fix: Prevent race when reading PID files (#1342)

.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

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. |
 

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")
@@ -508,6 +510,9 @@ createDevice () {
 
   [[ -z "${PCI_BUS:-}" && ( "${MACHINE,,}" == pc || "${MACHINE,,}" == pc-i440fx* ) ]] && bus="pci.0"
 
+  local options=""
+  [ -n "$DISK_OPTIONS" ] && options=",${DISK_OPTIONS#,}"
+
   local bootIndex=""
   local diskId="data$diskIndex"
   [ -n "$diskIndex" ] && bootIndex=",bootindex=$diskIndex"
@@ -520,29 +525,29 @@ createDevice () {
       ;;
     "usb" )
       result+=",if=none \
-      -device usb-storage,drive=${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
@@ -771,6 +776,11 @@ 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

src/network.sh

@@ -449,6 +449,7 @@ configureDNS() {
   local gateway="$6"
   local upstream="${7:-}"
   local arguments="$DNSMASQ_OPTS"
+  local pid
 
   if ! echo "$gateway" > /run/shm/qemu.gw; then
     error "Failed to write gateway file."
@@ -458,7 +459,10 @@ configureDNS() {
   enabled "${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

src/power.sh

@@ -67,16 +67,8 @@ displayReason() {
 
 readQemuPid() {
 
-  local -n _pid="$1"
+  readPidFile "$1" "$QEMU_START_PID" && return 0
-  local file
+  readPidFile "$1" "$QEMU_PID"
-
-  for file in "$QEMU_START_PID" "$QEMU_PID"; do
-    if [ -s "$file" ] && read -r _pid < "$file"; then
-      return 0
-    fi
-  done
-
-  return 1
 }
 
 qemuPidFile() {
@@ -100,16 +92,14 @@ waitQemuExit() {
 
 waitQemuPid() {
 
-  local -n _pid="$1"
+  local cnt=0
-  local cnt=0 value
 
-  while ! readQemuPid value; do
+  while ! readQemuPid "$1"; do
     sleep 0.02
     cnt=$((cnt + 1))
     (( cnt >= 50 )) && return 1
   done
 
-  _pid="$value"
   return 0
 }
 

src/serial.sh

@@ -73,7 +73,7 @@ startHostBinary() {
     pid=$!
   fi
 
-  echo "$pid" > "$HOST_PID"
+  printf '%s\n' "$pid" > "$HOST_PID"
 
   return 0
 }
@@ -86,7 +86,7 @@ waitForSocket() {
 
   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

src/server.sh

@@ -64,7 +64,7 @@ stopWebServer() {
 
   local pid
 
-  if [ -s "$WEB_PID" ] && read -r pid < "$WEB_PID" && [ -n "$pid" ]; then
+  if readPidFile pid "$WEB_PID"; then
     pKill "$pid" 2
 
     if isAlive "$pid"; then
@@ -88,7 +88,7 @@ stopWebsocketServer() {
 
   local pid
 
-  if [ -s "$WSD_PID" ] && read -r pid < "$WSD_PID" && [ -n "$pid" ]; then
+  if readPidFile pid "$WSD_PID"; then
     pKill "$pid" 2
 
     if isAlive "$pid"; then

src/utils.sh

@@ -7,6 +7,24 @@ 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; }
 
+readPidFile() {
+
+  local -n _pid="$1"
+  _pid=""
+
+  if ! _pid=$(cat -- "$2" 2>/dev/null); then
+    _pid=""
+    return 1
+  fi
+
+  if [[ ! "$_pid" =~ ^[1-9][0-9]*$ ]]; then
+    _pid=""
+    return 1
+  fi
+
+  return 0
+}
+
 hasFlag() {
 
   # Match a whitespace-delimited token in /proc/cpuinfo
@@ -137,9 +155,7 @@ waitPidFile() {
   local file="$1"
   local timeout="${2:-10}"
 
-  [ ! -s "$file" ] && return 0
+  ! readPidFile pid "$file" && return 0
-  ! read -r pid <"$file" && return 0
-  [ -z "$pid" ] && return 0
 
   while [ -s "$file" ] && isAlive "$pid"; do
     sleep 0.2
@@ -203,9 +219,7 @@ sKill() {
   local pid
   local file="$1"
 
-  [ ! -s "$file" ] && return 0
+  ! readPidFile pid "$file" && return 0
-  ! read -r pid <"$file" && return 0
-  [ -z "$pid" ] && return 0
 
   if isAlive "$pid"; then
     { kill -15 -- "$pid" || :; } 2>/dev/null

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) {