From owner-freebsd-hackers  Tue Apr 20  3:28:42 1999
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Date: Tue, 20 Apr 1999 11:25:35 +0100
To: Graham Wheeler <gram@cdsec.com>
From: Bob Bishop <rb@gid.co.uk>
Subject: Re: Using select() to implement a delay
Cc: hackers@FreeBSD.ORG
In-Reply-To: <199904200921.LAA09941@cdsec.com>
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Hi,

Most likely your select() is taking a signal; truss might be revealing. You
should in theory be able to write something along the lines of:

	do
		r = select(0, 0, 0, 0, &tv);
	while (r == -1 && errno == EINTR);

but AFAIK tv won't get updated correctly, see the BUGS entry in select(2).

At 11:21 20/04/99 +0200, Graham Wheeler wrote:
>Hi all
>
>I have an interesting problem. I have a routine to implement delays:
>
>void Sleep(int secs, int usecs = 0)
>{
>    struct timeval tv;
>    tv.tv_sec = secs;
>    tv.tv_usec = usecs;
>    (void)select(0, 0, 0, 0, &tv);
>}
>
>I am using this both because it gives better resolution than sleep(),
>and also because it doesn't require the use of SIGALRM, which I am
>using elsewhere.
>
>On my development machine, Sleep(60) does exactly what is expected. On
>my clients machine, Sleep(60) returns immediately. Both are running 
>FreeBSD 2.2.7. I don't have access to the clients machine, which is
>in another city, and has no development environment, so I can't run gdb,
>although it may not give away anything in any case.
>
>Does anyone have any ideas why the one works and the other doesn't?
>
>TIA
>gram
>-- 
>Dr Graham Wheeler                          E-mail: gram@cdsec.com
>Citadel Data Security                      Phone:  +27(21)423-6065/6/7
>Firewalls/Virtual Private Networks         Fax:    +27(21)24-3656
>Internet/Intranet Network Specialists      
>Data Security Products                     WWW:    http://www.cdsec.com/
>
>
>
>
>
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>
>

--
Bob Bishop		    +44 118 977 4017
rb@gid.co.uk		fax +44 118 989 4254 (0800-1800 UK)


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