc/sys/kernel/random/boot_id)
   fi
 
@@ -270,6 +307,27 @@ containerID() {
   return 0
 }
 
+canBindPrivilegedPort() {
+
+  local port="$1"
+  local proto="${2:-tcp}"
+  local start="1024"
+  local rc=1
+
+  [ -r /proc/sys/net/ipv4/ip_unprivileged_port_start ] &&
+    start=$(< /proc/sys/net/ipv4/ip_unprivileged_port_start)
+
+  (( port >= start )) && return 0
+
+  if [[ "$proto" == "udp" ]]; then
+    { timeout 0.1 nc -4 -n -d -u -l 127.0.0.1 "$port" > /dev/null 2>&1; rc=$?; } || :
+  else
+    { timeout 0.1 nc -4 -n -d -l 127.0.0.1 "$port" > /dev/null 2>&1; rc=$?; } || :
+  fi
+
+  (( rc == 124 ))
+}
+
 disableIPv6() {
 
   local dev="$1"
@@ -286,7 +344,7 @@ disableIPv6() {
 subnetInUse() {
 
   local subnet="$1"
-  local broader="" narrower="" routes=""
+  local broader narrower routes
 
   if ! broader=$(ip -4 route show table all match "$subnet" 2>/dev/null); then
     error "Failed to inspect existing routes for subnet $subnet."
@@ -324,17 +382,18 @@ guestIP() {
 natGuestIP() {
 
   local ip="$1"
-  local start="" guest="" subnet=""
-  local second="" third="" rc=""
+  local guest subnet second third
 
   third=$(cut -d. -f3 <<< "$ip")
 
   if [[ "$ip" == "172.30."* ]]; then
-    start="31"
+    local start="31"
   else
-    start="30"
+    local start="30"
   fi
 
+  # Scan adjacent 172.30/31 through 172.254 subnets to avoid Docker routes
+  # while retaining the original third octet and guest host number.
   for (( second=start; second<=254; second++ )); do
     guest=$(guestIP "172.$second.$third.0" 2)
     subnet=$(networkCIDR "$guest") || return 1
@@ -342,7 +401,7 @@ natGuestIP() {
     if subnetInUse "$subnet"; then
       continue
     else
-      rc=$?
+      local rc=$?
       (( rc == 1 )) || return 1
     fi
 
@@ -357,7 +416,7 @@ natGuestIP() {
     if subnetInUse "$subnet"; then
       continue
     else
-      rc=$?
+      local rc=$?
       (( rc == 1 )) || return 1
     fi
 
@@ -369,36 +428,6 @@ natGuestIP() {
   return 1
 }
 
-kernelAtLeast() {
-
-  local major="$1"
-  local minor="${2:-0}"
-
-  (( KERNEL > major || (KERNEL == major && MINOR >= minor) ))
-}
-
-canBindToDevice() {
-
-  local dev="$1"
-  [ -n "$dev" ] || return 1
-
-  kernelAtLeast 5 7 || return 1
-  [ -d "/sys/class/net/$dev" ] || return 1
-  command -v python3 > /dev/null 2>&1 || return 0
-
-  python3 - "$dev" > /dev/null 2>&1 <<'PY'
-import socket
-import sys
-
-with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
-    sock.setsockopt(
-        socket.SOL_SOCKET,
-        socket.SO_BINDTODEVICE,
-        sys.argv[1].encode() + b"\0",
-    )
-PY
-}
-
 # ######################################
 #  DNS / port helpers
 # ######################################
@@ -411,7 +440,9 @@ configureDNS() {
   local host="$4"
   local mask="$5"
   local gateway="$6"
-  local arguments="$DNSMASQ_OPTS" rc
+  local upstream="${7:-}"
+  local arguments="$DNSMASQ_OPTS"
+  local pid
 
   if ! echo "$gateway" > /run/shm/qemu.gw; then
     error "Failed to write gateway file."
@@ -421,7 +452,10 @@ configureDNS() {
   enabled "${DNSMASQ_DISABLE:-}" && return 0
   enabled "$DEBUG" && echo "Starting dnsmasq daemon..."
 
-  [ -s "$DNSMASQ_PID" ] && pKill "$(<"$DNSMASQ_PID")"
+  if readPidFile pid "$DNSMASQ_PID"; then
+    pKill "$pid"
+  fi
+
   rm -f "$DNSMASQ_PID"
 
   if isNAT; then
@@ -459,6 +493,11 @@ configureDNS() {
   # Add DNS entry for container
   arguments+=" --address=/host.lan/$gateway"
 
+  # Add DNS entry for the upstream gateway.
+  if isNAT && [ -n "$upstream" ]; then
+    arguments+=" --address=/system.lan/$upstream"
+  fi
+
   # Avoid returning IPv6 records when the active network mode is IPv4-only.
   if isNAT || [ -z "$IP6" ]; then
     arguments+=" --filter-AAAA"
@@ -476,9 +515,9 @@ configureDNS() {
   arguments+=" --log-facility=$log"
 
   arguments=$(echo "$arguments" | sed 's/\t/ /g' | tr -s ' ' | sed 's/^ *//')
-  enabled "$DEBUG" && printf "Dnsmasq arguments:\n\n%s\n\n" "${arguments// -/$'\n-'}"
+  enabled "$DEBUG" && printf "Dnsmasq arguments:\n\n    %s\n\n" "${arguments// -/$'\n    -'}"
 
-  { $DNSMASQ ${arguments:+ $arguments}; rc=$?; } || :
+  { $DNSMASQ ${arguments:+ $arguments}; local rc=$?; } || :
 
   if (( rc != 0 )); then
 
@@ -499,11 +538,12 @@ configureDNS() {
   return 0
 }
 
-getHostPorts() {
+normalizePorts() {
 
-  local port="" ports=""
-  local num="" mode="${1:-tcp}"
-  local list="${HOST_PORTS// /},"
+  local list="$1"
+  local mode="${2:-tcp}"
+  local port num
+  local ports=""
 
   for port in ${list//,/ }; do
 
@@ -513,6 +553,7 @@ getHostPorts() {
       "tcp" )
         [[ "$port" == *"/udp" ]] && continue
         num="${port%/tcp}"
+        [ -n "$num" ] && ports+="$num,"
         ;;
       "all" )
         if [[ "$port" == *"/udp" ]]; then
@@ -522,39 +563,82 @@ getHostPorts() {
           num="${port%/tcp}"
           [ -n "$num" ] && ports+="$num/tcp,"
         fi
-        continue
         ;;
       *)
         return 1
         ;;
     esac
 
-    [ -n "$num" ] && ports+="$num,"
-
   done
 
   # Remove duplicates
-  ports=$(echo "${ports//,,/,}," | awk 'BEGIN{RS=ORS=","} !seen[$0]++' | sed 's/,*$//g')
+  echo "${ports//,,/,}," | awk 'BEGIN{RS=ORS=","} !seen[$0]++' | sed 's/,*$//g'
 
-  echo "$ports"
   return 0
 }
 
+getReservedPorts() {
+
+  local list=""
+  local mode="${1:-tcp}"
+
+  # Reserve the DNS port while the internal dnsmasq resolver is active.
+  if ! enabled "${DNSMASQ_DISABLE:-}" && ! isNAT; then
+    list+="53/tcp,53/udp,"
+  fi
+
+  normalizePorts "$list" "$mode"
+  return $?
+}
+
+getCustomHostPorts() {
+
+  local mode="${1:-tcp}"
+  local reserved user port
+  local ports=""
+
+  reserved=$(getReservedPorts "all")
+  user=$(normalizePorts "$HOST_PORTS" "all")
+
+  for port in ${user//,/ }; do
+    [[ ",$reserved," == *",$port,"* ]] && continue
+    ports+="$port,"
+  done
+
+  normalizePorts "$ports" "$mode"
+  return $?
+}
+
+getHostPorts() {
+
+  local mode="${1:-tcp}"
+  local reserved custom
+
+  # Merge internal reservations with user-defined host ports without mutating HOST_PORTS.
+  # User entries already covered by an internal reservation are silently ignored.
+  reserved=$(getReservedPorts "all")
+  custom=$(getCustomHostPorts "all")
+  normalizePorts "$reserved,$custom" "$mode"
+  return $?
+}
+
 getUserPorts() {
 
