[Hackers] Re: any way to reset errno?

[Julian Cowley]

M. Warner Losh wrote:
> In message: <20050206132124.GA746 at daemon.unete.cl>
>             Daniel Molina Wegener <dmw at unete.cl> writes:
> :    Any way to reset errno?
> 
> errno = 0;
> 
> Routines that return an error status in errno generally don't set it
> to 0 to mean no error.

Which implies errno should never need to be set to zero since the 
convention is to only look at errno if a system call fails.  The only 
time errno needs to be explicitly set (to any value) is when preserving 
the error value between system calls.  Such as:

if (write(fd, buf, len) < 0) {
	int saved_errno;

	saved_errno = errno;
	close(fd); /* ignore any error */
	errno = saved_errno;
	return -1;
}