Re: [Qemu-devel] [PATCH] tap-linux: report an error for invalid sndbuf

[Michael S. Tsirkin]

On Sun, Apr 27, 2014 at 10:09:10PM +0800, Amos Kong wrote:
> We use default sndbuf (INT_MAX) if user assigns an invalid sndbuf.
> This patch just added an error note.
> 
> Signed-off-by: Amos Kong <address@hidden>
> ---
>  net/tap-linux.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/net/tap-linux.c b/net/tap-linux.c
> index 812bf2d..fc0cc0d 100644
> --- a/net/tap-linux.c
> +++ b/net/tap-linux.c
> @@ -130,9 +130,16 @@ int tap_set_sndbuf(int fd, const NetdevTapOptions *tap)
>  {
>      int sndbuf;
>  
> -    sndbuf = !tap->has_sndbuf       ? TAP_DEFAULT_SNDBUF :
> -             tap->sndbuf > INT_MAX  ? INT_MAX :
> -             tap->sndbuf;
> +    if (!tap->has_sndbuf) {
> +        sndbuf = TAP_DEFAULT_SNDBUF;
> +    } else if (tap->sndbuf > INT_MAX) {
> +        sndbuf = TAP_DEFAULT_SNDBUF;
> +        error_report("given sndbuf isn't an integer, "
> +                     "or it's larger than INT_MAX(%d). "
> +                     "use default sndbuf(%d)", INT_MAX, INT_MAX);

I think that converting a huge value to INT_MAX is
actually more reasonable.
For example, comment in json schema says:
# @sndbuf: #optional send buffer limit. Understands [TGMKkb] suffixes.
If someone sets it to 1T why not make it work?


Failing if it's not an integer sounds like a good feature.

> +    } else {
> +        sndbuf = tap->sndbuf;
> +    }
>  
>      if (!sndbuf) {
>          sndbuf = INT_MAX;
> -- 
> 1.9.0