gcc/ada/libgnat/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) 1992-2017, 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 3,  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.                                     --
  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 --  This is the generic template for Sequential_IO, i.e. the code that gets
  33 --  duplicated. We absolutely minimize this code by either calling routines
  34 --  in System.File_IO (for common file functions), or in System.Sequential_IO
  35 --  (for specialized Sequential_IO functions)
  36
  37 with Ada.Unchecked_Conversion;
  38
  39 with System;
  40 with System.Byte_Swapping;
  41 with System.CRTL;
  42 with System.File_Control_Block;
  43 with System.File_IO;
  44 with System.Storage_Elements;
  45
  46 with Interfaces.C_Streams; use Interfaces.C_Streams;
  47
  48 package body Ada.Sequential_IO is
  49
  50    package FIO renames System.File_IO;
  51    package FCB renames System.File_Control_Block;
  52    package SIO renames System.Sequential_IO;
  53    package SSE renames System.Storage_Elements;
  54
  55    SU : constant := System.Storage_Unit;
  56
  57    subtype AP is FCB.AFCB_Ptr;
  58    subtype FP is SIO.File_Type;
  59
  60    function To_FCB is new Ada.Unchecked_Conversion (File_Mode, FCB.File_Mode);
  61    function To_SIO is new Ada.Unchecked_Conversion (FCB.File_Mode, File_Mode);
  62
  63    use type System.Bit_Order;
  64    use type System.CRTL.size_t;
  65
  66    procedure Byte_Swap (Siz : in out size_t);
  67    --  Byte swap Siz
  68
  69    ---------------
  70    -- Byte_Swap --
  71    ---------------
  72
  73    procedure Byte_Swap (Siz : in out size_t) is
  74       use System.Byte_Swapping;
  75    begin
  76       case Siz'Size is
  77          when 32     => Siz := size_t (Bswap_32 (U32 (Siz)));
  78          when 64     => Siz := size_t (Bswap_64 (U64 (Siz)));
  79          when others => raise Program_Error;
  80       end case;
  81    end Byte_Swap;
  82
  83    -----------
  84    -- Close --
  85    -----------
  86
  87    procedure Close (File : in out File_Type) is
  88    begin
  89       FIO.Close (AP (File)'Unrestricted_Access);
  90    end Close;
  91
  92    ------------
  93    -- Create --
  94    ------------
  95
  96    procedure Create
  97      (File : in out File_Type;
  98       Mode : File_Mode := Out_File;
  99       Name : String := "";
 100       Form : String := "")
 101    is
 102    begin
 103       SIO.Create (FP (File), To_FCB (Mode), Name, Form);
 104    end Create;
 105
 106    ------------
 107    -- Delete --
 108    ------------
 109
 110    procedure Delete (File : in out File_Type) is
 111    begin
 112       FIO.Delete (AP (File)'Unrestricted_Access);
 113    end Delete;
 114
 115    -----------------
 116    -- End_Of_File --
 117    -----------------
 118
 119    function End_Of_File (File : File_Type) return Boolean is
 120    begin
 121       return FIO.End_Of_File (AP (File));
 122    end End_Of_File;
 123
 124    -----------
 125    -- Flush --
 126    -----------
 127
 128    procedure Flush (File : File_Type) is
 129    begin
 130       FIO.Flush (AP (File));
 131    end Flush;
 132
 133    ----------
 134    -- Form --
 135    ----------
 136
 137    function Form (File : File_Type) return String is
 138    begin
 139       return FIO.Form (AP (File));
 140    end Form;
 141
 142    -------------
 143    -- Is_Open --
 144    -------------
 145
 146    function Is_Open (File : File_Type) return Boolean is
 147    begin
 148       return FIO.Is_Open (AP (File));
 149    end Is_Open;
 150
 151    ----------
 152    -- Mode --
 153    ----------
 154
 155    function Mode (File : File_Type) return File_Mode is
 156    begin
 157       return To_SIO (FIO.Mode (AP (File)));
 158    end Mode;
 159
 160    ----------
 161    -- Name --
 162    ----------
 163
 164    function Name (File : File_Type) return String is
 165    begin
 166       return FIO.Name (AP (File));
 167    end Name;
 168
 169    ----------
 170    -- Open --
 171    ----------
 172
 173    procedure Open
 174      (File : in out File_Type;
 175       Mode : File_Mode;
 176       Name : String;
 177       Form : String := "")
 178    is
 179    begin
 180       SIO.Open (FP (File), To_FCB (Mode), Name, Form);
 181    end Open;
 182
 183    ----------
 184    -- Read --
 185    ----------
 186
 187    procedure Read (File : File_Type; Item : out Element_Type) is
 188       Siz  : constant size_t := (Item'Size + SU - 1) / SU;
 189       Rsiz : size_t;
 190
 191    begin
 192       FIO.Check_Read_Status (AP (File));
 193
 194       --  For non-definite type or type with discriminants, read size and
 195       --  raise Program_Error if it is larger than the size of the item.
