libs/interprocess/example/doc_bufferstream.cpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2006-2009. Distributed under the Boost
   4 // Software License, Version 1.0. (See accompanying file
   5 // LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
   6 //
   7 // See http://www.boost.org/libs/interprocess for documentation.
   8 //
   9 //////////////////////////////////////////////////////////////////////////////
  10 #include <boost/interprocess/detail/config_begin.hpp>
  11 #include <boost/interprocess/detail/workaround.hpp>
  12 //[doc_bufferstream
  13 #include <boost/interprocess/managed_shared_memory.hpp>
  14 #include <boost/interprocess/streams/bufferstream.hpp>
  15 #include <vector>
  16 #include <iterator>
  17 #include <cstddef>
  18 //<-
  19 #include "../test/get_process_id_name.hpp"
  20 //->
  21
  22 using namespace boost::interprocess;
  23
  24 int main ()
  25 {
  26    //Remove shared memory on construction and destruction
  27    struct shm_remove
  28    {
  29    //<-
  30    #if 1
  31       shm_remove() { shared_memory_object::remove(test::get_process_id_name()); }
  32       ~shm_remove(){ shared_memory_object::remove(test::get_process_id_name()); }
  33    #else
  34    //->
  35       shm_remove() { shared_memory_object::remove("MySharedMemory"); }
  36       ~shm_remove(){ shared_memory_object::remove("MySharedMemory"); }
  37    //<-
  38    #endif
  39    //->
  40    } remover;
  41
  42    //Create shared memory
  43    //<-
  44    #if 1
  45    managed_shared_memory segment(create_only,test::get_process_id_name(), 65536);
  46    #else
  47    //->
  48    managed_shared_memory segment(create_only,
  49                                  "MySharedMemory",  //segment name
  50                                  65536);
  51    //<-
  52    #endif
  53    //->
  54
  55    //Fill data
  56    std::vector<int> data;
  57    data.reserve(100);
  58    for(int i = 0; i < 100; ++i){
  59       data.push_back(i);
  60    }
  61    const std::size_t BufferSize = 100*5;
  62
  63    //Allocate a buffer in shared memory to write data
  64    char *my_cstring =
  65       segment.construct<char>("MyCString")[BufferSize](0);
  66    bufferstream mybufstream(my_cstring, BufferSize);
  67
  68    //Now write data to the buffer
  69    for(int i = 0; i < 100; ++i){
  70       mybufstream << data[i] << std::endl;
  71    }
  72
  73    //Check there was no overflow attempt
  74    assert(mybufstream.good());
  75
  76    //Extract all values from the shared memory string
  77    //directly to a vector.
  78    std::vector<int> data2;
  79    std::istream_iterator<int> it(mybufstream), itend;
  80    std::copy(it, itend, std::back_inserter(data2));
  81
  82    //This extraction should have ended will fail error since
  83    //the numbers formatted in the buffer end before the end
  84    //of the buffer. (Otherwise it would trigger eofbit)
  85    assert(mybufstream.fail());
  86
  87    //Compare data
  88    assert(std::equal(data.begin(), data.end(), data2.begin()));
  89
  90    //Clear errors and rewind
  91    mybufstream.clear();
  92    mybufstream.seekp(0, std::ios::beg);
  93
  94    //Now write again the data trying to do a buffer overflow
  95    for(int i = 0, m = data.size()*5; i < m; ++i){
  96       mybufstream << data[i%5] << std::endl;
  97    }
  98
  99    //Now make sure badbit is active
 100    //which means overflow attempt.
 101    assert(!mybufstream.good());
 102    assert(mybufstream.bad());
 103    segment.destroy_ptr(my_cstring);
 104    return 0;
 105 }
 106 //]
 107 #include <boost/interprocess/detail/config_end.hpp>