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#!/bin/bash
# Find compile servers for systemtap
#
# Copyright (C) 2008, 2009 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 uses avahi to find systemtap compile servers on the local
# network. Information about each server found is printed to stdout.
#-----------------------------------------------------------------------------
# Helper functions.
#-----------------------------------------------------------------------------
# function: configuration
function configuration {
avahi_service_tag=_stap._tcp
timeout=10 # seconds
}
# function: initialization
function initialization {
rc=1 # not found yet
if test "X$1" = "X--all"; then
find_all=1
else
find_all=0
fi
}
# function: find_servers
#
# Find and establish connection with a compatible stap server.
function find_servers {
# Create a temp file for the list of servers. We do this instead
# of using a pipe so that we can kill avahi-browse if it
# takes more than a minute.
tmpfile=`mktemp -t stap-serversXXXXXX` || \
fatal "Cannot create temporary file " $tmpfile
# Find servers
avahi-browse $avahi_service_tag --terminate -r 2>/dev/null > $tmpfile &
for ((attempt=0; $attempt < $timeout; ++attempt))
do
if ! jobs '%avahi-browse' >/dev/null 2>&1; then
break
fi
sleep 1
done
# Kill avahi-browse, if it's still running
test $attempt = $timeout && kill -s SIGTERM '%avahi-browse' 2>/dev/null
match_server < $tmpfile
rm -fr $tmpfile
}
# function: match_server
#
# Find a suitable server using the avahi-browse output provided on stdin.
function match_server {
local server_ip
local server_name
local server_sysinfo
local server_port
rc=1 # not found yet
# Loop over the avahi service descriptors.
read -t $timeout || return
while test "X$REPLY" != "X"
do
server_name=
server_ip=
server_port=
server_sysinfo=
# Examine the next service descriptor
# Is it a stap server?
if ! echo $REPLY | grep -q "=.* .* IPv4 .*_stap"; then
read -t $timeout || return
continue
fi
REPLY=
# Get the details of the service
local service_tag equal service_data
while read -t $timeout service_tag equal service_data
do
case $service_tag in
hostname )
server_name=`expr "$service_data" : '\[\([^]]*\)\]'`
;;
address )
# Sometimes (seems random), avahi-resolve-host-name resolves a local server to its
# hardware address rather its ip address. Keep trying until we get
# an ip address.
server_ip=`expr "$service_data" : '\[\([^]]*\)\]'`
local attempt
for ((attempt=0; $attempt < 5; ++attempt))
do
server_ip=`expr "$server_ip" : '\([0-9]*\.[0-9]*\.[0-9]*\.[0-9]*\)$'`
if test "X$server_ip" != "X"; then
break
fi
# Resolve the server.domain to an ip address.
server_ip=`avahi-resolve-host-name $server_name`
server_ip=`expr "$server_ip" : '.* \(.*\)$'`
done
;;
port )
server_port=`expr "$service_data" : '\[\([^]]*\)\]'`
;;
txt )
server_sysinfo=`expr "$service_data" : '\[.*\"\(sysinfo=[^]]*\)\"\]'`
;;
* )
REPLY="$service_tag $equal $service_data"
break
;;
esac
done
# It is a stap server, but is it compatible?
if test $find_all = 0 -a "$server_sysinfo" != "`client_sysinfo`"; then
continue
fi
# It's compatible, or we're finding all servers. Print a summary line
echo "$server_name $server_ip $server_port '$server_sysinfo'"
rc=0
done
}
# function client_sysinfo
#
# Generate the client's sysinfo and echo it to stdout
function client_sysinfo {
if test "X$sysinfo_client" = "X"; then
# Add some info from uname
sysinfo_client="`uname -rvm`"
fi
echo sysinfo=$sysinfo_client
}
# function: fatal [ MESSAGE ]
#
# Fatal error
# Prints its arguments to stderr and exits
function fatal {
echo "$0: ERROR:" "$@" >&2
exit 1
}
#-----------------------------------------------------------------------------
# Beginning of main line execution.
#-----------------------------------------------------------------------------
configuration
initialization "$@"
find_servers
exit $rc
|
