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Subject: Re: ioctl: FIONREAD and ENOTTY
From: "Yaakov (Cygwin/X)" <yselkowitz AT users DOT sourceforge DOT net>
To: cygwin AT cygwin DOT com
Date: Wed, 20 Jul 2011 17:37:00 -0500
In-Reply-To: <20110720154647.GA15150@calimero.vinschen.de>
References: <1311149476 DOT 7796 DOT 50 DOT camel AT YAAKOV04>	 <20110720154647 DOT GA15150 AT calimero DOT vinschen DOT de>
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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.


Yaakov



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