+  # User-mode networking forwards DSM management and SSH ports by default;
+  # internal container reservations and HOST_PORTS are removed below.
   local defaults="22/tcp,5000/tcp,5001/tcp"
   local list="$defaults,${USER_PORTS// /},"
 
-  local num="" ports="" proto=""
-  local userport="" hostport=""
+  local ports=""
+  local userport hostport exclude reserved
 
-  local exclude=""
+  reserved=$(getReservedPorts "all")
   exclude=$(getHostPorts "all")
 
   for userport in ${list//,/ }; do
 
-    proto="tcp"
-    num="$userport"
+    local proto="tcp"
+    local num="$userport"
 
     if [[ "$userport" == *"/udp" ]]; then
       proto="udp"
@@ -570,7 +654,9 @@ getUserPorts() {
 
       if [[ "$num/$proto" == "$hostport" ]]; then
 
-        if [[ "$hostport" != "${WEB_PORT:-}/tcp" ]]; then
+        if [[ ",$reserved," == *",$hostport,"* ]]; then
+          warn "Could not assign port $hostport to \"USER_PORTS\" because it is reserved by the container!"
+        elif [[ "$hostport" != "${WEB_PORT:-}/tcp" ]]; then
           warn "Could not assign port $hostport to \"USER_PORTS\" because it is already in \"HOST_PORTS\"!"
         fi
 
@@ -580,8 +666,14 @@ getUserPorts() {
 
     done
 
-    [ -n "$num" ] && ports+="$num/$proto,"
+    [ -z "$num" ] && continue
 
+    if ! canBindPrivilegedPort "$num" "$proto"; then
+      warn "Could not assign port $num/$proto to \"USER_PORTS\" because it cannot be bound by the current user!"
+      continue
+    fi
+
+    ports+="$num/$proto,"
   done
 
   # Remove duplicates
@@ -593,7 +685,7 @@ getUserPorts() {
 getSlirp() {
 
   local ip="$1"
-  local args="" list=""
+  local args="" list
 
   list=$(getUserPorts)
 
@@ -617,9 +709,8 @@ getSlirp() {
 
 getPasst() {
 
-  local args="" list="" port=""
-  local num="" tcp="" udp=""
-  local bind="$UPLINK"
+  local list port
+  local tcp="" udp="" args=""
 
   list=$(getUserPorts)
 
@@ -629,12 +720,12 @@ getPasst() {
 
     if [[ "$port" == *"/udp" ]]; then
 
-      num="${port%/udp}"
+      local num="${port%/udp}"
       [ -n "$num" ] && udp+="$num,"
 
     elif [[ "$port" == *"/tcp" ]]; then
 
-      num="${port%/tcp}"
+      local num="${port%/tcp}"
       [ -n "$num" ] && tcp+="$num,"
 
     else
@@ -648,12 +739,8 @@ getPasst() {
   tcp="${tcp%,}"
   udp="${udp%,}"
 
-  if canBindToDevice "$DEV"; then
-    bind="%$DEV"
-  fi
-
-  [ -n "$tcp" ] && args+=" -t $bind/$tcp"
-  [ -n "$udp" ] && args+=" -u $bind/$udp"
+  [ -n "$tcp" ] && args+=" -t $tcp"
+  [ -n "$udp" ] && args+=" -u $udp"
 
   echo "$args"
   return 0
@@ -665,8 +752,7 @@ getPasst() {
 
 configureVTAP() {
 
-  local msg=""
-  local rc
+  local msg dev
 
   enabled "$DEBUG" && echo "Configuring MACVTAP networking..."
 
@@ -678,7 +764,7 @@ configureVTAP() {
   fi
 
   # Create a macvtap network for the VM guest
-  { msg=$(ip link add link "$DEV" name "$TAP" address "$MAC" type macvtap mode bridge 2>&1); rc=$?; } || :
+  { msg=$(ip link add link "$DEV" name "$TAP" address "$MAC" type macvtap mode bridge 2>&1); local rc=$?; } || :
 
   case "$msg" in
     "RTNETLINK answers: File exists"* )
@@ -711,15 +797,35 @@ configureVTAP() {
     sleep 2
   done
 
-  local TAP_NR TAP_PATH MAJOR MINOR
-  TAP_NR=$(</sys/class/net/"$TAP"/ifindex)
-  TAP_PATH="/dev/tap${TAP_NR}"
+  local TAP_NR MAJOR MINOR
+
+  if ! dev=$(cat /sys/devices/virtual/net/"$TAP"/tap*/dev); then
+    error "Failed to determine device numbers for MACVTAP interface \"$TAP\" !"
+    return 1
+  fi
+
+  IFS=: read -r MAJOR MINOR <<< "$dev"
+
+  if [[ ! "$MAJOR" =~ ^[0-9]+$ || ! "$MINOR" =~ ^[0-9]+$ ]]; then
+    error "Failed to parse device numbers for MACVTAP interface \"$TAP\" !"
+    return 1
+  fi
+
+  if (( MAJOR < 1 )); then
+    error "Cannot find: sys/devices/virtual/net/$TAP"
+    return 1
+  fi
+
+  if ! TAP_NR=$(<"/sys/class/net/$TAP/ifindex"); then
+    error "Failed to determine interface index of MACVTAP interface \"$TAP\" !"
+    return 1
+  fi
 
   # Create dev file (there is no udev in container: need to be done manually)
-  IFS=: read -r MAJOR MINOR < <(cat /sys/devices/virtual/net/"$TAP"/tap*/dev)
-  (( MAJOR < 1)) && error "Cannot find: sys/devices/virtual/net/$TAP" && return 1
+  local TAP_PATH="/dev/tap${TAP_NR}"
 
-  [[ ! -e "$TAP_PATH" && -e "/dev0/${TAP_PATH##*/}" ]] && ln -s "/dev0/${TAP_PATH##*/}" "$TAP_PATH"
+  [[ ! -e "$TAP_PATH" && -e "/dev0/${TAP_PATH##*/}" ]] &&
+    ln -s "/dev0/${TAP_PATH##*/}" "$TAP_PATH"
 
   if [[ ! -e "$TAP_PATH" ]]; then
     { mknod "$TAP_PATH" c "$MAJOR" "$MINOR"; rc=$?; } || :
@@ -753,7 +859,7 @@ configureSlirp() {
 
   ip=$(guestIP "$ip" 4)
   local gateway="${ip%.*}.1"
-  local subnet=""
+  local subnet
   subnet=$(networkCIDR "$ip") || return 1
 
   local ipv6="ipv6=off,"
@@ -761,7 +867,7 @@ configureSlirp() {
 
   NET_OPTS="-netdev user,id=hostnet0,ipv4=on,host=$gateway,net=$subnet,dhcpstart=$ip,${ipv6}hostname=$HOST"
 
-  local forward=""
+  local forward
   forward=$(getSlirp "$ip")
   [ -n "$forward" ] && NET_OPTS+=",$forward"
 
@@ -818,12 +924,13 @@ configurePasst() {
   # Pass an explicit MTU to passt.
   PASST_OPTS+=" -m $passt_mtu"
 
-  local forward=""
+  local forward
   forward=$(getPasst)
   [ -n "$forward" ] && PASST_OPTS+="$forward"
 
   PASST_OPTS+=" -H $HOST"
   PASST_OPTS+=" -M $GATEWAY_MAC"
+  PASST_OPTS+=" --runas $EUID:$(id -g)"
   PASST_OPTS+=" -P $PASST_PID"
   PASST_OPTS+=" -s $PASST_SOCKET"
   PASST_OPTS+=" -l $log"
@@ -854,11 +961,10 @@ configurePasst() {
 
   if ! "$PASST" ${PASST_OPTS:+$PASST_OPTS} >/dev/null 2>&1; then
 
-    local rc=0
     rm -f "$log"
 
     PASST_OPTS="${PASST_OPTS/ -q/}"
-    { "$PASST" ${PASST_OPTS:+$PASST_OPTS}; rc=$?; } || :
+    { "$PASST" ${PASST_OPTS:+$PASST_OPTS}; local rc=$?; } || :
 
     if (( rc != 0 )); then
       [ -f "$log" ] && [ -s "$log" ] && cat "$log"
@@ -886,13 +992,24 @@ configurePasst() {
   return 0
 }
 
