timeout on os.popen3?

[Donn Cave]

Quoth selwyn <selwyn at home.net.nz>:
| I would like some advice on how I can include a timeout for a scanning 
| operation using unzip on linux and os.popen3.
|
| I am scanning through about 30g of rescued zip files, looking for xml 
| extensions within those files.  What I have put together 'works', but 
| only for what appears to be properly reconstructed files. 
| Unfortunately, some aren't AND for some reason no standard error 
| messages are being triggered. This causes my script to hang indefinitely.
|
| What I would like is for the script to move on to the next file, after 
| say a 10sec period of inactivity, but am unsure how this could be 
| included. I have googled around and think the select module may be 
| helpful, but after reading the docs I am still confused :-(

You might be able to manage it with select.  When you start up a program
on two or more pipes, you have kind of a juggling act.  Select is the
juggler, it can tell which pipe has data to read and which is ready for
more data to be written to it.  However, it's still a juggling act and
you need some skill, too.  If you decide to try it, also read about
os.read, and don't try to use the file object for reading.

On the other hand, if you don't mind writing to disk files instead, that
will completely eliminate this aspect of your problem.  Like

   file = '%s%s' % (sys.argv[1], i)
   ev = os.system('unzip -l "%s" > /tmp/zout 2> /tmp/zerr' % (file,)
   if os.WEXITSTATUS(ev) != 0 or nonEmptyFile('/tmp/zerr'):
      dealWithError(ev, open('/tmp/zerr', 'r'))
   elif searchFile('/tmp/zout', 'xml'):
      dealWithFile(file)

	Donn Cave, donn at drizzle.com