Registering for SIGPOLL signals from a named pipe

Hi,

I'd firstly like to apologise in advance in case this isn't the right group
for this message. If it's not the correct group, I'd appreciate some
indication of a better place to post.

A colleague has inherited rather a large lump of Solaris code which he is
porting to Linux. One area that is causing some difficulty is where the
original code uses ioctl in order to register for SIGPOLL signals when
events occur on a named pipe.

The code he has fails when calling ioctl. Having read the docs, he's sure
that this should work so he has simplified the code as much as possible and
it still fails.

I was wondering if any of our Linux developers can clarify whether or not
the following snippet should work:

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <stropts.h>
#include <unistd.h>

int main ()
{
int fd;

/* /tmp/testpipe has already been created using mkfifo */
if ((fd = open("/tmp/testpipe", O_NONBLOCK | O_RDONLY)) == -1)
{
perror("open");
exit(1);
}

if( ioctl( fd, I_SETSIG, S_RDNORM) < 0)
{
/* ioctl call fails, reporting "ioctl: Invalid argument" */
perror( "ioctl");
exit(1);
}

close (fd);

return 0;
}

Rgds and TIA,
MikeB

In article <f9abhd$qaf$1$8300dec7@news.demon.co.uk>,
MikeB <objectivedynamics RemoveThis @hotmail.com> wrote:
>
>Hi,
>
>I'd firstly like to apologise in advance in case this isn't the right group
>for this message. If it's not the correct group, I'd appreciate some
>indication of a better place to post.
>
>A colleague has inherited rather a large lump of Solaris code which he is
>porting to Linux. One area that is causing some difficulty is where the
>original code uses ioctl in order to register for SIGPOLL signals when
>events occur on a named pipe.

> if( ioctl( fd, I_SETSIG, S_RDNORM) < 0)

This is specific to STREAMS. There is a STREAMS package for Linux, but
it's an add-on, and I don't know anything about it.

Instead, try:

fcntl(fd, F_SETOWN, getpid())

followed by

fcntl(fd, F_SETFL, fcntl(fd, F_GETFL, 0) | FASYNC)

This is for a socket; I don't know the difference with named pipes.

Hope this helps.

--Paul Vojta, vojta RemoveThis @math.berkeley.edu