grml-screen: fix for screen race-conditions on boot [Closes: issue921]

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

diff --git a/usr_bin/grml-screen b/usr_bin/grml-screen
index 1288aa1..7deeb77 100755 (executable)
--- a/usr_bin/grml-screen
+++ b/usr_bin/grml-screen
@@ -1,16 +1,11 @@
 #!/bin/dash
 # Filename:      grml-screen
-# Purpose:       wrapper for screen
+# Purpose:       wrapper for screen to start with appropriate configuration
 # Authors:       grml-team (grml.org), (c) Michael Prokop <mika@grml.org>
 # Bug-Reports:   see http://grml.org/bugs/
 # License:       This file is licensed under the GPL v2.
-# Latest change: Sun Jan 08 15:30:06 CET 2006 [mika]
 ################################################################################
 
-# fix tty permissions
-#  sudo chmod 660      $TTY
-#  sudo chown root.tty $TTY
-
 # export variable USER for use withing GNU screen:
   export USER=`id -un`
 
@@ -19,14 +14,51 @@
   sudo chmod 660       $TTY
   sudo chown $USER.tty $TTY
 
+# FIXME: fix for screen race-conditions
+PID_FILE_="/var/run/grml-screen"
+MY_PID_="$$"
+if [ ! -d "/var/run/screen/S-$USER" ]; then
+    # no /var/run/screen/S-$USER and possible no /var/run/screen either -> locking
+    for i in `seq 40`; do   # 40*0.25 = 10 seconds
+        if lockfile-create --retry 0 $PID_FILE_; then
+            echo $MY_PID_ >$PID_FILE_
+            break
+        fi
+        sleep 0.25
+    done
+fi
+if [ -f $PID_FILE_ ]; then
+    # FORK BEGIN
+    (
+    for i in `seq 40`; do   # 40*0.25 = 10 seconds
+        if [ ! -d "/var/run/screen/S-$USER" ]; then
+            sleep 0.25  # educated guess
+        else
+            break
+        fi
+    done
+    if [ `cat $PID_FILE_` = $MY_PID_ ]; then
+        rm $PID_FILE_
+        lockfile-remove $PID_FILE_
+    fi
+    )&
+    # FORK END
+else
+    SLEEP_TIME_="$(( $$ % 5 * 5 + 5 ))"
+    echo "grml-screen: Error could not create lockfile! (sleeping for $SLEEP_TIME_)"
+    sleep $SLEEP_TIME_
+fi
+
 # now run screen with config
   cd $HOME     # important for e.g. hardcopy-feature
+  # do we have a utf8 enabled terminal?
+  [ -x /usr/bin/vt-is-UTF8 ] && /usr/bin/vt-is-UTF8 -q && UTF='-U'
   if [ `id -u` = 0 ] ; then
-    exec screen -c /etc/grml/screenrc
-  elif [ -r $HOME/.screenrc ] ; then
-    exec screen -c $HOME/.screenrc
+    exec screen $UTF -c /etc/grml/screenrc
+  elif [ -r "$HOME/.screenrc" ] ; then
+    exec screen $UTF -c "$HOME/.screenrc"
   else
-    exec screen -c /etc/grml/screenrc_grml
+    exec screen $UTF -c /etc/grml/screenrc_grml
   fi
 
 ## END OF FILE #################################################################