+configureBridge() {
+
+  local file="/etc/qemu/bridge.conf"
+
+  [ -e "$file" ] && return 0
+  mkdir -p "${file%/*}" || return 0
+  echo "allow br0" > "$file" || return 0
+
+  return 0
+}
+
 createBridge() {
 
   local gateway="$1"
-  local rc msg=""
+  local msg
 
   # Create a bridge with a static IP for the VM guest
-  { msg=$(ip link add dev "$BRIDGE" type bridge 2>&1); rc=$?; } || :
+  { msg=$(ip link add dev "$BRIDGE" type bridge 2>&1); local rc=$?; } || :
 
   if (( rc != 0 )); then
     enabled "$ROOTLESS" && ! enabled "$DEBUG" && return 1
@@ -930,10 +1047,10 @@ createBridge() {
 createTap() {
 
   local tuntap="$1"
-  local rc msg=""
+  local msg
 
   # Set tap to the bridge created
-  { msg=$(ip tuntap add dev "$TAP" mode tap 2>&1); rc=$?; } || :
+  { msg=$(ip tuntap add dev "$TAP" mode tap 2>&1); local rc=$?; } || :
 
   if (( rc != 0 )); then
     enabled "$ROOTLESS" && ! enabled "$DEBUG" && return 1
@@ -976,7 +1093,7 @@ hasTable() {
 
 getTablesBackend() {
 
-  local version=""
+  local version
   version=$(iptables --version 2>/dev/null || true)
 
   case "$version" in
@@ -989,7 +1106,7 @@ getTablesBackend() {
 setTables() {
 
   local mode="$1"
-  local path=""
+  local path
 
   path=$(command -v "iptables-$mode" 2>/dev/null || true)
   [ -z "$path" ] && return 1
@@ -1003,7 +1120,7 @@ showRules() {
   local chain="$2"
   local label="$3"
   local rule_tag="$4"
-  local rules=""
+  local rules
   local own_rule="--comment[[:space:]]+\"?$rule_tag\"?([[:space:]]|\$)"
 
   enabled "$DEBUG" || return 0
@@ -1022,7 +1139,7 @@ showRules() {
 
 checkExistingTables() {
 
-  local msg="" rules="" conflicts=""
+  local rules conflicts
   local rule_tag="QEMU_DNAT"
   local own_rule="--comment[[:space:]]+\"?$rule_tag\"?([[:space:]]|\$)"
 
@@ -1040,7 +1157,7 @@ checkExistingTables() {
     <<< "$rules" || true)
 
   if [ -n "$conflicts" ]; then
-    msg="your existing NAT rules may take precedence over VM port forwarding"
+    local msg="your existing NAT rules may take precedence over VM port forwarding"
 
     if enabled "$DEBUG"; then
       warn "${msg}."
@@ -1060,7 +1177,7 @@ checkExistingTables() {
     <<< "$rules" || true)
 
   if [ -n "$conflicts" ]; then
-    msg="your existing firewall rules may block traffic forwarded to or from the VM"
+    local msg="your existing firewall rules may block traffic forwarded to or from the VM"
 
     if enabled "$DEBUG"; then
       warn "${msg}."
@@ -1088,13 +1205,13 @@ runTableRule() {
 
   local silent="$1"
   local result="$2"
-  local rc msg=""
+  local msg
 
   shift 2
 
   printf -v "$result" '%s' ""
 
-  { msg=$("$@" 2>&1); rc=$?; } || :
+  { msg=$("$@" 2>&1); local rc=$?; } || :
   (( rc == 0 )) && return 0
 
   printf -v "$result" '%s' "$msg"
@@ -1154,8 +1271,8 @@ applyTables() {
   local ip="$1"
   local subnet="$2"
   local silent="${3:-N}"
-  local exclude="" port=""
-  local table_error=""
+  local exclude port
+  local table_error
   local dnat_chain="QEMU_DNAT"
   local rule_tag="$dnat_chain"
 
@@ -1283,8 +1400,8 @@ applyTables() {
 
 clearTables() {
 
-  local table="" line="" chain=""
-  local rules="" remaining="" message=""
+  local line
+  local rules remaining message
   local dnat_chain="QEMU_DNAT"
   local rule_tag="$dnat_chain"
   local own_rule="--comment[[:space:]]+\"?$rule_tag\"?([[:space:]]|\$)"
@@ -1309,15 +1426,15 @@ clearTables() {
     while IFS= read -r line; do
 
       case "$line" in
-        \*nat ) table="nat" ;;
-        \*filter ) table="filter" ;;
-        \*mangle ) table="mangle" ;;
-        \*raw ) table="raw" ;;
+        \*nat ) local table="nat" ;;
+        \*filter ) local table="filter" ;;
+        \*mangle ) local table="mangle" ;;
+        \*raw ) local table="raw" ;;
       esac
 
       if [[ "$line" == -A* ]] && [[ "$line" =~ $own_rule ]]; then
 
-        chain="${line#-A }"
+        local chain="${line#-A }"
         chain="${chain%% *}"
 
         # Rules inside this chain are removed together by the flush below.
@@ -1383,7 +1500,7 @@ clearTables() {
 hasTaggedRules() {
 
   local save="$1"
-  local rules=""
+  local rules
   local dnat_chain="QEMU_DNAT"
   local rule_tag="$dnat_chain"
   local own_rule="--comment[[:space:]]+\"?$rule_tag\"?([[:space:]]|\$)"
@@ -1405,9 +1522,8 @@ configureTables() {
 
   local ip="$1"
   local subnet="$2"
-  local preferred=""
-  local alternate=""
-  local alternate_save=""
+  local preferred
+  local alternate_save
   local preferred_clean="N"
   local alternate_dirty="N"
 
@@ -1418,8 +1534,8 @@ configureTables() {
   }
 
   case "$preferred" in
-    "nft" ) alternate="legacy" ;;
-    "legacy" ) alternate="nft" ;;
+    "nft" ) local alternate="legacy" ;;
+    "legacy" ) local alternate="nft" ;;
     * )
       enabled "$ROOTLESS" && ! enabled "$DEBUG" && return 1
       warn "unsupported IP tables backend: $preferred"
@@ -1605,10 +1721,46 @@ configureTables() {
   return 1
 }
 
+addUpstream() {
+
+  local upstream="$1"
+  local table_error
+  local rule_tag="QEMU_DNAT"
+
+  [ -n "$upstream" ] || return 1
+  [ -n "$GATEWAY" ] || return 1
+
+  if ! ip address add "$upstream/32" dev "$BRIDGE"; then
+    if ! enabled "$ROOTLESS" || enabled "$DEBUG"; then
+      warn "failed to add the system.lan address; access through that name will be unavailable."
+    fi
+    return 1
+  fi
+
+  if ! runTableRule "Y" table_error \
+    iptables -t nat -A PREROUTING \
+    -i "$BRIDGE" \
+    -d "$upstream" \
+    -m comment --comment "$rule_tag" \
+    -j DNAT --to-destination "$GATEWAY"; then
+
+    ip address del "$upstream/32" dev "$BRIDGE" > /dev/null 2>&1 || :
+
+    if ! enabled "$ROOTLESS" || enabled "$DEBUG"; then
+      [ -n "$table_error" ] && echo "$table_error" >&2
+      warn "failed to configure system.lan forwarding; access through that name will be unavailable."
+    fi
+
+    return 1
+  fi
+
+  return 0
+}
+
 configureNAT() {
 
   local tuntap="TUN device is missing. $ADD_ERR --device /dev/net/tun"
-  local rc ip subnet msg="" forwarding=""
+  local ip subnet upstream="" forwarding=""
 
   enabled "$DEBUG" && echo "Configuring NAT networking..."
 
