Re: [PATCH 2/4] linux-user: Fix accept4(SOCK_NONBLOCK) syscall

[Richard Henderson <richard.henderson@linaro.org>]

On 7/7/23 14:19, Helge Deller wrote:
> The accept4() syscall takes two flags only: SOCK_NONBLOCK and
> SOCK_CLOEXEC.
> Even the real Linux kernel returns -EINVAL if any other bits
> have been set.
> 
> Change the implementation of accept4() to recognize those two values
> only, instead of using the fcntl_flags_tbl[] bitmask translation.
> 
> Beside this correction in behaviour, it actually fixes the accept4()
> emulation for hppa, mips and alpha targets for which SOCK_NONBLOCK is
> different than TARGET_SOCK_NONBLOCK.
> 
> I noticed this wrong behaviour with the testcase of the debian lwt package
> which failed (by timeout while hanging in the read() syscall) in qemu but
> succeeded on real hardware.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   linux-user/syscall.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 3f1e8e7ad9..9e9317237d 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -3440,7 +3440,18 @@ static abi_long do_accept4(int fd, abi_ulong target_addr,
>       abi_long ret;
>       int host_flags;
> 
> -    host_flags = target_to_host_bitmask(flags, fcntl_flags_tbl);
> +    host_flags = 0;
> +#if defined(SOCK_NONBLOCK)
> +    if (flags & ~(TARGET_SOCK_CLOEXEC | TARGET_SOCK_NONBLOCK)) {
> +        return -TARGET_EINVAL;
> +    }
> +    if (flags & TARGET_SOCK_NONBLOCK) {
> +        host_flags |= SOCK_NONBLOCK;
> +    }
> +#endif

Can we avoid the ifdef?  Anyway, surely the TARGET bit check should not be protected by 
the #ifdef.


r~