boost/interprocess/anonymous_shared_memory.hpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2005-2009. 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
  11 #ifndef BOOST_INTERPROCESS_ANONYMOUS_SHARED_MEMORY_HPP
  12 #define BOOST_INTERPROCESS_ANONYMOUS_SHARED_MEMORY_HPP
  13
  14 #include <boost/interprocess/detail/config_begin.hpp>
  15 #include <boost/interprocess/detail/workaround.hpp>
  16 #include <boost/interprocess/creation_tags.hpp>
  17 #include <boost/interprocess/detail/move.hpp>
  18 #include <boost/interprocess/interprocess_fwd.hpp>
  19 #include <boost/interprocess/mapped_region.hpp>
  20 #include <cstddef>
  21
  22 #if (!defined(BOOST_INTERPROCESS_WINDOWS))
  23 #  include <fcntl.h>        //open, O_CREAT, O_*...
  24 #  include <sys/mman.h>     //mmap
  25 #  include <sys/stat.h>     //mode_t, S_IRWXG, S_IRWXO, S_IRWXU,
  26 #else
  27 #include <boost/interprocess/windows_shared_memory.hpp>
  28 #endif
  29
  30
  31 //!\file
  32 //!Describes a function that creates anonymous shared memory that can be
  33 //!shared between forked processes
  34
  35 namespace boost {
  36 namespace interprocess {
  37
  38 /// @cond
  39
  40 namespace detail{
  41
  42    class raw_mapped_region_creator
  43    {
  44       public:
  45       static mapped_region
  46          create_posix_mapped_region(void *address, offset_t offset, std::size_t size)
  47       {
  48          mapped_region region;
  49          region.m_base = address;
  50          region.m_offset = offset;
  51          region.m_extra_offset = 0;
  52          region.m_size = size;
  53          return region;
  54       }
  55    };
  56 }
  57
  58 /// @endcond
  59
  60 //!A function that creates an anonymous shared memory segment of size "size".
  61 //!If "address" is passed the function will try to map the segment in that address.
  62 //!Otherwise the operating system will choose the mapping address.
  63 //!The function returns a mapped_region holding that segment or throws
  64 //!interprocess_exception if the function fails.
  65 //static mapped_region
  66 static mapped_region
  67 anonymous_shared_memory(std::size_t size, void *address = 0)
  68 #if (!defined(BOOST_INTERPROCESS_WINDOWS))
  69 {
  70    int flags;
  71    int fd = -1;
  72
  73    #if defined(MAP_ANONYMOUS) //Use MAP_ANONYMOUS
  74    flags = MAP_ANONYMOUS | MAP_SHARED;
  75    #elif !defined(MAP_ANONYMOUS) && defined(MAP_ANON) //use MAP_ANON
  76    flags = MAP_ANON | MAP_SHARED;
  77    #else // Use "/dev/zero"
  78    fd = open("/dev/zero", O_RDWR);
  79    flags = MAP_SHARED;
  80    if(fd == -1){
  81       error_info err = system_error_code();
  82       throw interprocess_exception(err);
  83    }
  84    #endif
  85
  86
  87    address = mmap( address
  88                   , size
  89                   , PROT_READ|PROT_WRITE
  90                   , flags
  91                   , fd
  92                   , 0);
  93
  94    if(address == MAP_FAILED){
  95       if(fd != -1)
  96          close(fd);
  97       error_info err = system_error_code();
  98       throw interprocess_exception(err);
  99    }
 100
 101    if(fd != -1)
 102       close(fd);
 103
 104    return detail::raw_mapped_region_creator::create_posix_mapped_region(address, 0, size);
 105 }
 106 #else
 107 {
 108    windows_shared_memory anonymous_mapping(create_only, 0, read_write, size);
 109    return mapped_region(anonymous_mapping, read_write, 0, size, address);
 110 }
 111
 112 #endif
 113
 114 }  //namespace interprocess {
 115 }  //namespace boost {
 116
 117 #include <boost/interprocess/detail/config_end.hpp>
 118
 119 #endif   //BOOST_INTERPROCESS_ANONYMOUS_SHARED_MEMORY_HPP