@@ -1616,7 +1768,8 @@ configureNAT() {
   if [ ! -c /dev/net/tun ]; then
     [ ! -d /dev/net ] && mkdir -m 755 /dev/net > /dev/null 2>&1 || :
 
-    { msg=$(mknod /dev/net/tun c 10 200 2>&1); rc=$?; } || :
+    local msg
+    { msg=$(mknod /dev/net/tun c 10 200 2>&1); local rc=$?; } || :
 
     if (( rc == 0 )); then
       chmod 666 /dev/net/tun
@@ -1635,7 +1788,7 @@ configureNAT() {
     forwarding=$(< /proc/sys/net/ipv4/ip_forward)
 
   if [[ "$forwarding" != "1" ]]; then
-    { sysctl -w net.ipv4.ip_forward=1 > /dev/null 2>&1; rc=$?; } || :
+    { sysctl -w net.ipv4.ip_forward=1 > /dev/null 2>&1; local rc=$?; } || :
 
     forwarding=""
     [ -r /proc/sys/net/ipv4/ip_forward ] &&
@@ -1657,11 +1810,15 @@ configureNAT() {
   local gateway="${ip%.*}.1"
   subnet=$(networkCIDR "$ip") || return 1
 
+  if [ -n "$GATEWAY" ]; then
+    upstream=$(upstreamIP "$subnet" "$ip" "$gateway") || upstream=""
+  fi
+
   if subnetInUse "$subnet"; then
     error "VM subnet $subnet conflicts with an existing route inside the container."
     return 1
   else
-    rc=$?
+    local rc=$?
     (( rc == 1 )) || return 1
   fi
 
@@ -1675,16 +1832,20 @@ configureNAT() {
 
   configureTables "$ip" "$subnet" || return 1
 
+  if [ -n "$upstream" ] && ! addUpstream "$upstream"; then
+    upstream=""
+  fi
+
   NET_OPTS="-netdev tap,id=hostnet0,ifname=$TAP"
 
   if [ -c /dev/vhost-net ]; then
-    { exec 40>>/dev/vhost-net; rc=$?; } 2>/dev/null || :
+    { exec 40>>/dev/vhost-net; local rc=$?; } 2>/dev/null || :
     (( rc == 0 )) && NET_OPTS+=",vhost=on,vhostfd=40"
   fi
 
   NET_OPTS+=",script=no,downscript=no"
 
-  configureDNS "$BRIDGE" "$ip" "$MAC" "$HOST" "$MASK" "$gateway" || return 1
+  configureDNS "$BRIDGE" "$ip" "$MAC" "$HOST" "$MASK" "$gateway" "$upstream" || return 1
 
   IP="$ip"
   return 0
@@ -1740,7 +1901,7 @@ closeNetwork() {
 checkOS() {
 
   local iface="macvlan"
-  local os="" kernel=""
+  local os="" kernel
 
   kernel=$(uname -a)
 
@@ -1798,7 +1959,10 @@ validateHost() {
 
 validateHostPorts() {
 
-  if isNAT && [[ "${HOST_PORTS,,}" == *"/udp"* ]]; then
+  local custom
+  custom=$(getCustomHostPorts "all")
+
+  if isNAT && [[ "$custom" == *"/udp"* ]]; then
     warn "UDP ports in \"HOST_PORTS\" are not yet implemented for NAT networking."
   fi
 
@@ -1891,14 +2055,12 @@ configureMTU() {
 
 configureMAC() {
 
-  local container=""
-  local file=""
-
+  local container
   container=$(containerID)
 
   if [ -z "$MAC" ]; then
 
-    file="$STORAGE/dsm.mac"
+    local file="$STORAGE/dsm.mac"
 
     if [ -s "$file" ]; then
       if ! MAC=$(readFile "$file"); then
@@ -1941,7 +2103,7 @@ configureMAC() {
 
 showHostInfo() {
 
-  local mtu="" host="" uplink="" prefix=""
+  local mtu host uplink prefix
 
   prefix=$(ip -4 -o address show dev "$DEV" scope global 2>/dev/null |
     awk -v ip="$UPLINK" '
@@ -2010,6 +2172,7 @@ showHostInfo() {
     echo "❯ DNS: $nameservers"
   fi
 
+  enabled "$DEBUG" && echo
   return 0
 }
 
@@ -2028,10 +2191,10 @@ showGuestInfo() {
 
   local mode="${NETWORK,,}"
 
-  if isNAT; then
-    mode="NAT"
-  elif enabled "$DHCP"; then
+  if enabled "$DHCP"; then
     mode="DHCP"
+  elif isNAT; then
+    mode="NAT"
   elif isUserMode; then
     mode="User ($mode)"
   elif [ -z "$mode" ]; then
@@ -2064,6 +2227,7 @@ initializeNetwork() {
 
   configureMTU
   configureMAC
+  configureBridge
 
   showHostInfo
 
@@ -2117,6 +2281,8 @@ else
     if ! configureNAT; then
 
       closeInterfaces
+      # NAT setup failure is recoverable: tear down partial interfaces and
+      # continue with the default user-mode backend.
       NETWORK="user"
 
       if ! enabled "$ROOTLESS" || enabled "$DEBUG"; then
@@ -2164,6 +2330,8 @@ else
 
 fi
 
+# Suppress the adapter option ROM because firmware network boot is unused and
+# would otherwise alter boot order and startup timing.
 NET_OPTS+=" -device $ADAPTER,id=net0,netdev=hostnet0,romfile=,mac=$MAC"
 
 if [[ "$GUEST_MTU" != "0" && "$GUEST_MTU" != "1500" ]]; then
@@ -2174,6 +2342,8 @@ if [[ "$GUEST_MTU" != "0" && "$GUEST_MTU" != "1500" ]]; then
   fi
 fi
 
+# Publish the container address and detected driver for the healthcheck and
+# post-boot login-message helper.
 if ! echo "$UPLINK" > "$QEMU_DIR"/qemu.ip; then
   error "Failed to write QEMU IP file!"
   exit 24

src/power.sh

@@ -67,16 +67,10 @@ displayReason() {
 
 readQemuPid() {
 
-  local -n _pid="$1"
-  local file
-
-  for file in "$QEMU_START_PID" "$QEMU_PID"; do
-    if [ -s "$file" ] && read -r _pid < "$file"; then
-      return 0
-    fi
-  done
-
-  return 1
+  # Interactive startup uses a wrapper-created PID file before QEMU writes its
+  # own pidfile, so accept either during startup and shutdown races.
+  readPidFile "$1" "$QEMU_START_PID" && return 0
+  readPidFile "$1" "$QEMU_PID"
 }
 
 qemuPidFile() {
@@ -92,7 +86,7 @@ qemuPidFile() {
 waitQemuExit() {
 
   local timeout="${1:-10}"
-  local file=""
+  local file
 
   qemuPidFile file
   waitPidFile "$file" "$timeout"
@@ -100,26 +94,24 @@ waitQemuExit() {
 
 waitQemuPid() {
 
-  local -n _pid="$1"
-  local cnt=0 value=""
+  local cnt=0
 
-  while ! readQemuPid value; do
+  while ! readQemuPid "$1"; do
     sleep 0.02
     cnt=$((cnt + 1))
     (( cnt >= 50 )) && return 1
   done
 
-  _pid="$value"
   return 0
 }
 
 forceKillQemu() {
 
   local reason="$1"
-  local pid="" display
+  local pid display
 
-  ! readQemuPid pid && return 0
-  ! isAlive "$pid" && return 0
+  readQemuPid pid || return 0
+  isAlive "$pid" || return 0
 
   display=$(displayReason "$reason")
   error "Forcefully terminating $(app), reason: $display..."
@@ -145,7 +137,7 @@ cleanupHelpers() {
 startConsole() {
 
   local output="${1:-/dev/tty}"
-  local cnt=0 pid=""
+  local cnt=0
 
   rm -f -- "$CONSOLE_SOCKET" "$CONSOLE_PID"
 
@@ -159,7 +151,7 @@ startConsole() {
     exec nc -lU "$CONSOLE_SOCKET" </dev/tty >"$output"
   ) &
 
-  pid=$!
+  local pid="$!"
   echo "$pid" > "$CONSOLE_PID"
 
   while [ ! -S "$CONSOLE_SOCKET" ]; do
@@ -194,6 +186,8 @@ startQemu() {
 
   rm -f -- "$QEMU_START_PID"
 
+  # Launch QEMU in a separate session while recording the real child PID;
+  # setsid's wrapper PID is not suitable for guest shutdown or forced cleanup.
   (
     trap '' INT QUIT
 
@@ -246,14 +240,16 @@ finish() {
 sendGuestShutdown() {
 
   local pid="$1"
-  local response url
+  local response
 
+  # Virtual DSM ignores ACPI powerdown, so graceful shutdown must go through
+  # the qemu-host guest API exposed on the Unix socket.
   # Don't send the powerdown signal because vDSM ignores ACPI signals
   # nc -q 1 -w 1 -U "$QEMU_DIR/monitor.sock" &> /dev/null <<<'system_powerdown' || :
 
   # Send shutdown command to guest agent via serial port
   API_TIMEOUT=$(strip "$API_TIMEOUT")
-  url="http://localhost/read?command=$API_CMD&timeout=$API_TIMEOUT"
+  local url="http://localhost/read?command=$API_CMD&timeout=$API_TIMEOUT"
   response=$(curl --unix-socket "$HOST_API_SOCKET" -sk -m "$(( API_TIMEOUT+2 ))" -S "$url" 2>&1)
 
   if [[ "$response" =~ "\"success\"" ]]; then
@@ -275,6 +271,8 @@ sendGuestShutdown() {
 
 normalizeTimeout() {
 
+  # Divide the remaining timeout into guest wait, SIGTERM grace, and final
+  # cleanup instead of allowing the API call to consume the entire budget.
   local term_grace=3      # seconds before loop ends to send SIGTERM
   local cleanup_grace=3   # seconds reserved after the loop for cleanup
 
@@ -315,8 +313,10 @@ waitForShutdown() {
     local slp=$!
 
