[Discuss-gnuradio] Passing file descriptors via SWIG

[Martin Braun]

Hi,

following
http://lists.gnu.org/archive/html/discuss-gnuradio/2009-02/msg00400.html,
I tried connecting two processes with a FIFO using gr.file_descriptor_*.

However, I can't seem to pass the file descriptor from the Python to the
C++ domain. This is the error message I get:

gr_file_descriptor_sink: Bad file descriptor

This is the code (pipe1 was created by using 'mkfifo pipe1'):

Source-File:

<<< SNIP >>>
from gnuradio import gr
class sig_source(gr.top_block):
    def __init__(self):
        gr.top_block.__init__(self)

        src = gr.sig_source_f(8000, gr.GR_SIN_WAVE, 2000, 1.0)
        head = gr.head(gr.sizeof_float, 8000)

        print "Opening pipe..."
        fid = open('pipe1', 'wb')
        print "Done. fileno: ", fid.fileno()
        sink = gr.file_descriptor_sink(gr.sizeof_float, fid.fileno())

        self.connect(src, head, sink)

if __name__ == '__main__':
    try:
        sig_source().run()
    except KeyboardInterrupt:
        pass
<<< SNIP >>>

Sink:
<<< SNIP >>>
from gnuradio import gr
class sig_sink(gr.top_block):
    def __init__(self):
        gr.top_block.__init__(self)

        print "Opening pipe..."
        fid = open('pipe1', 'rb')
        print "Done. fileno: ", fid.fileno()
        src = gr.file_descriptor_source(gr.sizeof_float, fid.fileno())
        self.sink = gr.vector_sink_f()

        self.connect(src, self.sink)

if __name__ == '__main__':
    try:
        sigsnk = sig_sink()
        sigsnk.run()
        print sigsnk.sink.data()[0:4]
    except KeyboardInterrupt:
        pass
<<< SNIP >>>

When I start both scripts, this is what I get: 

Opening pipe...
Done. fileno:  3
file_descriptor_source[read]: Bad file descriptor

on both the write and read ends of the pipe. This does work when I open
the pipe with gr_file_sink, but then I have to think about the
buffering.

Has anyone ever done this and could drop me some example code that
works? I'd really appreciate it...

Cheers
MB

-- 
Dipl.-Ing. Martin Braun           Phone: +49-(0)721-608 3790
Institut fuer Nachrichtentechnik  Fax:   +49-(0)721-608 6071
Universitaet Karlsruhe (TH)       http://www.int.uni-karlsruhe.de/

pgpWd7HKtnHkO.pgp
Description: PGP signature