snapshot: implement new APIs for qemu

The two APIs are rather trivial; based on bits and pieces of other
existing APIs.  It leaves the door open for future extension to
qemu to report snapshots without metadata based on reading qcow2
internal snapshot names.

* src/qemu/qemu_driver.c (qemuDomainSnapshotIsCurrent)
(qemuDomainSnapshotHasMetadata): New functions.

src/qemu/qemu_driver.c

@@ -10916,6 +10916,87 @@ cleanup:
     return xml;
 }
 
+static int
+qemuDomainSnapshotIsCurrent(virDomainSnapshotPtr snapshot,
+                            unsigned int flags)
+{
+    struct qemud_driver *driver = snapshot->domain->conn->privateData;
+    virDomainObjPtr vm = NULL;
+    int ret = -1;
+    virDomainSnapshotObjPtr snap = NULL;
+    char uuidstr[VIR_UUID_STRING_BUFLEN];
+
+    virCheckFlags(0, -1);
+
+    qemuDriverLock(driver);
+    virUUIDFormat(snapshot->domain->uuid, uuidstr);
+    vm = virDomainFindByUUID(&driver->domains, snapshot->domain->uuid);
+    if (!vm) {
+        qemuReportError(VIR_ERR_NO_DOMAIN,
+                        _("no domain with matching uuid '%s'"), uuidstr);
+        goto cleanup;
+    }
+
+    snap = virDomainSnapshotFindByName(&vm->snapshots, snapshot->name);
+    if (!snap) {
+        qemuReportError(VIR_ERR_NO_DOMAIN_SNAPSHOT,
+                        _("no domain snapshot with matching name '%s'"),
+                        snapshot->name);
+        goto cleanup;
+    }
+
+    ret = (vm->current_snapshot &&
+           STREQ(snapshot->name, vm->current_snapshot->def->name));
+
+cleanup:
+    if (vm)
+        virDomainObjUnlock(vm);
+    qemuDriverUnlock(driver);
+    return ret;
+}
+
+
+static int
+qemuDomainSnapshotHasMetadata(virDomainSnapshotPtr snapshot,
+                              unsigned int flags)
+{
+    struct qemud_driver *driver = snapshot->domain->conn->privateData;
+    virDomainObjPtr vm = NULL;
+    int ret = -1;
+    virDomainSnapshotObjPtr snap = NULL;
+    char uuidstr[VIR_UUID_STRING_BUFLEN];
+
+    virCheckFlags(0, -1);
+
+    qemuDriverLock(driver);
+    virUUIDFormat(snapshot->domain->uuid, uuidstr);
+    vm = virDomainFindByUUID(&driver->domains, snapshot->domain->uuid);
+    if (!vm) {
+        qemuReportError(VIR_ERR_NO_DOMAIN,
+                        _("no domain with matching uuid '%s'"), uuidstr);
+        goto cleanup;
+    }
+
+    snap = virDomainSnapshotFindByName(&vm->snapshots, snapshot->name);
+    if (!snap) {
+        qemuReportError(VIR_ERR_NO_DOMAIN_SNAPSHOT,
+                        _("no domain snapshot with matching name '%s'"),
+                        snapshot->name);
+        goto cleanup;
+    }
+
+    /* XXX Someday, we should recognize internal snapshots in qcow2
+     * images that are not tied to a libvirt snapshot; if we ever do
+     * that, then we would have a reason to return 0 here.  */
+    ret = 1;
+
+cleanup:
+    if (vm)
+        virDomainObjUnlock(vm);
+    qemuDriverUnlock(driver);
+    return ret;
+}
+
 /* The domain is expected to be locked and inactive. */
 static int
 qemuDomainSnapshotRevertInactive(struct qemud_driver *driver,
@@ -13073,6 +13154,8 @@ static virDriver qemuDriver = {
     .domainHasCurrentSnapshot = qemuDomainHasCurrentSnapshot, /* 0.8.0 */
     .domainSnapshotGetParent = qemuDomainSnapshotGetParent, /* 0.9.7 */
     .domainSnapshotCurrent = qemuDomainSnapshotCurrent, /* 0.8.0 */
+    .domainSnapshotIsCurrent = qemuDomainSnapshotIsCurrent, /* 0.9.13 */
+    .domainSnapshotHasMetadata = qemuDomainSnapshotHasMetadata, /* 0.9.13 */
     .domainRevertToSnapshot = qemuDomainRevertToSnapshot, /* 0.8.0 */
     .domainSnapshotDelete = qemuDomainSnapshotDelete, /* 0.8.0 */
     .qemuDomainMonitorCommand = qemuDomainMonitorCommand, /* 0.8.3 */