gcc/ada/s-direio.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                     S Y S T E M . D I R E C T _ I O                      --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2006, 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 with Ada.IO_Exceptions;      use Ada.IO_Exceptions;
  35 with Interfaces.C_Streams;   use Interfaces.C_Streams;
  36 with System;                 use System;
  37 with System.CRTL;
  38 with System.File_IO;
  39 with System.Soft_Links;
  40 with Unchecked_Deallocation;
  41
  42 package body System.Direct_IO is
  43
  44    package FIO renames System.File_IO;
  45    package SSL renames System.Soft_Links;
  46
  47    subtype AP is FCB.AFCB_Ptr;
  48    use type FCB.Shared_Status_Type;
  49
  50    use type System.CRTL.long;
  51    use type System.CRTL.size_t;
  52
  53    -----------------------
  54    -- Local Subprograms --
  55    -----------------------
  56
  57    procedure Set_Position (File : File_Type);
  58    --  Sets file position pointer according to value of current index
  59
  60    -------------------
  61    -- AFCB_Allocate --
  62    -------------------
  63
  64    function AFCB_Allocate (Control_Block : Direct_AFCB) return FCB.AFCB_Ptr is
  65       pragma Unreferenced (Control_Block);
  66
  67    begin
  68       return new Direct_AFCB;
  69    end AFCB_Allocate;
  70
  71    ----------------
  72    -- AFCB_Close --
  73    ----------------
  74
  75    --  No special processing required for Direct_IO close
  76
  77    procedure AFCB_Close (File : access Direct_AFCB) is
  78       pragma Unreferenced (File);
  79
  80    begin
  81       null;
  82    end AFCB_Close;
  83
  84    ---------------
  85    -- AFCB_Free --
  86    ---------------
  87
  88    procedure AFCB_Free (File : access Direct_AFCB) is
  89
  90       type FCB_Ptr is access all Direct_AFCB;
  91
  92       FT : FCB_Ptr := FCB_Ptr (File);
  93
  94       procedure Free is new
  95         Unchecked_Deallocation (Direct_AFCB, FCB_Ptr);
  96
  97    begin
  98       Free (FT);
  99    end AFCB_Free;
 100
 101    ------------
 102    -- Create --
 103    ------------
 104
 105    procedure Create
 106      (File : in out File_Type;
 107       Mode : FCB.File_Mode := FCB.Inout_File;
 108       Name : String := "";
 109       Form : String := "")
 110    is
 111       Dummy_File_Control_Block : Direct_AFCB;
 112       pragma Warnings (Off, Dummy_File_Control_Block);
 113       --  Yes, we know this is never assigned a value, only the tag
 114       --  is used for dispatching purposes, so that's expected.
 115
 116    begin
 117       FIO.Open (File_Ptr  => AP (File),
 118                 Dummy_FCB => Dummy_File_Control_Block,
 119                 Mode      => Mode,
 120                 Name      => Name,
 121                 Form      => Form,
 122                 Amethod   => 'D',
 123                 Creat     => True,
 124                 Text      => False);
 125    end Create;
 126
 127    -----------------
 128    -- End_Of_File --
 129    -----------------
 130
 131    function End_Of_File (File : File_Type) return Boolean is
 132    begin
 133       FIO.Check_Read_Status (AP (File));
 134       return Count (File.Index) > Size (File);
 135    end End_Of_File;
 136
 137    -----------
 138    -- Index --
 139    -----------
 140
 141    function Index (File : File_Type) return Positive_Count is
 142    begin
 143       FIO.Check_File_Open (AP (File));
 144       return Count (File.Index);
 145    end Index;
 146
 147    ----------
 148    -- Open --
 149    ----------
 150
 151    procedure Open
 152      (File : in out File_Type;
 153       Mode : FCB.File_Mode;
 154       Name : String;
 155       Form : String := "")
 156    is
 157       Dummy_File_Control_Block : Direct_AFCB;
 158       pragma Warnings (Off, Dummy_File_Control_Block);
 159       --  Yes, we know this is never assigned a value, only the tag
 160       --  is used for dispatching purposes, so that's expected.
 161
 162    begin
 163       FIO.Open (File_Ptr  => AP (File),
 164                 Dummy_FCB => Dummy_File_Control_Block,
 165                 Mode      => Mode,
 166                 Name      => Name,
 167                 Form      => Form,
 168                 Amethod   => 'D',
 169                 Creat     => False,
 170                 Text      => False);
 171    end Open;
 172
 173    ----------
 174    -- Read --
 175    ----------
 176
 177    procedure Read
 178      (File : File_Type;
 179       Item : Address;
 180       Size : Interfaces.C_Streams.size_t;
 181       From : Positive_Count)
 182    is
 183    begin
 184       Set_Index (File, From);
 185       Read (File, Item, Size);
 186    end Read;
 187
 188    procedure Read
 189      (File : File_Type;
 190       Item : Address;
 191       Size : Interfaces.C_Streams.size_t)
 192    is
 193    begin
 194       FIO.Check_Read_Status (AP (File));
 195
 196       --  If last operation was not a read, or if in file sharing mode,
 197       --  then reset the physical pointer of the file to match the index
 198       --  We lock out task access over the two operations in this case.
