Re: [Qemu-devel] [PATCH] linux-user: implement renameat2

[Laurent Vivier]

Le 22/01/2018 à 18:44, Andreas Schwab a écrit :
> This is needed for new architectures like RISC-V which do not provide any
> other rename-like syscall.
> 
> Signed-off-by: Andreas Schwab <address@hidden>
> ---
>  linux-user/syscall.c | 33 +++++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 5e54889522..12ca06c65a 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -598,6 +598,23 @@ static int sys_utimensat(int dirfd, const char *pathname,
>  #endif
>  #endif /* TARGET_NR_utimensat */
>  
> +#ifdef TARGET_NR_renameat2
> +#if defined(__NR_renameat2)
> +#define __NR_sys_renameat2 __NR_renameat2
> +_syscall5(int, sys_renameat2, int, oldfd, const char *, old, int, newfd,
> +          const char *, new, unsigned int, flags)
> +#else
> +static int sys_renameat2(int oldfd, const char *old,
> +                         int newfd, const chat *new, int flags)
> +{
> +    if (flags == 0)
> +        return renameat(oldfd, old, newfd, new);

Please fix style problem reported by patchew
(or ./scripts/checkpatch.pl)

> +    errno = ENOSYS;
> +    return -1;
> +}
> +#endif
> +#endif /* TARGET_NR_renameat2 */
> +
>  #ifdef CONFIG_INOTIFY
>  #include <sys/inotify.h>
>  
> @@ -8342,6 +8359,22 @@ abi_long do_syscall(void *cpu_env, int num, abi_long 
> arg1,
>          }
>          break;
>  #endif
> +#if defined(TARGET_NR_renameat2)
> +    case TARGET_NR_renameat2:
> +        {
> +            void *p2;
> +            p  = lock_user_string(arg2);
> +            p2 = lock_user_string(arg4);
> +            if (!p || !p2)
> +                ret = -TARGET_EFAULT;
> +            else
> +                ret = get_errno(sys_renameat2(arg1, p, arg3, p2,
> +                                              target_to_host_bitmask(arg5, 
> fcntl_flags_tbl)));

You can't use fcntl_flags_tbl
(because it converts fcntl/open flags O_*).

I think you can provide directly arg5 to sys_renameat2() because flags
are the same for all architectures (and value is already byte-swapped).

Thanks,
Laurent