Re: [libvirt] [PATCH v2] buf: Fix possible infinite loop in EscapeString, VSnprintf

On Wed, Sep 01, 2010 at 05:41:46PM -0400, Cole Robinson wrote: > The current code will go into an infinite loop if the printf generated > string is >= 1000, AND exactly 1 character smaller than the amount of free > space in the buffer. When this happens, we are dropped into the loop body, > but nothing will actually change, because count == (buf->size - buf->use - 1), > and virBufferGrow returns unchanged if count < (buf->size - buf->use) > > Fix this by removing the '- 1' bit from 'size'. The *nprintf functions handle > the NULL byte for us anyways, so we shouldn't need to manually accomodate > for it. > > Here's a bug where we are actually hitting this issue: > https://bugzilla.redhat.com/show_bug.cgi?id=602772 > > v2: Eric's improvements: while -> if (), remove extra va_list variable, > make sure we report buffer error if snprintf fails How about adding a unit test for the virBuffer APIs to verify all this stuff is working as designed. It is nicely self-contained code so we ought to be able to get 100% coverage of all codepaths and error conditions like this one Daniel