On Fri, 15 Jul 2005, Jan Engelhardt wrote:
> >
> >This is why I want to get rid of sendfile(). It's a fundamentally broken
> >interface. Really. In contrast, the pipe buffers _can_ be used for direct
> >socket->file interfaces.
>
> How will userspace access these pipe buffers?
You can fill them from a user-space buffer with "write()", and you can
read them into a user-space buffer with "read()".
It's really a pipe.
The idea of the pipe buffers is that you can _also_ send them to other
file descriptors, or fill them from other file descriptors, without having
to copy the data to/from user space.
Linus
---
See the example patch that I posted months ago (and that I referred to in
my other email, here is that thing repeated in case you missed it):
> For anybody interested in zero-copy work, here's a LWN write-up of some of
> the original discussion:
>
> http://lwn.net/Articles/118750/
>
> and my (very ugly) example patch can be found for example here:
>
>
> http://groups-beta.google.com/group/linux.kernel/msg/782bd9e5cb647207?hl=en&;
>
> (it's not a a complete implementation, but it shows how to go from a file
> _to_ a pipe buffer, but not back to a file again).
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