 196
 197       if not Element_Type'Definite
 198         or else Element_Type'Has_Discriminants
 199       then
 200          FIO.Read_Buf
 201            (AP (File), Rsiz'Address, size_t'Size / System.Storage_Unit);
 202
 203          --  If item read has non-default scalar storage order, then the size
 204          --  will have been written with that same order, so byte swap it.
 205
 206          if Element_Type'Scalar_Storage_Order /= System.Default_Bit_Order then
 207             Byte_Swap (Rsiz);
 208          end if;
 209
 210          --  For a type with discriminants, we have to read into a temporary
 211          --  buffer if Item is constrained, to check that the discriminants
 212          --  are correct.
 213
 214          if Element_Type'Has_Discriminants and then Item'Constrained then
 215             declare
 216                RsizS : constant SSE.Storage_Offset :=
 217                          SSE.Storage_Offset (Rsiz - 1);
 218
 219                type SA is new SSE.Storage_Array (0 .. RsizS);
 220
 221                for SA'Alignment use Standard'Maximum_Alignment;
 222                --  We will perform an unchecked conversion of a pointer-to-SA
 223                --  into pointer-to-Element_Type. We need to ensure that the
 224                --  source is always at least as strictly aligned as the target.
 225
 226                type SAP   is access all SA;
 227                type ItemP is access all Element_Type;
 228
 229                pragma Warnings (Off);
 230                --  We have to turn warnings off for function To_ItemP,
 231                --  because it gets analyzed for all types, including ones
 232                --  which can't possibly come this way, and for which the
 233                --  size of the access types differs.
 234
 235                function To_ItemP is new Ada.Unchecked_Conversion (SAP, ItemP);
 236
 237                pragma Warnings (On);
 238
 239                Buffer : aliased SA;
 240
 241                pragma Unsuppress (Discriminant_Check);
 242
 243             begin
 244                FIO.Read_Buf (AP (File), Buffer'Address, Rsiz);
 245                Item := To_ItemP (Buffer'Access).all;
 246                return;
 247             end;
 248          end if;
 249
 250          --  In the case of a non-definite type, make sure the length is OK.
 251          --  We can't do this in the variant record case, because the size is
 252          --  based on the current discriminant, so may be apparently wrong.
 253
 254          if not Element_Type'Has_Discriminants and then Rsiz > Siz then
 255             raise Program_Error;
 256          end if;
 257
 258          FIO.Read_Buf (AP (File), Item'Address, Rsiz);
 259
 260       --  For definite type without discriminants, use actual size of item
 261
 262       else
 263          FIO.Read_Buf (AP (File), Item'Address, Siz);
 264       end if;
 265    end Read;
 266
 267    -----------
 268    -- Reset --
 269    -----------
 270
 271    procedure Reset (File : in out File_Type; Mode : File_Mode) is
 272    begin
 273       FIO.Reset (AP (File)'Unrestricted_Access, To_FCB (Mode));
 274    end Reset;
 275
 276    procedure Reset (File : in out File_Type) is
 277    begin
 278       FIO.Reset (AP (File)'Unrestricted_Access);
 279    end Reset;
 280
 281    -----------
 282    -- Write --
 283    -----------
 284
 285    procedure Write (File : File_Type; Item : Element_Type) is
 286       Siz : constant size_t := (Item'Size + SU - 1) / SU;
 287       --  Size to be written, in native representation
 288
 289       Swapped_Siz : size_t := Siz;
 290       --  Same, possibly byte swapped to account for Element_Type endianness
 291
 292    begin
 293       FIO.Check_Write_Status (AP (File));
 294
 295       --  For non-definite types or types with discriminants, write the size
 296
 297       if not Element_Type'Definite
 298         or else Element_Type'Has_Discriminants
 299       then
 300          --  If item written has non-default scalar storage order, then the
 301          --  size is written with that same order, so byte swap it.
 302
 303          if Element_Type'Scalar_Storage_Order /= System.Default_Bit_Order then
 304             Byte_Swap (Swapped_Siz);
 305          end if;
 306
 307          FIO.Write_Buf
 308            (AP (File), Swapped_Siz'Address, size_t'Size / System.Storage_Unit);
 309       end if;
 310
 311       FIO.Write_Buf (AP (File), Item'Address, Siz);
 312    end Write;
 313
 314 end Ada.Sequential_IO;