gcc/ada/a-sequio.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                    A D A . S E Q U E N T I A L _ I O                     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2008, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  This is the generic template for Sequential_IO, i.e. the code that gets
  35 --  duplicated. We absolutely minimize this code by either calling routines
  36 --  in System.File_IO (for common file functions), or in System.Sequential_IO
  37 --  (for specialized Sequential_IO functions)
  38
  39 with Interfaces.C_Streams; use Interfaces.C_Streams;
  40 with System;
  41 with System.CRTL;
  42 with System.File_Control_Block;
  43 with System.File_IO;
  44 with System.Storage_Elements;
  45 with Ada.Unchecked_Conversion;
  46
  47 package body Ada.Sequential_IO is
  48
  49    package FIO renames System.File_IO;
  50    package FCB renames System.File_Control_Block;
  51    package SIO renames System.Sequential_IO;
  52    package SSE renames System.Storage_Elements;
  53
  54    SU : constant := System.Storage_Unit;
  55
  56    subtype AP is FCB.AFCB_Ptr;
  57    subtype FP is SIO.File_Type;
  58
  59    function To_FCB is new Ada.Unchecked_Conversion (File_Mode, FCB.File_Mode);
  60    function To_SIO is new Ada.Unchecked_Conversion (FCB.File_Mode, File_Mode);
  61
  62    use type System.CRTL.size_t;
  63
  64    -----------
  65    -- Close --
  66    -----------
  67
  68    procedure Close (File : in out File_Type) is
  69    begin
  70       FIO.Close (AP (File)'Unrestricted_Access);
  71    end Close;
  72
  73    ------------
  74    -- Create --
  75    ------------
  76
  77    procedure Create
  78      (File : in out File_Type;
  79       Mode : File_Mode := Out_File;
  80       Name : String := "";
  81       Form : String := "")
  82    is
  83    begin
  84       SIO.Create (FP (File), To_FCB (Mode), Name, Form);
  85    end Create;
  86
  87    ------------
  88    -- Delete --
  89    ------------
  90
  91    procedure Delete (File : in out File_Type) is
  92    begin
  93       FIO.Delete (AP (File)'Unrestricted_Access);
  94    end Delete;
  95
  96    -----------------
  97    -- End_Of_File --
  98    -----------------
  99
 100    function End_Of_File (File : File_Type) return Boolean is
 101    begin
 102       return FIO.End_Of_File (AP (File));
 103    end End_Of_File;
 104
 105    ----------
 106    -- Form --
 107    ----------
 108
 109    function Form (File : File_Type) return String is
 110    begin
 111       return FIO.Form (AP (File));
 112    end Form;
 113
 114    -------------
 115    -- Is_Open --
 116    -------------
 117
 118    function Is_Open (File : File_Type) return Boolean is
 119    begin
 120       return FIO.Is_Open (AP (File));
 121    end Is_Open;
 122
 123    ----------
 124    -- Mode --
 125    ----------
 126
 127    function Mode (File : File_Type) return File_Mode is
 128    begin
 129       return To_SIO (FIO.Mode (AP (File)));
 130    end Mode;
 131
 132    ----------
 133    -- Name --
 134    ----------
 135
 136    function Name (File : File_Type) return String is
 137    begin
 138       return FIO.Name (AP (File));
 139    end Name;
 140
 141    ----------
 142    -- Open --
 143    ----------
 144
 145    procedure Open
 146      (File : in out File_Type;
 147       Mode : File_Mode;
 148       Name : String;
 149       Form : String := "")
 150    is
 151    begin
 152       SIO.Open (FP (File), To_FCB (Mode), Name, Form);
 153    end Open;
 154
 155    ----------
 156    -- Read --
 157    ----------
 158
 159    procedure Read (File : File_Type; Item : out Element_Type) is
 160       Siz  : constant size_t := (Item'Size + SU - 1) / SU;
 161       Rsiz : size_t;
 162
 163    begin
 164       FIO.Check_Read_Status (AP (File));
 165
 166       --  For non-definite type or type with discriminants, read size and
 167       --  raise Program_Error if it is larger than the size of the item.
