Re: [Minios-devel] [UNIKRAFT PATCH 3/3] lib/posix-process: Implement getpriority() and setpriority()

[Stefan Teodorescu <stefanl.teodorescu@xxxxxxxxx>]

Reviewed-by: Stefan Teodorescu <stefanl.teodorescu@xxxxxxxxx>

On Mon, Nov 25, 2019 at 12:58 PM Costin Lupu <costin.lupu@xxxxxxxxx> wrote:
>
> We allow getting and setting priority only for the calling process (or its
> process group or its real user ID), meaning that 0 is the only accepted value
> for the 'who' parameter. This patch also introduces the default value for the
> Unikraft "process" priority. This is also the only value that can be set using
> setpriority() (i.e. basically it doesn't change anything).
>
> Signed-off-by: Costin Lupu <costin.lupu@xxxxxxxxx>
> ---
>  lib/posix-process/include/uk/process.h |  1 +
>  lib/posix-process/process.c            | 54 ++++++++++++++++++++++++--
>  2 files changed, 52 insertions(+), 3 deletions(-)
>
> diff --git a/lib/posix-process/include/uk/process.h 
> b/lib/posix-process/include/uk/process.h
> index 67208e3d..b5eeb90a 100644
> --- a/lib/posix-process/include/uk/process.h
> +++ b/lib/posix-process/include/uk/process.h
> @@ -39,5 +39,6 @@
>  #define UNIKRAFT_PPID     0
>  #define UNIKRAFT_SID      0
>  #define UNIKRAFT_PGID     0
> +#define UNIKRAFT_PROCESS_PRIO 0
>
>  #endif /* __UK_PROCESS_H__ */
> diff --git a/lib/posix-process/process.c b/lib/posix-process/process.c
> index 74961db8..b2ace4c6 100644
> --- a/lib/posix-process/process.c
> +++ b/lib/posix-process/process.c
> @@ -298,10 +298,58 @@ int nice(int inc __unused)
>         return -1;
>  }
>
> -int setpriority(int which __unused, id_t who __unused, int prio __unused)
> +int getpriority(int which, id_t who)
>  {
> -       WARN_STUBBED();
> -       return 0;
> +       int rc = 0;
> +
> +       switch (which) {
> +       case PRIO_PROCESS:
> +       case PRIO_PGRP:
> +       case PRIO_USER:
> +               if (who == 0)
> +                       /* Allow only for the calling "process" */
> +                       rc = UNIKRAFT_PROCESS_PRIO;
> +               else {
> +                       errno = ESRCH;
> +                       rc = -1;
> +               }
> +               break;
> +       default:
> +               errno = EINVAL;
> +               rc = -1;
> +               break;
> +       }
> +
> +       return rc;
> +}
> +
> +int setpriority(int which, id_t who, int prio)
> +{
> +       int rc = 0;
> +
> +       switch (which) {
> +       case PRIO_PROCESS:
> +       case PRIO_PGRP:
> +       case PRIO_USER:
> +               if (who == 0) {
> +                       /* Allow only for the calling "process" */
> +                       if (prio != UNIKRAFT_PROCESS_PRIO) {
> +                               /* Allow setting only the default prio */
> +                               errno = EACCES;
> +                               rc = -1;
> +                       }
> +               } else {
> +                       errno = ESRCH;
> +                       rc = -1;
> +               }
> +               break;
> +       default:
> +               errno = EINVAL;
> +               rc = -1;
> +               break;
> +       }
> +
> +       return rc;
>  }
>
>  int prctl(int option __unused, ...)
> --
> 2.20.1
>

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