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#!/usr/bin/python
# 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, os, syslog, glob, socket, stat
CONTROL_SOCKET = "/var/run/gpsd.sock"
def gpsd_control_connect():
"Acquire a connection to the GPSD control socket."
try:
sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM, 0)
sock.connect(CONTROL_SOCKET)
sockfile = sock.makefile()
except socket.error, msg:
if sock:
sock.close()
sock = None
sockfile = None
if not sock:
syslog.syslog("gpsd is not running or %s is unreachable" % CONTROL_SOCKET)
return None
else:
return sockfile
def gpsd_control(action, argument):
"Pass a command to gpsd; start the daemon if not already running."
connect = gpsd_control_connect()
if connect:
syslog.syslog("reached a running gpsd")
elif action == 'add':
syslog.syslog("attempting to launch gpsd")
os.system("gpsd -F " + CONTROL_SOCKET)
connect = gpsd_control_connect()
if not connect:
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.write("+%s\r\n" % argument)
elif action == 'remove':
connect.write("-%s\r\n" % argument)
connect.close()
return action
def hotplug(action, devpath):
syslog.openlog('gpsd.hotplug', 0, syslog.LOG_DAEMON)
syslog.syslog("gpsd.hotplug begins with action: %s" % action)
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(tty + " has gone active")
gpsd_control(action, tty)
return
syslog.syslog("gpsd.hotplug ends")
syslog.closelog()
if __name__ == '__main__':
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
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