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) 1992-2021, 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 size_t'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
314end Ada.Sequential_IO;
315