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Date:      Mon, 28 Feb 2005 17:41:11 -0800
From:      Brooks Davis <brooks@one-eyed-alien.net>
To:        "David C. Myers" <myers@aedifice.net>
Cc:        freebsd-amd64@freebsd.org
Subject:   Re: VNC on amd64: SIOCGIFCONF problems
Message-ID:  <20050301014111.GA6907@odin.ac.hmc.edu>
In-Reply-To: <4222A870.2090500@aedifice.net>
References:  <4222A870.2090500@aedifice.net>

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On Sun, Feb 27, 2005 at 09:13:20PM -0800, David C. Myers wrote:
>=20
>=20
> VNC-3.3.7 in ports looks like it doesn't work because of 64-bit=20
> alignment issues with SIOCGIFCONF.  The offending code is in=20
> Xvnc/programs/Xserver/os/access.c:
>=20
>    if (ifioctl (fd, (int) SIOCGIFCONF, (pointer) &ifc) < 0)
>        Error ("Getting interface configuration (4)");
>=20
> which comes out in the trace file as:
>=20
> 28138 Xvnc     CALL  bind(0x1,0x7fffffffe670,0x13)
> 28138 Xvnc     NAMI  "/tmp/.X11-unix/X1"
> 28138 Xvnc     RET   bind 0
> 28138 Xvnc     CALL  listen(0x1,0x80)
> 28138 Xvnc     RET   listen 0
> 28138 Xvnc     CALL  umask(0x12)
> 28138 Xvnc     RET   umask 0
> 28138 Xvnc     CALL  ioctl(0,0xffffffffc0106924 ,0x7fffffffe030)
> 28138 Xvnc     RET   ioctl -1 errno 6 Device not configured
> 28138 Xvnc     CALL  writev(0x2,0x7fffffffd790,0x4)
> 28138 Xvnc     GIO   fd 2 wrote 59 bytes
>       "Getting interface configuration (4): Device not configured
>       "
>=20
>=20
> (Actually, the very first error you'll  get is a "Could not open default=
=20
> font 'fixed'" message, but you can make that go away by running a font=20
> server and passing its address to Xvnc...)
>=20
> Is there a quick solution to this?  A 32-bit compatibility shim? =20
> Judging from Google, issues with this ioctl go back years, on all kinds=
=20
> of platforms.  getifaddrs() is the right way to do this on BSD?

You need to copy the misaligned element(s) into properly aligned temporary
storage or use getifaddrs instead.  SIOCGIFCONF is a really crappy
inteface.

-- Brooks

--=20
Any statement of the form "X is the one, true Y" is FALSE.
PGP fingerprint 655D 519C 26A7 82E7 2529  9BF0 5D8E 8BE9 F238 1AD4

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