How to get an X11 Window from a Process ID?

Question

Under Linux, my C++ application is using fork() and execv() to launch multiple instances of OpenOffice so as to view some powerpoint slide shows. This part works.

Ne

Answer 1

If you use python, I found a way here, the idea is from BurntSushi

If you launched the application, then you should know its cmd string, with which you can reduce calls to xprop, you can always loop through all the xids and check if the pid is the same as the pid you want

import subprocess
import re

import struct
import xcffib as xcb
import xcffib.xproto

def get_property_value(property_reply):
    assert isinstance(property_reply, xcb.xproto.GetPropertyReply)

    if property_reply.format == 8:
        if 0 in property_reply.value:
            ret = []
            s = ''
            for o in property_reply.value:
                if o == 0:
                    ret.append(s)
                    s = ''
                else:
                    s += chr(o)
        else:
            ret = str(property_reply.value.buf())

        return ret
    elif property_reply.format in (16, 32):
        return list(struct.unpack('I' * property_reply.value_len,
                                  property_reply.value.buf()))

    return None

def getProperty(connection, ident, propertyName):

    propertyType = eval(' xcb.xproto.Atom.%s' % propertyName)

    try:
        return connection.core.GetProperty(False, ident, propertyType,
                                        xcb.xproto.GetPropertyType.Any,
                                        0, 2 ** 32 - 1)
    except:
        return None


c = xcb.connect()
root = c.get_setup().roots[0].root

_NET_CLIENT_LIST = c.core.InternAtom(True, len('_NET_CLIENT_LIST'),
                                     '_NET_CLIENT_LIST').reply().atom


raw_clientlist = c.core.GetProperty(False, root, _NET_CLIENT_LIST,
                                    xcb.xproto.GetPropertyType.Any,
                                    0, 2 ** 32 - 1).reply()

clientlist = get_property_value(raw_clientlist)

cookies = {}

for ident in clientlist:
    wm_command = getProperty(c, ident, 'WM_COMMAND')
    cookies[ident] = (wm_command)

xids=[]

for ident in cookies:
    cmd = get_property_value(cookies[ident].reply())
    if cmd and spref in cmd:
        xids.append(ident)

for xid in xids:
    pid = subprocess.check_output('xprop -id %s _NET_WM_PID' % xid, shell=True)
    pid = re.search('(?<=\s=\s)\d+', pid).group()

    if int(pid) == self.pid:
        print 'found pid:', pid
        break

print 'your xid:', xid