Re: [UNIKRAFT PATCH 6/7] lib/vfscore: Expose max fds to sysconf

[Costin Lupu <costin.lupu@xxxxxxxxx>]

Thanks for adding this, Cristi!
I'll upstream this now and we shall skip it from the v2.

Reviewed-by: Costin Lupu <costin.lupu@xxxxxxxxx>

On 5/2/20 6:13 PM, Cristian Banu wrote:
> Expose FDTABLE_MAX_FILES from vfscore as the return value of
> sysconf(_SC_OPEN_MAX) if CONFIG_LIBVFSCORE is enabled.
> 
> This allows language runtimes to inspect the number of active
> fds (e.g. for tests).
> 
> Signed-off-by: Cristian Banu <cristb@xxxxxxxxx>
> ---
>  lib/posix-sysinfo/sysinfo.c        | 10 ++++++++++
>  lib/vfscore/fd.c                   |  2 --
>  lib/vfscore/include/vfscore/file.h |  3 +++
>  3 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/posix-sysinfo/sysinfo.c b/lib/posix-sysinfo/sysinfo.c
> index 7bcfc8b..075f320 100644
> --- a/lib/posix-sysinfo/sysinfo.c
> +++ b/lib/posix-sysinfo/sysinfo.c
> @@ -43,6 +43,11 @@
>  #include <sys/sysinfo.h>
>  #include <uk/syscall.h>
>  
> +#if CONFIG_LIBVFSCORE
> +/* For FDTABLE_MAX_FILES. */
> +#include <vfscore/file.h>
> +#endif
> +
>  static struct utsname utsname = {
>       .sysname        = "Unikraft",
>       .nodename       = "unikraft",
> @@ -85,6 +90,11 @@ long sysconf(int name)
>       if (name == _SC_PAGESIZE)
>               return __PAGE_SIZE;
>  
> +#if CONFIG_LIBVFSCORE
> +     if (name == _SC_OPEN_MAX)
> +             return FDTABLE_MAX_FILES;
> +#endif
> +
>       return 0;
>  }
>  
> diff --git a/lib/vfscore/fd.c b/lib/vfscore/fd.c
> index 684ea50..956846f 100644
> --- a/lib/vfscore/fd.c
> +++ b/lib/vfscore/fd.c
> @@ -42,8 +42,6 @@
>  #include <errno.h>
>  #include <uk/ctors.h>
>  
> -#define FDTABLE_MAX_FILES 1024
> -
>  void init_stdio(void);
>  
>  struct fdtable {
> diff --git a/lib/vfscore/include/vfscore/file.h 
> b/lib/vfscore/include/vfscore/file.h
> index be23974..ec45a08 100644
> --- a/lib/vfscore/include/vfscore/file.h
> +++ b/lib/vfscore/include/vfscore/file.h
> @@ -80,6 +80,9 @@ int fdrop(struct vfscore_file* fp);
>  
>  #define FOF_OFFSET  0x0800    /* Use the offset in uio argument */
>  
> +/* Used from posix-sysinfo to determine sysconf(_SC_OPEN_MAX). */
> +#define FDTABLE_MAX_FILES 1024
> +
>  #ifdef __cplusplus
>  }
>  #endif
>