[PATCH 2/4] ui/clipboard: keep track of clipboard peer side

Add a "guest" flag to QemuClipboardPeer and set it on vdagent peer.

Use the flag to keep track of number of registered guest peers and
allow to query for their presence with
qemu_clipboard_guest_peer_present().

This change makes it possible for a clipboard peer to determine if
any guest side peers are present so they can tell whether a guest is
actually able to participate in clipboard exchange.

Change-Id: I6f39b846fb560ea52f19e14cbee34267ba404453
Signed-off-by: Lukasz Kornicki <[email protected]>
---
 include/ui/clipboard.h |  8 ++++++++
 ui/clipboard.c         | 16 ++++++++++++++++
 ui/vdagent.c           |  1 +
 3 files changed, 25 insertions(+)

diff --git a/include/ui/clipboard.h b/include/ui/clipboard.h
index 6166af5139..df7fa5e491 100644
--- a/include/ui/clipboard.h
+++ b/include/ui/clipboard.h
@@ -69,6 +69,7 @@ enum QemuClipboardSelection {
  */
 struct QemuClipboardPeer {
     const char *name;
+    bool guest;
     Notifier notifier;
     void (*request)(QemuClipboardInfo *info,
                     QemuClipboardType type);
@@ -179,6 +180,13 @@ void qemu_clipboard_peer_register(QemuClipboardPeer *peer);
  */
 void qemu_clipboard_peer_unregister(QemuClipboardPeer *peer);
 
+/**
+ * qemu_clipboard_guest_peer_present
+ *
+ * Return TRUE if a guest side clipboard peer is currently registered.
+ */
+bool qemu_clipboard_guest_peer_present(void);
+
 /**
  * qemu_clipboard_peer_owns
  *
diff --git a/ui/clipboard.c b/ui/clipboard.c
index beecb40e6f..928aa435e0 100644
--- a/ui/clipboard.c
+++ b/ui/clipboard.c
@@ -12,6 +12,8 @@ static VMChangeStateEntry *cb_change_state_entry = NULL;
 
 static bool cb_reset_serial_on_resume = false;
 
+static int guest_peer_count;
+
 static const VMStateDescription vmstate_cbcontent = {
     .name = "clipboard/content",
     .version_id = 0,
@@ -80,6 +82,10 @@ void qemu_clipboard_peer_register(QemuClipboardPeer *peer)
         cb_change_state_entry = qemu_add_vm_change_state_handler(qemu_clipboard_change_state, NULL);
     }
 
+    if (peer->guest) {
+        guest_peer_count++;
+    }
+
     notifier_list_add(&clipboard_notifiers, &peer->notifier);
     qemu_clipboard_notify_peer_update(peer, true);
 }
@@ -92,9 +98,19 @@ void qemu_clipboard_peer_unregister(QemuClipboardPeer *peer)
         qemu_clipboard_peer_release(peer, i);
     }
     notifier_remove(&peer->notifier);
+
+    if (peer->guest) {
+        guest_peer_count--;
+    }
+
     qemu_clipboard_notify_peer_update(peer, false);
 }
 
+bool qemu_clipboard_guest_peer_present(void)
+{
+    return guest_peer_count > 0;
+}
+
 bool qemu_clipboard_peer_owns(QemuClipboardPeer *peer,
                               QemuClipboardSelection selection)
 {
diff --git a/ui/vdagent.c b/ui/vdagent.c
index cc32a94fb9..cdd4cedad2 100644
--- a/ui/vdagent.c
+++ b/ui/vdagent.c
@@ -695,6 +695,7 @@ static void vdagent_clipboard_peer_register(VDAgentChardev *vd)
     }
 
     vd->cbpeer.name = "vdagent";
+    vd->cbpeer.guest = true;
     vd->cbpeer.notifier.notify = vdagent_clipboard_notify;
     vd->cbpeer.request = vdagent_clipboard_request;
     qemu_clipboard_peer_register(&vd->cbpeer);
-- 
2.43.0