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) 1992-2014, 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 38with Ada.Streams; 39with Interfaces.C_Streams; 40with System.CRTL; 41 42package 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 null-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, using tmpfile). This 112 -- is currently not used since temporary files are deleted by the 113 -- operating system, but it is set properly in case some systems 114 -- need this information in the future. 115 116 Is_System_File : Boolean; 117 -- A flag set only for system files (stdin, stdout, stderr) 118 119 Text_Encoding : Interfaces.C_Streams.Content_Encoding; 120 -- A flag set to describe file content encoding 121 122 Shared_Status : Shared_Status_Type; 123 -- Indicates sharing status of file, see description of type above 124 125 Access_Method : Character; 126 -- Set to 'Q', 'S', 'T', 'D' for Sequential_IO, Stream_IO, Text_IO, 127 -- Direct_IO file (used to validate file sharing request). 128 129 Next : AFCB_Ptr; 130 Prev : AFCB_Ptr; 131 -- All open files are kept on a doubly linked chain, with these 132 -- pointers used to maintain the next and previous pointers. 133 134 end record; 135 136 ---------------------------------- 137 -- Primitive Operations of AFCB -- 138 ---------------------------------- 139 140 -- Note that we inherit the abstract operations Read and Write from 141 -- the base type. These must be overridden by the individual file 142 -- access methods to provide Stream Read/Write access. 143 144 function AFCB_Allocate (Control_Block : AFCB) return AFCB_Ptr is abstract; 145 -- Given a control block, allocate space for a control block of the same 146 -- type on the heap, and return the pointer to this allocated block. Note 147 -- that the argument Control_Block is not used other than as the argument 148 -- that controls which version of AFCB_Allocate is called. 149 150 procedure AFCB_Close (File : not null access AFCB) is abstract; 151 -- Performs any specialized close actions on a file before the file is 152 -- actually closed at the system level. This is called by Close, and 153 -- the reason we need the primitive operation is for the automatic 154 -- close operations done as part of finalization. 155 156 procedure AFCB_Free (File : not null access AFCB) is abstract; 157 -- Frees the AFCB referenced by the given parameter. It is not necessary 158 -- to free the strings referenced by the Form and Name fields, but if the 159 -- extension has any other heap objects, they must be freed as well. This 160 -- procedure must be overridden by each individual file package. 161 162end System.File_Control_Block; 163