Re: [Qemu-trivial] [PATCH] slirp: workaround gcc __warn_memset_zero_len warnings

[Alon Levy]

On Fri, Feb 24, 2012 at 08:29:54AM +0000, Stefan Hajnoczi wrote:
> On Thu, Feb 23, 2012 at 10:29:42PM +0200, Alon Levy wrote:
> > --- a/slirp/misc.c
> > +++ b/slirp/misc.c
> > @@ -358,7 +358,9 @@ void slirp_connection_info(Slirp *slirp, Monitor *mon)
> >              dst_port = so->so_fport;
> >          }
> >          n = snprintf(buf, sizeof(buf), "  TCP[%s]", state);
> > -        memset(&buf[n], ' ', 19 - n);
> > +        if (n < 19) {
> > +            memset(&buf[n], ' ', 19 - n);
> > +        }
> >          buf[19] = 0;
> >          monitor_printf(mon, "%s %3d %15s %5d ", buf, so->s,
> >                         src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*",
> 
> This whole memset approach is not necessary.  Let's drop this and use a
> left-justified format string to do the space padding.  Feel free to try
> this and send the patch:
> 

Haven't tried yet, but looks better just by reading.

> diff --git a/slirp/misc.c b/slirp/misc.c
> index 3432fbf..0308a62 100644
> --- a/slirp/misc.c
> +++ b/slirp/misc.c
> @@ -333,7 +333,6 @@ void slirp_connection_info(Slirp *slirp, Monitor *mon)
>      struct socket *so;
>      const char *state;
>      char buf[20];
> -    int n;
>  
>      monitor_printf(mon, "  Protocol[State]    FD  Source Address  Port   "
>                          "Dest. Address  Port RecvQ SendQ\n");
> @@ -357,10 +356,8 @@ void slirp_connection_info(Slirp *slirp, Monitor *mon)
>              dst_addr = so->so_faddr;
>              dst_port = so->so_fport;
>          }
> -        n = snprintf(buf, sizeof(buf), "  TCP[%s]", state);
> -        memset(&buf[n], ' ', 19 - n);
> -        buf[19] = 0;
> -        monitor_printf(mon, "%s %3d %15s %5d ", buf, so->s,
> +        snprintf(buf, sizeof(buf), "  TCP[%s]", state);
> +        monitor_printf(mon, "%-19s %3d %15s %5d ", buf, so->s,
>                         src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*",
>                         ntohs(src.sin_port));
>          monitor_printf(mon, "%15s %5d %5d %5d\n",
> @@ -370,22 +367,20 @@ void slirp_connection_info(Slirp *slirp, Monitor *mon)
>  
>      for (so = slirp->udb.so_next; so != &slirp->udb; so = so->so_next) {
>          if (so->so_state & SS_HOSTFWD) {
> -            n = snprintf(buf, sizeof(buf), "  UDP[HOST_FORWARD]");
> +            snprintf(buf, sizeof(buf), "  UDP[HOST_FORWARD]");
>              src_len = sizeof(src);
>              getsockname(so->s, (struct sockaddr *)&src, &src_len);
>              dst_addr = so->so_laddr;
>              dst_port = so->so_lport;
>          } else {
> -            n = snprintf(buf, sizeof(buf), "  UDP[%d sec]",
> +            snprintf(buf, sizeof(buf), "  UDP[%d sec]",
>                           (so->so_expire - curtime) / 1000);
>              src.sin_addr = so->so_laddr;
>              src.sin_port = so->so_lport;
>              dst_addr = so->so_faddr;
>              dst_port = so->so_fport;
>          }
> -        memset(&buf[n], ' ', 19 - n);
> -        buf[19] = 0;
> -        monitor_printf(mon, "%s %3d %15s %5d ", buf, so->s,
> +        monitor_printf(mon, "%-19s %3d %15s %5d ", buf, so->s,
>                         src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*",
>                         ntohs(src.sin_port));
>          monitor_printf(mon, "%15s %5d %5d %5d\n",
> @@ -394,13 +389,11 @@ void slirp_connection_info(Slirp *slirp, Monitor *mon)
>      }
>  
>      for (so = slirp->icmp.so_next; so != &slirp->icmp; so = so->so_next) {
> -        n = snprintf(buf, sizeof(buf), "  ICMP[%d sec]",
> +        snprintf(buf, sizeof(buf), "  ICMP[%d sec]",
>                       (so->so_expire - curtime) / 1000);
>          src.sin_addr = so->so_laddr;
>          dst_addr = so->so_faddr;
> -        memset(&buf[n], ' ', 19 - n);
> -        buf[19] = 0;
> -        monitor_printf(mon, "%s %3d %15s  -    ", buf, so->s,
> +        monitor_printf(mon, "%-19s %3d %15s  -    ", buf, so->s,
>                         src.sin_addr.s_addr ? inet_ntoa(src.sin_addr) : "*");
>          monitor_printf(mon, "%15s  -    %5d %5d\n", inet_ntoa(dst_addr),
>                         so->so_rcv.sb_cc, so->so_snd.sb_cc);