     # Stop waiting if the process has exited
-    ! isAlive "$pid" && break
+    isAlive "$pid" || break
 
+    # The process state is authoritative, but disappearance of both pidfiles
+    # also ends the wait when a wrapper exits before process reaping completes.
     # Workaround for stale/zombie QEMU pid file
     [ ! -s "$QEMU_START_PID" ] && [ ! -s "$QEMU_PID" ] && break
 
@@ -335,17 +335,19 @@ waitForShutdown() {
   return 0
 }
 
-graceful_shutdown() {
+gracefulShutdown() {
 
   local sig="$1"
-  local pid="" code=0
+  local pid code
 
   [[ $BASHPID != "$TRAP_PID" ]] && return
 
   code=$(signalCode "$sig")
 
-  if [ -f "$QEMU_END" ]; then
+  if (( SHUTDOWN_SIGNAL != 0 )); then
 
+    # A second Ctrl-C is the explicit user request to skip the remaining
+    # graceful-shutdown wait and proceed to forced cleanup.
     if (( code == 130 && SHUTDOWN_SIGNAL == code )); then
       SHUTDOWN_SKIP=1
       echo && info "Received SIGINT again, forcing shutdown..."
@@ -356,11 +358,14 @@ graceful_shutdown() {
     return
   fi
 
-  set +e
   start=$SECONDS
   SHUTDOWN_SIGNAL=$code
 
+  # Shutdown handlers must continue through missing processes and failed cleanup
+  # commands instead of being aborted by errexit.
+  set +e
   touch "$QEMU_END"
+
   echo && info "Received $sig signal, sending shutdown command..."
 
   if ! readQemuPid pid; then
@@ -382,13 +387,21 @@ graceful_shutdown() {
   finish "$code"
 }
 
-! enabled "$SHUTDOWN" && return 0
+enableTrap() {
+
+  enabled "$SHUTDOWN" || return 0
+
+  # Keep Ctrl-C available to interactive users without installing an unnecessary
+  # SIGINT handler for background/container execution.
+  if interactive; then
+    _trap gracefulShutdown SIGINT
+  fi
+
+  _trap gracefulShutdown SIGTERM SIGHUP SIGABRT SIGQUIT
+
+  return 0
+}
+
 [ -n "${QEMU_TIMEOUT:-}" ] && TIMEOUT="$QEMU_TIMEOUT"
 
-if interactive; then
-  _trap graceful_shutdown SIGINT
-fi
-
-_trap graceful_shutdown SIGTERM SIGHUP SIGABRT SIGQUIT
-
 return 0

src/print.sh

@@ -9,6 +9,7 @@ cd /run
 . utils.sh      # Load functions
 
 info () { printf "%b%s%b" "\E[1;34m❯ \E[1;36m" "$1" "\E[0m\n" >&2; }
+warn () { printf "%b%s%b" "\E[1;33m❯ " "WARNING: $1" "\E[0m\n" >&2; }
 error () { printf "%b%s%b" "\E[1;31m❯ " "ERROR: $1" "\E[0m\n" >&2; }
 
 disabled "$NETWORK" && exit 0
@@ -36,9 +37,9 @@ exitIfShuttingDown() {
 
 queryGuest() {
 
-  local rc
-
-  { json=$(curl --unix-socket "$socket" -m 20 -sk "$url"); rc=$?; } || :
+  # Query DSM through the qemu-host sidecar rather than the guest network,
+  # which may not be configured yet.
+  { json=$(curl --unix-socket "$socket" -m 20 -sk "$url"); local rc=$?; } || :
 
   exitIfShuttingDown
 
@@ -54,9 +55,8 @@ readJsonField() {
 
   local query="$1"
   local result
-  local rc
 
-  { result=$(jq -r "$query" <<< "$json"); rc=$?; } || :
+  { result=$(jq -r "$query" <<< "$json"); local rc=$?; } || :
 
   if (( rc != 0 )); then
     error "$jq_err $rc ( $json )"
@@ -74,12 +74,12 @@ readJsonField() {
 
 readGuestStatus() {
 
-  local result msg rc
+  local result msg
 
   result=$(readJsonField '.status') || return 1
 
   if [[ "$result" != "success" ]]; then
-    { msg=$(jq -r '.message // empty' <<< "$json"); rc=$?; } || :
+    { msg=$(jq -r '.message // empty' <<< "$json"); local rc=$?; } || :
 
     if (( rc != 0 )); then
       error "$jq_err $rc ( $json )"
@@ -118,6 +118,8 @@ writeDsmLocation() {
 
 pollGuestLocation() {
 
+  # Keep polling until the guest reports a usable address, but stop promptly
+  # when container shutdown begins.
   while [ ! -s "$file" ]; do
 
     # Check if not shutting down
@@ -140,14 +142,29 @@ pollGuestLocation() {
   return 0
 }
 
+checkAddressConflict() {
+
+  local guest_ip="${location%:*}"
+  local container_ip=""
+
+  [ -s "$address" ] && container_ip=$(<"$address")
+  [ -z "$container_ip" ] && return 0
+  [[ "$guest_ip" != "$container_ip" ]] && return 0
+
+  warn "DSM is using the same IP as the container, this will cause connectivity issues."
+  warn "change the container's macvlan IP or assign DSM a different address in your router."
+
+  return 0
+}
+
 writeDhcpPage() {
 
-  local title body script html
+  local html
 
   msg="http://$location"
-  title="<title>Virtual DSM</title>"
-  body="The location of DSM is <a href='http://$location'>http://$location</a>"
-  script="<script>setTimeout(function(){ window.location.assign('http://$location'); }, 3000);</script>"
+  local title="<title>Virtual DSM</title>"
+  local body="The location of DSM is <a href='http://$location'>http://$location</a>"
+  local script="<script>setTimeout(function(){ window.location.assign('http://$location'); }, 3000);</script>"
 
   html=$(<"$template")
   html="${html/\[1\]/$title}"
@@ -164,12 +181,14 @@ writeDhcpPage() {
 
 buildStaticMessage() {
 
-  local nic ip port
+  local nic ip
 
   nic=$(<"$driver")
   ip=$(<"$address")
-  port="${location##*:}"
+  local port="${location##*:}"
 
+  # NAT and user-mode networking are reached through a forwarded host port;
+  # macvlan exposes DSM directly on the container-facing LAN address.
   if [[ "${nic,,}" != "macvlan" ]]; then
     msg="port $port"
   else
@@ -196,6 +215,7 @@ exitIfShuttingDown
 location=$(<"$file")
 
 if enabled "$DHCP"; then
+  checkAddressConflict
   writeDhcpPage
 else
   buildStaticMessage

src/proc.sh

@@ -47,7 +47,7 @@ checkSse42() {
 
   if ! hasFlag "sse4_2"; then
     error "Your CPU does not have the SSE4 instruction set that Virtual DSM requires!"
-    ! enabled "$DEBUG" && exit 88
+    enabled "$DEBUG" || exit 88
   fi
 
   return 0
@@ -66,6 +66,8 @@ trimSpaces() {
 
 removeCpuArgument() {
 
+  # CPU configuration has dedicated variables. Remove raw -cpu arguments so
+  # option ordering cannot silently override the validated model and flags.
   local args=" ${ARGUMENTS:-} "
 
   while [[ "$args" =~ [[:space:]]-cpu([[:space:]][^[:space:]]+|=[^[:space:]]+)? ]]; do
@@ -94,6 +96,8 @@ configureKvmCpuModel() {
 
 appendKvmInvtscFeature() {
 
+  # invtsc is safe only when the active accelerator can scale the host TSC;
+  # AMD and Intel expose that capability through different host flags.
   if hasFlag "svm"; then
 
