On Sun, Aug 12, 2007 at 07:11:38PM -0400, Jim Paris wrote:
The save file format consists of a header, XML for the domain, and the raw QEMU/KVM migration data stream. -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];
I suggest to add an "int version" field here to be able to extend the format.
+ int xml_len; + int was_running;
and "int unused[16];" With those 2 we should be able to cope with backward compatibility on saved domain even if we don't know yet what may be needed. At worse it's a few bytes lost in a very big file, at best it's a life saver.
+ memset(&header, 0, sizeof(header)); + memcpy(header.magic, QEMUD_SAVE_MAGIC, sizeof(header.magic));
#define QEMU_SAVE_VERSION 1 somewhere and then header.version = QEMU_SAVE_VERSION;
+ header.xml_len = strlen(xml);
maybe + 1 to account for the trailing 0
+ 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; + }
I suggest to define or reuse existing safe write and read routines which handle interruped calls with EAGAIN. Daniel -- Red Hat Virtualization group http://redhat.com/virtualization/ Daniel Veillard | virtualization library http://libvirt.org/ veillard@redhat.com | libxml GNOME XML XSLT toolkit http://xmlsoft.org/ http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/