Using file descriptor sink?

GNU Radio
#1

Hello GR,

Can anyone please give me some hints on how to use gr-file descriptor
sink
in a gnuradio python flowgraph.

Regards,
Ruecan

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#2

Hi Ruecan,

if you’re asking this question, you probably shouldn’t use
file_descriptor_sink.
It works quite like file_sink, but instead of a filename, you pass a
file descriptor, which is the int handler the open() syscall will
return.

Greetings,
Marcus

#3

Ah sorry, forgot the important part: If you have opened a file from
python, let’s say by:

myfile = open("/home/ruecan/secretplanforworlddominance.pdf", “r”)

you can get the file descriptor by doing
fd = myfile.fileno()

Greetings,
Marcus

#4

My question is let say I have this socket

 self.blocks_socket_pdu_0_Rx = blocks.socket_pdu("UDP_CLIENT",

“localhost”, “4000”, 10000)

And then I need to associate a file descriptor to it.
How can I have the int handler like the open() syscall would return ?

 self.myFileDescriptor = blocks.file_descriptor_sink(2048, ??)

Ruecan.

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#5

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Sorry, I don’t understand. Could you rephrase/elaborate on that?
Where does the file descriptor come into play?

On 30.05.2014 18:15, Ruecan wrote:

Ruecan.

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#6

I mean if I try this:

self.blocks_socket_pdu_0_Rx = blocks.socket_pdu(“UDP_CLIENT”, “localhost”,
“4000”, 10000)
self.myFileDescriptor = blocks.file_descriptor_sink(2048,
open(self.blocks_socket_pdu_0_Rx, ‘r+b’))

I got:
TypeError: coercing to Unicode: need string or buffer, socket_pdu_sptr
found

I don’t know how to get a file descriptor out of that to read it and
retrieve packets received.

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#7

I think you’re mixing things up.
open() like you use it is a call to generate a python “file” object,
which is not the file descriptor a file_destructor_sink needs.
open() expects a string, but you offer a socket_pdu shared pointer (ie.
the python (swig) representation of the C++ block of that name).

I don’t really understand what you are trying to do; could you explain?
I’m fairly certain file_descriptor_sink is not what you want…

Greetings,
Marcus