Re: [PATCH v4 14/32] tools/xen-9pfsd: add 9pfs read request support

[Jürgen Groß <jgross@xxxxxxxx>]

On 08.02.24 02:28, Jason Andryuk wrote:
> On Mon, Feb 5, 2024 at 5:51 AM Juergen Gross <jgross@xxxxxxxx> wrote:
> > Add the read request of the 9pfs protocol.
> >
> > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > Reviewed-by: Jason Andryuk <jandryuk@xxxxxxxxx>
> > Acked-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> > ---
> > V2:
> > - make error check more readable (Jason Andryuk)
> > V4:
> > - add directory read support
> > ---
> >   tools/xen-9pfsd/io.c | 90 ++++++++++++++++++++++++++++++++++++++++++++
> >   1 file changed, 90 insertions(+)
> >
> > diff --git a/tools/xen-9pfsd/io.c b/tools/xen-9pfsd/io.c
> > index b763e3d8d9..cfbf3bef59 100644
> > --- a/tools/xen-9pfsd/io.c
> > +++ b/tools/xen-9pfsd/io.c
> > +
> > +    len = count;
> > +    buf = ring->buffer + sizeof(*hdr) + sizeof(uint32_t);
> > +
> > +    if ( fidp->isdir )
> > +    {
> > +        struct dirent *dirent;
> > +        struct stat st;
> > +        struct p9_stat p9s;
> > +
> """
> For directories, read returns an integral number of direc- tory
> entries exactly as in stat (see stat(5)), one for each member of the
> directory. The read request message must have offset equal to zero or
> the value of offset in the previous read on the directory, plus the
> number of bytes returned in the previous read. In other words, seeking
> other than to the beginning is illegal in a directory (see seek(2)).
> """
>
> I think you need to check `off`.  Looks like QEMU only checks for off
> == 0 and rewinds in that case.  QEMU ignores other values.
Oh, indeed. Thanks for noticing. I'll use the same approach as qemu.


Juergen