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Message-ID: <37BDD253.2109E564@mindless.com>
Date: Fri, 20 Aug 1999 16:10:27 -0600
From: "joshua M. Schmidlkofer" <menion AT mindless DOT com>
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To: cygwin AT sourceware DOT cygnus DOT com
Subject: Re: cygwin32 and select()
References: <37BDB1CD DOT BD7FB4EF AT mindless DOT com> <19990820171317 DOT A6337 AT cygnus DOT com>
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Actually, I do not mean to be in any way offensive, or anything like
that.  I have been investigating the problem, and have not found
resolution.  I would like to emphasize 'seems'.  I am a big time linux
user, and I beleive in free software.  I also understand the
development process, and that occasionally somone misunderstands an
API, etc.


I am writing a little udp library to do some dirtywork for my other
interests.  It's simply job is to send, receive, and listen for data
on a given port.  I am writing it to be relativley flexible, but
targetted to basic UDP communications.  

This code allows me to do that.  In the example have a single socket
open, and am waiting for data to come in on it. The following are a
couple snippets. The code is availible @:
http://www.cyberhighway.net/~iwpsrci/sockets/code.tar  Inside are the
gzip'd files. [yes I know, tar the files, and gzip the tar]  Oh well,
the code works find on Linux, however, it does not work on cygwin. 
The timing in select() is perfect, and it seems normal however, one
question remains.  When I was trying to learn about select() I found
the two differing explainations, in differnt man pages:

<snip> Man page 1:<snip> 
int select(int numfds, fd_set *readfds, fd_set *writefds , fd_set
*exceptfds, struct timeval * timeout); 
<snip>         ^^^^^^

This leads me to beleive that I put the number of fd's that I have in
select()
However, this is from the most recent man pages that I have found:

<snip> Man Page 2:<snip>
int  select(int  n,  fd_set  *readfds,  fd_set  *writefds, fd_set
*exceptfds, struct timeval *timeout);                             
[.....]
       n  is  the highest-numbered descriptor in any of the three
       sets, plus 1.

<snip>

This could be my problem, but still.... select() IS working under
Linux 2.2

Just for info, here is me structure, so you know what's up.
.<snip>..
typedef struct 
{
  int fd;
  struct sockaddr_in sa, sout, sinlast;
  struct timeval tv;
  fd_set fds;
  int max_bufsize;
} SOCKET_TYPE;
.<snip>..

here is the routing that calls select:
.<snip>..

int socket_listen (SOCKET_TYPE * st, struct timeval *tv){
  struct timeval t_tv;
  
  if (tv==NULL) 
    tv=&t_tv;
  memcpy(tv, &(st->tv), sizeof(struct timeval));
  return select ((st->fd + 1), &(st->fds), NULL, NULL, tv);
}

.<snip>..

This returns '0' everytime.  If I remove select I can get the data, or
at least, a udp comm utility that I wrote will get the data.

thanks,
  Joshua



  

Chris Faylor wrote:
> 
> On Fri, Aug 20, 1999 at 01:51:41PM -0600, joshua M. Schmidlkofer wrote:
> >I am looking for more information with using select(), and cygwin32.
> >So far select() seems completely broken, at least for read fd's..  Did
> >I miss a 'to be developed' page?
> 
> Perhaps if you provided more information than "completely broken"
> somebody *might* be able to answer this question.
> 
> -chris

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