fix: Use shared PID reader for helper processes (#1335)

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

@@ -69,9 +69,11 @@ readQemuPid() {
 
   local -n _pid="$1"
   local file
+  local pid
 
   for file in "$QEMU_START_PID" "$QEMU_PID"; do
-    if [ -s "$file" ] && read -r _pid < "$file"; then
+    if readPidFile pid "$file"; then
+      _pid="$pid"
       return 0
     fi
   done

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 +7,20 @@ 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"
+  local file="$2"
+
+  _pid=""
+
+  [ -s "$file" ] || return 1
+
+  _pid=$(<"$file")
+
+  [[ "$_pid" =~ ^[1-9][0-9]*$ ]]
+}
+
 hasFlag() {
 
   # Match a whitespace-delimited token in /proc/cpuinfo
@@ -137,9 +151,7 @@ waitPidFile() {
   local file="$1"
   local timeout="${2:-10}"
 
-  [ ! -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
     sleep 0.2
@@ -203,9 +215,7 @@ sKill() {
   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