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) 1992-2013, 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
37with Ada.Unchecked_Conversion;
38
39with System;
40with System.Byte_Swapping;
41with System.CRTL;
42with System.File_Control_Block;
43with System.File_IO;
44with System.Storage_Elements;
45
46with Interfaces.C_Streams; use Interfaces.C_Streams;
47
48package 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   -- Form --
126   ----------
127
128   function Form (File : File_Type) return String is
129   begin
130      return FIO.Form (AP (File));
131   end Form;
132
133   -------------
134   -- Is_Open --
135   -------------
136
137   function Is_Open (File : File_Type) return Boolean is
138   begin
139      return FIO.Is_Open (AP (File));
140   end Is_Open;
141
142   ----------
143   -- Mode --
144   ----------
145
146   function Mode (File : File_Type) return File_Mode is
147   begin
148      return To_SIO (FIO.Mode (AP (File)));
149   end Mode;
150
151   ----------
152   -- Name --
153   ----------
154
155   function Name (File : File_Type) return String is
156   begin
157      return FIO.Name (AP (File));
158   end Name;
159
160   ----------
161   -- Open --
162   ----------
163
164   procedure Open
165     (File : in out File_Type;
166      Mode : File_Mode;
167      Name : String;
168      Form : String := "")
169   is
170   begin
171      SIO.Open (FP (File), To_FCB (Mode), Name, Form);
172   end Open;
173
174   ----------
175   -- Read --
176   ----------
177
178   procedure Read (File : File_Type; Item : out Element_Type) is
179      Siz  : constant size_t := (Item'Size + SU - 1) / SU;
180      Rsiz : size_t;
181
182   begin
183      FIO.Check_Read_Status (AP (File));
184
185      --  For non-definite type or type with discriminants, read size and
186      --  raise Program_Error if it is larger than the size of the item.
187
188      if not Element_Type'Definite
189        or else Element_Type'Has_Discriminants
190      then
191         FIO.Read_Buf
192           (AP (File), Rsiz'Address, size_t'Size / System.Storage_Unit);
193
194         --  If item read has non-default scalar storage order, then the size
195         --  will have been written with that same order, so byte swap it.
196
197         if Element_Type'Scalar_Storage_Order /= System.Default_Bit_Order then
198            Byte_Swap (Rsiz);
199         end if;
200
201         --  For a type with discriminants, we have to read into a temporary
202         --  buffer if Item is constrained, to check that the discriminants
203         --  are correct.
204
205         if Element_Type'Has_Discriminants and then Item'Constrained then
206            declare
207               RsizS : constant SSE.Storage_Offset :=
208                         SSE.Storage_Offset (Rsiz - 1);
209
210               type SA is new SSE.Storage_Array (0 .. RsizS);
211
212               for SA'Alignment use Standard'Maximum_Alignment;
213               --  We will perform an unchecked conversion of a pointer-to-SA
214               --  into pointer-to-Element_Type. We need to ensure that the
215               --  source is always at least as strictly aligned as the target.
216
217               type SAP   is access all SA;
218               type ItemP is access all Element_Type;
219
220               pragma Warnings (Off);
221               --  We have to turn warnings off for function To_ItemP,
222               --  because it gets analyzed for all types, including ones
223               --  which can't possibly come this way, and for which the
224               --  size of the access types differs.
225
226               function To_ItemP is new Ada.Unchecked_Conversion (SAP, ItemP);
227
228               pragma Warnings (On);
229
230               Buffer : aliased SA;
231
232               pragma Unsuppress (Discriminant_Check);
233
234            begin
235               FIO.Read_Buf (AP (File), Buffer'Address, Rsiz);
236               Item := To_ItemP (Buffer'Access).all;
237               return;
238            end;
239         end if;
240
241         --  In the case of a non-definite type, make sure the length is OK.
242         --  We can't do this in the variant record case, because the size is
243         --  based on the current discriminant, so may be apparently wrong.
244
245         if not Element_Type'Has_Discriminants and then Rsiz > Siz then
246            raise Program_Error;
247         end if;
248
249         FIO.Read_Buf (AP (File), Item'Address, Rsiz);
250
251      --  For definite type without discriminants, use actual size of item
252
253      else
254         FIO.Read_Buf (AP (File), Item'Address, Siz);
255      end if;
256   end Read;
257
258   -----------
259   -- Reset --
260   -----------
261
262   procedure Reset (File : in out File_Type; Mode : File_Mode) is
263   begin
264      FIO.Reset (AP (File)'Unrestricted_Access, To_FCB (Mode));
265   end Reset;
266
267   procedure Reset (File : in out File_Type) is
268   begin
269      FIO.Reset (AP (File)'Unrestricted_Access);
270   end Reset;
271
272   -----------
273   -- Write --
274   -----------
275
276   procedure Write (File : File_Type; Item : Element_Type) is
277      Siz : constant size_t := (Item'Size + SU - 1) / SU;
278      --  Size to be written, in native representation
279
280      Swapped_Siz : size_t := Siz;
281      --  Same, possibly byte swapped to account for Element_Type endianness
282
283   begin
284      FIO.Check_Write_Status (AP (File));
285
286      --  For non-definite types or types with discriminants, write the size
287
288      if not Element_Type'Definite
289        or else Element_Type'Has_Discriminants
290      then
291         --  If item written has non-default scalar storage order, then the
292         --  size is written with that same order, so byte swap it.
293
294         if Element_Type'Scalar_Storage_Order /= System.Default_Bit_Order then
295            Byte_Swap (Swapped_Siz);
296         end if;
297
298         FIO.Write_Buf
299           (AP (File), Swapped_Siz'Address, size_t'Size / System.Storage_Unit);
300      end if;
301
302      FIO.Write_Buf (AP (File), Item'Address, Siz);
303   end Write;
304
305end Ada.Sequential_IO;
306