From ef8f3322f390e3a35bf2117af0dfe3266db2405f Mon Sep 17 00:00:00 2001
From: Ben Peddell <klightspeed@killerwolves.net>
Date: Sat, 15 Apr 2023 02:15:42 +1000
Subject: [PATCH] Restart server if it double-forks

Processes that double-fork themselves by double-forking cannot be waited
upon, and cannot be properly monitored.

The ARK server will sometimes restart itself by performing a fork and
execve instead of just an execve (presumably because that is what it has
to do under Windows).

If the server restarts itself, then we need to restart it again so it
can be properly monitored.
---
 tools/arkmanager | 36 +++++++++++++++++++++++++++++++-----
 1 file changed, 31 insertions(+), 5 deletions(-)

diff --git a/tools/arkmanager b/tools/arkmanager
index 9d1d780..1faea7f 100755
--- a/tools/arkmanager
+++ b/tools/arkmanager
@@ -980,6 +980,8 @@ function getServerPID(){
     if kill -0 "$serverpid" >/dev/null 2>&1; then
       echo "$serverpid"
       return
+    elif kill -0 "-$serverpid" >/dev/null 2>&1; then
+      pgrep -g "$serverpid" && return
     fi
   fi
   if [ -f "${arkserverroot}/${arkserveroldpidfile}" ]; then
@@ -987,6 +989,8 @@ function getServerPID(){
     if kill -0 "$serverpid" >/dev/null 2>&1; then
       echo "$serverpid"
       return
+    elif kill -0 "-$serverpid" >/dev/null 2>&1; then
+      pgrep -g "$serverpid" && return
     fi
   fi
 }
@@ -1316,13 +1320,16 @@ doRun() {
     notify "${notifyMsgShuttingDown:-Shutting down}"
     rm -f "$arkserverroot/$arkautorestartfile"
     if [ "$serverpid" -ne 0 ]; then
-      kill -INT $serverpid >/dev/null 2>&1
+      kill -INT -$serverpid >/dev/null 2>&1
     fi
     exit 0
   }
 
   trap shutdown_server INT TERM
 
+  # Enable job control so server gets its own process group
+  set -m
+
   # Auto-restart loop
   while [ $restartserver -ne 0 ]; do
     echo -n "$(timestamp): Running"
@@ -1374,21 +1381,40 @@ doRun() {
             echo "$(timestamp): Restarting server"
             notify "${notifyMsgStoppedListening:-Server has stopped listening - restarting}"
             for (( i = 0; i < 5; i++ )); do
-              if ! kill -0 "$serverpid"; then
+              if ! kill -0 "-$serverpid"; then
                 break
               fi
-              kill -INT "$serverpid"
+              kill -INT "-$serverpid"
               sleep 5
             done
-            if kill -0 "$serverpid"; then
+            if kill -0 "-$serverpid"; then
               echo "$(timestamp): Graceful restart failed - killing server"
-              kill -KILL "$serverpid"
+              kill -KILL "-$serverpid"
             fi
 
             # Exit the server check loop
             break
           fi
         fi
+      elif [ "$pid" == "$(pgrep --pgroup $serverpid)" ]; then
+        restartserver=1
+        echo "${timestamp}: Server has double-forked and cannot be effectively monitored"
+	echo "${timestamp}: Restarting server"
+        notify "${notifyMsgDoubleForked:-Server has daemonized itself - restarting}"
+        for (( i = 0; i < 5; i++ )); do
+          if ! kill -0 "-$serverpid"; then
+            break
+          fi
+          kill -INT "-$serverpid"
+          sleep 5
+        done
+        if kill -0 "-$serverpid"; then
+          echo "$(timestamp): Graceful restart failed - killing server"
+          kill -KILL "-$serverpid"
+        fi
+
+        # Exit the server check loop
+        break
       else
         echo "$(timestamp): Bad PID '$pid'; expected '$serverpid'"
         if [ "$pid" != "" ]; then