tests/qtest: defer connection

Add an option to defer making the connecting to the monitor and qtest
sockets when calling qtest_init_with_env.  The client makes the connection
later by calling qtest_connect and qtest_qmp_handshake.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Link: https://lore.kernel.org/r/1736967650-129648-20-git-send-email-steven.sistare@oracle.com
[plumb capabilities list into qtest_qmp_handshake]
Signed-off-by: Fabiano Rosas <farosas@suse.de>

tests/qtest/libqtest.c

@@ -75,6 +75,8 @@ struct QTestState
 {
     int fd;
     int qmp_fd;
+    int sock;
+    int qmpsock;
     pid_t qemu_pid;  /* our child QEMU process */
     int wstatus;
 #ifdef _WIN32
@@ -458,18 +460,19 @@ static QTestState *G_GNUC_PRINTF(2, 3) qtest_spawn_qemu(const char *qemu_bin,
     return s;
 }
 
+static char *qtest_socket_path(const char *suffix)
+{
+    return g_strdup_printf("%s/qtest-%d.%s", g_get_tmp_dir(), getpid(), suffix);
+}
+
 static QTestState *qtest_init_internal(const char *qemu_bin,
-                                       const char *extra_args)
+                                       const char *extra_args,
+                                       bool do_connect)
 {
     QTestState *s;
     int sock, qmpsock, i;
-    gchar *socket_path;
+    g_autofree gchar *socket_path = qtest_socket_path("sock");
-    gchar *qmp_socket_path;
+    g_autofree gchar *qmp_socket_path = qtest_socket_path("qmp");
-
-    socket_path = g_strdup_printf("%s/qtest-%d.sock",
-                                  g_get_tmp_dir(), getpid());
-    qmp_socket_path = g_strdup_printf("%s/qtest-%d.qmp",
-                                      g_get_tmp_dir(), getpid());
 
     /*
      * It's possible that if an earlier test run crashed it might
@@ -501,22 +504,19 @@ static QTestState *qtest_init_internal(const char *qemu_bin,
     qtest_client_set_rx_handler(s, qtest_client_socket_recv_line);
     qtest_client_set_tx_handler(s, qtest_client_socket_send);
 
-    s->fd = socket_accept(sock);
-    if (s->fd >= 0) {
-        s->qmp_fd = socket_accept(qmpsock);
-    }
-    unlink(socket_path);
-    unlink(qmp_socket_path);
-    g_free(socket_path);
-    g_free(qmp_socket_path);
-
-    g_assert(s->fd >= 0 && s->qmp_fd >= 0);
-
     s->rx = g_string_new("");
     for (i = 0; i < MAX_IRQ; i++) {
         s->irq_level[i] = false;
     }
 
+    s->fd = -1;
+    s->qmp_fd = -1;
+    s->sock = sock;
+    s->qmpsock = qmpsock;
+    if (do_connect) {
+        qtest_connect(s);
+    }
+
     /*
      * Stopping QEMU for debugging is not supported on Windows.
      *
@@ -531,28 +531,38 @@ static QTestState *qtest_init_internal(const char *qemu_bin,
     }
 #endif
 
-    /* ask endianness of the target */
-
-    s->big_endian = qtest_query_target_endianness(s);
-
    return s;
 }
 
+void qtest_connect(QTestState *s)
+{
+    g_autofree gchar *socket_path = qtest_socket_path("sock");
+    g_autofree gchar *qmp_socket_path = qtest_socket_path("qmp");
+
+    g_assert(s->sock >= 0 && s->qmpsock >= 0);
+    s->fd = socket_accept(s->sock);
+    if (s->fd >= 0) {
+        s->qmp_fd = socket_accept(s->qmpsock);
+    }
+    unlink(socket_path);
+    unlink(qmp_socket_path);
+    g_assert(s->fd >= 0 && s->qmp_fd >= 0);
+    s->sock = s->qmpsock = -1;
+    /* ask endianness of the target */
+    s->big_endian = qtest_query_target_endianness(s);
+}
+
 QTestState *qtest_init_without_qmp_handshake(const char *extra_args)
 {
-    return qtest_init_internal(qtest_qemu_binary(NULL), extra_args);
+    return qtest_init_internal(qtest_qemu_binary(NULL), extra_args, true);
 }
 
-QTestState *qtest_init_with_env_and_capabilities(const char *var,
+void qtest_qmp_handshake(QTestState *s, QList *capabilities)
-                                                 const char *extra_args,
-                                                 QList *capabilities)
 {
-    QTestState *s = qtest_init_internal(qtest_qemu_binary(var), extra_args);
-    QDict *greeting;
-
     /* Read the QMP greeting and then do the handshake */
-    greeting = qtest_qmp_receive(s);
+    QDict *greeting = qtest_qmp_receive(s);
     qobject_unref(greeting);
+
     if (capabilities) {
         qtest_qmp_assert_success(s,
                                  "{ 'execute': 'qmp_capabilities', "
@@ -561,18 +571,37 @@ QTestState *qtest_init_with_env_and_capabilities(const char *var,
     } else {
         qtest_qmp_assert_success(s, "{ 'execute': 'qmp_capabilities' }");
     }
+}
 
+QTestState *qtest_init_with_env_and_capabilities(const char *var,
+                                                 const char *extra_args,
+                                                 QList *capabilities,
+                                                 bool do_connect)
+{
+    QTestState *s = qtest_init_internal(qtest_qemu_binary(var), extra_args,
+                                        do_connect);
+
+    if (do_connect) {
+        qtest_qmp_handshake(s, capabilities);
+    } else {
+        /*
+         * If the connection is delayed, the capabilities must be set
+         * at that moment.
+         */
+        assert(!capabilities);
+    }
     return s;
 }
 
