libqtest: make qtest_qmp_add_client work on win32

Use the "get-win32-socket" function to pass an opened socket to QEMU,
instead of using "getfd", which relies on socket ancillary FD message
passing.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20230306122751.2355515-10-marcandre.lureau@redhat.com>

tests/qtest/libqtest.c

@@ -1478,13 +1478,28 @@ void qtest_qmp_device_add(QTestState *qts, const char *driver, const char *id,
     qobject_unref(args);
 }
 
-#ifndef _WIN32
 void qtest_qmp_add_client(QTestState *qts, const char *protocol, int fd)
 {
     QDict *resp;
 
+#ifdef WIN32
+    WSAPROTOCOL_INFOW info;
+    g_autofree char *info64  = NULL;
+    SOCKET s;
+
+    assert(fd_is_socket(fd));
+    s = _get_osfhandle(fd);
+    if (WSADuplicateSocketW(s, GetProcessId((HANDLE)qts->qemu_pid), &info) == SOCKET_ERROR) {
+        g_autofree char *emsg = g_win32_error_message(WSAGetLastError());
+        g_error("WSADuplicateSocketW failed: %s", emsg);
+    }
+    info64 = g_base64_encode((guchar *)&info, sizeof(info));
+    resp = qtest_qmp(qts, "{'execute': 'get-win32-socket',"
+                     "'arguments': {'fdname': 'fdname', 'info': %s}}", info64);
+#else
     resp = qtest_qmp_fds(qts, &fd, 1, "{'execute': 'getfd',"
                          "'arguments': {'fdname': 'fdname'}}");
+#endif
     g_assert(resp);
     g_assert(!qdict_haskey(resp, "event")); /* We don't expect any events */
     g_assert(!qdict_haskey(resp, "error"));
@@ -1498,7 +1513,6 @@ void qtest_qmp_add_client(QTestState *qts, const char *protocol, int fd)
     g_assert(!qdict_haskey(resp, "error"));
     qobject_unref(resp);
 }
-#endif
 
 /*
  * Generic hot-unplugging test via the device_del QMP command.

tests/qtest/libqtest.h

@@ -758,17 +758,16 @@ void qtest_qmp_device_add_qdict(QTestState *qts, const char *drv,
 void qtest_qmp_device_add(QTestState *qts, const char *driver, const char *id,
                           const char *fmt, ...) G_GNUC_PRINTF(4, 5);
 
-#ifndef _WIN32
 /**
  * qtest_qmp_add_client:
  * @qts: QTestState instance to operate on
  * @protocol: the protocol to add to
  * @fd: the client file-descriptor
  *
- * Call QMP ``getfd`` followed by ``add_client`` with the given @fd.
+ * Call QMP ``getfd`` (on Windows ``get-win32-socket``) followed by
+ * ``add_client`` with the given @fd.
  */
 void qtest_qmp_add_client(QTestState *qts, const char *protocol, int fd);
-#endif /* _WIN32 */
 
 /**
  * qtest_qmp_device_del_send: