Boost C++ Libraries: Ticket #2002: bugs in load_binary and save_binary on 64 bit machines

attachment set

Tue, 10 Jun 2008 07:36:42 GMT

attachment → main.cpp

Small test program for the bug

owner changed

Robert Ramey — Tue, 10 Jun 2008 15:14:50 GMT

owner changed from Robert Ramey to Matias Capeletto

Mattias,

Could you take a look at this please. It looks like that our basic assumption about arrays - that elements are contiguous and a multiple of the size of the element may not be holding true on a 64 bit platform. As this is intimately related to optimization for arrays maybe you know something about this.

Robert Ramey

Daryle Walker — Wed, 11 Jun 2008 22:56:03 GMT

Closed the preceding bug in deference to this one

owner changed

Matthias Troyer — Sat, 14 Jun 2008 20:36:28 GMT

owner changed from Matias Capeletto to Matthias Troyer

Robert, I guess you wanted to assign this to me and not to matias. Contiguity of arrays and vectors is guaranteed by the standard. The first thing that comes to my mind is that actually instead of using save_binary and load_binary, array wrappers should be used. save_binary and load_binary can be dangerous. I don't have CentOS but can try it on one of our 64-bit machines.

status changed; resolution set

Matthias Troyer — Sat, 14 Jun 2008 20:49:41 GMT

status new → closed
resolution → invalid

The bug is in your code. You write:

ar.save_binary(data,Nel*sizeof(size_t));

while data is an array of type T, which in your example is float. On 32 bit machines this works by chance since there sizeof(float)==sizeof(size_t), but on 64-bit machines a size_t is bigger than a float. This is the reason for the bug. It is much safer to just serialize using array wrappers:

ar << serialization::make_array(data,Nel)

which gets the correct size automatically

Matthias

micdestefano@… — Mon, 16 Jun 2008 16:41:37 GMT

You are right. I'm really sorry for the "false alarm". Thank you very much.

Michele.

milestone deleted

Mon, 03 Nov 2008 14:20:34 GMT

milestone Boost 1.35.1

Milestone Boost 1.35.1 deleted