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gcc 7
author kono
date Fri, 27 Oct 2017 22:46:09 +0900
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children 84e7813d76e9
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68:561a7518be6b 111:04ced10e8804
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME COMPONENTS --
4 -- --
5 -- S Y S T E M . F I L E _ C O N T R O L _ B L O C K --
6 -- --
7 -- S p e c --
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 package contains the declaration of the basic file control block
33 -- shared between Text_IO, Sequential_IO, Direct_IO and Streams.Stream_IO.
34 -- The actual control blocks are derived from this block by extension. The
35 -- control block is itself derived from Ada.Streams.Root_Stream_Type which
36 -- facilitates implementation of Stream_IO.Stream and Text_Streams.Stream.
37
38 with Ada.Streams;
39 with Interfaces.C_Streams;
40 with System.CRTL;
41
42 package System.File_Control_Block is
43 pragma Preelaborate;
44
45 ----------------------------
46 -- Ada File Control Block --
47 ----------------------------
48
49 -- The Ada file control block is an abstract extension of the root
50 -- stream type. This allows a file to be treated directly as a stream
51 -- for the purposes of Stream_IO, or stream operations on a text file.
52 -- The individual I/O packages extend this type with package specific
53 -- fields to create the concrete types to which the routines in this
54 -- package can be applied.
55
56 -- The type File_Type in the individual packages is an access to the
57 -- extended file control block. The value is null if the file is not
58 -- open, and a pointer to the control block if the file is open.
59
60 type Pstring is access all String;
61 -- Used to hold name and form strings
62
63 type File_Mode is (In_File, Inout_File, Out_File, Append_File);
64 subtype Read_File_Mode is File_Mode range In_File .. Inout_File;
65 -- File mode (union of file modes permitted by individual packages,
66 -- the types File_Mode in the individual packages are declared to
67 -- allow easy conversion to and from this general type.
68
69 type Shared_Status_Type is (Yes, No, None);
70 -- This type is used to define the sharing status of a file. The default
71 -- setting of None is used if no "shared=xxx" appears in the form string
72 -- when a file is created or opened. For a file with Shared_Status set to
73 -- None, Use_Error will be raised if any other file is opened or created
74 -- with the same full name. Yes/No are set in response to the presence
75 -- of "shared=yes" or "shared=no" in the form string. In either case it
76 -- is permissible to have multiple files opened with the same full name.
77 -- All files opened simultaneously with "shared=yes" will share the same
78 -- stream with the semantics specified in the RM for file sharing. All
79 -- files opened with "shared=no" will have their own stream.
80
81 type AFCB is tagged;
82 type AFCB_Ptr is access all AFCB'Class;
83
84 type AFCB is abstract new Ada.Streams.Root_Stream_Type with record
85
86 Stream : Interfaces.C_Streams.FILEs;
87 -- The file descriptor
88
89 Name : Pstring;
90 -- A pointer to the file name. The file name is null for temporary
91 -- files, and also for standard files (stdin, stdout, stderr). The
92 -- name is always NUL-terminated if it is non-null.
93
94 Encoding : System.CRTL.Filename_Encoding;
95 -- Encoding used to specified the filename
96
97 Form : Pstring;
98 -- A pointer to the form string. This is the string used in the
99 -- fopen call, and must be supplied by the caller (there are no
100 -- defaults at this level). The string is always null-terminated.
101
102 Mode : File_Mode;
103 -- The file mode. No checks are made that the mode is consistent
104 -- with the form used to fopen the file.
105
106 Is_Regular_File : Boolean;
107 -- A flag indicating if the file is a regular file
108
109 Is_Temporary_File : Boolean;
110 -- A flag set only for temporary files (i.e. files created using the
111 -- Create function with a null name parameter).
112
113 Is_System_File : Boolean;
114 -- A flag set only for system files (stdin, stdout, stderr)
115
116 Text_Encoding : Interfaces.C_Streams.Content_Encoding;
117 -- A flag set to describe file content encoding
118
119 Shared_Status : Shared_Status_Type;
120 -- Indicates sharing status of file, see description of type above
121
122 Access_Method : Character;
123 -- Set to 'Q', 'S', 'T', 'D' for Sequential_IO, Stream_IO, Text_IO,
124 -- Direct_IO file (used to validate file sharing request).
125
126 Next : AFCB_Ptr;
127 Prev : AFCB_Ptr;
128 -- All open files are kept on a doubly linked chain, with these
129 -- pointers used to maintain the next and previous pointers.
130
131 end record;
132
133 ----------------------------------
134 -- Primitive Operations of AFCB --
135 ----------------------------------
136
137 -- Note that we inherit the abstract operations Read and Write from
138 -- the base type. These must be overridden by the individual file
139 -- access methods to provide Stream Read/Write access.
140
141 function AFCB_Allocate (Control_Block : AFCB) return AFCB_Ptr is abstract;
142 -- Given a control block, allocate space for a control block of the same
143 -- type on the heap, and return the pointer to this allocated block. Note
144 -- that the argument Control_Block is not used other than as the argument
145 -- that controls which version of AFCB_Allocate is called.
146
147 procedure AFCB_Close (File : not null access AFCB) is abstract;
148 -- Performs any specialized close actions on a file before the file is
149 -- actually closed at the system level. This is called by Close, and
150 -- the reason we need the primitive operation is for the automatic
151 -- close operations done as part of finalization.
152
153 procedure AFCB_Free (File : not null access AFCB) is abstract;
154 -- Frees the AFCB referenced by the given parameter. It is not necessary
155 -- to free the strings referenced by the Form and Name fields, but if the
156 -- extension has any other heap objects, they must be freed as well. This
157 -- procedure must be overridden by each individual file package.
158
159 end System.File_Control_Block;