Re: [Xen-devel] Re: [Xen-changelog] Make xenstored reopen its trace file on SIGHUP. This allows one to rotate the

[Anthony Liguori <aliguori@xxxxxxxxxx>]

Hollis Blanchard wrote:

> On Monday 07 November 2005 11:15, Anthony Liguori wrote:
>  
>
> > perror and strlen are not safe to call from a signal handler.
> >
> > I suggest just removing the perror call altogether and replacing strlen
> > with sizeof() - 1.
> >    
> I'm really not sure how strlen could be non-threadsafe. I don't care if it's 
> not in your list; your list doesn't include strtok_r either, and that is 
> explicitly thread-safe. :-P
>  
So re-reading the manpage, the list of safe functions is a POSIX-ism.  
That's perhaps why the thread-safe string functions aren't there since 
those are defined by ANSI not POSIX.
Regards,

Anthony Liguori

> However, in addition to perror, another thread could try to use tracefd 
> between the close and the open. You'd probably want to do something like:
>         oldfd = tracefd;
>         newfd = open();
>         if (newfd < 0) {
>                 ...
>         }
>         tracefd = newfd;
>         close(oldfd);
>
> Finally, you really should do error-checking on close(). See the close(2) man 
> page...
>  

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