Re: [Qemu-devel] [PATCH v7 2/4] net/socket: Convert several helper functions to Error

[Markus Armbruster]

Mao Zhongyi <address@hidden> writes:

> Currently, net_socket_mcast_create(), net_socket_fd_init_dgram() and
> net_socket_fd_init() use the function such as fprintf(), perror() to
> report an error message.
>
> Now, convert these functions to Error.
>
> Cc: address@hidden
> Cc: address@hidden
> Cc: address@hidden
> Signed-off-by: Mao Zhongyi <address@hidden>
> Reviewed-by: Daniel P. Berrange <address@hidden>
> ---
>  net/socket.c | 81 
> +++++++++++++++++++++++++++++++++++++-----------------------
>  1 file changed, 50 insertions(+), 31 deletions(-)
>
> diff --git a/net/socket.c b/net/socket.c
> index 7d05e70..44fb504 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -209,7 +209,9 @@ static void net_socket_send_dgram(void *opaque)
>      }
>  }
>  
> -static int net_socket_mcast_create(struct sockaddr_in *mcastaddr, struct 
> in_addr *localaddr)
> +static int net_socket_mcast_create(struct sockaddr_in *mcastaddr,
> +                                   struct in_addr *localaddr,
> +                                   Error **errp)
>  {
>      struct ip_mreq imr;
>      int fd;
> @@ -221,16 +223,16 @@ static int net_socket_mcast_create(struct sockaddr_in 
> *mcastaddr, struct in_addr
>  #endif
>  
>      if (!IN_MULTICAST(ntohl(mcastaddr->sin_addr.s_addr))) {
> -        fprintf(stderr, "qemu: error: specified mcastaddr \"%s\" (0x%08x) "
> -                "does not contain a multicast address\n",
> -                inet_ntoa(mcastaddr->sin_addr),
> -                (int)ntohl(mcastaddr->sin_addr.s_addr));
> +        error_setg(errp, "specified mcastaddr %s (0x%08x) "
> +                   "does not contain a multicast address",
> +                   inet_ntoa(mcastaddr->sin_addr),
> +                   (int)ntohl(mcastaddr->sin_addr.s_addr));
>          return -1;
>  

You could drop the empty line here, and ...

>      }

... maybe insert one here.

>      fd = qemu_socket(PF_INET, SOCK_DGRAM, 0);
>      if (fd < 0) {
> -        perror("socket(PF_INET, SOCK_DGRAM)");
> +        error_setg_errno(errp, errno, "failed to create datagram socket");

I suggested "can't create datagram socket" in my review of v5.  I prefer
"can't <do something>" over "failed to <do something>" myself, but grep
shows more strings starting "failed to" than with "can't".  I guess
reporting "failed to <do something>" is more common.  Okay.

>          return -1;
>      }
>  
> @@ -242,13 +244,15 @@ static int net_socket_mcast_create(struct sockaddr_in 
> *mcastaddr, struct in_addr
>      val = 1;
>      ret = qemu_setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
>      if (ret < 0) {
> -        perror("setsockopt(SOL_SOCKET, SO_REUSEADDR)");
> +        error_setg_errno(errp, errno, "set the socket 'SO_REUSEADDR'"
> +                         " attribute failed");

Adapting my review of v5 to the next instance: I'm not a native speaker,
but "set FOO failed" doesn't feel right to me.  Where's the subject?
"Create" is a verb.  "Setting FOO failed" has a subject, but doesn't
feel right.  What about "can't set socket option SO_REUSEADDR"?

Also, please avoid breaking the line in the middle of an argument when
you could just as well break it between arguments, like this:

           error_setg_errno(errp, errno,
                            "can't set socket attribute SO_REUSEADDR");

>          goto fail;
>      }
>  
>      ret = bind(fd, (struct sockaddr *)mcastaddr, sizeof(*mcastaddr));
>      if (ret < 0) {
> -        perror("bind");
> +        error_setg_errno(errp, errno, "bind ip=%s to socket failed",
> +                         inet_ntoa(mcastaddr->sin_addr));

Likewise, "can't bind ip=%s to socket".