     # AMD processor
@@ -131,6 +135,8 @@ configureTcgCpuModel() {
     return 0
   fi
 
+  # TCG uses the broad max model on native x86, but qemu64 is the compatible
+  # cross-architecture fallback.
   if [[ "$ARCH" == "amd64" ]]; then
     CPU_MODEL="max"
     CPU_FEATURES+=",migratable=no"
@@ -158,6 +164,8 @@ configureTcg() {
 
 composeCpuFlags() {
 
+  # Compose one -cpu value in precedence order: model, required features,
+  # then user-provided overrides.
   CPU_FLAGS="${CPU_MODEL}${CPU_FEATURES:+,$CPU_FEATURES}${CPU_FLAGS:+,$CPU_FLAGS}"
 
   return 0
@@ -170,6 +178,8 @@ configureHostCpuName() {
   fi
 
   if [ -n "$HOST_CPU" ]; then
+    # qemu-host expects a comma-separated CPU description with empty family
+    # and suffix fields, not QEMU's -cpu syntax.
     HOST_CPU="${HOST_CPU%%,*},,"
   else
     HOST_CPU="QEMU, Virtual CPU,"

src/progress.sh

@@ -22,6 +22,8 @@ writeInfo() {
 
   local content="$1"
 
+  # Replace the web status atomically so websocket readers never observe a
+  # partially written HTML fragment.
   if ! printf '%s\n' "$content" > "$info_tmp"; then
     rm -f -- "$info_tmp"
     return 1
@@ -153,6 +155,16 @@ printSizeProgress() {
   return 0
 }
 
+stopProgress() {
+
+  if [ -z "$status_file" ]; then
+    exit 0
+  fi
+
+  stopping="Y"
+  return 0
+}
+
 finishProgress() {
 
   rm -f -- "$info_tmp"
@@ -202,13 +214,17 @@ printed="N"
 next_percent=10
 next_bytes="$step_bytes"
 log_mode="percent"
+stopping="N"
 
 if [ -z "$total" ] || [[ "$total" == "0" ]]; then
   log_mode="size"
 fi
 
 trap finishProgress EXIT
-trap 'exit 0' HUP INT QUIT TERM
+trap 'exit 0' HUP INT QUIT
+# SIGTERM requests one final measurement and web update rather than
+# terminating between progress samples.
+trap stopProgress TERM
 
 if [[ "$body" == *"..." ]]; then
   body="<p class=\"loading\">${body::-3}</p>"
@@ -216,9 +232,12 @@ fi
 
 while true; do
 
+  final_pass="${stopping:-}"
   bytes=$(getBytes "$path" "$mode")
   effective_total="$total"
 
+  # An external downloader may provide authoritative completed and total byte
+  # counters; use them instead of filesystem size when available.
   if [ -n "$status_file" ] && status=$(getStatus "$status_file"); then
     read -r status_bytes status_total <<< "$status"
     bytes="$status_bytes"
@@ -255,6 +274,8 @@ while true; do
         fi
       fi
     else
+      # Floor the percentage rather than rounding so displayed completion
+      # never gets ahead of bytes actually written.
       # Truncate to one decimal so progress is never reported early.
       progress=$((bytes * 1000 / effective_total))
       (( progress > 1000 )) && progress=1000
@@ -282,5 +303,8 @@ while true; do
     fi
   fi
 
-  sleep 1 & wait $!
+  [[ "$final_pass" == "Y" ]] && break
+
+  sleep 1 &
+  wait $! || :
 done

src/serial.sh

@@ -42,6 +42,8 @@ validateHostMac() {
 
 buildHostArguments() {
 
+  # qemu-host is a sidecar that bridges DSM's proprietary serial agent to
+  # Unix sockets used by shutdown and post-boot discovery helpers.
   HOST_ARGS=()
   HOST_ARGS+=("-cpu=$CPU_CORES")
   HOST_ARGS+=("-cpu_arch=$HOST_CPU")
@@ -60,6 +62,8 @@ startHostBinary() {
 
   local pid
 
+  # Remove stale sockets and pid state before starting the sidecar; a Unix
+  # socket path cannot be rebound while an old filesystem entry remains.
   rm -f -- "$HOST_PID" "$HOST_API_SOCKET" "$HOST_AGENT_SOCKET" || return 1
 
   if enabled "$HOST_DEBUG"; then
@@ -73,7 +77,7 @@ startHostBinary() {
     pid=$!
   fi
 
-  echo "$pid" > "$HOST_PID"
+  printf '%s\n' "$pid" > "$HOST_PID"
 
   return 0
 }
@@ -82,23 +86,24 @@ waitForSocket() {
 
   local socket="$1"
   local exit_code="$2"
-  local pid cnt=0
+  local timeout=5 pid
+  local deadline=$((SECONDS + timeout))
 
+  # Do not start QEMU until both sidecar sockets are ready; otherwise the
+  # VirtIO serial channel or API client may race initial creation.
   while [ ! -S "$socket" ]; do
 
-    if ! read -r pid < "$HOST_PID" || ! isAlive "$pid"; then
+    if ! readPidFile pid "$HOST_PID" || ! isAlive "$pid"; then
       error "qemu-host exited unexpectedly!"
       exit "$exit_code"
     fi
 
-    sleep 0.1
-    cnt=$((cnt + 1))
-
-    if (( cnt > 50 )); then
+    if (( SECONDS >= deadline )); then
       error "Failed to create qemu-host socket: $socket"
       exit "$exit_code"
     fi
 
+    sleep 0.1
   done
 
   return 0
@@ -106,6 +111,11 @@ waitForSocket() {
 
 configureSerialPorts() {
 
+  local bus
+  bus=$(getPciBus)
+
+  # Managed interactive mode separates the console and QEMU monitor into
+  # reconnecting sockets; other runs keep the simple combined stdio monitor.
   if enabled "${SHUTDOWN:-Y}" && interactive; then
 
     CONSOLE_SOCKET="$QEMU_DIR/console.sock"
@@ -123,7 +133,7 @@ configureSerialPorts() {
   fi
 
   SERIAL_OPTS+=" \
-        -device virtio-serial-pci,id=virtio-serial0,bus=pcie.0,addr=0x3 \
+        -device virtio-serial-pci,id=virtio-serial0,bus=$bus,addr=0x3 \
         -chardev socket,id=charchannel0,path=$HOST_AGENT_SOCKET,reconnect-ms=1000 \
         -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=vchannel"
 

src/server.sh

@@ -2,20 +2,19 @@
 set -Eeuo pipefail
 
 : "${WEB_PORT:="5000"}"    # Webserver port
-: "${WSD_PORT:="8004"}"    # Websockets port
 
 # Sanitize port variables
 WEB_PORT=$(strip "$WEB_PORT")
-WSD_PORT=$(strip "$WSD_PORT")
 
 WEB_PID="/run/nginx.pid"
 WSD_LOG="/var/log/websocketd.log"
 WSD_PID="$QEMU_DIR/websocketd.pid"
+WSD_SOCKET="$QEMU_DIR/status-ws.sock"
 
 prepareWebFiles() {
 
   cp -r /var/www/* "$QEMU_DIR" || return 1
-  rm -f "$WSD_PID" "$WEB_PID" "$WSD_LOG" || return 1
+  rm -f -- "$WSD_PID" "$WSD_SOCKET" "$WEB_PID" "$WSD_LOG" || return 1
 
   return 0
 }
@@ -24,9 +23,8 @@ configureWebPorts() {
 
   if ! sed -i \
     -e "s|listen 5000 default_server;|listen $WEB_PORT default_server;|g" \
-    -e "s|proxy_pass http://127.0.0.1:8004/;|proxy_pass http://127.0.0.1:$WSD_PORT/;|g" \
     /etc/nginx/sites-enabled/web.conf; then
-    error "Failed to configure webserver ports!"
+    error "Failed to configure webserver port!"
     return 1
   fi
 
