Re: [Xen-devel] [PATCH] libxen-3.0 (libxc rewrite)

[Anthony Liguori <aliguori@xxxxxxxxxx>]

Christian Limpach wrote:

> On Mon, 21 Mar 2005 15:25:09 -0600, Anthony Liguori <aliguori@xxxxxxxxxx> wrote:
>  
>
> > o Provide consistent error semantics for all functions (-errno is
> > returned on error).
> >    
> Why -errno?  What's wrong with regular errno, like used everywhere
> else in userspace?
>  
errno's a global variable and it's way to easy to lose it's value.  For 
instance:
if (read(fd, buffer, sizeof(buffer)) == -1) {
   close(fd);
   perror("read");
}

Doesn't do what you'd expect.  It gets particularly hairy when you're 
not sure what functions modify errno and which functions don't.
Regards,
Anthony Liguori

>    christian
>
>  


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