Re: [Xen-devel] [PATCH] Fix bug #709 by daemonizing blktapctrl and closing stdin, stdout and stderr

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

On Aug 1, 2006, at 6:33 AM, Keir Fraser wrote:

> On 1 Aug 2006, at 11:27, Muli Ben-Yehuda wrote:
>
> > > > Does it make sense for this to be folded into a common utility
> > > > library?
> > > Anil Madhavapeddy pointed out it already is: man 3 daemon.
> > Cool! I wasn't aware of it. How portable is it? how portable should
> > the tools be in general?
> Ah, that might be a concern, for the Solaris port in particular.  
> daemon() is I think a BSD function ported to Linux. It's not POSIX.  
> Keeping the existing code is uglier but probably more portable.
IMHO, it is better to use a system provided feature that has a large  
peer review audience than roll our own.
There are plenty of portable projects that use this method and fall  
back to a compatibility library for daemon(3), the OpenSSH project in  
particular has had to deal with it, I suggest if Solaris needs to  
borrow any code they borrow it from sshd.
Please also remember that daemons, since they are typically started  
from the craziest init scripts, should close _all_ file descriptors  
not explicitly opened or required by the daemon.
    for (i = 0; i < sysconf(_SC_OPEN_MAX); i++) {
        if (i not explicit)
           close(i);
    }

-JX

 
 

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