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

[Anthony Liguori <aliguori@us.ibm.com>]

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...
>
>  
>