[libvirt] [PATCHv3 2/3] save: let qemu driver manipulate save files

[Eric Blake]

On 07/28/2011 12:47 PM, Laine Stump wrote:
> On 07/22/2011 12:21 AM, Eric Blake wrote:
>> The goal here is that save-image-dumpxml fed back to save
>> image-define without changing the save file; anywhere that
>> this is not the case is probably a bug in domain_conf.c.

I'll do a v4 of patch 3/3 to plug those domain_conf.c holes, but in the 
meantime, this patch is good enough on its own even if the edit cycle is 
not idempotent yet.

>>
>> + if (edit&& STREQ(xml, xmlin)) {
>> + VIR_FREE(xml);
>> + if (VIR_CLOSE(fd)< 0) {
>> + virReportSystemError(errno, _("cannot close file: %s"), path);
>> + goto error;
>> + }
>> + return -2;
>> + }
>
>
> So "unchanged" is indicated with a < 0 return code, but that only
> happens when edit == true, and only one of the callers does that (and
> properly handles the special case).

Yes, because it cannot return a positive value for this case (the 
function returns an fd on normal success - so one way of looking at it 
is that no edits needed is a special case failure).

>> +
>> + if (len> header.xml_len) {
>> + qemuReportError(VIR_ERR_OPERATION_FAILED, "%s",
>> + _("new xml too large to fit in file"));
>> + }
>
> Did you forget a goto cleanup there?
>
>> + if (VIR_EXPAND_N(xml, len, header.xml_len - len)< 0) {
>
> because if len > header.xml_len, that's going to be a *very large*
> number :-)

*very large* indeed - I'd love to have a 64-bit machine with that much 
RAM :-)  I've added the missing goto.

>
> ACK with the goto cleanup added in when the new length is too big to fit
> (unless I've misunderstood the code).

You were right, so I made the change, and pushed.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org