 199
 200       if File.Last_Op /= Op_Read
 201         or else File.Shared_Status = FCB.Yes
 202       then
 203          if End_Of_File (File) then
 204             raise End_Error;
 205          end if;
 206
 207          Locked_Processing : begin
 208             SSL.Lock_Task.all;
 209             Set_Position (File);
 210             FIO.Read_Buf (AP (File), Item, Size);
 211             SSL.Unlock_Task.all;
 212
 213          exception
 214             when others =>
 215                SSL.Unlock_Task.all;
 216                raise;
 217          end Locked_Processing;
 218
 219       else
 220          FIO.Read_Buf (AP (File), Item, Size);
 221       end if;
 222
 223       File.Index := File.Index + 1;
 224
 225       --  Set last operation to read, unless we did not read a full record
 226       --  (happens with the variant record case) in which case we set the
 227       --  last operation as other, to force the file position to be reset
 228       --  on the next read.
 229
 230       if File.Bytes = Size then
 231          File.Last_Op := Op_Read;
 232       else
 233          File.Last_Op := Op_Other;
 234       end if;
 235    end Read;
 236
 237    --  The following is the required overriding for Stream.Read, which is
 238    --  not used, since we do not do Stream operations on Direct_IO files.
 239
 240    procedure Read
 241      (File : in out Direct_AFCB;
 242       Item : out Ada.Streams.Stream_Element_Array;
 243       Last : out Ada.Streams.Stream_Element_Offset)
 244    is
 245    begin
 246       raise Program_Error;
 247    end Read;
 248
 249    -----------
 250    -- Reset --
 251    -----------
 252
 253    procedure Reset (File : in out File_Type; Mode : FCB.File_Mode) is
 254    begin
 255       FIO.Reset (AP (File), Mode);
 256       File.Index := 1;
 257       File.Last_Op := Op_Read;
 258    end Reset;
 259
 260    procedure Reset (File : in out File_Type) is
 261    begin
 262       FIO.Reset (AP (File));
 263       File.Index := 1;
 264       File.Last_Op := Op_Read;
 265    end Reset;
 266
 267    ---------------
 268    -- Set_Index --
 269    ---------------
 270
 271    procedure Set_Index (File : File_Type; To : Positive_Count) is
 272    begin
 273       FIO.Check_File_Open (AP (File));
 274       File.Index := Count (To);
 275       File.Last_Op := Op_Other;
 276    end Set_Index;
 277
 278    ------------------
 279    -- Set_Position --
 280    ------------------
 281
 282    procedure Set_Position (File : File_Type) is
 283    begin
 284       if fseek
 285            (File.Stream, long (File.Bytes) *
 286               long (File.Index - 1), SEEK_SET) /= 0
 287       then
 288          raise Use_Error;
 289       end if;
 290    end Set_Position;
 291
 292    ----------
 293    -- Size --
 294    ----------
 295
 296    function Size (File : File_Type) return Count is
 297    begin
 298       FIO.Check_File_Open (AP (File));
 299       File.Last_Op := Op_Other;
 300
 301       if fseek (File.Stream, 0, SEEK_END) /= 0 then
 302          raise Device_Error;
 303       end if;
 304
 305       return Count (ftell (File.Stream) / long (File.Bytes));
 306    end Size;
 307
 308    -----------
 309    -- Write --
 310    -----------
 311
 312    procedure Write
 313      (File   : File_Type;
 314       Item   : Address;
 315       Size   : Interfaces.C_Streams.size_t;
 316       Zeroes : System.Storage_Elements.Storage_Array)
 317
 318    is
 319       procedure Do_Write;
 320       --  Do the actual write
 321
 322       procedure Do_Write is
 323       begin
 324          FIO.Write_Buf (AP (File), Item, Size);
 325
 326          --  If we did not write the whole record (happens with the variant
 327          --  record case), then fill out the rest of the record with zeroes.
 328          --  This is cleaner in any case, and is required for the last
 329          --  record, since otherwise the length of the file is wrong.
 330
 331          if File.Bytes > Size then
 332             FIO.Write_Buf (AP (File), Zeroes'Address, File.Bytes - Size);
 333          end if;
 334       end Do_Write;
 335
 336    --  Start of processing for Write
 337
 338    begin
 339       FIO.Check_Write_Status (AP (File));
 340
 341       --  If last operation was not a write, or if in file sharing mode,
 342       --  then reset the physical pointer of the file to match the index
 343       --  We lock out task access over the two operations in this case.
 344
 345       if File.Last_Op /= Op_Write
 346         or else File.Shared_Status = FCB.Yes
 347       then
 348          Locked_Processing : begin
 349             SSL.Lock_Task.all;
 350             Set_Position (File);
 351             Do_Write;
 352             SSL.Unlock_Task.all;
 353
 354          exception
 355             when others =>
 356                SSL.Unlock_Task.all;
 357                raise;
 358          end Locked_Processing;
 359
 360       else
 361          Do_Write;
 362       end if;
 363
 364       File.Index := File.Index + 1;
 365
 366       --  Set last operation to write, unless we did not read a full record
 367       --  (happens with the variant record case) in which case we set the
 368       --  last operation as other, to force the file position to be reset
 369       --  on the next write.
 370
 371       if File.Bytes = Size then
 372          File.Last_Op := Op_Write;
 373       else
 374          File.Last_Op := Op_Other;
 375       end if;
 376    end Write;
 377
 378    --  The following is the required overriding for Stream.Write, which is
 379    --  not used, since we do not do Stream operations on Direct_IO files.
 380
 381    procedure Write
 382      (File : in out Direct_AFCB;
 383       Item : Ada.Streams.Stream_Element_Array)
 384    is
 385    begin
 386       raise Program_Error;
 387    end Write;
 388
 389 end System.Direct_IO;