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To: cs551@merlot.usc.edu
Subject: Re: Select from stdin
Date: Mon, 24 Nov 2008 22:05:25 -0800
From: Bill Cheng <william@bourbon.usc.edu>

Someone wrote:

  > I was facing a somewhat similar problem a couple of days back. This might
  > help.
  > 
  > I made a variable true and forgot to make it false while looping. Something
  > like the following:
  > 
  > if(message type is STOR) {
  > ....bigData = true)
  > }
  > 
  > if(bigData is false) {
  > ....recv data into buffer
  > }
  > else {
  > ....recv byte by byte
  > //FORGOT TO MAKE IT FALSE
  > }

Certainly, that's one out of many possible bugs.
--
Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>





  On Mon, Nov 24, 2008 at 9:15 PM, Bill Cheng <william@bourbon.usc.edu> wrote:
  > Someone wrote:
  >
  >  > To read the commands from the user we are using select as follows:
  >  >
  >  > select(1,&readfds, NULL,NULL,NULL);
  >  >
  >  > This never gave us any problems earlier. Even now it works perfectly for
  > all
  >  > the commands except for a "search keywords " command. In this case, it
  > does
  >  > what "search keywords" asks it to do and then from there, it is not able
  > to
  >  > detect ANY commands.
  >
  > Sounds like a bug somewhere.
  >
  >  > We did a printf before the select and determined that it is blocking on
  >  > select() and not detecting any sort of input commands after that "search
  >  > keywords" operation is done. We have been trying to debug this for quite
  >  > some time and are unable to come up with any solution. Could you please
  > help
  >  > us regarding this ? Any hints or ideas on what could be causing this
  > problem
  >  > ?
  >
  > If "search keywords" is the only command that breaks things,
  > my guess is that it's the usual memory corruption bug and
  > somehow it affects you reading from stdin.
  >
  > I don't have any great idea in how to find the bug.  Sorry.
  > --
  > Bill Cheng // bill.cheng@usc.edu <URL:http://merlot.usc.edu/william/usc/>