This may help as well: http://clinuxpro.com/Cprogramming/structurepadding.php On Wed, Jun 2, 2010 at 12:26 PM, Brian Budge <brian.budge@xxxxxxxxx> wrote: > I'm surprised this wasn't the case before. AFAIK, structs with > doubles have been aligned to at least an 8 byte boundary for years. > > You may need to write a new reader that knows the layout on disk and > reconstructs the data. > > Brian > > On Wed, Jun 2, 2010 at 9:16 AM, Christian Convey > <christian.convey@xxxxxxxxx> wrote: >> Are you sure that's a bug in the legalistic sense? IIRC, C and C++ >> don't promise any particular memory layout for structs. >> >> On Wed, Jun 2, 2010 at 11:53 AM, David R. Doucette >> <ddoucette@xxxxxxxxxxxxxxxx> wrote: >>> We just installed Lucid Lynx a few days ago, and have hit a fatal flaw with >>> g++ that has forced us to stop the deployment and roll back the systems we >>> could. >>> >>> Structures in Lucid are now mapping differently than in the past, so we can >>> no longer read our own files! Further, if any files are written by code >>> produced by the new g++, they are corrupted. >>> >>> The problem is that doubles are now being mapped onto a boundary divisible >>> by 8 rather than a boundary divisible by 4, meaning that offsets change and >>> structs get bigger. >>> >>> I've attached a tar file showing the mapping on Jaunty, Karmic, and Lucid to >>> show the change. This is a greatly simplified program that shows the >>> problem, but it's happening in all of our C++ programs. >>> >>> HELP! >>> >>> System is Ubuntu 10.4 Lucid Lynx 64 bit. >>> >>> David Doucette >>> >> >
