Re: [PATCH 05/15] build: syscalls: Add clone syscall wrapper.

[Ludovic Courtès]

David Thompson <address@hidden> skribis:

> From: David Thompson <address@hidden>
>
> * guix/build/syscalls.scm (clone): New procedure.
>   (CLONE_NEWNS, CLONE_NEWUTS, CLONE_NEWIPC, CLONE_NEWUSER, CLONE_NEWPID,
>   CLONE_NEWNET): New variables.
> * tests/syscalls.scm: Test it.

[...]

> +;; The libc interface to sys_clone is not useful for Scheme programs, so the
> +;; low-level system call is wrapped instead.
> +(define clone
> +  (let* ((ptr        (dynamic-func "syscall" (dynamic-link)))
> +         (proc       (pointer->procedure int ptr (list int int '*)))
> +         ;; TODO: Handle all supported architectures
> +         (syscall-id (match (utsname:machine (uname))
> +                       ("x86_64" 56)
> +                       (_        120))))

Please add the value for at least i386, mips64el, and armv7 (grep -r
NR_clone arch/ in the kernel tree.)

> +  (match (clone (logior CLONE_NEWUSER))

No need for logior.

> +    (0 (primitive-exit 0))

Maybe exit with code 42 here...

> +    (pid
> +     ;; Check if user namespaces are different.
> +     (not (equal? (readlink (user-namespace pid))
> +                  (readlink (user-namespace "self")))))))

... and here to a waitpid and check the status:exit-val.

OK with these changes.

Thanks,
Ludo’.