ceph/src/boost/libs/interprocess/example/doc_file_mapping.cpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2006-2012. 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 //[doc_file_mapping
  12 #include <boost/interprocess/file_mapping.hpp>
  13 #include <boost/interprocess/mapped_region.hpp>
  14 #include <iostream>
  15 #include <fstream>
  16 #include <string>
  17 #include <vector>
  18 #include <cstring>
  19 #include <cstddef>
  20 #include <cstdlib>
  21 //<-
  22 #include "../test/get_process_id_name.hpp"
  23 //->
  24
  25 int main(int argc, char *argv[])
  26 {
  27    using namespace boost::interprocess;
  28
  29    //Define file names
  30    //<-
  31    #if 1
  32    std::string file_name(boost::interprocess::ipcdetail::get_temporary_path());
  33    file_name += "/"; file_name += test::get_process_id_name();
  34    const char *FileName = file_name.c_str();
  35    #else
  36    //->
  37    const char *FileName  = "file.bin";
  38    //<-
  39    #endif
  40    //->
  41    const std::size_t FileSize = 10000;
  42
  43    if(argc == 1){ //Parent process executes this
  44       {  //Create a file
  45          file_mapping::remove(FileName);
  46          std::filebuf fbuf;
  47          fbuf.open(FileName, std::ios_base::in | std::ios_base::out
  48                               | std::ios_base::trunc | std::ios_base::binary);
  49          //Set the size
  50          fbuf.pubseekoff(FileSize-1, std::ios_base::beg);
  51          fbuf.sputc(0);
  52       }
  53
  54       //Remove on exit
  55       struct file_remove
  56       {
  57          file_remove(const char *FileName)
  58             : FileName_(FileName) {}
  59          ~file_remove(){ file_mapping::remove(FileName_); }
  60          const char *FileName_;
  61       } remover(FileName);
  62
  63       //Create a file mapping
  64       file_mapping m_file(FileName, read_write);
  65
  66       //Map the whole file with read-write permissions in this process
  67       mapped_region region(m_file, read_write);
  68
  69       //Get the address of the mapped region
  70       void * addr       = region.get_address();
  71       std::size_t size  = region.get_size();
  72
  73       //Write all the memory to 1
  74       std::memset(addr, 1, size);
  75
  76       //Launch child process
  77       std::string s(argv[0]); s += " child ";
  78       //<-
  79       s += "\""; s+= FileName; s += "\"";
  80       //->
  81       if(0 != std::system(s.c_str()))
  82          return 1;
  83    }
  84    else{  //Child process executes this
  85       {  //Open the file mapping and map it as read-only
  86          //<-
  87          #if 1
  88          file_mapping m_file(argv[2], read_only);
  89          #else
  90          //->
  91          file_mapping m_file(FileName, read_only);
  92          //<-
  93          #endif
  94          //->
  95
  96          mapped_region region(m_file, read_only);
  97
  98          //Get the address of the mapped region
  99          void * addr       = region.get_address();
 100          std::size_t size  = region.get_size();
 101
 102          //Check that memory was initialized to 1
 103          const char *mem = static_cast<char*>(addr);
 104          for(std::size_t i = 0; i < size; ++i)
 105             if(*mem++ != 1)
 106                return 1;   //Error checking memory
 107       }
 108       {  //Now test it reading the file
 109          std::filebuf fbuf;
 110          //<-
 111          #if 1
 112          fbuf.open(argv[2], std::ios_base::in | std::ios_base::binary);
 113          #else
 114          //->
 115          fbuf.open(FileName, std::ios_base::in | std::ios_base::binary);
 116          //<-
 117          #endif
 118          //->
 119
 120          //Read it to memory
 121          std::vector<char> vect(FileSize, 0);
 122          fbuf.sgetn(&vect[0], std::streamsize(vect.size()));
 123
 124          //Check that memory was initialized to 1
 125          const char *mem = static_cast<char*>(&vect[0]);
 126          for(std::size_t i = 0; i < FileSize; ++i)
 127             if(*mem++ != 1)
 128                return 1;   //Error checking memory
 129       }
 130    }
 131
 132    return 0;
 133 }
 134 //]
 135 #include <boost/interprocess/detail/config_end.hpp>