[Libvir] [PATCH 6/7] Add KVM save support using migration.

[Jim Paris]

The save file format consists of a header, XML for the domain,
and the raw QEMU/KVM migration data stream.

Signed-off-by: Jim Paris <jim at jtan.com>
---
 src/qemu_driver.c |  109 ++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 files changed, 103 insertions(+), 6 deletions(-)

diff --git a/src/qemu_driver.c b/src/qemu_driver.c
index 5d310fe..50ab702 100644
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -1932,20 +1932,117 @@ static char *qemudEscapeShellArg(const char *in)
 }
 
 
-static int qemudDomainSave(virDomainPtr dom,
-                    const char *path ATTRIBUTE_UNUSED) {
+#define QEMUD_SAVE_MAGIC "LibvirtQemudSave"
+struct qemud_save_header {
+    char magic[sizeof(QEMUD_SAVE_MAGIC)-1];
+    int xml_len;
+    int was_running;
+};
+
+static int qemudDomainSave(virDomainPtr dom, 
+                           const char *path) {
     struct qemud_driver *driver = (struct qemud_driver *)dom->conn->privateData;
     struct qemud_vm *vm = qemudFindVMByID(driver, dom->id);
+    char *command, *info;
+    int fd;
+    char *safe_path;
+    char *xml;
+    struct qemud_save_header header;
+    
+    memset(&header, 0, sizeof(header));
+    memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
+
     if (!vm) {
-        qemudReportError(dom->conn, dom, NULL, VIR_ERR_INVALID_DOMAIN, "no domain with matching id %d", dom->id);
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_INVALID_DOMAIN,
+                         "no domain with matching id %d", dom->id);
         return -1;
     }
+
     if (!qemudIsActiveVM(vm)) {
-        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, "domain is not running");
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
+                         "domain is not running");
         return -1;
     }
-    qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, "save is not supported");
-    return -1;
+    
+    /* Pause */
+    if (vm->state == VIR_DOMAIN_RUNNING) {
+        header.was_running = 1;
+        if (qemudDomainSuspend(dom) != 0) {
+            qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
+                             "failed to pause domain");
+            return -1;
+        }
+    }
+
+    /* Get XML for the domain */
+    xml = qemudGenerateXML(dom->conn, driver, vm, vm->def, 0);
+    if (!xml) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, 
+                         "failed to get domain xml");
+        return -1;
+    }
+    header.xml_len = strlen(xml);
+
+    /* Write header to file, followed by XML */
+    if ((fd = open(path, O_CREAT|O_TRUNC|O_WRONLY, S_IRUSR|S_IWUSR)) < 0) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
+                         "failed to create '%s'", path);
+        free(xml);
+        return -1;
+    }
+
+    if (write(fd, &header, sizeof(header)) != sizeof(header)) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
+                         "failed to write save header");
+        close(fd);
+        free(xml);
+        return -1;
+    }
+
+    if (write(fd, xml, header.xml_len) != header.xml_len) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED,
+                         "failed to write xml");
+        close(fd);
+        free(xml);
+        return -1;
+    }
+
+    close(fd);
+    free(xml);
+    
+    /* Migrate to file */
+    safe_path = qemudEscapeShellArg(path);
+    if (!safe_path) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, 
+                         "out of memory");
+        return -1;
+    }
+    if (asprintf (&command, "migrate \"exec:" 
+                  "dd of='%s' oflag=append conv=notrunc 2>/dev/null"
+                  "\"\n", safe_path) == -1) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, 
+                         "out of memory");
+        free(safe_path);
+        return -1;
+    }
+    free(safe_path);
+
+    if (qemudMonitorCommand(driver, vm, command, &info) < 0) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, 
+                         "migrate operation failed");
+        free(command);
+        return -1;
+    }
+
+    free(info);
+    free(command);
+
+    /* Shut it down */
+    qemudShutdownVMDaemon(dom->conn, driver, vm);
+    if (!vm->configFile[0])
+        qemudRemoveInactiveVM(driver, vm);
+
+    return 0;
 }
 
 
-- 
1.5.3.rc4