PR1245 device lseek

Victor Vengerov Victor.Vengerov at oktetlabs.ru
Tue Aug 7 19:03:21 CDT 2007


Hi,

Hard disk etc. represented in RTEMS device driver with 
open/close/read/write/control interface. rtems_libio_rw_args_t argument 
is passed to device read/write primitives, which contains the offset 
attribute. offset filled in device_write (deviceio.c) from iop->offset.

May be I've missed something, but it looks for me you just need to 
adjust iop->offset in device_lseek in accordance to offset and whence 
arguments.

Regards,
Victor

Joel Sherrill wrote:
> Hi,
>
> This PR notes that device_lseek() always succeeds but
> does nothing.  According to OpenGroup
> http://www.opengroup.org/onlinepubs/000095399/functions/lseek.html,
> lseek() should return ESPIPE for ttys, sockets, and pipes.
>
> I may be having a brain freeze, but right now, I don't
> see how to implement a seek on a block device like
> a hard disk.  I know you have to be able to do it.
>
> Any thoughts?
>
> --joel
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-- 
Victor Vengerov
OKTET Labs, St.-Petersburg, Russia   Web: www.oktetlabs.ru
Phone +7 812 4286709(office) +7 921 9389372(mobile) +7 812 4281653(home)




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