migration: don't rely on any QERR_SOCKET_*

Use the in_progress argument for QERR_SOCKET_CONNECT_IN_PROGRESS. The
other errors are handled the same by checking if the error is set and
then calling migrate_fd_error() if it's.

It's also necessary to change inet_connect_opts() not to set
QERR_SOCKET_CONNECT_IN_PROGRESS. This error is only used by
tcp_start_outgoing_migration() and not changing it along with the
usage of in_progress would break migration.

Furthermore this commit fixes a bug. Today, there's a spurious error
report when migration succeeds:

(qemu) migrate tcp:0:4444
migrate: Connection can not be completed immediately
(qemu)

After this commit no spurious error is reported anymore.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>

migration-tcp.c

@@ -82,27 +82,23 @@ static void tcp_wait_for_connect(void *opaque)
 int tcp_start_outgoing_migration(MigrationState *s, const char *host_port,
                                  Error **errp)
 {
+    bool in_progress;
+
     s->get_error = socket_errno;
     s->write = socket_write;
     s->close = tcp_close;
 
-    s->fd = inet_connect(host_port, false, NULL, errp);
+    s->fd = inet_connect(host_port, false, &in_progress, errp);
+    if (error_is_set(errp)) {
+        migrate_fd_error(s);
+        return -1;
+    }
 
-    if (!error_is_set(errp)) {
-        migrate_fd_connect(s);
-    } else if (error_is_type(*errp, QERR_SOCKET_CONNECT_IN_PROGRESS)) {
+    if (in_progress) {
         DPRINTF("connect in progress\n");
         qemu_set_fd_handler2(s->fd, NULL, NULL, tcp_wait_for_connect, s);
-    } else if (error_is_type(*errp, QERR_SOCKET_CREATE_FAILED)) {
-        DPRINTF("connect failed\n");
-        return -1;
-    } else if (error_is_type(*errp, QERR_SOCKET_CONNECT_FAILED)) {
-        DPRINTF("connect failed\n");
-        migrate_fd_error(s);
-        return -1;
     } else {
-        DPRINTF("unknown error\n");
-        return -1;
+        migrate_fd_connect(s);
     }
 
     return 0;

qemu-sockets.c

@@ -284,8 +284,6 @@ int inet_connect_opts(QemuOpts *opts, bool *in_progress, Error **errp)
             if (in_progress) {
                 *in_progress = true;
             }
-
-            error_set(errp, QERR_SOCKET_CONNECT_IN_PROGRESS);
         } else if (rc < 0) {
             if (NULL == e->ai_next)
                 fprintf(stderr, "%s: connect(%s,%s,%s,%s): %s\n", __FUNCTION__,