stap-serverd

   1 #!/bin/bash
   2
   3 # Compile server manager for systemtap
   4 #
   5 # Copyright (C) 2008 Red Hat Inc.
   6 #
   7 # This file is part of systemtap, and is free software.  You can
   8 # redistribute it and/or modify it under the terms of the GNU General
   9 # Public License (GPL); either version 2, or (at your option) any
  10 # later version.
  11
  12 # This script publishes its presence on the network and then listens for
  13 # incoming connections. When a connection is detected, the stap-server script
  14 # is run to handle the request.
  15
  16 # Catch ctrl-c and other termination signals
  17 trap 'terminate' SIGTERM SIGINT
  18
  19 #-----------------------------------------------------------------------------
  20 # Helper functions.
  21 #-----------------------------------------------------------------------------
  22 # function: initialization PORT
  23 function initialization {
  24     # Default settings.
  25     avahi_type=_stap._tcp
  26     port=$1
  27     test "X$port" = "X" && port=65000
  28     export port2=$(($port + 1))
  29     if netstat -atn | awk '{print $4}' | cut -f2 -d: | egrep -q "^($port|$port2)\$"; then
  30         # Whoops, the port is busy; try another one.
  31         initialization $((1024+($port + $RANDOM)%64000))
  32     fi
  33 }
  34
  35 # function: advertise_presence
  36 #
  37 # Advertise the availability of the server on the network.
  38 function advertise_presence {
  39     # Build up a string representing our server's properties.
  40     # TODO: this needs fleshing out.
  41     local sysinfo=`uname -rvm`
  42     local txt="sysinfo=$sysinfo"
  43
  44     # Call avahi-publish-service to advertise our presence.
  45     avahi-publish-service "Systemtap Compile Server on `uname -n`" \
  46         $avahi_type $port "$txt" > /dev/null 2>&1 &
  47
  48     echo "Systemtap Compile Server on `uname -n` listening on port $port"
  49 }
  50
  51 # function: listen
  52 #
  53 # Listen for and handle requests to the server.
  54 function listen {
  55     # Loop forever accepting requests
  56     while true
  57     do
  58         for ((attempt=0; $attempt < 5; ++attempt))
  59         do
  60             nc -ld $port 2>/dev/null | process_request &
  61             wait '%nc -l'
  62             rc=$?
  63             if test $rc = 0 -o $rc = 127; then
  64                 break; # port was read ok
  65             fi
  66         done
  67         if test $attempt = 5; then
  68             fatal "ERROR: cannot listen on port $port. rc==$rc"
  69         fi
  70     done
  71 }
  72
  73 # function: process_request
  74 #
  75 # Process an incoming request on stdin
  76 function process_request {
  77     read
  78     case $REPLY in
  79         request:)
  80             stap-server $port2 >/dev/null 2>&1 &
  81             wait '%stap-server'
  82             rc=$?
  83             test $rc = 127 && rc=0
  84             ;;
  85         *)
  86             rc=1
  87     esac
  88
  89     exit $rc
  90 }
  91
  92 # function: fatal [ MESSAGE ]
  93 #
  94 # Fatal error
  95 # Prints its arguments to stderr and exits
  96 function fatal {
  97     echo "$@" >&2
  98     terminate
  99     exit 1
 100 }
 101
 102 # function: terminate
 103 #
 104 # Terminate gracefully.
 105 function terminate {
 106     echo "$0: Exiting"
 107
 108     # Kill the running 'avahi-publish-service' job
 109     kill -s SIGTERM %avahi-publish-service 2> /dev/null
 110     wait '%avahi-publish-service' >/dev/null 2>&1
 111
 112     # Kill any running 'stap-server' job.
 113     kill -s SIGTERM "%stap-server" 2> /dev/null
 114     wait "%stap-server"  >/dev/null 2>&1
 115
 116     # Kill any running 'nc -l' job.
 117     kill -s SIGTERM "%?nc -l" 2> /dev/null
 118     wait "%?nc - l"  >/dev/null 2>&1
 119
 120     exit
 121 }
 122
 123 #-----------------------------------------------------------------------------
 124 # Beginning of main line execution.
 125 #-----------------------------------------------------------------------------
 126 initialization "$@"
 127 advertise_presence
 128 listen