@@ -35,6 +33,8 @@ configureWebPorts() {
 
 configureIpv6Listen() {
 
+  # Use one dual-stack listener when IPv6 is active, avoiding separate IPv4
+  # and IPv6 sockets that can conflict on the same port.
   if [ -f /proc/net/if_inet6 ] && [[ "$(cat /proc/sys/net/ipv6/conf/all/disable_ipv6 2>/dev/null)" != "1" ]]; then
 
     if ! sed -i \
@@ -49,17 +49,56 @@ configureIpv6Listen() {
   return 0
 }
 
+configureNginx() {
+
+  mkdir -p /etc/nginx/sites-enabled || return 1
+  rm -f /etc/nginx/sites-enabled/default || return 1
+
+  # TODO: Use setfacl to grant www-data access to the Unix sockets
+  # and restore unprivileged nginx workers.
+  if ! sed -i \
+    -e 's/^user .*/user root;/' \
+    -e 's/^worker_processes.*/worker_processes 1;/' \
+    /etc/nginx/nginx.conf; then
+    error "Failed to configure nginx!"
+    return 1
+  fi
+
+  if ! cp /etc/nginx/default.conf /etc/nginx/sites-enabled/web.conf; then
+    error "Failed to copy nginx config!"
+    return 1
+  fi
+
+  return 0
+}
+
 configureWebServer() {
 
-  mkdir -p /etc/nginx/sites-enabled
-  cp /etc/nginx/default.conf /etc/nginx/sites-enabled/web.conf
-
+  configureNginx || return 1
   configureWebPorts || return 1
   configureIpv6Listen || return 1
 
   return 0
 }
 
+stopWebServer() {
+
+  local pid
+
+  if readPidFile pid "$WEB_PID"; then
+    pKill "$pid" 2
+
+    # Escalate only after the normal termination grace period; stale nginx
+    # processes would otherwise keep the configured web port occupied.
+    if isAlive "$pid"; then
+      kill -9 -- "$pid" 2>/dev/null || :
+    fi
+  fi
+
+  rm -f -- "$WEB_PID"
+  return 0
+}
+
 startWebServer() {
 
   # Start webserver
@@ -68,12 +107,27 @@ startWebServer() {
   return 0
 }
 
+stopWebsocketServer() {
+
+  local pid
+
+  if readPidFile pid "$WSD_PID"; then
+    pKill "$pid" 2
+
+    if isAlive "$pid"; then
+      kill -9 -- "$pid" 2>/dev/null || :
+    fi
+  fi
+
+  rm -f -- "$WSD_PID" "$WSD_SOCKET"
+  return 0
+}
+
 startWebsocketServer() {
 
   # Start websocket server
   websocketd \
-    --address 127.0.0.1 \
-    --port="$WSD_PORT" \
+    --unixsocket="$WSD_SOCKET" \
     /run/socket.sh \
     >"$WSD_LOG" 2>&1 &
 
@@ -81,19 +135,36 @@ startWebsocketServer() {
 
   if ! echo "$pid" > "$WSD_PID"; then
     kill "$pid" 2>/dev/null || :
+    rm -f -- "$WSD_PID"
     return 1
   fi
 
-  sleep 0.1
+  local i
+  for (( i = 1; i <= 50; i++ )); do
 
-  if ! isAlive "$pid"; then
-    rm -f "$WSD_PID"
-    [ -s "$WSD_LOG" ] && cat "$WSD_LOG" >&2
-    error "Failed to start websocket server!"
-    return 1
+    if ! isAlive "$pid"; then
+      rm -f -- "$WSD_PID" "$WSD_SOCKET"
+      [ -s "$WSD_LOG" ] && cat "$WSD_LOG" >&2
+      error "Failed to start websocket server!"
+      return 1
+    fi
+
+    [ -S "$WSD_SOCKET" ] && return 0
+
+    sleep 0.1
+
+  done
+
+  pKill "$pid" 2
+
+  if isAlive "$pid"; then
+    kill -9 -- "$pid" 2>/dev/null || :
   fi
 
-  return 0
+  rm -f -- "$WSD_PID" "$WSD_SOCKET"
+  [ -s "$WSD_LOG" ] && cat "$WSD_LOG" >&2
+  error "Websocket server did not create its socket!"
+  return 1
 }
 
 prepareWebFiles
@@ -104,7 +175,11 @@ disabled "${WEB:-}" && return 0
 
 configureWebServer
 
-startWebServer
-startWebsocketServer
+if startWebServer && startWebsocketServer; then
+  return 0
+fi
 
-return 0
+stopWebsocketServer || :
+stopWebServer || :
+
+return 1

src/socket.sh

@@ -18,6 +18,8 @@ refresh() {
   [[ "$msg" == "$lastmsg" ]] && return 0
 
   lastmsg="$msg"
+  # websocketd clients interpret s: as a status update and c: as a command;
+  # suppress unchanged status to avoid redundant browser work.
   echo "s: $msg"
 
   return 0
@@ -37,6 +39,8 @@ inotifywait \
     case "${event,,}" in
       "delete"* )
         echo "c: vnc" ;;
+      # moved_to covers the atomic replacement used by html()/writeAtomic(),
+      # while close_write handles direct writers.
       "close_write"* | "moved_to"* )
         refresh ;;
     esac

src/utils.sh

@@ -7,6 +7,32 @@ info () { printf "%b%s%b" "\E[1;34m❯ \E[1;36m" "${1:-}" "\E[0m\n"; }
 error () { printf "%b%s%b" "\E[1;31m❯ " "ERROR: ${1:-}" "\E[0m\n" >&2; }
 warn () { printf "%b%s%b" "\E[1;31m❯ " "Warning: ${1:-}" "\E[0m\n" >&2; }
 
+app() {
+
+  echo "Virtual DSM"
+  return 0
+}
+
+readPidFile() {
+
+  local -n _pid="$1"
+  _pid=""
+
+  if ! _pid=$(cat -- "$2" 2>/dev/null); then
+    _pid=""
+    return 1
+  fi
+
+  # Reject empty, zero, or nonnumeric pidfiles so cleanup can never signal an
+  # unintended process group.
+  if [[ ! "$_pid" =~ ^[1-9][0-9]*$ ]]; then
+    _pid=""
+    return 1
+  fi
+
+  return 0
+}
+
 hasFlag() {
 
   # Match a whitespace-delimited token in /proc/cpuinfo
@@ -29,8 +55,27 @@ isAmdCpu() {
   [[ "$vendor" == "AuthenticAMD" ]]
 }
 
+getPciBus() {
+
+  local machine="${1:-${MACHINE:-q35}}"
+
+  if [ -n "${PCI_BUS:-}" ]; then
+    echo "$PCI_BUS"
+    return 0
+  fi
+
+  case "${machine,,}" in
+    pc|pc-i440fx*) echo "pci.0" ;;
+    *)             echo "pcie.0" ;;
+  esac
+
+  return 0
+}
+
 interactive() {
 
+  # A TTY on stdin is insufficient when /dev/tty is unavailable; require both
+  # before enabling interactive console handling.
   [ -t 0 ] && : 2>/dev/null </dev/tty >/dev/tty
 
 }
@@ -118,14 +163,13 @@ isAlive() {
 
 waitPid() {
 
-  local i=0
   local pid="$1"
   local timeout="${2:-10}"
+  local deadline=$((SECONDS + timeout))
 
   while [ -n "$pid" ] && isAlive "$pid"; do
+    (( SECONDS >= deadline )) && return 1
     sleep 0.2
-    i=$((i + 1))
-    (( i >= timeout * 5 )) && return 1
   done
 
   return 0
@@ -133,19 +177,16 @@ waitPid() {
 
 waitPidFile() {
 
-  local i=0
-  local pid=""
+  local pid
   local file="$1"
   local timeout="${2:-10}"
+  local deadline=$((SECONDS + timeout))
 
-  [ ! -s "$file" ] && return 0
-  ! read -r pid <"$file" && return 0
-  [ -z "$pid" ] && return 0
+  readPidFile pid "$file" || return 0
 
   while [ -s "$file" ] && isAlive "$pid"; do
+    (( SECONDS >= deadline )) && return 1
     sleep 0.2
-    i=$((i + 1))
-    (( i >= timeout * 5 )) && return 1
   done
 
   rm -f -- "$file"
@@ -168,19 +209,19 @@ pKill() {
 
 fWait() {
 
-  local i=0
   local name="$1"
   local timeout="${2:-10}"
+  local deadline=$((SECONDS + timeout))
 