>          goto fail;
>      }
>  
> @@ -263,7 +267,8 @@ static int net_socket_mcast_create(struct sockaddr_in 
> *mcastaddr, struct in_addr
>      ret = qemu_setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
>                            &imr, sizeof(struct ip_mreq));
>      if (ret < 0) {
> -        perror("setsockopt(IP_ADD_MEMBERSHIP)");
> +        error_setg_errno(errp, errno, "add socket to multicast group %s"
> +                         " failed", inet_ntoa(imr.imr_multiaddr));

Likewise.

>          goto fail;
>      }
>  
> @@ -272,7 +277,8 @@ static int net_socket_mcast_create(struct sockaddr_in 
> *mcastaddr, struct in_addr
>      ret = qemu_setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP,
>                            &loop, sizeof(loop));
>      if (ret < 0) {
> -        perror("setsockopt(SOL_IP, IP_MULTICAST_LOOP)");
> +        error_setg_errno(errp, errno, "force multicast message to loopback"
> +                         " failed");

Likwise.

>          goto fail;
>      }
>  
> @@ -281,7 +287,8 @@ static int net_socket_mcast_create(struct sockaddr_in 
> *mcastaddr, struct in_addr
>          ret = qemu_setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF,
>                                localaddr, sizeof(*localaddr));
>          if (ret < 0) {
> -            perror("setsockopt(IP_MULTICAST_IF)");
> +            error_setg_errno(errp, errno, "set the default network send "
> +                             "interface failed");

Likewise.

>              goto fail;
>          }
>      }
> @@ -320,7 +327,8 @@ static NetClientInfo net_dgram_socket_info = {
>  static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
>                                                  const char *model,
>                                                  const char *name,
> -                                                int fd, int is_connected)
> +                                                int fd, int is_connected,
> +                                                Error **errp)
>  {
>      struct sockaddr_in saddr;
>      int newfd;
> @@ -337,14 +345,13 @@ static NetSocketState 
> *net_socket_fd_init_dgram(NetClientState *peer,
>          if (getsockname(fd, (struct sockaddr *) &saddr, &saddr_len) == 0) {
>              /* must be bound */
>              if (saddr.sin_addr.s_addr == 0) {
> -                fprintf(stderr, "qemu: error: init_dgram: fd=%d unbound, "
> -                        "cannot setup multicast dst addr\n", fd);
> +                error_setg(errp, "init_dgram: fd=%d unbound, "
> +                           "cannot setup multicast dst addr", fd);

Yet another awful error message: "init_dgram" and the value of @fd are
useful to a developer, but not to the user, and "dst addr" aren't even
words.  What about "can't setup multicast destination address"?

Aside: I wonder whether this is actually a programming error.  How can
it happen?  Mao, I don't expect you to answer this :)

>                  goto err;
>              }
>              /* clone dgram socket */
> -            newfd = net_socket_mcast_create(&saddr, NULL);
> +            newfd = net_socket_mcast_create(&saddr, NULL, errp);
>              if (newfd < 0) {
> -                /* error already reported by net_socket_mcast_create() */
>                  goto err;
>              }
>              /* clone newfd to fd, close newfd */
> @@ -352,9 +359,9 @@ static NetSocketState 
> *net_socket_fd_init_dgram(NetClientState *peer,
>              close(newfd);
>  
>          } else {
> -            fprintf(stderr,
> -                    "qemu: error: init_dgram: fd=%d failed getsockname(): 
> %s\n",
> -                    fd, strerror(errno));
> +            error_setg(errp,
> +                       "init_dgram: fd=%d failed getsockname(): %s",
> +                       fd, strerror(errno));

Similarly awful error message.  What about "can't get socket name"?

error_setg_errno() instead of strerror(), please.

