qemu: fd: Add helpers allowing storing FD set data in status XML

Rollback of FD sets passed to qemu is also needed after possible restart
of libvirtd when we need to serialize the data into status XML. For this
purpose we need to access the fdset ID once it was passed to qemu and
potentially re-create a 'qemuFDPass' struct in passed state.

Introduce 'qemuFDPassNewPassed' and 'qemuFDPassIsPassed'.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Martin Kletzander <mkletzan@redhat.com>

src/qemu/qemu_fd.c

@@ -96,6 +96,47 @@ qemuFDPassNew(const char *prefix,
 }
 
 
+/**
+ * qemuFDPassNewPassed:
+ * @fdSetID: ID of an FDset which was allready passed to qemu
+ *
+ * Create qemuFDPass pointing to an already passed FD. Useful to usw with
+ * qemuFDPassTransferMonitorRollback, when restoring after restart.
+ */
+qemuFDPass *
+qemuFDPassNewPassed(unsigned int fdSetID)
+{
+    qemuFDPass *fdpass = g_new0(qemuFDPass, 1);
+
+    fdpass->fdSetID = fdSetID;
+    fdpass->passed = true;
+
+    return fdpass;
+}
+
+
+/**
+ * qemuFDPassIsPassed:
+ * @fdpass: The fd passing helper struct
+ * @id: when non-NULL filled with the fdset ID
+ *
+ * Returns true if @fdpass was passed to qemu. In such case @id is also filled
+ * with the ID of the fdset if non-NULL.
+ */
+bool
+qemuFDPassIsPassed(qemuFDPass *fdpass,
+                   unsigned *id)
+{
+    if (!fdpass || !fdpass->passed)
+        return false;
+
+    if (id)
+        *id = fdpass->fdSetID;
+
+    return true;
+}
+
+
 /**
  * qemuFDPassAddFD:
  * @fdpass: The fd passing helper struct

src/qemu/qemu_fd.h

@@ -31,6 +31,13 @@ qemuFDPass *
 qemuFDPassNew(const char *prefix,
               void *dompriv);
 
+qemuFDPass *
+qemuFDPassNewPassed(unsigned int fdSetID);
+
+bool
+qemuFDPassIsPassed(qemuFDPass *fdpass,
+                   unsigned *id);
+
 void
 qemuFDPassAddFD(qemuFDPass *fdpass,
                 int *fd,