Re: Zero-copy CameraFile transfer?

That would work for transferring a file to the camera, right?  I'm
more concerned about transferring a file from the camera.

        =-ddt->

On Wed, Mar 9, 2022 at 11:32 PM Marcus Meissner <[email protected]> wrote:
>
> On Wed, Mar 09, 2022 at 07:02:40PM -0800, Dave Taylor wrote:
> > Hi, I've been looking through the libgphoto2 API for a way to
> > implement zero-copy transfers such as through Linux's sendfile(2)
> > system call, but it seems there isn't currently an exposed way to get
> > at an open CameraFile's file descriptor to pull this off.
> >
> > I do see that the CameraFile object has an fd member in it that
> > gp_file_slurp() references, but the comments say that gp_file_slurp()
> > is an internal function and that gp_file_open() is now deprecated.
> >
> > Is there a cleaner way to do this?  Or should I not play with matches?  :)
>
> If you create a CameraFile from a fd or a handler (gp_file_new_from_fd /
> gp_file_new_from_handler), it will only use a small local buffer (currently 512kb)
> to transfer data.
>
> gp_file_new() itself would use in-memory storage for the full image.
>
> I can take a look to avoid any kind of buffering, not sure if libusb1 allows this.
>
> Ciao, Marcus