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317 | ------------------------------------------------------------------------------
-- G N A T C O L L --
-- --
-- Copyright (C) 2007-2018, 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/>. --
-- --
------------------------------------------------------------------------------
with Ada.IO_Exceptions;
with System; use System;
with GNAT.Strings; use GNAT.Strings;
with GNATCOLL.IO.Native; use GNATCOLL.IO.Native;
package body GNATCOLL.Mmap.System is
use Win;
function Align
(Addr : File_Size) return File_Size;
-- Align some offset/length to the lowest page boundary
function Open_Common
(Filename : String;
Use_Mmap_If_Available : Boolean;
Write : Boolean) return System_File;
-----------------
-- Open_Common --
-----------------
function Open_Common
(Filename : String;
Use_Mmap_If_Available : Boolean;
Write : Boolean) return System_File
is
dwDesiredAccess, dwShareMode : DWORD;
PageFlags : DWORD;
W_Filename : constant Wide_String :=
Codec.From_UTF8 (Filename) & Wide_Character'Val (0);
File_Handle, Mapping_Handle : HANDLE;
Size : aliased LARGE_INTEGER;
Status : BOOL;
begin
if Write then
dwDesiredAccess := GENERIC_READ + GENERIC_WRITE;
dwShareMode := 0;
PageFlags := Win.PAGE_READWRITE;
else
dwDesiredAccess := GENERIC_READ;
dwShareMode := Win.FILE_SHARE_READ;
PageFlags := Win.PAGE_READONLY;
end if;
-- Actually open the file
File_Handle := CreateFile
(W_Filename'Address, dwDesiredAccess, dwShareMode,
null, OPEN_EXISTING, Win.FILE_ATTRIBUTE_NORMAL, 0);
if File_Handle = Win.INVALID_HANDLE_VALUE then
raise Ada.IO_Exceptions.Name_Error
with "Cannot open " & Filename;
end if;
-- Compute its size
Status := Win.GetFileSizeEx (File_Handle, Size'Access);
if Status = Win.FALSE then
-- Raise an error either if we can't compute the size.
raise Ada.IO_Exceptions.Use_Error with "cannot compute file size";
end if;
if File_Size'Size <= 32 and then Size > 2 ** 32 then
-- Likewise if user tries to map a file for which size is superior
-- than 4GB on 32bits systems. In theory this is supported but this
-- would require change in gnatcoll.mmap API.
raise Ada.IO_Exceptions.Use_Error with "cannot open file >4GB";
end if;
-- Then create a mapping object, if needed. On Win32, file memory
-- mapping is always available.
if Use_Mmap_If_Available then
Mapping_Handle :=
Win.CreateFileMapping
(File_Handle, null, PageFlags,
DWORD (Size / 2 ** 32),
DWORD (Size mod 2 ** 32),
Standard.System.Null_Address);
else
Mapping_Handle := Win.INVALID_HANDLE_VALUE;
end if;
-- Note that conversioin to File_Size is safe at this stage because of
-- previous checks.
return
(Handle => File_Handle,
Mapped => Use_Mmap_If_Available,
Mapping_Handle => Mapping_Handle,
Write => Write,
Length => File_Size (Size));
end Open_Common;
---------------
-- Open_Read --
---------------
function Open_Read
(Filename : String;
Use_Mmap_If_Available : Boolean := True) return System_File is
begin
return Open_Common (Filename, Use_Mmap_If_Available, False);
end Open_Read;
----------------
-- Open_Write --
----------------
function Open_Write
(Filename : String;
Use_Mmap_If_Available : Boolean := True) return System_File is
begin
return Open_Common (Filename, Use_Mmap_If_Available, True);
end Open_Write;
-----------
-- Close --
-----------
procedure Close (File : in out System_File) is
Ignored : BOOL;
pragma Unreferenced (Ignored);
begin
Ignored := CloseHandle (File.Mapping_Handle);
Ignored := CloseHandle (File.Handle);
File.Handle := Win.INVALID_HANDLE_VALUE;
File.Mapping_Handle := Win.INVALID_HANDLE_VALUE;
end Close;
--------------------
-- Read_From_Disk --
--------------------
function Read_From_Disk
(File : System_File;
Offset, Length : File_Size) return GNAT.Strings.String_Access
is
Buffer : String_Access := new String (1 .. Integer (Length));
Pos : DWORD;
NbRead : aliased DWORD;
pragma Unreferenced (Pos);
begin
Pos := Win.SetFilePointer
(File.Handle, Win.LONG (Offset), null, Win.FILE_BEGIN);
if Win.ReadFile
(File.Handle, Buffer.all'Address,
DWORD (Length), NbRead'Unchecked_Access, null) = Win.FALSE
then
GNAT.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 : GNAT.Strings.String_Access)
is
Pos : DWORD;
NbWritten : aliased DWORD;
pragma Unreferenced (Pos);
begin
pragma Assert (File.Write);
Pos := Win.SetFilePointer
(File.Handle, Win.LONG (Offset), null, Win.FILE_BEGIN);
if Win.WriteFile
(File.Handle, Buffer.all'Address,
DWORD (Length), NbWritten'Unchecked_Access, null) = Win.FALSE
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;
Advice : Use_Advice := Use_Normal)
is
pragma Unreferenced (Advice);
Flags : DWORD;
Offset64 : LARGE_INTEGER;
begin
if File.Write then
Flags := Win.FILE_MAP_WRITE;
elsif Mutable then
Flags := Win.FILE_MAP_COPY;
else
Flags := Win.FILE_MAP_READ;
end if;
-- Check that limits are valid regarding overflow and/or file size.
if Offset > File_Size'Last - Length or else
Offset + Length > File.Length
then
raise Ada.IO_Exceptions.Use_Error with "Invalid mapping limits";
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.
-- By construction Align return an integer >= 0 lower than the
-- original one. As consequence the following 2 statements cannot
-- overflow. Addition of Get_Page_Size to length is done afterwards
-- to avoid possible overflow.
Length := Length + Queried_Offset - Offset;
Length := Align (Length - 1);
-- But do not exceed the length of the file
-- By construction File.Length - Offset - Length is >=0 (no overflow)
if Get_Page_Size > File.Length - Offset - Length then
Length := File.Length - Offset;
else
Length := Length + Get_Page_Size;
end if;
end;
-- Force conversion of Offset to 64bits format in order to able to
-- split it in two DWORD on both 32bits and 64bits systems.
Offset64 := LARGE_INTEGER (Offset);
Mapping :=
(Address => Win.MapViewOfFile
(File.Mapping_Handle, Flags,
DWORD (Offset64 / 2 ** 32),
DWORD (Offset64 mod 2 ** 32),
SIZE_T (Length)),
Length => Length);
end Create_Mapping;
---------------------
-- Dispose_Mapping --
---------------------
procedure Dispose_Mapping
(Mapping : in out System_Mapping)
is
Ignored : BOOL;
pragma Unreferenced (Ignored);
begin
Ignored := Win.UnmapViewOfFile (Mapping.Address);
Mapping := Invalid_System_Mapping;
end Dispose_Mapping;
-------------------
-- Get_Page_Size --
-------------------
function Get_Page_Size return File_Size is
SystemInfo : aliased SYSTEM_INFO;
begin
GetSystemInfo (SystemInfo'Unchecked_Access);
return File_Size (SystemInfo.dwAllocationGranularity);
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 GNATCOLL.Mmap.System;
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