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From: John Baldwin <jhb@freebsd.org>
To: freebsd-drivers@freebsd.org
Subject: Re: uiomove question
Date: Mon, 08 May 2017 13:35:42 -0700
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On Saturday, March 11, 2017 02:03:06 PM Anindya Mukherjee wrote:
> An example of the usage I am talking about:
> 
> xxx_write(...)
> {
> ...
> amount = MIN(uio->uio_resid,  // 0. This is the no of bytes in the uio left to write
>              (BUFFER_SIZE - 1 - uio->uio_offset > 0) ?
>              BUFFER_SIZE - 1 - uio->uio_offset : 0); // 1. amount to write is computed
> //assuming write will happen at uio_offset in sc_buffer
> if (amount == 0)
>   return (error);
> error = uiomove(sc->sc_buffer, amount, uio);  // 2. sc_buffer is not offset
> ...
> }
> 
> xxx_read(...)
> {
> ...
> amount = MIN(uio->uio_resid,
>              (sc->sc_length - uio->uio_offset > 0) ?
>              sc->sc_length - uio->uio_offset : 0); // 3. Same as comment 1 above
> error = uiomove(sc->sc_buffer + uio->uio_offset, amount, uio); // 4. Here buffer is offset
> ...
> }
> 
> Anindya

Yes, I think your point is correct.

-- 
John Baldwin