notifications

#!/bin/bash

# NOTE: Will go away when reliable messaging is introduced.

# This is currently set up to accomodate the scheme where the account used
# to call this script and write information to NOTIFICATION_FILE (the account
# configured in jndi-config.xml) is the same account reading and deleting
# entries from NOTIFICATION_FILE (the service container)

# To accomodate a different scheme, you could use a UNIX group common to the
# service container and the account used for notifications.  You would need
# to set this script to chmod 550 instead of 500 and also alter the umask line
# below from 177 to 117, this controls the permissions on NOTIFICATION_FILE

NOTIFICATION_FILE="$0.txt"
TEMPFILE="$0.$$"
LOCKFILE="$0.lock"

set +e

function my_lockfile ()
{
    echo $$ > $TEMPFILE || {
            echo "You don't have permission to access `dirname $TEMPFILE`"
            return 1
    }

    ln $TEMPFILE $LOCKFILE && {
            rm -f $TEMPFILE
            return 0
    }

    rm -f $TEMPFILE
    return 1
}

function stale_check ()
{
  PID=""
  PID=`cat $LOCKFILE`
  if [ "X$PID" != "X" ]; then
    echo "checking if LOCKFILE pid $PID is stale"
    kill -0 $PID
    if [ $? != 0 ]; then
      echo "pid $PID does not exist, removing lockfile"
      rm -f $LOCKFILE
    fi
  fi
}

# wait for a lock
num=5
until my_lockfile ; do
    sleep 0.1

    num=`expr $num - 1`
    if [ $num = 0 ]; then
      stale_check
      num=5
    fi
done

if test ! -e $NOTIFICATION_FILE ;
then
   umask 177
   touch $NOTIFICATION_FILE
fi

line=''
if [ "$1" == "readanddelete" ]
then
    cat $NOTIFICATION_FILE
    rm $NOTIFICATION_FILE
elif [ "$1" == "write" ];
then
    shift
    for str in $* ;
    do
    line="$line$str::" 
    done
    line="$line<eon>" 

    echo $line >> $NOTIFICATION_FILE
fi

rm -f $LOCKFILE