libqtest: add qtest_socket_server()

Add an API that returns a new UNIX domain socket in the listen state.
The code for this was already there but only used internally in
init_socket().

This new API will be used by vhost-user-blk-test.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Wainer dos Santos Moschetta <wainersm@redhat.com>
Message-Id: <20210223144653.811468-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

tests/qtest/libqos/libqtest.h

@@ -132,6 +132,14 @@ void qtest_qmp_send(QTestState *s, const char *fmt, ...)
 void qtest_qmp_send_raw(QTestState *s, const char *fmt, ...)
     GCC_FMT_ATTR(2, 3);
 
+/**
+ * qtest_socket_server:
+ * @socket_path: the UNIX domain socket path
+ *
+ * Create and return a listen socket file descriptor, or abort on failure.
+ */
+int qtest_socket_server(const char *socket_path);
+
 /**
  * qtest_vqmp_fds:
  * @s: #QTestState instance to operate on.

tests/qtest/libqtest.c

@@ -81,24 +81,8 @@ static void qtest_client_set_rx_handler(QTestState *s, QTestRecvFn recv);
 
 static int init_socket(const char *socket_path)
 {
-    struct sockaddr_un addr;
-    int sock;
-    int ret;
-
-    sock = socket(PF_UNIX, SOCK_STREAM, 0);
-    g_assert_cmpint(sock, !=, -1);
-
-    addr.sun_family = AF_UNIX;
-    snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", socket_path);
+    int sock = qtest_socket_server(socket_path);
     qemu_set_cloexec(sock);
-
-    do {
-        ret = bind(sock, (struct sockaddr *)&addr, sizeof(addr));
-    } while (ret == -1 && errno == EINTR);
-    g_assert_cmpint(ret, !=, -1);
-    ret = listen(sock, 1);
-    g_assert_cmpint(ret, !=, -1);
-
     return sock;
 }
 
@@ -638,6 +622,28 @@ QDict *qtest_qmp_receive_dict(QTestState *s)
     return qmp_fd_receive(s->qmp_fd);
 }
 
+int qtest_socket_server(const char *socket_path)
+{
+    struct sockaddr_un addr;
+    int sock;
+    int ret;
+
+    sock = socket(PF_UNIX, SOCK_STREAM, 0);
+    g_assert_cmpint(sock, !=, -1);
+
+    addr.sun_family = AF_UNIX;
+    snprintf(addr.sun_path, sizeof(addr.sun_path), "%s", socket_path);
+
+    do {
+        ret = bind(sock, (struct sockaddr *)&addr, sizeof(addr));
+    } while (ret == -1 && errno == EINTR);
+    g_assert_cmpint(ret, !=, -1);
+    ret = listen(sock, 1);
+    g_assert_cmpint(ret, !=, -1);
+
+    return sock;
+}
+
 /**
  * Allow users to send a message without waiting for the reply,
  * in the case that they choose to discard all replies up until