Re: [UNIKRAFT PATCH] lib/vfscore: Implement `getcwd` with a raw system call

[Liza Babu <lizzababu@xxxxxxxxx>]

Hi, Simon.

Looks good to me.

Liza Babu

Reviewed-by: Liza Babu <lizza.babu@xxxxxxxxx>

On Mon, Dec 21, 2020 at 5:48 PM Simon Kuenzer <simon.kuenzer@xxxxxxxxx> wrote:
>
> Implements `getcwd` with a raw system call (`UK_SYSCALL_R_DEFINE`) instead.
> This variant should be preferred because it avoids the usage of `errno`.
>
> Signed-off-by: Simon Kuenzer <simon.kuenzer@xxxxxxxxx>
> ---
>  lib/vfscore/main.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/lib/vfscore/main.c b/lib/vfscore/main.c
> index bd1fcea5e..a3d3a7440 100644
> --- a/lib/vfscore/main.c
> +++ b/lib/vfscore/main.c
> @@ -1346,7 +1346,7 @@ UK_TRACEPOINT(trace_vfs_getcwd, "%p %d", char*, size_t);
>  UK_TRACEPOINT(trace_vfs_getcwd_ret, "\"%s\"", const char*);
>  UK_TRACEPOINT(trace_vfs_getcwd_err, "%d", int);
>
> -UK_SYSCALL_DEFINE(char*, getcwd, char*, path, size_t, size)
> +UK_SYSCALL_R_DEFINE(char*, getcwd, char*, path, size_t, size)
>  {
>         trace_vfs_getcwd(path, size);
>         struct task *t = main_task;
> @@ -1355,7 +1355,7 @@ UK_SYSCALL_DEFINE(char*, getcwd, char*, path, size_t, 
> size)
>
>         if (size < len) {
>                 error = ERANGE;
> -               goto out_errno;
> +               goto out_error;
>         }
>
>         if (!path) {
> @@ -1364,12 +1364,12 @@ UK_SYSCALL_DEFINE(char*, getcwd, char*, path, size_t, 
> size)
>                 path = (char*)malloc(size);
>                 if (!path) {
>                         error = ENOMEM;
> -                       goto out_errno;
> +                       goto out_error;
>                 }
>         } else {
>                 if (!size) {
>                         error = EINVAL;
> -                       goto out_errno;
> +                       goto out_error;
>                 }
>         }
>
> @@ -1377,10 +1377,9 @@ UK_SYSCALL_DEFINE(char*, getcwd, char*, path, size_t, 
> size)
>         trace_vfs_getcwd_ret(path);
>         return path;
>
> -       out_errno:
> +out_error:
>         trace_vfs_getcwd_err(error);
> -       errno = error;
> -       return NULL;
> +       return ERR2PTR(-error);
>  }
>
>  UK_TRACEPOINT(trace_vfs_dup, "%d", int);
> --
> 2.20.1
>