[PATCH] libcamera: dma_buf_allocator: Work around lack of memfd_create() in uClibc

[Laurent Pinchart]

Hi Nicolas,

On Wed, Jun 05, 2024 at 01:53:47PM -0400, Nicolas Dufresne wrote:
> I know this is merged already, but for future style improvements ....

We can still fix or improve code that has been merged already :-)

> Le mercredi 05 juin 2024 à 11:37 +0300, Laurent Pinchart a écrit :
> > uClibc doesn't provide a memfd_create() implementation. Fix it by using
> > a direct syscall when the function isn't available.
> > 
> > Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > ---
> > I should have bundled this in a series with "[PATCH] libcamera:
> > dma_buf_allocator: Work around lack of file seals in uClibc", sorry
> > about that.
> > ---
> >  src/libcamera/dma_buf_allocator.cpp | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/src/libcamera/dma_buf_allocator.cpp b/src/libcamera/dma_buf_allocator.cpp
> > index 5ec29949c66a..d7d08e188a62 100644
> > --- a/src/libcamera/dma_buf_allocator.cpp
> > +++ b/src/libcamera/dma_buf_allocator.cpp
> > @@ -13,6 +13,7 @@
> >  #include <sys/ioctl.h>
> >  #include <sys/mman.h>
> >  #include <sys/stat.h>
> > +#include <sys/syscall.h>
> >  #include <sys/types.h>
> >  #include <unistd.h>
> >  
> > @@ -132,7 +133,11 @@ UniqueFD DmaBufAllocator::allocFromUDmaBuf(const char *name, std::size_t size)
> >  	std::size_t pageMask = sysconf(_SC_PAGESIZE) - 1;
> >  	size = (size + pageMask) & ~pageMask;
> >  
> > +#if HAVE_MEMFD_CREATE
> >  	int ret = memfd_create(name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
> > +#else
> > +	int ret = syscall(SYS_memfd_create, name, MFD_ALLOW_SEALING | MFD_CLOEXEC);
> > +#endif
> 
> Instead of polluting code with ifdefs, a strongly suggest using a compat header
> (or C++ file):
> 
>   #ifndef HAVE_MEMFD_CREATE
>   inline int memfd_create(...)
>   {
>   }
>   #endif

That's a good idea. I'll test it out.

> >  	if (ret < 0) {
> >  		ret = errno;
> >  		LOG(DmaBufAllocator, Error)
> > 
> > base-commit: 98071d3109c131820439f61d9380c0bd4cd2119a

-- 
Regards,

Laurent Pinchart