On Fri, Apr 12, 2013 at 02:04:41PM -0600, Eric Blake wrote: > On 04/12/2013 01:55 PM, Benoît Canet wrote: > > Le Friday 12 Apr 2013 à 19:37:48 (+0200), Stefan Hajnoczi a écrit : > >> Image file compression works at cluster granularity. It is not possible > >> to compress less than a cluster of data at a time. > > Shouldn't it be possible to treat a file that is not rounded to a > cluster boundary as though the rest of the final cluster is all NUL > bytes, and compress that? As long as you know the original size, this > operation is reversible, instead of having to error out just because the > original wasn't a complete multiple. > > >> I considered automatically adjusting the output file size but think it's > >> better to be explicit. This avoids confusion when users notice that > >> image file size changed after conversion. > > I agree that changing the final image size on a round trip through > compression is not appropriate, but does that mean we have to reject the > file completely if it wasn't sized to a multiple to begin with?
I will send a new patch that does this. kwolf also suggested it on Friday and it sounds like a good idea. Stefan
