Using os.popen3() to get binary data

[Christoph Krammer]

Hello everybody,

I need to get the different frames from a GIF image in my python
script and want to use the giftopnm program from netpbm to get the
frames and directly convert them to pnm files. I tried to use the
following code:

for image in images:
    if (image[0:3] == 'GIF'):
      (si, so, se) = os.popen3('giftopnm -image=all', 'b')
      si.write(image)
      frame = so.readlines()

But with this code the script just hangs. When I interrupt the script,
I get the following error message:
Traceback (most recent call last):
  File "/home/tiger/stock-spam/scripts/all_in_one.py", line 46, in ?
    frames = so.readlines()
KeyboardInterrupt
close failed: [Errno 32] Broken pipe

Can somebody tell me, which command I have to use that the pipe will
be closed when the giftopnm returns? This program just prints the
converted images to stdout and terminates.

Thanks in advance,
 Christoph