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@xxxxxxxxxx | libxml GNOME XML XSLT toolkit http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine http://rpmfind.net/
--
Libvir-list mailing list
Libvir-list@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/libvir-list