-QTestState *qtest_init_with_env(const char *var, const char *extra_args)
+QTestState *qtest_init_with_env(const char *var, const char *extra_args,
+                                bool do_connect)
 {
-    return qtest_init_with_env_and_capabilities(var, extra_args, NULL);
+    return qtest_init_with_env_and_capabilities(var, extra_args, NULL, true);
 }
 
 QTestState *qtest_init(const char *extra_args)
 {
-    return qtest_init_with_env(NULL, extra_args);
+    return qtest_init_with_env(NULL, extra_args, true);
 }
 
 QTestState *qtest_vinitf(const char *fmt, va_list ap)
@@ -1580,7 +1609,7 @@ static struct MachInfo *qtest_get_machines(const char *var)
 
     silence_spawn_log = !g_test_verbose();
 
-    qts = qtest_init_with_env(qemu_var, "-machine none");
+    qts = qtest_init_with_env(qemu_var, "-machine none", true);
     response = qtest_qmp(qts, "{ 'execute': 'query-machines' }");
     g_assert(response);
     list = qdict_get_qlist(response, "return");
@@ -1635,7 +1664,7 @@ static struct CpuModel *qtest_get_cpu_models(void)
 
     silence_spawn_log = !g_test_verbose();
 
-    qts = qtest_init_with_env(NULL, "-machine none");
+    qts = qtest_init_with_env(NULL, "-machine none", true);
     response = qtest_qmp(qts, "{ 'execute': 'query-cpu-definitions' }");
     g_assert(response);
     list = qdict_get_qlist(response, "return");

tests/qtest/libqtest.h

@@ -61,13 +61,15 @@ QTestState *qtest_init(const char *extra_args);
  * @var: Environment variable from where to take the QEMU binary
  * @extra_args: Other arguments to pass to QEMU.  CAUTION: these
  * arguments are subject to word splitting and shell evaluation.
+ * @do_connect: connect to qemu monitor and qtest socket.
  *
  * Like qtest_init(), but use a different environment variable for the
  * QEMU binary.
  *
  * Returns: #QTestState instance.
  */
-QTestState *qtest_init_with_env(const char *var, const char *extra_args);
+QTestState *qtest_init_with_env(const char *var, const char *extra_args,
+                                bool do_connect);
 
 /**
  * qtest_init_with_env_and_capabilities:
@@ -75,6 +77,7 @@ QTestState *qtest_init_with_env(const char *var, const char *extra_args);
  * @extra_args: Other arguments to pass to QEMU.  CAUTION: these
  * arguments are subject to word splitting and shell evaluation.
  * @capabilities: list of QMP capabilities (strings) to enable
+ * @do_connect: connect to qemu monitor and qtest socket.
  *
  * Like qtest_init_with_env(), but enable specified capabilities during
  * hadshake.
@@ -83,7 +86,8 @@ QTestState *qtest_init_with_env(const char *var, const char *extra_args);
  */
 QTestState *qtest_init_with_env_and_capabilities(const char *var,
                                                  const char *extra_args,
-                                                 QList *capabilities);
+                                                 QList *capabilities,
+                                                 bool do_connect);
 
 /**
  * qtest_init_without_qmp_handshake:
@@ -94,6 +98,22 @@ QTestState *qtest_init_with_env_and_capabilities(const char *var,
  */
 QTestState *qtest_init_without_qmp_handshake(const char *extra_args);
 
+/**
+ * qtest_connect
+ * @s: #QTestState instance to connect
+ * Connect to qemu monitor and qtest socket, after skipping them in
+ * qtest_init_with_env.  Does not handshake with the monitor.
+ */
+void qtest_connect(QTestState *s);
+
+/**
+ * qtest_qmp_handshake:
+ * @s: #QTestState instance to operate on.
+ * @capabilities: list of QMP capabilities (strings) to enable
+ * Perform handshake after connecting to qemu monitor.
+ */
+void qtest_qmp_handshake(QTestState *s, QList *capabilities);
+
 /**
  * qtest_init_with_serial:
  * @extra_args: other arguments to pass to QEMU.  CAUTION: these

tests/qtest/migration/framework.c

@@ -196,9 +196,10 @@ static void cleanup(const char *filename)
 
 static QList *migrate_start_get_qmp_capabilities(const MigrateStart *args)
 {
-    QList *capabilities = qlist_new();
+    QList *capabilities = NULL;
 
     if (args->oob) {
+        capabilities = qlist_new();
         qlist_append_str(capabilities, "oob");
     }
     return capabilities;
@@ -333,7 +334,7 @@ int migrate_start(QTestState **from, QTestState **to, const char *uri,
                                  ignore_stderr);
     if (!args->only_target) {
         *from = qtest_init_with_env_and_capabilities(QEMU_ENV_SRC, cmd_source,
-                                                     capabilities);
+                                                     capabilities, true);
         qtest_qmp_set_event_callback(*from,
                                      migrate_watch_for_events,
                                      &src_state);
@@ -354,7 +355,7 @@ int migrate_start(QTestState **from, QTestState **to, const char *uri,
                                  args->opts_target ? args->opts_target : "",
                                  ignore_stderr);
     *to = qtest_init_with_env_and_capabilities(QEMU_ENV_DST, cmd_target,
-                                               capabilities);
+                                               capabilities, true);
     qtest_qmp_set_event_callback(*to,
                                  migrate_watch_for_events,
                                  &dst_state);