osdep: add wrappers for socket functions

The windows socket functions look identical to the normal POSIX
sockets functions, but instead of setting errno, the caller needs
to call WSAGetLastError(). QEMU has tried to deal with this
incompatibility by defining a socket_error() method that callers
must use that abstracts the difference between WSAGetLastError()
and errno.

This approach is somewhat error prone though - many callers of
the sockets functions are just using errno directly because it
is easy to forget the need use a QEMU specific wrapper. It is
not always immediately obvious that a particular function will
in fact call into Windows sockets functions, so the dev may not
even realize they need to use socket_error().

This introduces an alternative approach to portability inspired
by the way GNULIB fixes portability problems. We use a macro to
redefine the original socket function names to refer to a QEMU
wrapper function. The wrapper function calls the original Win32
sockets method and then sets errno from the WSAGetLastError()
value.

Thus all code can simply call the normal POSIX sockets APIs are
have standard errno reporting on error, even on Windows. This
makes the socket_error() method obsolete.

We also bring closesocket & ioctlsocket into this approach. Even
though they are non-standard Win32 names, we can't wrap the normal
close/ioctl methods since there's no reliable way to distinguish
between a file descriptor and HANDLE in Win32.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

util/oslib-win32.c

@@ -581,3 +581,204 @@ pid_t qemu_fork(Error **errp)
                      "cannot fork child process");
     return -1;
 }
+
+
+#undef connect
+int qemu_connect_wrap(int sockfd, const struct sockaddr *addr,
+                      socklen_t addrlen)
+{
+    int ret;
+    ret = connect(sockfd, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef listen
+int qemu_listen_wrap(int sockfd, int backlog)
+{
+    int ret;
+    ret = listen(sockfd, backlog);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef bind
+int qemu_bind_wrap(int sockfd, const struct sockaddr *addr,
+                   socklen_t addrlen)
+{
+    int ret;
+    ret = bind(sockfd, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef socket
+int qemu_socket_wrap(int domain, int type, int protocol)
+{
+    int ret;
+    ret = socket(domain, type, protocol);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef accept
+int qemu_accept_wrap(int sockfd, struct sockaddr *addr,
+                     socklen_t *addrlen)
+{
+    int ret;
+    ret = accept(sockfd, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef shutdown
+int qemu_shutdown_wrap(int sockfd, int how)
+{
+    int ret;
+    ret = shutdown(sockfd, how);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef ioctlsocket
+int qemu_ioctlsocket_wrap(int fd, int req, void *val)
+{
+    int ret;
+    ret = ioctlsocket(fd, req, val);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef closesocket
+int qemu_closesocket_wrap(int fd)
+{
+    int ret;
+    ret = closesocket(fd);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef getsockopt
+int qemu_getsockopt_wrap(int sockfd, int level, int optname,
+                         void *optval, socklen_t *optlen)
+{
+    int ret;
+    ret = getsockopt(sockfd, level, optname, optval, optlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef setsockopt
+int qemu_setsockopt_wrap(int sockfd, int level, int optname,
+                         const void *optval, socklen_t optlen)
+{
+    int ret;
+    ret = setsockopt(sockfd, level, optname, optval, optlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef getpeername
+int qemu_getpeername_wrap(int sockfd, struct sockaddr *addr,
+                          socklen_t *addrlen)
+{
+    int ret;
+    ret = getpeername(sockfd, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef getsockname
+int qemu_getsockname_wrap(int sockfd, struct sockaddr *addr,
+                          socklen_t *addrlen)
+{
+    int ret;
+    ret = getsockname(sockfd, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef send
+ssize_t qemu_send_wrap(int sockfd, const void *buf, size_t len, int flags)
+{
+    int ret;
+    ret = send(sockfd, buf, len, flags);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef sendto
+ssize_t qemu_sendto_wrap(int sockfd, const void *buf, size_t len, int flags,
+                         const struct sockaddr *addr, socklen_t addrlen)
+{
+    int ret;
+    ret = sendto(sockfd, buf, len, flags, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef recv
+ssize_t qemu_recv_wrap(int sockfd, void *buf, size_t len, int flags)
+{
+    int ret;
+    ret = recv(sockfd, buf, len, flags);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}
+
+
+#undef recvfrom
+ssize_t qemu_recvfrom_wrap(int sockfd, void *buf, size_t len, int flags,
+                           struct sockaddr *addr, socklen_t *addrlen)
+{
+    int ret;
+    ret = recvfrom(sockfd, buf, len, flags, addr, addrlen);
+    if (ret < 0) {
+        errno = socket_error();
+    }
+    return ret;
+}