| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME COMPONENTS -- |
| -- -- |
| -- S Y S T E M . F I L E _ C O N T R O L _ B L O C K -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2012, Free Software Foundation, Inc. -- |
| -- -- |
| -- GNAT is free software; you can redistribute it and/or modify it under -- |
| -- terms of the GNU General Public License as published by the Free Soft- -- |
| -- ware Foundation; either version 3, or (at your option) any later ver- -- |
| -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- |
| -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- |
| -- or FITNESS FOR A PARTICULAR PURPOSE. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- GNAT was originally developed by the GNAT team at New York University. -- |
| -- Extensive contributions were provided by Ada Core Technologies Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- This package contains the declaration of the basic file control block |
| -- shared between Text_IO, Sequential_IO, Direct_IO and Streams.Stream_IO. |
| -- The actual control blocks are derived from this block by extension. The |
| -- control block is itself derived from Ada.Streams.Root_Stream_Type which |
| -- facilitates implementation of Stream_IO.Stream and Text_Streams.Stream. |
| |
| with Ada.Streams; |
| with Interfaces.C_Streams; |
| with System.CRTL; |
| |
| package System.File_Control_Block is |
| pragma Preelaborate; |
| |
| ---------------------------- |
| -- Ada File Control Block -- |
| ---------------------------- |
| |
| -- The Ada file control block is an abstract extension of the root |
| -- stream type. This allows a file to be treated directly as a stream |
| -- for the purposes of Stream_IO, or stream operations on a text file. |
| -- The individual I/O packages extend this type with package specific |
| -- fields to create the concrete types to which the routines in this |
| -- package can be applied. |
| |
| -- The type File_Type in the individual packages is an access to the |
| -- extended file control block. The value is null if the file is not |
| -- open, and a pointer to the control block if the file is open. |
| |
| type Pstring is access all String; |
| -- Used to hold name and form strings |
| |
| type File_Mode is (In_File, Inout_File, Out_File, Append_File); |
| subtype Read_File_Mode is File_Mode range In_File .. Inout_File; |
| -- File mode (union of file modes permitted by individual packages, |
| -- the types File_Mode in the individual packages are declared to |
| -- allow easy conversion to and from this general type. |
| |
| type Shared_Status_Type is (Yes, No, None); |
| -- This type is used to define the sharing status of a file. The default |
| -- setting of None is used if no "shared=xxx" appears in the form string |
| -- when a file is created or opened. For a file with Shared_Status set to |
| -- None, Use_Error will be raised if any other file is opened or created |
| -- with the same full name. Yes/No are set in response to the presence |
| -- of "shared=yes" or "shared=no" in the form string. In either case it |
| -- is permissible to have multiple files opened with the same full name. |
| -- All files opened simultaneously with "shared=yes" will share the same |
| -- stream with the semantics specified in the RM for file sharing. All |
| -- files opened with "shared=no" will have their own stream. |
| |
| type AFCB is tagged; |
| type AFCB_Ptr is access all AFCB'Class; |
| |
| type AFCB is abstract new Ada.Streams.Root_Stream_Type with record |
| |
| Stream : Interfaces.C_Streams.FILEs; |
| -- The file descriptor |
| |
| Name : Pstring; |
| -- A pointer to the file name. The file name is null for temporary |
| -- files, and also for standard files (stdin, stdout, stderr). The |
| -- name is always null-terminated if it is non-null. |
| |
| Encoding : System.CRTL.Filename_Encoding; |
| -- Encoding used to specified the filename |
| |
| Form : Pstring; |
| -- A pointer to the form string. This is the string used in the |
| -- fopen call, and must be supplied by the caller (there are no |
| -- defaults at this level). The string is always null-terminated. |
| |
| Mode : File_Mode; |
| -- The file mode. No checks are made that the mode is consistent |
| -- with the form used to fopen the file. |
| |
| Is_Regular_File : Boolean; |
| -- A flag indicating if the file is a regular file |
| |
| Is_Temporary_File : Boolean; |
| -- A flag set only for temporary files (i.e. files created using the |
| -- Create function with a null name parameter, using tmpfile). This |
| -- is currently not used since temporary files are deleted by the |
| -- operating system, but it is set properly in case some systems |
| -- need this information in the future. |
| |
| Is_System_File : Boolean; |
| -- A flag set only for system files (stdin, stdout, stderr) |
| |
| Is_Text_File : Boolean; |
| -- A flag set if the file was opened in text mode |
| |
| Shared_Status : Shared_Status_Type; |
| -- Indicates sharing status of file, see description of type above |
| |
| Access_Method : Character; |
| -- Set to 'Q', 'S', 'T', 'D' for Sequential_IO, Stream_IO, Text_IO, |
| -- Direct_IO file (used to validate file sharing request). |
| |
| Next : AFCB_Ptr; |
| Prev : AFCB_Ptr; |
| -- All open files are kept on a doubly linked chain, with these |
| -- pointers used to maintain the next and previous pointers. |
| |
| end record; |
| |
| ---------------------------------- |
| -- Primitive Operations of AFCB -- |
| ---------------------------------- |
| |
| -- Note that we inherit the abstract operations Read and Write from |
| -- the base type. These must be overridden by the individual file |
| -- access methods to provide Stream Read/Write access. |
| |
| function AFCB_Allocate (Control_Block : AFCB) return AFCB_Ptr is abstract; |
| -- Given a control block, allocate space for a control block of the same |
| -- type on the heap, and return the pointer to this allocated block. Note |
| -- that the argument Control_Block is not used other than as the argument |
| -- that controls which version of AFCB_Allocate is called. |
| |
| procedure AFCB_Close (File : not null access AFCB) is abstract; |
| -- Performs any specialized close actions on a file before the file is |
| -- actually closed at the system level. This is called by Close, and |
| -- the reason we need the primitive operation is for the automatic |
| -- close operations done as part of finalization. |
| |
| procedure AFCB_Free (File : not null access AFCB) is abstract; |
| -- Frees the AFCB referenced by the given parameter. It is not necessary |
| -- to free the strings referenced by the Form and Name fields, but if the |
| -- extension has any other heap objects, they must be freed as well. This |
| -- procedure must be overridden by each individual file package. |
| |
| end System.File_Control_Block; |