   [ -z "$name" ] && return 0
 
   while pgrep -f -l "$name" >/dev/null; do
-    sleep 0.2
-    i=$((i + 1))
-    if (( i >= timeout * 5 )); then
+    if (( SECONDS >= deadline )); then
       warn "Timed out while waiting for process: $name"
       break
     fi
+
+    sleep 0.2
   done
 
   return 0
@@ -201,12 +242,10 @@ fKill() {
 
 sKill() {
 
-  local pid=""
+  local pid
   local file="$1"
 
-  [ ! -s "$file" ] && return 0
-  ! read -r pid <"$file" && return 0
-  [ -z "$pid" ] && return 0
+  readPidFile pid "$file" || return 0
 
   if isAlive "$pid"; then
     { kill -15 -- "$pid" || :; } 2>/dev/null
@@ -240,11 +279,13 @@ setOwner() {
 
   [ ! -f "$file" ] && return 1
 
+  # Match generated files to the owner of their bind-mounted parent directory
+  # instead of assuming a fixed container or host UID.
   dir=$(dirname -- "$file")
   uid=$(stat -c '%u' "$dir") || return 1
   gid=$(stat -c '%g' "$dir") || return 1
 
-  ! chown "$uid:$gid" "$file" && return 1
+  chown "$uid:$gid" "$file" || return 1
 
   return 0
 }
@@ -255,7 +296,7 @@ makeDir() {
   local dir uid gid
 
   [ -d "$path" ] && return 0
-  ! mkdir -p "$path" && return 1
+  mkdir -p "$path" || return 1
 
   dir=$(dirname -- "$path")
 
@@ -272,6 +313,64 @@ makeDir() {
   return 0
 }
 
+finiteMemoryLimit() {
+
+  local limit="$1"
+  # cgroup v1 commonly reports this enormous sentinel for an unlimited memory
+  # limit; compare as decimal strings to avoid shell integer overflow.
+  local sentinel="4611686018427387904"
+  local i
+
+  [[ "$limit" =~ ^[0-9]+$ ]] || return 1
+
+  (( ${#limit} < ${#sentinel} )) && return 0
+  (( ${#limit} > ${#sentinel} )) && return 1
+
+  for (( i=0; i<${#sentinel}; i++ )); do
+    local left="${limit:i:1}"
+    local right="${sentinel:i:1}"
+
+    (( left < right )) && return 0
+    (( left > right )) && return 1
+  done
+
+  return 1
+}
+
+getMemoryInfo() {
+
+  local host_total
+  local host_avail
+  local limit=""
+  local current=""
+
+  host_total=$(free -b | awk '/^Mem:/ {print $2; exit}')
+  host_avail=$(free -b | awk '/^Mem:/ {print $7; exit}')
+
+  RAM_TOTAL="$host_total"
+  RAM_AVAIL="$host_avail"
+
+  if [ -r /sys/fs/cgroup/memory.max ] && [ -r /sys/fs/cgroup/memory.current ]; then
+    limit=$(< /sys/fs/cgroup/memory.max)
+    current=$(< /sys/fs/cgroup/memory.current)
+  elif [ -r /sys/fs/cgroup/memory/memory.limit_in_bytes ] && [ -r /sys/fs/cgroup/memory/memory.usage_in_bytes ]; then
+    limit=$(< /sys/fs/cgroup/memory/memory.limit_in_bytes)
+    current=$(< /sys/fs/cgroup/memory/memory.usage_in_bytes)
+  fi
+
+  # Use the tighter of host availability and the container's remaining cgroup
+  # allowance so RAM sizing cannot exceed either boundary.
+  if finiteMemoryLimit "$limit" && [[ "$current" =~ ^[0-9]+$ ]]; then
+    (( limit < RAM_TOTAL )) && RAM_TOTAL="$limit"
+
+    local available=$(( limit - current ))
+    (( available < 0 )) && available=0
+    (( available < RAM_AVAIL )) && RAM_AVAIL="$available"
+  fi
+
+  return 0
+}
+
 stateFile() {
 
   local name="$1"
@@ -304,6 +403,8 @@ writeAtomic() {
 
   local path="$1"
   local content="$2"
+  # Use a per-process temporary file and rename so readers see either the old
+  # complete value or the new complete value.
   local tmp="${path}.${BASHPID}.tmp"
 
   if ! printf '%s\n' "$content" > "$tmp"; then
@@ -368,6 +469,8 @@ restoreState() {
   local prefix="${4:-$PROCESS}"
   local value
 
+  # Persistent state fills only unset variables unless force is requested,
+  # preserving explicit environment overrides.
   if ! enabled "$force"; then
     [ -z "${!var:-}" ] || return 0
   fi
@@ -381,8 +484,7 @@ restoreState() {
 
 escape () {
 
-  local s
-  s=${1//&/\&amp;}
+  local s=${1//&/\&amp;}
   s=${s//</\&lt;}
   s=${s//>/\&gt;}
   s=${s//'"'/\&quot;}
@@ -408,7 +510,7 @@ html() {
 
   local title
   local body
-  local script
+  local script="${2:-}"
   local footer
 
   title=$(escape "$APP")
@@ -420,8 +522,6 @@ html() {
     body="<p class=\"loading\">${body/.../}</p>"
   fi
 
-  [ -n "${2:-}" ] && script="$2" || script=""
-
   local HTML
   HTML=$(<"$TEMPLATE")
   HTML="${HTML/\[1\]/$title}"
@@ -430,6 +530,8 @@ html() {
   HTML="${HTML/\[4\]/$footer}"
   HTML="${HTML/\[5\]/$FOOTER2}"
 
+  # Publish both the full page and websocket fragment atomically because nginx
+  # and websocketd may read them concurrently.
   writeAtomic "$PAGE" "$HTML" || return 1
   writeAtomic "$INFO" "$body" || return 1
 
@@ -478,9 +580,9 @@ getCountry() {
 
   local url=$1
   local query=$2
-  local rc json result
+  local json result
 
-  { json=$(curl -m 5 -H "Accept: application/json" -sfk "$url"); rc=$?; } || :
+  { json=$(curl -m 5 -H "Accept: application/json" -sfk "$url"); local rc=$?; } || :
   (( rc != 0 )) && return 0
 
   { result=$(echo "$json" | jq -r "$query" 2> /dev/null); rc=$?; } || :
@@ -503,6 +605,8 @@ setCountry() {
   [[ "${TZ,,}" == "asia/shanghai" ]] && COUNTRY="CN"
   [[ "${TZ,,}" == "asia/chongqing" ]] && COUNTRY="CN"
 
+  # Country detection is best-effort and tries independent services in order;
+  # failure leaves mirror selection at its global default.
   [ -z "$COUNTRY" ] && getCountry "https://api.ipapi.is" ".location.country_code"
   [ -z "$COUNTRY" ] && getCountry "https://ifconfig.co/json" ".country_iso"
   [ -z "$COUNTRY" ] && getCountry "https://api.ip2location.io" ".country_code"
@@ -527,6 +631,8 @@ addPackage() {
 
   [ -z "$COUNTRY" ] && setCountry
 
+  # Use a mainland mirror only for on-demand package installation, avoiding
+  # slow or inaccessible Debian endpoints in that region.
   if [[ "${COUNTRY^^}" == "CN" ]]; then
     sed -i 's/deb.debian.org/mirrors.ustc.edu.cn/g' /etc/apt/sources.list.d/debian.sources
   fi

web/conf/nginx.conf

@@ -39,6 +39,6 @@ server {
       proxy_read_timeout 3600s;
       proxy_send_timeout 3600s;
 
-      proxy_pass http://127.0.0.1:8004/;
-    }    
+      proxy_pass http://unix:/run/shm/status-ws.sock:/;
+    }
 }

web/js/script.js

@@ -71,6 +71,13 @@ function processInfo() {
         var response = request;
         request = null;
 
+        var status = response.status;
+
+        if (status == 502 || status == 503 || status == 504) {
+            schedule();
+            return true;
+        }
+
         var msg = response.responseText;
         if (msg == null || msg.length == 0) {
 
@@ -83,9 +90,9 @@ function processInfo() {
             return false;
         }
 
-        var notFound = (response.status == 404);
+        var notFound = (status == 404);
 
-        if (response.status == 200) {
+        if (status == 200) {
             if (msg.toLowerCase().indexOf("<html>") !== -1) {
                 notFound = true;
             } else {
@@ -103,7 +110,7 @@ function processInfo() {
             return true;
         }
 
-        setError("Error: Received statuscode " + response.status);
+        setError("Error: Received statuscode " + status);
         return false;
 
     } catch (e) {