>              goto err;
>          }
>      }
> @@ -432,20 +439,22 @@ static NetSocketState 
> *net_socket_fd_init_stream(NetClientState *peer,
>  
>  static NetSocketState *net_socket_fd_init(NetClientState *peer,
>                                            const char *model, const char 
> *name,
> -                                          int fd, int is_connected)
> +                                          int fd, int is_connected,
> +                                          Error **errp)
>  {
>      int so_type = -1, optlen=sizeof(so_type);
>  
>      if(getsockopt(fd, SOL_SOCKET, SO_TYPE, (char *)&so_type,
>          (socklen_t *)&optlen)< 0) {
> -        fprintf(stderr, "qemu: error: getsockopt(SO_TYPE) for fd=%d 
> failed\n",
> -                fd);
> +        error_setg(errp, "getsockopt(SO_TYPE) for fd=%d failed",
> +                   fd);

Another awful one.  What about "can't get socket option SO_TYPE"?

>          closesocket(fd);
>          return NULL;
>      }
>      switch(so_type) {
>      case SOCK_DGRAM:
> -        return net_socket_fd_init_dgram(peer, model, name, fd, is_connected);
> +        return net_socket_fd_init_dgram(peer, model, name, fd, is_connected,
> +                                        errp);
>      case SOCK_STREAM:
>          return net_socket_fd_init_stream(peer, model, name, fd, 
> is_connected);
>      default:
> @@ -536,6 +545,7 @@ static int net_socket_connect_init(NetClientState *peer,
>      NetSocketState *s;
>      int fd, connected, ret;
>      struct sockaddr_in saddr;
> +    Error *err = NULL;
>  
>      if (parse_host_port(&saddr, host_str) < 0)
>          return -1;
> @@ -567,9 +577,11 @@ static int net_socket_connect_init(NetClientState *peer,
>              break;
>          }
>      }
> -    s = net_socket_fd_init(peer, model, name, fd, connected);
> -    if (!s)
> +    s = net_socket_fd_init(peer, model, name, fd, connected, &err);
> +    if (!s) {
> +        error_report_err(err);
>          return -1;
> +    }
>      snprintf(s->nc.info_str, sizeof(s->nc.info_str),
>               "socket: connect to %s:%d",
>               inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
> @@ -586,6 +598,7 @@ static int net_socket_mcast_init(NetClientState *peer,
>      int fd;
>      struct sockaddr_in saddr;
>      struct in_addr localaddr, *param_localaddr;
> +    Error *err = NULL;
>  
>      if (parse_host_port(&saddr, host_str) < 0)
>          return -1;
> @@ -598,13 +611,17 @@ static int net_socket_mcast_init(NetClientState *peer,
>          param_localaddr = NULL;
>      }
>  
> -    fd = net_socket_mcast_create(&saddr, param_localaddr);
> -    if (fd < 0)
> +    fd = net_socket_mcast_create(&saddr, param_localaddr, &err);
> +    if (fd < 0) {
> +        error_report_err(err);
>          return -1;
> +    }
>  
> -    s = net_socket_fd_init(peer, model, name, fd, 0);
> -    if (!s)
> +    s = net_socket_fd_init(peer, model, name, fd, 0, &err);
> +    if (!s) {
> +        error_report_err(err);
>          return -1;
> +    }
>  
>      s->dgram_dst = saddr;
>  
> @@ -624,6 +641,7 @@ static int net_socket_udp_init(NetClientState *peer,
>      NetSocketState *s;
>      int fd, ret;
>      struct sockaddr_in laddr, raddr;
> +    Error *err = NULL;
>  
>      if (parse_host_port(&laddr, lhost) < 0) {
>          return -1;
> @@ -652,8 +670,9 @@ static int net_socket_udp_init(NetClientState *peer,
>      }
>      qemu_set_nonblock(fd);
>  
> -    s = net_socket_fd_init(peer, model, name, fd, 0);
> +    s = net_socket_fd_init(peer, model, name, fd, 0, &err);
>      if (!s) {
> +        error_report_err(err);
>          return -1;
>      }
>  
> @@ -696,7 +715,7 @@ int net_init_socket(const Netdev *netdev, const char 
> *name,
>              return -1;
>          }
>          qemu_set_nonblock(fd);
> -        if (!net_socket_fd_init(peer, "socket", name, fd, 1)) {
> +        if (!net_socket_fd_init(peer, "socket", name, fd, 1, errp)) {
>              return -1;
>          }
>          return 0;

Looks good to me otherwise.