#include <boost/interprocess/shared_memory_object.hpp>
#include <boost/interprocess/mapped_region.hpp>
#include <cstring>
#include <cstdlib>
#include <string>
 
int main(int argc, char *argv[])
{
   using namespace boost::interprocess;
 
   if(argc == 1){  //Parent process
      //Remove shared memory on construction and destruction
      struct shm_remove
      {
         shm_remove() { shared_memory_object::remove("MySharedMemory"); }
         ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
      } remover;
 
      //Create a shared memory object.
      shared_memory_object shm (create_only, "MySharedMemory", read_write);
 
      //Set size
      shm.truncate(1000);
 
      //Map the whole shared memory in this process
      mapped_region region(shm, read_write);
 
      //Write all the memory to 1
      std::memset(region.get_address(), 1, region.get_size());
 
      //Launch child process
      std::string s(argv[0]); s += " child ";
      if(0 != std::system(s.c_str()))
         return 1;
   }
   else{
      //Open already created shared memory object.
      shared_memory_object shm (open_only, "MySharedMemory", read_only);
 
      //Map the whole shared memory in this process
      mapped_region region(shm, read_only);
 
      //Check that memory was initialized to 1
      char *mem = static_cast<char*>(region.get_address());
      for(std::size_t i = 0; i < region.get_size(); ++i)
         if(*mem++ != 1)
            return 1;   //Error checking memory
   }
   return 0;
}

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