grml-screen: internal state cleanup for racecondition fix

[grml-scripts.git] / usr_bin / grml-screen

diff --git a/usr_bin/grml-screen b/usr_bin/grml-screen
index 7deeb77..55de1c8 100755 (executable)
--- a/usr_bin/grml-screen
+++ b/usr_bin/grml-screen
@@ -15,38 +15,46 @@
   sudo chown $USER.tty $TTY
 
 # FIXME: fix for screen race-conditions
-PID_FILE_="/var/run/grml-screen"
+PID_FILE_="/var/lock/grml-screen"
+PID_FILE_CREATED_="false"
 MY_PID_="$$"
 if [ ! -d "/var/run/screen/S-$USER" ]; then
     # no /var/run/screen/S-$USER and possible no /var/run/screen either -> locking
     for i in `seq 40`; do   # 40*0.25 = 10 seconds
         if lockfile-create --retry 0 $PID_FILE_; then
             echo $MY_PID_ >$PID_FILE_
+            PID_FILE_CREATED_="true"
             break
+        else
+            PID_FILE_CREATED_="error"
         fi
         sleep 0.25
     done
 fi
-if [ -f $PID_FILE_ ]; then
+if [ $PID_FILE_CREATED_ = "true" ]; then
     # FORK BEGIN
     (
-    for i in `seq 40`; do   # 40*0.25 = 10 seconds
-        if [ ! -d "/var/run/screen/S-$USER" ]; then
-            sleep 0.25  # educated guess
-        else
-            break
+        for i in `seq 40`; do   # 40*0.25 = 10 seconds
+            if [ ! -d "/var/run/screen/S-$USER" ]; then
+                sleep 0.25  # educated guess
+            else
+                break
+            fi
+        done
+        if [ `cat $PID_FILE_` = $MY_PID_ ]; then
+            rm $PID_FILE_
+            lockfile-remove $PID_FILE_
         fi
-    done
-    if [ `cat $PID_FILE_` = $MY_PID_ ]; then
-        rm $PID_FILE_
-        lockfile-remove $PID_FILE_
-    fi
     )&
     # FORK END
-else
+elif [ $PID_FILE_CREATED_ = "error" ]; then
     SLEEP_TIME_="$(( $$ % 5 * 5 + 5 ))"
     echo "grml-screen: Error could not create lockfile! (sleeping for $SLEEP_TIME_)"
     sleep $SLEEP_TIME_
+elif [ $PID_FILE_CREATED_ = "false" ]; then
+    echo "nothing to do" &>/dev/null
+else
+    echo "grml-screen: internal error - PID_FILE_CREATED_ == \"$PID_FILE_CREATED_\""
 fi
 
 # now run screen with config