Introduce virConnectIsAlive API

This API can be used to check if the socket associated with
virConnectPtr is still open or it was closed (probably because keepalive
protocol timed out). If there the connection is local (i.e., no socket
is associated with the connection, it is trivially always alive.

include/libvirt/libvirt.h.in

@@ -2655,6 +2655,7 @@ int virInterfaceIsActive(virInterfacePtr iface);
 
 int virConnectIsEncrypted(virConnectPtr conn);
 int virConnectIsSecure(virConnectPtr conn);
+int virConnectIsAlive(virConnectPtr conn);
 
 /*
  * CPU specification API

src/driver.h

@@ -508,6 +508,8 @@ typedef int
     (*virDrvConnectIsEncrypted)(virConnectPtr conn);
 typedef int
     (*virDrvConnectIsSecure)(virConnectPtr conn);
+typedef int
+    (*virDrvConnectIsAlive)(virConnectPtr conn);
 typedef int
     (*virDrvDomainIsActive)(virDomainPtr dom);
 typedef int
@@ -904,6 +906,7 @@ struct _virDriver {
     virDrvDomainBlockJobSetSpeed domainBlockJobSetSpeed;
     virDrvDomainBlockPull domainBlockPull;
     virDrvSetKeepAlive setKeepAlive;
+    virDrvConnectIsAlive isAlive;
 };
 
 typedef int

src/libvirt.c

@@ -17246,3 +17246,39 @@ error:
     virDispatchError(conn);
     return -1;
 }
+
+/**
+ * virConnectIsAlive:
+ * @conn: pointer to the connection object
+ *
+ * Determine if the connection to the hypervisor is still alive
+ *
+ * A connection will be classed as alive if it is either local, or running
+ * over a channel (TCP or UNIX socket) which is not closed.
+ *
+ * Returns 1 if alive, 0 if dead, -1 on error
+ */
+int virConnectIsAlive(virConnectPtr conn)
+{
+    VIR_DEBUG("conn=%p", conn);
+
+    virResetLastError();
+
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(VIR_ERR_INVALID_CONN, __FUNCTION__);
+        virDispatchError(NULL);
+        return -1;
+    }
+    if (conn->driver->isAlive) {
+        int ret;
+        ret = conn->driver->isAlive(conn);
+        if (ret < 0)
+            goto error;
+        return ret;
+    }
+
+    virLibConnError(VIR_ERR_NO_SUPPORT, __FUNCTION__);
+error:
+    virDispatchError(conn);
+    return -1;
+}

src/libvirt_public.syms

@@ -500,6 +500,7 @@ LIBVIRT_0.9.7 {
 
 LIBVIRT_0.9.8 {
     global:
+        virConnectIsAlive;
         virConnectSetKeepAlive;
 } LIBVIRT_0.9.7;