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Date: Thu, 21 Jul 2011 19:47:17 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: ioctl: FIONREAD and ENOTTY
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On Jul 21 13:05, Christopher Faylor wrote:
> On Thu, Jul 21, 2011 at 04:39:31PM +0200, Corinna Vinschen wrote:
> >On Jul 20 17:37, Yaakov (Cygwin/X) wrote:
> >> On Wed, 2011-07-20 at 17:46 +0200, Corinna Vinschen wrote:
> >> > On Jul 20 03:11, Yaakov (Cygwin/X) wrote:
> >> > > On Linux, ioctl(2) returns several different errors[1]:
> >> > > 
> >> > > EBADF  d is not a valid descriptor.
> >> > > EFAULT argp references an inaccessible memory area.
> >> > > EINVAL Request or argp is not valid.
> >> > > ENOTTY d is not associated with a character special device.
> >> > > ENOTTY The specified request does not apply to the kind of object that
> >> > >        the descriptor d references.
> >> > > 
> >> > > In the case of FIONREAD, Cygwin doesn't seem to distinguish between
> >> > > EINVAL and ENOTTY, and this causes at least one major bug:
> >> > > 
> >> > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35536
> >> > > 
> >> > > I have patched GCJ and GNU classpath to work around it, but this really
> >> > > needs to be fixed in Cygwin itself.
> >> > 
> >> > Would this patch be sufficient?
> >> > 
> >> > Index: fhandler.cc
> >> > ===================================================================
> >> > RCS file: /cvs/src/src/winsup/cygwin/fhandler.cc,v
> >> > retrieving revision 1.397
> >> > diff -u -p -r1.397 fhandler.cc
> >> > --- fhandler.cc	5 Jul 2011 12:02:10 -0000	1.397
> >> > +++ fhandler.cc	20 Jul 2011 15:46:40 -0000
> >> > @@ -1151,6 +1151,10 @@ fhandler_base::ioctl (unsigned int cmd, 
> >> >        set_nonblocking (*(int *) buf);
> >> >        res = 0;
> >> >        break;
> >> > +    case FIONREAD:
> >> > +      set_errno (ENOTTY);
> >> > +      res = -1;
> >> > +      break;
> >> >      default:
> >> >        set_errno (EINVAL);
> >> >        res = -1;
> >> 
> >> Given my testcases, give me a few days to check this out.
> >
> >Ok, but the patch doesn't build as is.  You have to add
> >
> >  #include <asm/socket.h>
> >
> >to get the FIONREAD definition.  Sorry about that.
> 
> Btw, I don't think the above is sufficient.  I think you'll have to add a
> similar test to other fhandlers (like fhandler_windows) which completely
> implement ioctl without reverting to fhandler_base.

Hmm, isn't that just a bug in these ioctl methods?  I think they
all should fall through to fhandler_base::ioctl.


Corinna

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

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