gcc/ada/s-mmosin-unix.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --              S Y S T E M . M M A P . O S _ I N T E R F A C E             --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --                     Copyright (C) 2007-2016, AdaCore                     --
  10 --                                                                          --
  11 -- This library is free software;  you can redistribute it and/or modify it --
  12 -- under terms of the  GNU General Public License  as published by the Free --
  13 -- Software  Foundation;  either version 3,  or (at your  option) any later --
  14 -- version. This library is distributed in the hope that it will be useful, --
  15 -- but WITHOUT ANY WARRANTY;  without even the implied warranty of MERCHAN- --
  16 -- TABILITY or FITNESS FOR A PARTICULAR PURPOSE.                            --
  17 --                                                                          --
  18 -- As a special exception under Section 7 of GPL version 3, you are granted --
  19 -- additional permissions described in the GCC Runtime Library Exception,   --
  20 -- version 3.1, as published by the Free Software Foundation.               --
  21 --                                                                          --
  22 -- You should have received a copy of the GNU General Public License and    --
  23 -- a copy of the GCC Runtime Library Exception along with this program;     --
  24 -- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
  25 -- <http://www.gnu.org/licenses/>.                                          --
  26 --                                                                          --
  27 -- GNAT was originally developed  by the GNAT team at  New York University. --
  28 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  29 --                                                                          --
  30 ------------------------------------------------------------------------------
  31
  32 with System.OS_Lib;
  33
  34 --  OS pecularities abstraction package for Unix systems.
  35
  36 package System.Mmap.OS_Interface is
  37
  38    type System_File is record
  39       Fd     : System.OS_Lib.File_Descriptor;
  40
  41       Mapped : Boolean;
  42       --  Whether mapping is requested by the user and available on the system
  43
  44       Write  : Boolean;
  45       --  Whether this file can be written to
  46
  47       Length : File_Size;
  48       --  Length of the file. Used to know what can be mapped in the file
  49    end record;
  50
  51    type System_Mapping is record
  52       Address : Standard.System.Address;
  53       Length  : File_Size;
  54    end record;
  55
  56    Invalid_System_File    : constant System_File :=
  57      (System.OS_Lib.Invalid_FD, False, False, 0);
  58    Invalid_System_Mapping : constant System_Mapping :=
  59      (Standard.System.Null_Address, 0);
  60
  61    function Open_Read
  62      (Filename              : String;
  63       Use_Mmap_If_Available : Boolean := True) return System_File;
  64    --  Open a file for reading and return the corresponding System_File. Return
  65    --  Invalid_System_File if unsuccessful.
  66
  67    function Open_Write
  68      (Filename              : String;
  69       Use_Mmap_If_Available : Boolean := True) return System_File;
  70    --  Likewise for writing to a file
  71
  72    procedure Close (File : in out System_File);
  73    --  Close a system file
  74
  75    function Read_From_Disk
  76      (File           : System_File;
  77       Offset, Length : File_Size) return System.Strings.String_Access;
  78    --  Read a fragment of a file. It is up to the caller to free the result
  79    --  when done with it.
  80
  81    procedure Write_To_Disk
  82      (File           : System_File;
  83       Offset, Length : File_Size;
  84       Buffer         : System.Strings.String_Access);
  85    --  Write some content to a fragment of a file
  86
  87    procedure Create_Mapping
  88      (File           : System_File;
  89       Offset, Length : in out File_Size;
  90       Mutable        : Boolean;
  91       Mapping        : out System_Mapping);
  92    --  Create a memory mapping for the given File, for the area starting at
  93    --  Offset and containing Length bytes. Store it to Mapping.
  94    --  Note that Offset and Length may be modified according to the system
  95    --  needs (for boudaries, for instance). The caller must cope with actually
  96    --  wider mapped areas.
  97
  98    procedure Dispose_Mapping
  99      (Mapping : in out System_Mapping);
 100    --  Unmap a previously-created mapping
 101
 102    function Get_Page_Size return File_Size;
 103    --  Return the number of bytes in a system page.
 104
 105 end System.Mmap.OS_Interface;