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#!/bin/bash
# Compile server manager for systemtap
#
# Copyright (C) 2008 Red Hat Inc.
#
# This file is part of systemtap, and is free software. You can
# redistribute it and/or modify it under the terms of the GNU General
# Public License (GPL); either version 2, or (at your option) any
# later version.
# This script publishes its presence on the network and then listens for
# incoming connections. When a connection is detected, the stap-server script
# is run to handle the request.
# Catch ctrl-c and other termination signals
trap 'terminate' SIGTERM SIGINT
#-----------------------------------------------------------------------------
# Helper functions.
#-----------------------------------------------------------------------------
# function: initialization PORT
function initialization {
# Default settings.
avahi_type=_stap._tcp
port=$1
test "X$port" = "X" && port=65000
export port2=$(($port + 1))
if netstat -atn | awk '{print $4}' | cut -f2 -d: | egrep -q "^($port|$port2)\$"; then
# Whoops, the port is busy; try another one.
initialization $((1024+($port + $RANDOM)%64000))
fi
}
# function: advertise_presence
#
# Advertise the availability of the server on the network.
function advertise_presence {
# Build up a string representing our server's properties.
# TODO: this needs fleshing out.
local sysinfo=`uname -rvm`
local txt="sysinfo=$sysinfo"
# Call avahi-publish-service to advertise our presence.
avahi-publish-service "Systemtap Compile Server on `uname -n`" \
$avahi_type $port "$txt" > /dev/null 2>&1 &
echo "Systemtap Compile Server on `uname -n` listening on port $port"
}
# function: listen
#
# Listen for and handle requests to the server.
function listen {
# Loop forever accepting requests
while true
do
for ((attempt=0; $attempt < 5; ++attempt))
do
nc -ld $port 2>/dev/null | process_request &
wait '%nc -l'
rc=$?
if test $rc = 0 -o $rc = 127; then
break; # port was read ok
fi
done
if test $attempt = 5; then
fatal "ERROR: cannot listen on port $port. rc==$rc"
fi
done
}
# function: process_request
#
# Process an incoming request on stdin
function process_request {
read
case $REPLY in
request:)
stap-server $port2 >/dev/null 2>&1 &
wait '%stap-server'
rc=$?
test $rc = 127 && rc=0
;;
*)
rc=1
esac
exit $rc
}
# function: fatal [ MESSAGE ]
#
# Fatal error
# Prints its arguments to stderr and exits
function fatal {
echo "$@" >&2
terminate
exit 1
}
# function: terminate
#
# Terminate gracefully.
function terminate {
echo "$0: Exiting"
# Kill the running 'avahi-publish-service' job
kill -s SIGTERM %avahi-publish-service 2> /dev/null
wait '%avahi-publish-service' >/dev/null 2>&1
# Kill any running 'stap-server' job.
kill -s SIGTERM "%stap-server" 2> /dev/null
wait "%stap-server" >/dev/null 2>&1
# Kill any running 'nc -l' job.
kill -s SIGTERM "%?nc -l" 2> /dev/null
wait "%?nc - l" >/dev/null 2>&1
exit
}
#-----------------------------------------------------------------------------
# Beginning of main line execution.
#-----------------------------------------------------------------------------
initialization "$@"
advertise_presence
listen
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