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VNC on amd64: SIOCGIFCONF problems



On Sun, Feb 27, 2005 at 09:13:20PM -0800, David C. Myers wrote:
> 
> 
> VNC-3.3.7 in ports looks like it doesn't work because of 64-bit 
> alignment issues with SIOCGIFCONF.  The offending code is in 
> Xvnc/programs/Xserver/os/access.c:
> 
>    if (ifioctl (fd, (int) SIOCGIFCONF, (pointer) &ifc) < 0)
>        Error ("Getting interface configuration (4)");
> 
> which comes out in the trace file as:
> 
> 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
>       "
> 
> 
> (Actually, the very first error you'll  get is a "Could not open default 
> font 'fixed'" message, but you can make that go away by running a font 
> server and passing its address to Xvnc...)
> 
> Is there a quick solution to this?  A 32-bit compatibility shim?  
> Judging from Google, issues with this ioctl go back years, on all kinds 
> 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

-- 
Any statement of the form "X is the one, true Y" is FALSE.
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