 168
 169       if not Element_Type'Definite
 170         or else Element_Type'Has_Discriminants
 171       then
 172          FIO.Read_Buf
 173            (AP (File), Rsiz'Address, size_t'Size / System.Storage_Unit);
 174
 175          --  For a type with discriminants, we have to read into a temporary
 176          --  buffer if Item is constrained, to check that the discriminants
 177          --  are correct.
 178
 179          pragma Extensions_Allowed (On);
 180          --  Needed to allow Constrained reference here
 181
 182          if Element_Type'Has_Discriminants
 183            and then Item'Constrained
 184          then
 185             declare
 186                RsizS : constant SSE.Storage_Offset :=
 187                          SSE.Storage_Offset (Rsiz - 1);
 188
 189                type SA is new SSE.Storage_Array (0 .. RsizS);
 190
 191                for SA'Alignment use Standard'Maximum_Alignment;
 192                --  We will perform an unchecked conversion of a pointer-to-SA
 193                --  into pointer-to-Element_Type. We need to ensure that the
 194                --  source is always at least as strictly aligned as the target.
 195
 196                type SAP   is access all SA;
 197                type ItemP is access all Element_Type;
 198
 199                pragma Warnings (Off);
 200                --  We have to turn warnings off for function To_ItemP,
 201                --  because it gets analyzed for all types, including ones
 202                --  which can't possibly come this way, and for which the
 203                --  size of the access types differs.
 204
 205                function To_ItemP is new Ada.Unchecked_Conversion (SAP, ItemP);
 206
 207                pragma Warnings (On);
 208
 209                Buffer : aliased SA;
 210
 211                pragma Unsuppress (Discriminant_Check);
 212
 213             begin
 214                FIO.Read_Buf (AP (File), Buffer'Address, Rsiz);
 215                Item := To_ItemP (Buffer'Access).all;
 216                return;
 217             end;
 218          end if;
 219
 220          --  In the case of a non-definite type, make sure the length is OK.
 221          --  We can't do this in the variant record case, because the size is
 222          --  based on the current discriminant, so may be apparently wrong.
 223
 224          if not Element_Type'Has_Discriminants and then Rsiz > Siz then
 225             raise Program_Error;
 226          end if;
 227
 228          FIO.Read_Buf (AP (File), Item'Address, Rsiz);
 229
 230       --  For definite type without discriminants, use actual size of item
 231
 232       else
 233          FIO.Read_Buf (AP (File), Item'Address, Siz);
 234       end if;
 235    end Read;
 236
 237    -----------
 238    -- Reset --
 239    -----------
 240
 241    procedure Reset (File : in out File_Type; Mode : File_Mode) is
 242    begin
 243       FIO.Reset (AP (File)'Unrestricted_Access, To_FCB (Mode));
 244    end Reset;
 245
 246    procedure Reset (File : in out File_Type) is
 247    begin
 248       FIO.Reset (AP (File)'Unrestricted_Access);
 249    end Reset;
 250
 251    -----------
 252    -- Write --
 253    -----------
 254
 255    procedure Write (File : File_Type; Item : Element_Type) is
 256       Siz : constant size_t := (Item'Size + SU - 1) / SU;
 257
 258    begin
 259       FIO.Check_Write_Status (AP (File));
 260
 261       --  For non-definite types or types with discriminants, write the size
 262
 263       if not Element_Type'Definite
 264         or else Element_Type'Has_Discriminants
 265       then
 266          FIO.Write_Buf
 267            (AP (File), Siz'Address, size_t'Size / System.Storage_Unit);
 268       end if;
 269
 270       FIO.Write_Buf (AP (File), Item'Address, Siz);
 271    end Write;
 272
 273 end Ada.Sequential_IO;