Re: [Qemu-devel] [RFC PATCH 01/11] linux-user/strace: dump AF_NETLINK sockaddr content

[Laurent Vivier]

Le 24/01/2018 à 14:01, Philippe Mathieu-Daudé a écrit :
> Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
> ---
> please double check __pad and ntohl()
> 
>  linux-user/syscall_defs.h |  7 +++++++
>  linux-user/strace.c       | 34 ++++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
> index bec3680b94..550e7d2939 100644
> --- a/linux-user/syscall_defs.h
> +++ b/linux-user/syscall_defs.h
> @@ -151,6 +151,13 @@ struct target_sockaddr_un {
>      uint8_t sun_path[108];
>  };
>  
> +struct target_sockaddr_nl {
> +    uint16_t nl_family;     /* AF_NETLINK */
> +    int16_t __pad;

netlink.h uses an unsigned type here.

> +    uint32_t nl_pid;
> +    uint32_t nl_groups;
> +};
> +
>  struct target_in_addr {
>      uint32_t s_addr; /* big endian */
>  };
> diff --git a/linux-user/strace.c b/linux-user/strace.c
> index bd897a3f20..7eb5e2ab48 100644
> --- a/linux-user/strace.c
> +++ b/linux-user/strace.c
> @@ -8,6 +8,7 @@
>  #include <arpa/inet.h>
>  #include <netinet/tcp.h>
>  #include <linux/if_packet.h>
> +#include <linux/netlink.h>
>  #include <sched.h>
>  #include "qemu.h"
>  
> @@ -397,6 +398,12 @@ print_sockaddr(abi_ulong addr, abi_long addrlen)
>              gemu_log("}");
>              break;
>          }
> +        case AF_NETLINK: {
> +            struct target_sockaddr_nl *nl = (struct target_sockaddr_nl *)sa;
> +            gemu_log("{nl_family=AF_NETLINK,nl_pid=%u,nl_groups=%u}",
> +                     ntohl(nl->nl_pid), ntohl(nl->nl_groups));

Both sides of the netlink pipe are local and have the same endianness,
so I don't think we need the ntohl() here. Moreover, I didn't find any
endianness change in the kernel for them.

Thanks,
Laurent