#!/usr/bin/env python
#GenerateHostInfo - Joey Hagedorn - hagedorn@mcs.anl.gov

'''Generates hostinfo.xml at a regular interval'''
__revision__ = '$Revision$'

from os import dup2, execl, fork, uname, wait
import lxml.etree, sys, time, ConfigParser
from Bcfg2.Settings import settings


if __name__ == '__main__':


    # override default settings
    if '-C' in sys.argv:
        settings.read_config_file(sys.argv[sys.argv.index('-C') + 1])

    clientdatapath = "%s/Metadata/clients.xml" % settings.SERVER_REPOSITORY
    
    try:
        clientElement = lxml.etree.parse(clientdatapath)
    except:
        print "Failed to parse '%s'" % clientdatapath
        raise SystemExit, 1
    hostlist = [client.get('name') for client in clientElement.findall("Client")]

    pids = {}
    null = open('/dev/null', 'w+')

    #use uname to detect OS and use -t for darwin and -w for linux
    #/bin/ping on linux /sbin/ping on os x
    osname = uname()[0]

    
    while hostlist or pids:
        if hostlist and len(pids.keys()) < 15:
            host = hostlist.pop()
            pid = fork()
            if pid == 0:
                # in child
                dup2(null.fileno(), sys.__stdin__.fileno())
                dup2(null.fileno(), sys.__stdout__.fileno())
                dup2(null.fileno(), sys.__stderr__.fileno())
                if osname == 'Linux':
                    execl('/bin/ping', 'ping', '-w', '5', '-c', '1', host)
                elif osname in ['Darwin', 'FreeBSD']:
                    execl('/sbin/ping', 'ping', '-t', '5', '-c', '1', host)
                elif osname == 'SunOS':
                    execl('/usr/sbin/ping', 'ping', host, '56', '1')
                else: #default
                    execl('/bin/ping', 'ping', '-w', '5', '-c', '1', host)
            else:
                pids[pid] = host
        else:
            try:
                (cpid, status) = wait()
            except OSError:
                continue
            chost = pids[cpid]
            del pids[cpid]
            elm = clientElement.xpath("//Client[@name='%s']"%chost)[0]
            if status == 0:
                elm.set("pingable",'Y')
                elm.set("pingtime", str(time.time()))
            else:
                elm.set("pingable",'N')

    fout = open(clientdatapath, 'w')
    fout.write(lxml.etree.tostring(clientElement.getroot()))
    fout.close()