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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.
tmpdir_prefix_serverd=stap.serverd
avahi_type=_stap._tcp
port=$1
test "X$port" = "X" && port=65000
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 {
# Work in a temporary directory
tmpdir=`mktemp -dt $tmpdir_prefix_serverd.XXXXXX` || \
fatal "ERROR: cannot create temporary directory " $tmpdir
cd $tmpdir
# Create a fifo for communicating with the server
local fifo_name=$tmpdir_prefix_serverd.fifo
mknod $fifo_name p || \
fatal "ERROR: cannot create temporary fifo " $tmpdir/$fifo_name
# Loop forever accepting requests
first=1
set -o pipefail # We want the status of 'nc' not 'stap-server'.
while true
do
# Run this in the background and wait for it. This way any signals
# received (i.e. SIGTERM) will be processed. Make sure we don't
# advertise our presence until we're actually listening.
for ((attempt=0; $attempt < 5; ++attempt))
do
nc -l $port < $fifo_name | stap-server $((port + 1)) > $fifo_name 2>&1 &
if test $first = 1; then
advertise_presence
first=0
fi
wait %nc
rc=$?
if test $rc = 127 -o $rc = 0; then
break; # success
fi
sleep 1
done
if test $attempt = 10; then
fatal "ERROR: cannot listen on port $port. rc==$rc"
fi
done
set +o pipefail # restore
}
# 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 2> /dev/null
# Kill any running 'nc -l' job.
kill -s SIGTERM "%nc -l" 2> /dev/null
wait "%nc - l" 2> /dev/null
# Clean up
cd `dirname $tmpdir`
rm -fr $tmpdir
exit
}
#-----------------------------------------------------------------------------
# Beginning of main line execution.
#-----------------------------------------------------------------------------
initialization "$@"
listen
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