Date: Tue, 1 Nov 2005 00:04:19 EST-10EDT,10,-1,0,7200,3,-1,0,7200,3600
Subject: [UnixOS2_Archive] No. 643

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Monday 31 October 2005
 Number  643
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Subjects for today
 
1   Help me understand this code : Paul Smedley <paul at smedley.info>
2  Re:  Help me understand this code : Tobias Huerlimann <tobias at tobiashuerlimann.de>


**= Email   1 ==========================**

Date:  Mon, 31 Oct 2005 21:35:22 +1030
From:  Paul Smedley <paul at smedley.info>
Subject:   Help me understand this code

Hi guys,.
I'm trying to build the latest bind, currently it compiles but fails on 
running with this error:
[E:\bind\bin]nslookup ibm.com
socket.c:443: fcntl(20, F_SETFL, 6): Invalid argument
nslookup: isc_socket_create: unexpected error

The last parameter is obviously invalid for F_SETFL.

The code in question is:
make_nonblock(int fd) {
	int ret;
	int flags;
	char strbuf[ISC_STRERRORSIZE];

	flags = fcntl(fd, F_GETFL, 0);

	flags |= O_NONBLOCK;
	ret = fcntl(fd, F_SETFL, flags);

	if (ret == -1) {
		isc__strerror(errno, strbuf, sizeof(strbuf));
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "fcntl(%d, F_SETFL, %d): %s",
				 fd, flags, strbuf);

		return (ISC_R_UNEXPECTED);
	}

The line I don't understand is "flags |= O_NONBLOCK;" what does |= mean?

Thanks in advance,

Paul.


**= Email   2 ==========================**

Date:  Mon, 31 Oct 2005 12:26:45 +0100
From:  Tobias Huerlimann <tobias at tobiashuerlimann.de>
Subject:  Re:  Help me understand this code

Paul Smedley wrote:
> The line I don't understand is "flags |= O_NONBLOCK;" what does |= mean?
It's a shortcut for:

flags = flags | O_NONBLOCK;


Tobias Hürlimann