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

[Nicolas Dufresne]

I know this is merged already, but for future style improvements ....

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

Nicolas

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