[libvirt] Re: [PATCH v2] implement virsh dump for qemu guests

This patch uses a "migrate"+"cont" combination to implement "virsh dump" for QEMU guests (BZ507551). The code is mostly based on qemudDomainSave, except that the XML prolog is not included as it is not needed to examine the dump with e.g. crash.

+ if (virAsprintf(&command, "migrate \"exec:" + "dd of='%s' 2>/dev/null" + "\"", safe_path) == -1) { + virReportOOMError(dom->conn); + command = NULL; + goto cleanup; + } + + if (qemudMonitorCommand(vm, command, &info) < 0) { + qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, + "%s", _("migrate operation failed")); + goto cleanup; + } + + DEBUG ("%s: migrate reply: %s", vm->def->name, info); + + /* If the command isn't supported then qemu prints: + * unknown command: migrate" */ + if (strstr(info, "unknown command:")) { + qemudReportError (dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT, + "%s", + _("'migrate' not supported by this qemu")); + goto cleanup; + } + + /* Migrate always stops the VM. However, since the monitor is always + attached to a pty for libvirt, it will support synchronous + operations so we get here just after the end of the migration. */ + if (vm->state == VIR_DOMAIN_RUNNING) { + if (qemudMonitorCommand(vm, "cont", &info) < 0) { + qemudReportError(dom->conn, dom, NULL, VIR_ERR_OPERATION_FAILED, + "%s", _("continue operation failed")); + goto cleanup; + } + DEBUG("Reply %s", info); + VIR_FREE(info); + }