sem_init() fails (when used in a certain way)

Corinna Vinschen corinna-cygwin@cygwin.com
Wed Mar 30 14:31:00 GMT 2011


On Mar 30 08:07, Eric Blake wrote:
> On 03/30/2011 02:01 AM, Corinna Vinschen wrote:
> > Thanks for clarifying.  We just have to keep in mind to return EINVAL
> > rather than EFAULT.
> > 
> > Btw., glibc does not test the validity of the semaphore at all.  If you
> > give an invalid sem pointer to the sem functions, it just crashes:
> 
> Which is allowed by POSIX.  In fact, my understanding is that older
> POSIX used to require that invalid objects be identified, until Ulrich
> argued that there are pathological cases (such as reuse of heap that
> already contains contents from a prior pointer) that make such detection
> practically impossible in any reasonable amount of time, so POSIX was
> intentionally relaxed to no longer require detection of invalid objects
> (they are just as undefined as any other use of a bad pointer) in order
> to cater to glibc.

So we could not add myfault handler's *and* remove the is_good_object
tests everywhere and we would still be on the safe side of Linux and
POSIX, right?  That would perhaps speed up extensive usage of the
pthread functions noticably.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat



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