Re: [Qemu-devel] [PATCH v2] linux-user: Implement copy_file_range

[Laurent Vivier]

Le 06/02/2018 à 11:31, Andreas Schwab a écrit :
> No attempt is made to emulate it on the host.

I don't understand what you mean here...

> Signed-off-by: Andreas Schwab <address@hidden>
> ---
> v2: fix spacing
> ---
>  linux-user/syscall.c | 39 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index bed154139e..92b4f59c05 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
...
> +#if defined(TARGET_NR_copy_file_range) && defined(__NR_copy_file_range)
> +    case TARGET_NR_copy_file_range:
> +        {
> +            loff_t inoff, outoff;
> +            loff_t *pinoff = NULL, *poutoff = NULL;
> +
> +            if (arg2) {
> +                if (get_user_u64(inoff, arg2)) {
> +                    goto efault;
> +                }
> +                pinoff = &inoff;
> +            }
> +            if (arg4) {
> +                if (get_user_u64(outoff, arg4)) {
> +                    goto efault;
> +                }
> +                poutoff = &outoff;
> +            }
> +            ret = get_errno(safe_copy_file_range(arg1, pinoff, arg3, poutoff,
> +                                                 arg5, arg6));
> +            if (arg2) {
> +                if (put_user_u64(inoff, arg2)) {
> +                    goto efault;
> +                }
> +            }
> +            if (arg4) {
> +                if (put_user_u64(outoff, arg4)) {
> +                    goto efault;
> +                }
> +            }

According to the linux implementation, this should be something like:

if (ret > 0) {
    if (arg2) {
        if (put_user_u64(inoff, arg2)) {
            ret = -TARGET_EFAULT;
        }
    }
    if (arg4) {
        if (put_user_u64(outoff, arg4)) {
            ret = -TARGET_EFAULT;
        }
    }
}

[TARGET_NR_splice should do this the same way]

Thanks,
Laurent