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228 | ------------------------------------------------------------------------------
-- --
-- GNAT RUN-TIME COMPONENTS --
-- --
-- S Y S T E M . M M A P . O S _ I N T E R F A C E --
-- --
-- B o d y --
-- --
-- Copyright (C) 2007-2023, AdaCore --
-- --
-- This library is free software; you can redistribute it and/or modify it --
-- under terms of the GNU General Public License as published by the Free --
-- Software Foundation; either version 3, or (at your option) any later --
-- version. This library is distributed in the hope that it will be useful, --
-- but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN- --
-- TABILITY or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Ada.IO_Exceptions;
with System.OS_Lib; use System.OS_Lib;
with System.Mmap.Unix; use System.Mmap.Unix;
package body System.Mmap.OS_Interface is
function Align
(Addr : File_Size) return File_Size;
-- Align some offset/length to the lowest page boundary
function Is_Mapping_Available return Boolean renames
System.Mmap.Unix.Is_Mapping_Available;
-- Wheter memory mapping is actually available on this system. It is an
-- error to use Create_Mapping and Dispose_Mapping if this is False.
---------------
-- Open_Read --
---------------
function Open_Read
(Filename : String;
Use_Mmap_If_Available : Boolean := True) return System_File is
Fd : constant File_Descriptor :=
Open_Read (Filename, Binary);
begin
if Fd = Invalid_FD then
return Invalid_System_File;
end if;
return
(Fd => Fd,
Mapped => Use_Mmap_If_Available and then Is_Mapping_Available,
Write => False,
Length => File_Size (File_Length (Fd)));
end Open_Read;
----------------
-- Open_Write --
----------------
function Open_Write
(Filename : String;
Use_Mmap_If_Available : Boolean := True) return System_File is
Fd : constant File_Descriptor :=
Open_Read_Write (Filename, Binary);
begin
if Fd = Invalid_FD then
return Invalid_System_File;
end if;
return
(Fd => Fd,
Mapped => Use_Mmap_If_Available and then Is_Mapping_Available,
Write => True,
Length => File_Size (File_Length (Fd)));
end Open_Write;
-----------
-- Close --
-----------
procedure Close (File : in out System_File) is
begin
Close (File.Fd);
File.Fd := Invalid_FD;
end Close;
--------------------
-- Read_From_Disk --
--------------------
function Read_From_Disk
(File : System_File;
Offset, Length : File_Size) return System.Strings.String_Access
is
Buffer : String_Access := new String (1 .. Integer (Length));
begin
-- ??? Lseek offset should be a size_t instead of a Long_Integer
Lseek (File.Fd, Long_Integer (Offset), Seek_Set);
if System.OS_Lib.Read (File.Fd, Buffer.all'Address, Integer (Length))
/= Integer (Length)
then
System.Strings.Free (Buffer);
raise Ada.IO_Exceptions.Device_Error;
end if;
return Buffer;
end Read_From_Disk;
-------------------
-- Write_To_Disk --
-------------------
procedure Write_To_Disk
(File : System_File;
Offset, Length : File_Size;
Buffer : System.Strings.String_Access) is
begin
pragma Assert (File.Write);
Lseek (File.Fd, Long_Integer (Offset), Seek_Set);
if System.OS_Lib.Write (File.Fd, Buffer.all'Address, Integer (Length))
/= Integer (Length)
then
raise Ada.IO_Exceptions.Device_Error;
end if;
end Write_To_Disk;
--------------------
-- Create_Mapping --
--------------------
procedure Create_Mapping
(File : System_File;
Offset, Length : in out File_Size;
Mutable : Boolean;
Mapping : out System_Mapping)
is
Prot : Mmap_Prot;
Flags : Mmap_Flags;
begin
if File.Write then
Prot := PROT_READ + PROT_WRITE;
Flags := MAP_SHARED;
else
Prot := PROT_READ;
if Mutable then
Prot := Prot + PROT_WRITE;
end if;
Flags := MAP_PRIVATE;
end if;
-- Adjust offset and mapping length to account for the required
-- alignment of offset on page boundary.
declare
Queried_Offset : constant File_Size := Offset;
begin
Offset := Align (Offset);
-- First extend the length to compensate the offset shift, then align
-- it on the upper page boundary, so that the whole queried area is
-- covered.
Length := Length + Queried_Offset - Offset;
Length := Align (Length + Get_Page_Size - 1);
end;
if Length > File_Size (Integer'Last) then
raise Ada.IO_Exceptions.Device_Error;
else
Mapping :=
(Address => System.Mmap.Unix.Mmap
(Offset => off_t (Offset),
Length => Interfaces.C.size_t (Length),
Prot => Prot,
Flags => Flags,
Fd => File.Fd),
Length => Length);
end if;
end Create_Mapping;
---------------------
-- Dispose_Mapping --
---------------------
procedure Dispose_Mapping
(Mapping : in out System_Mapping)
is
Ignored : Integer;
pragma Unreferenced (Ignored);
begin
Ignored := Munmap
(Mapping.Address, Interfaces.C.size_t (Mapping.Length));
Mapping := Invalid_System_Mapping;
end Dispose_Mapping;
-------------------
-- Get_Page_Size --
-------------------
function Get_Page_Size return File_Size is
function Internal return Integer;
pragma Import (C, Internal, "getpagesize");
begin
return File_Size (Internal);
end Get_Page_Size;
-----------
-- Align --
-----------
function Align
(Addr : File_Size) return File_Size is
begin
return Addr - Addr mod Get_Page_Size;
end Align;
end System.Mmap.OS_Interface;
|