On Tue, Feb 8, 2022 at 7:20 AM Christian Schoenebeck <qemu_...@crudebyte.com>
wrote:
> On Montag, 7. Februar 2022 23:40:19 CET Will Cohen wrote:
> > From: Keno Fischer <k...@juliacomputing.com>
> >
> > Signed-off-by: Keno Fischer <k...@juliacomputing.com>
> > Signed-off-by: Michael Roitzsch <reactorcont...@icloud.com>
> >
> > Because XATTR_SIZE_MAX is not defined on Darwin,
> > create a cross-platform P9_XATTR_SIZE_MAX instead.
> >
> > [Will Cohen: - Adjust coding style
> > - Lower XATTR_SIZE_MAX to 64k
> > - Add explanatory context related to XATTR_SIZE_MAX]
> > [Fabian Franz: - Move XATTR_SIZE_MAX reference from 9p.c to
> > P9_XATTR_SIZE_MAX in 9p.h]
> > Signed-off-by: Will Cohen <wwco...@gmail.com>
> > Signed-off-by: Fabian Franz <fabianfranz....@gmail.com>
> > ---
> > hw/9pfs/9p.c | 2 +-
> > hw/9pfs/9p.h | 11 +++++++++++
> > 2 files changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
> > index 14e84c3bcf..7405352c37 100644
> > --- a/hw/9pfs/9p.c
> > +++ b/hw/9pfs/9p.c
> > @@ -3949,7 +3949,7 @@ static void coroutine_fn v9fs_xattrcreate(void
> > *opaque) rflags |= XATTR_REPLACE;
> > }
> >
> > - if (size > XATTR_SIZE_MAX) {
> > + if (size > P9_XATTR_SIZE_MAX) {
> > err = -E2BIG;
> > goto out_nofid;
> > }
> > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
> > index 1567b67841..6a1856b4dc 100644
> > --- a/hw/9pfs/9p.h
> > +++ b/hw/9pfs/9p.h
> > @@ -479,4 +479,15 @@ struct V9fsTransport {
> > void (*push_and_notify)(V9fsPDU *pdu);
> > };
> >
> > +/*
> > + * Darwin doesn't seem to define a maximum xattr size in its user
> > + * space header, so manually configure it across platforms as 64k.
> > + *
> > + * Having no limit at all can lead to QEMU crashing during large
> g_malloc()
> > + * calls. Because QEMU does not currently support macOS guests, the
> below
> > + * preliminary solution only works due to its being a reflection of the
> limit of
> > + * Linux guests.
> > + */
> > +#define P9_XATTR_SIZE_MAX 65536
>
> It would be cleaner in a way like this:
>
> #if defined(XATTR_SIZE_MAX)
> /* Linux */
> #define P9_XATTR_SIZE_MAX XATTR_SIZE_MAX
> #elif defined(CONFIG_DARWIN)
> /* darwin comment goes here */
> #define P9_XATTR_SIZE_MAX 65536
> #else
> #error Missing definition for P9_XATTR_SIZE_MAX for this host system
> #endif
>
> Sorry, I haven't noticed that before. You actually had that wrapped into
> some
> ifdefs in v2 before:
>
> #if defined(CONFIG_DARWIN) && !defined(XATTR_SIZE_MAX)
> ...
> #endif
>
> > +
> > #endif
>
> Agreed, that is cleaner. Adjusting for the next round.
