Synnefo » snf-image

    parser.add_option("-o", "--output", dest="output", default=None,

                    metavar="FILE",

                    help="Write output notifications to this file")

    to.write("%s\n" % json.dumps(message))

    to.flush()

    with open(opts.output, 'w') as out:

        pid = os.fork()

        if pid == 0:

            # In child process:

            # Make sure we die with the parent and are not left behind

            # WARNING: This uses the prctl(2) call and is Linux-specific.

            prctl.set_pdeathsig(signal.SIGHUP)

            # exec command specified in arguments,

            # searching the $PATH, keeping all environment

            os.execvpe(args[0], args, os.environ)

            sys.stderr.write("execvpe failed, exiting with non-zero status")

            os.exit(1)

        # In parent process:

        iofname = "/proc/%d/io" % pid

        iof = open(iofname, "r", 0)   # 0: unbuffered open

        sys.stderr.write("%s: created child PID = %d, monitoring file %s\n" %

                         (sys.argv[0], pid, iofname))

        message = {}

        message['type'] = 'copy-progress'

        message['total'] = opts.read_bytes

        while True:

            # check if the child process is still alive

            (wpid, status) = os.waitpid(pid, os.WNOHANG)

            if wpid == pid:

                report_wait_status(pid, status)

                if (os.WIFEXITED(status) or os.WIFSIGNALED(status)):

                    if not (os.WIFEXITED(status) and

                                                os.WEXITSTATUS(status) == 0):

                        return 1

                    else:

                        message['position'] = message['total']

                        message['progress'] = float(100)

                        send_message(out, message)

                        return 0

            iof.seek(0)

            for l in iof.readlines():

                if l.startswith("rchar:"):

                    message['position'] = int(l.split(': ')[1])

                    message['progress'] = float(100) if opts.read_bytes == 0 \

                        else float("%2.2f" % (

                            message['position'] * 100.0 / message['total']))

                    break

            # Sleep for a while

            time.sleep(3)