#!/usr/bin/python# $Id: gpsd.hotplug 3486 2006-09-21 00:58:22Z ckuethe $# Hotplug script for gpsd by Eric S. Raymond, March 2005# This script is part of the gpsd distribution: see http://gpsd.berlios.de# Can be called like "gpsd.hotplug [add|remove] /dev/ttyUSB0" for test# purposes.import sys, time, os, syslog, glob, socket, statCONTROL_SOCKET = "/var/run/gpsd.sock"WHEREAMI = "/etc/hotplug/usb/gpsd.hotplug"def gpsd_control_connect():    "Acquire a connection to the GPSD control socket."    if not os.path.exists(CONTROL_SOCKET):        syslog.syslog("socket %s doesn't exist" % CONTROL_SOCKET)        return None    try:        sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM, 0)        sock.connect(CONTROL_SOCKET)    except socket.error, msg:        syslog.syslog("socket %s creation failure: %s" % (CONTROL_SOCKET, msg))        if sock:            sock.close()        sock = None    #else:    #    syslog.syslog("socket %s created OK" % CONTROL_SOCKET)    return sockdef gpsd_control(action, argument):    "Pass a command to gpsd; start the daemon if not already running."    syslog.syslog("gpsd_control(action=%s, arg=%s)" % (action, argument))    connect = gpsd_control_connect()    if connect:        syslog.syslog("reached a running gpsd")    elif action == 'add':        gpsdcmd = "gpsd -F " + CONTROL_SOCKET        syslog.syslog("launching %s" % gpsdcmd)        os.system(gpsdcmd)        connect = gpsd_control_connect()    if not connect:        syslog.syslog("can't reach gpsd")        return None    # We've got a live connection to the gpsd control socket.  No    # need to parse the response, because gpsd will lock on to the    # device if it's really a GPS and ignore it if it's not.    if action == 'add':        # Force the group-read & group-write bits on, so gpsd will still be        # able to use this device after dropping root privileges.        os.chmod(argument, stat.S_IMODE(os.stat(argument)[stat.ST_MODE])|0660)        connect.sendall("+%s\r\n" % argument)        connect.recv(12)    elif action == 'remove':        connect.sendall("-%s\r\n" % argument)        connect.recv(12)    connect.close()    #syslog.syslog("gpsd_control ends")    return actiondef hotplug(action, devpath):    #syslog.syslog("ACTION=%s DEVPATH=%s" % (action,devpath))    if not devpath:        syslog.syslog("No device")    else:        subnodes = glob.glob("/sys" + devpath + "/*")        subnodes = map(os.path.basename, subnodes)        subnodes = filter(lambda s: s.startswith("ttyUSB"), subnodes)         if len(subnodes) == 0:            syslog.syslog("no ttyUSB device under " + devpath)            return        elif len(subnodes) > 1:            syslog.syslog("too many ttyUSB devices under " + devpath)            return        else:            tty = "/dev/" + subnodes[0]            syslog.syslog("waiting for " + tty)            while not os.path.exists(tty):                time.sleep(1)            syslog.syslog(tty + " has gone active")            gpsd_control(action, tty)            remover = os.getenv("REMOVER")            #syslog.syslog("REMOVER=%s" % remover)            fp = open(remover, "w")            fp.write(WHEREAMI + " remove " + tty)            fp.close()            os.chmod(remover, stat.S_IRUSR|stat.S_IXUSR|stat.S_IRGRP|stat.S_IXGRP)            returnif __name__ == '__main__':    # In recent versions of udev, the gpsd script runs in series with    # the task that creates the real /dev/ttyUSB0 device    # node. Unfortunately, the gpsd script runs BEFORE the creation of    # the node, and the node is not created until after you kill the    # gpsd script, because the gpsd script waits forever for the node    # to appear.    #     # This is a race condition, and is best fixed by running the    # actual wait/hotplug portion in the background.    pid = os.fork()    if not pid:        syslog.openlog('gpsd.hotplug', 0, syslog.LOG_DAEMON)        try:             if len(sys.argv) == 1:	# Called as hotplug script                hotplug(os.getenv("ACTION"), os.getenv("DEVPATH"))            else:			# Called by hand for testing                gpsd_control(sys.argv[1], sys.argv[2])        except:            (exc_type, exc_value, exc_traceback) = sys.exc_info()            syslog.syslog("gpsd.hotplug: exception %s yields %s" % (exc_type, exc_value))            raise exc_type, exc_value, exc_traceback        #syslog.syslog("gpsd.hotplug ends")        syslog.closelog()