Non-blocking socket still blocking!

[Joel Sherrill]

Eric N read this carefully and see if I am on the money.
[And no comments about the libio flags being a pain.  I
know... the extra mapping causes nothing but trouble...

I think we introduced a minor glitch when we added the 
RTEMS filesystem infrastructure.  Gene.. follow this logic..

You call fcntl() which sets things for the file descriptor
in a generic sense.  And it seems to correctly get to 
rtems_bsdnet_fcntl().  But it checks for (iop->flags & O_NONBLOCK).
Unfortunately, the fcntl() routine mapped the bits into internal
settings.  Since O_NONBLOCK is 0x4000 and LIBIO_FLAGS_NO_DELAY
is 0x0001, the code fails to note that iop->flags has changed. 

So try this patch and let us all know.  

Index: rtems/rtems_syscall.c
===================================================================
RCS file: /usr1/CVS/rtems/c/src/libnetworking/rtems/rtems_syscall.c,v
retrieving revision 1.14
diff -u -r1.14 rtems_syscall.c
--- rtems/rtems_syscall.c	2000/06/12 15:00:08	1.14
+++ rtems/rtems_syscall.c	2000/09/01 16:23:38
@@ -730,7 +730,7 @@
 			rtems_bsdnet_semaphore_release ();
 			return EBADF;
 		}
-		if (iop->flags & O_NONBLOCK)
+		if (iop->flags & LIBIO_FLAGS_NO_DELAY)
 			so->so_state |= SS_NBIO;
 		else
 			so->so_state &= ~SS_NBIO;


"Smith, Gene" wrote:
> 
> I noticed that my read() on a supposedly non-blocking socket still blocked
> after
> I had read all data from the socket and called read() again.  I then checked
> 
> the socket flags more closely to make sure I was really setting it
> non-blocking
> (O_NONBLOCK is 0x4000) with the following code:
> 
> /* set new_sock non-blocking */
> flags = 0;
> flags = fcntl( new_sock, F_GETFL, 0);
> DTRACE(("\nOrig flags = 0x%x", flags));
> flags = flags | O_NONBLOCK;
> DTRACE(("\nflags|O_NON_BLOCK=0x%x", flags));
> if ( fcntl( new_sock, F_SETFL, flags ) < 0)
>         RTEMS_PANIC(("\nCan't set new_sock non-blocking"));
> DTRACE(("\nflags set to 0x%x", flags));
> 
> /* verify non-blocking flag set */
> flags = 0;
> flags = fcntl( new_sock, F_GETFL, 0);
> if ( (flags & O_NONBLOCK) == 0 )
>         DTRACE(("\nBad flags = 0x%x", flags));
> else
>         DTRACE(("\nGood flags = 0x%x", flags));
> 
> The following output trace indicates that my attempt to set the socket
> non-blocking does not "stick."  (The value "new_sock" is the return value
> from
> accept().) Any ideas why the socket seems to remain blocking?
> 
> Orig flags = 0x2
> flags|O_NON_BLOCK=0x4002
> flags set to 0x4002
> Bad flags = 0x2
> 
> --Gene

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
Ask me about RTEMS: a free RTOS  Huntsville AL 35805
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