Re: [BUG] Win32: rb_sys_fail() - errno == 0

On Thu, Jan 06, 2005 at 12:34:27AM +0900, Berger, Daniel wrote:
> I'm not sure I follow, because this has worked as expected in certain
> circumstances in the past (i.e. it raised Errno::ENOENT).
> 
> Perhaps I need more detail on how rb_sys_fail() actually works.

Perhaps you need an abstraction like this one (from
http://www.cs.wustl.edu/~schmidt/ACE_wrappers/ace/OS_NS_errno.inl):

  ACE_INLINE int
  ACE_OS::last_error (void)
  {
    // ACE_OS_TRACE ("ACE_OS::last_error");

  #if defined (ACE_WIN32)
    // ACE_OS::last_error() prefers errnor since started out as a way to
    // avoid directly accessing errno in ACE code - particularly the ACE
    // C++ socket wrapper facades.  On Windows, some things that would
    // use errno on UNIX require ::GetLastError(), so this method tries
    // to shield the rest of ACE from having to know about this.
    int lerror = ::GetLastError ();
    int lerrno = errno;
    return lerrno == 0 ? lerror : lerrno;
  #else
    return errno;
  #endif /* ACE_WIN32 */

Or perhaps rb_sys_fail() should do this behind the scenes.

> That, or I need to figure out a way to explicitly raise Errno::ENOENT within
> a C extension.

The easiest way is to set errno to ENOENT before calling rb_sys_fail().

Paul