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.
Dan.
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