[Boost-users] [Interprocess] Communication between x86 and x64 issue

[Toni Neubert]

I want to communicate between different platforms using boost interprocess.

I am using vc12 and boost 1.58 on windows 7.

My code below is a very simple example, that should work. But it doesn't for communications between different platforms...

If I create it in x64 and open in win32, the process stuck at a lock at function try_based_lock in boost/int/sync/detail/common_algorithms.hpp

In the other way around: win32 create, x64 open: the process crashes at name_length in segment_manager_helper.hpp while trying to find the name in index (priv_generic_find in segment_manager).

#include <iostream>
#include <boost/interprocess/managed_shared_memory.hpp>

int main() {
namespace bip = boost::interprocess;

// open in WIN32, create in x64
#ifdef _WIN32
    bip::managed_shared_memory msm(bip::open_only, "TestIPC");
#elsif X64
    bip::shared_memory_object::remove("TestIPC");
    bip::managed_shared_memory msm(bip::create_only, "TestIPC", 4096);
    msm.construct<uint32_t>("Data")[1](10);
#endif

// Get Data and print it
auto data = msm.find<uint32_t>("Data");
if (data.second == 1) {
    std::cout << *data.first << std::endl;
}
std::cin.ignore();

return 0;
}

Does anybody have experience in this? Thank you in advance!

[Jan Boehme]

Hello,

some things indicate that's not possible to do with boost::interprocess:

#1 The internal structure, look at the header struct for example, uses data types that are different in length at 32 vs 64 bit arch.

#2 Using a hex editor and looking at the shm for the object shows that there are major differences in the area before your actual data ( which might be safe). The reason for this is #1.And this is the reason for undefined behavior when trying to access it.

Regards, Jan

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[TUELLER, SHAYNE R CIV USAF AFMC 519 SMXS/MXDEC]

If memory serves, boost::interprocess::managed_shared_memory has issues with
shared memory between 32-bit and 64-bit applications, at least on Windows 7.


I've used boost::interprocess::shared_memory_object to map shared memory
between 32-bit and 64-bit applications without any trouble.

Here's some code snippets to set things up...

struct SMdata
{
....
}

32-bit application code (creates shared memory for read/write):

boost::interprocess::shared_memory_object* shm;
boost::interprocess::mapped_region* region;
SMdata* data;
shm = new boost::interprocess::shared_memory_object(create_only, "SHMEM",
read_write);
shm->truncate(sizeof(SMdata));
region = new mapped_region(*shm, read_write);
void* addr = region->get_address();
data = new (addr)SMdata;
// data can now be written to and read from

64-bit application code (opens shared memory for read/write):

SMdata* data;
boost::interprocess::shared_memory_object shm(open_only, "SHMEM",
read_write);
mapped_region region(shm, read_write);
void* addr = region.get_address();
data = static_cast<SMdata*>(addr);
// data can now be written to and read from

Obviously, you'll need to synchronize/protect the shared memory with the
objects provided for in boost::interprocess when you do the reads and writes
to the shared memory structure...

HTH

Shayne