Re: [libvirt] [PATCH] blockjob: avoid compiler uncertainty in info sizing

On 06/14/14 14:50, Eric Blake wrote: > We have a policy of avoiding enum types in structs in our public > API, because it is possible for a client to choose compiler options > that can change the in-memory ABI of that struct based on whether > the enum value occupies an int or a minimal size. But we missed > this for virDomainBlockJobInfo. We got lucky on little-endian > machines - if the enum fits minimal size (a char), we still end > up padding to the next long before the next field; but on > big-endian, a client interpreting the enum as a char would always > see 0 when the server supplies contents as an int. > > While at it, I noticed that the web page lacked documentation: > http://libvirt.org/html/libvirt-libvirt.html#virDomainBlockJobType > not only for the recently added active commit, but also for all > the other job types. >

> VIR_DOMAIN_BLOCK_JOB_TYPE_ACTIVE_COMMIT = 4, > + /* Active Block Commit (virDomainBlockCommit with flags), job > + * exists as long as sync is active */ > > #ifdef VIR_ENUM_SENTINELS > VIR_DOMAIN_BLOCK_JOB_TYPE_LAST ACK to the above hunk,

> @@ -2537,7 +2544,7 @@ typedef unsigned long long virDomainBlockJobCursor; > > typedef struct _virDomainBlockJobInfo virDomainBlockJobInfo; > struct _virDomainBlockJobInfo { > - virDomainBlockJobType type; > + int type; /* virDomainBlockJobType */ > unsigned long bandwidth; > /* > * The following fields provide an indication of block job progress. @cur > I don't object to this one, but I'd like to see a second opinion.