[libvirt] [PATCH] trivial libvirt example code
The examples directory doesn't have a trivial example of how to connect
to a hypervisor, make a few calls, and disconnect, so I put one
together. I would appreciate any suggestions on anything that I've done
wrong as well as suggestions for other fundamental API calls that should
be illustrated.
Dave
commit 14531c0fa3680890086d61ae4d66aec525f9c9a0
Author: David Allan <dallan(a)redhat.com>
Date: Fri Jan 23 14:27:39 2009 -0500
Added a trivial example program to illustrate connecting to the hypervisor and making
some simple API calls.
diff --git a/examples/hellolibvirt/hellolibvirt.c b/examples/hellolibvirt/hellolibvirt.c
new file mode 100644
index 0000000..aae79b8
--- /dev/null
+++ b/examples/hellolibvirt/hellolibvirt.c
@@ -0,0 +1,137 @@
+/* This file contains trivial example code to connect to the running
+ * hypervisor and gather a few bits of information. */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <libvirt/libvirt.h>
+
+static int
+showHypervisorInfo(virConnectPtr conn)
+{
+ int ret = 0;
+ unsigned long hvVer, major, minor, release;
+ const char *hvType;
+
+ /* virConnectGetType returns a pointer to a static string, so no
+ * allocation or freeing is necessary; it is possible for the call
+ * to fail if, for example, there is no connection to a
+ * hypervisor, so check what it returns. */
+ hvType = virConnectGetType(conn);
+ if (NULL == hvType) {
+ ret = 1;
+ printf("Failed to get hypervisor type\n");
+ goto out;
+ }
+
+ if (0 != virConnectGetVersion(conn, &hvVer)) {
+ ret = 1;
+ printf("Failed to get hypervisor version\n");
+ goto out;
+ }
+
+ major = hvVer / 1000000;
+ hvVer %= 1000000;
+ minor = hvVer / 1000;
+ release = hvVer % 1000;
+
+ printf("Hypervisor: \"%s\" version: %lu.%lu.%lu\n",
+ hvType,
+ major,
+ minor,
+ release);
+
+out:
+ return ret;
+}
+
+
+static int
+showDomains(virConnectPtr conn)
+{
+ int ret = 0, i, numNames, numInactiveDomains, numActiveDomains;
+ char **nameList = NULL;
+
+ numActiveDomains = virConnectNumOfDomains(conn);
+ numInactiveDomains = virConnectNumOfDefinedDomains(conn);
+
+ printf("There are %d active and %d inactive domains\n",
+ numActiveDomains, numInactiveDomains);
+
+ nameList = malloc(sizeof(char *) * (unsigned int)numInactiveDomains);
+
+ if (NULL == nameList) {
+ ret = 1;
+ printf("Could not allocate memory for list of inactive domains\n");
+ goto out;
+ }
+
+ numNames = virConnectListDefinedDomains(conn,
+ nameList,
+ numInactiveDomains);
+
+ if (-1 == numNames) {
+ ret = 1;
+ printf("Could not get list of defined domains from hypervisor\n");
+ goto out;
+ }
+
+ if (numNames > 0) {
+ printf("Inactive domains:\n");
+ }
+
+ for (i = 0 ; i < numNames ; i++) {
+ printf(" %s\n", *(nameList + i));
+ /* The API documentation doesn't say so, but the names
+ * returned by virConnectListDefinedDomains are strdup'd and
+ * must be freed here. */
+ free(*(nameList + i));
+ }
+
+out:
+ if (NULL != nameList) {
+ free(nameList);
+ }
+
+ return ret;
+}
+
+
+int
+main(void)
+{
+ int ret = 0;
+ virConnectPtr conn = NULL;
+
+ printf("Attempting to connect to hypervisor\n");
+
+ /* virConnectOpenAuth called here with all default parameters */
+ conn = virConnectOpenAuth(NULL, virConnectAuthPtrDefault, 0);
+
+ if (NULL == conn) {
+ ret = 1;
+ printf("No connection to hypervisor\n");
+ goto out;
+ }
+
+ printf("Connected to hypervisor\n");
+
+ if (0 != showHypervisorInfo(conn)) {
+ ret = 1;
+ goto disconnect;
+ }
+
+ if (0 != showDomains(conn)) {
+ ret = 1;
+ goto disconnect;
+ }
+
+disconnect:
+ if (0 != virConnectClose(conn)) {
+ printf("Failed to disconnect from hypervisor\n");
+ } else {
+ printf("Disconnected from hypervisor\n");
+ }
+
+out:
+ return ret;
+}