Re: [Libvir] PATCH 2/4: Xen driver support for serial/paralle

On Fri, Apr 25, 2008 at 03:11:44AM -0400, Daniel Veillard wrote: > On Thu, Apr 24, 2008 at 10:14:49PM +0100, Daniel P. Berrange wrote: > > On Thu, Apr 24, 2008 at 10:42:34PM +0200, Jim Meyering wrote: > > > All of the virBufferAddLit and virBufferVSprintf calls > > > above can fail with ENOMEM. I see that there are *many* more > > > virBufferAddLit and virBufferVSprintf calls that ignore their > > > return values (over 300), so maybe I'm missing something. > > > > Yes, the entire set of Xen drivers is basically fubar wrt to checking > > virBufferXXX return values. I felt that needed addresing independantly > > changing everything in one go, so didn't try to address that in this > > patch. > > Maybe the best is to store in the buffer the fact that there have been > an error at some point, and check that value before extracting the content > in a single place, that would make the code cleaner, and makes harder to > miss one test. So we've two options: - Make all the virBuffer* functions be void, and keep an internal error flag to be checked at the end - Annotate all the virBuffer* functions with __attribute((warn_unused_result)) which forces the caller to check the return value I'm acutally inclined to go for the former, since it'll let us remove a large number of 'goto no_memory' statements giving clearer code

I think I'd also like to mak the virBuffer struct private, so people can't access the data field directly - force them to go via an API to get hold of the internal char * - this lets us ensure they don't access the data if an error has occurred.