boost/interprocess/file_mapping.hpp

   1 //////////////////////////////////////////////////////////////////////////////
   2 //
   3 // (C) Copyright Ion Gaztanaga 2005-2008. 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_FILE_MAPPING_HPP
  12 #define BOOST_INTERPROCESS_FILE_MAPPING_HPP
  13
  14 #include <boost/interprocess/detail/config_begin.hpp>
  15 #include <boost/interprocess/detail/workaround.hpp>
  16
  17 #include <boost/interprocess/interprocess_fwd.hpp>
  18 #include <boost/interprocess/exceptions.hpp>
  19 #include <boost/interprocess/detail/utilities.hpp>
  20 #include <boost/interprocess/creation_tags.hpp>
  21 #include <boost/interprocess/detail/os_file_functions.hpp>
  22 #include <boost/interprocess/detail/move.hpp>
  23 #include <string>    //std::string
  24
  25 //!\file
  26 //!Describes file_mapping and mapped region classes
  27
  28 namespace boost {
  29 namespace interprocess {
  30
  31 //!A class that wraps a file-mapping that can be used to
  32 //!create mapped regions from the mapped files
  33 class file_mapping
  34 {
  35    /// @cond
  36    //Non-copyable and non-assignable
  37    file_mapping(file_mapping &);
  38    file_mapping &operator=(file_mapping &);
  39    /// @endcond
  40
  41    public:
  42    BOOST_INTERPROCESS_ENABLE_MOVE_EMULATION(file_mapping)
  43
  44    //!Constructs an empty file mapping.
  45    //!Does not throw
  46    file_mapping();
  47
  48    //!Opens a file mapping of file "filename", starting in offset
  49    //!"file_offset", and the mapping's size will be "size". The mapping
  50    //!can be opened for read-only "read_only" or read-write "read_write"
  51    //!modes. Throws interprocess_exception on error.
  52    file_mapping(const char *filename, mode_t mode);
  53
  54    //!Moves the ownership of "moved"'s file mapping object to *this.
  55    //!After the call, "moved" does not represent any file mapping object.
  56    //!Does not throw
  57    file_mapping(BOOST_INTERPROCESS_RV_REF(file_mapping) moved)
  58       :  m_handle(file_handle_t(detail::invalid_file()))
  59    {  this->swap(moved);   }
  60
  61    //!Moves the ownership of "moved"'s file mapping to *this.
  62    //!After the call, "moved" does not represent any file mapping.
  63    //!Does not throw
  64    file_mapping &operator=(BOOST_INTERPROCESS_RV_REF(file_mapping) moved)
  65    {
  66       file_mapping tmp(boost::interprocess::move(moved));
  67       this->swap(tmp);
  68       return *this;
  69    }
  70
  71    //!Swaps to file_mappings.
  72    //!Does not throw.
  73    void swap(file_mapping &other);
  74
  75    //!Returns access mode
  76    //!used in the constructor
  77    mode_t get_mode() const;
  78
  79    //!Obtains the mapping handle
  80    //!to be used with mapped_region
  81    mapping_handle_t get_mapping_handle() const;
  82
  83    //!Destroys the file mapping. All mapped regions created from this are still
  84    //!valid. Does not throw
  85    ~file_mapping();
  86
  87    //!Returns the name of the file
  88    //!used in the constructor.
  89    const char *get_name() const;
  90
  91    //!Removes the file named "filename" even if it's been memory mapped.
  92    //!Returns true on success.
  93    //!The function might fail in some operating systems if the file is
  94    //!being used other processes and no deletion permission was shared.
  95    static bool remove(const char *filename);
  96
  97    /// @cond
  98    private:
  99    //!Closes a previously opened file mapping. Never throws.
 100    void priv_close();
 101    file_handle_t  m_handle;
 102    mode_t    m_mode;
 103    std::string       m_filename;
 104    /// @endcond
 105 };
 106
 107 inline file_mapping::file_mapping()
 108    :  m_handle(file_handle_t(detail::invalid_file()))
 109 {}
 110
 111 inline file_mapping::~file_mapping()
 112 {  this->priv_close(); }
 113
 114 inline const char *file_mapping::get_name() const
 115 {  return m_filename.c_str(); }
 116
 117 inline void file_mapping::swap(file_mapping &other)
 118 {
 119    std::swap(m_handle, other.m_handle);
 120    std::swap(m_mode, other.m_mode);
 121    m_filename.swap(other.m_filename);
 122 }
 123
 124 inline mapping_handle_t file_mapping::get_mapping_handle() const
 125 {  return detail::mapping_handle_from_file_handle(m_handle);  }
 126
 127 inline mode_t file_mapping::get_mode() const
 128 {  return m_mode; }
 129
 130 inline file_mapping::file_mapping
 131    (const char *filename, mode_t mode)
 132    :  m_filename(filename)
 133 {
 134    //Check accesses
 135    if (mode != read_write && mode != read_only){
 136       error_info err = other_error;
 137       throw interprocess_exception(err);
 138    }
 139
 140    //Open file
 141    m_handle = detail::open_existing_file(filename, mode);
 142
 143    //Check for error
 144    if(m_handle == detail::invalid_file()){
 145       error_info err = system_error_code();
 146       this->priv_close();
 147       throw interprocess_exception(err);
 148    }
 149    m_mode = mode;
 150 }
 151
 152 inline bool file_mapping::remove(const char *filename)
 153 {  return detail::delete_file(filename);  }
 154
 155 ///@cond
 156
 157 inline void file_mapping::priv_close()
 158 {
 159    if(m_handle != detail::invalid_file()){
 160       detail::close_file(m_handle);
 161       m_handle = detail::invalid_file();
 162    }
 163 }
 164
 165 ///@endcond
 166
 167 //!A class that stores the name of a file
 168 //!and tries to remove it in its destructor
 169 //!Useful to remove temporary files in the presence
 170 //!of exceptions
 171 class remove_file_on_destroy
 172 {
 173    const char * m_name;
 174    public:
 175    remove_file_on_destroy(const char *name)
 176       :  m_name(name)
 177    {}
 178
 179    ~remove_file_on_destroy()
 180    {  detail::delete_file(m_name);  }
 181 };
 182
 183 }  //namespace interprocess {
 184 }  //namespace boost {
 185
 186 #include <boost/interprocess/detail/config_end.hpp>
 187
 188 #endif   //BOOST_INTERPROCESS_FILE_MAPPING_HPP