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Text File | 2000-07-19 | 30KB | 1,000 lines

------------------------------------------------------------------------------ -- -- -- GNAT RUN-TIME COMPONENTS -- -- -- -- S Y S T E M . F I L E _ I O -- -- -- -- B o d y -- -- -- -- $Revision: 1.53 $ -- -- -- Copyright (C) 1992-2000 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 2, 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. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNAT; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- It is now maintained by Ada Core Technologies Inc (http://www.gnat.com). -- -- -- ------------------------------------------------------------------------------ with Ada.Finalization; use Ada.Finalization; with Ada.IO_Exceptions; use Ada.IO_Exceptions; with Interfaces.C_Streams; use Interfaces.C_Streams; with System.Soft_Links; with Unchecked_Deallocation; package body System.File_IO is use System.File_Control_Block; package SSL renames System.Soft_Links; ---------------------- -- Global Variables -- ---------------------- Open_Files : AFCB_Ptr; -- This points to a list of AFCB's for all open files. This is a doubly -- linked list, with the Prev pointer of the first entry, and the Next -- pointer of the last entry containing null. type Temp_File_Record; type Temp_File_Record_Ptr is access all Temp_File_Record; type Temp_File_Record is record Name : String (1 .. L_tmpnam + 1); Next : Temp_File_Record_Ptr; end record; -- One of these is allocated for each temporary file created Temp_Files : Temp_File_Record_Ptr; -- Points to list of names of temporary files type File_IO_Clean_Up_Type is new Controlled with null record; -- The closing of all open files and deletion of temporary files is an -- action which takes place at the end of execution of the main program. -- This action can be implemented using a library level object which -- gets finalized at the end of the main program execution. The above is -- a controlled type introduced for this purpose. procedure Finalize (V : in out File_IO_Clean_Up_Type); -- This is the finalize operation that is used to do the cleanup. File_IO_Clean_Up_Object : File_IO_Clean_Up_Type; -- This is the single object of the type that triggers the finalization -- call. Since it is at the library level, this happens just before the -- environment task is finalized. text_translation_required : Boolean; pragma Import (C, text_translation_required, "text_translation_required"); -- If true, add appropriate suffix to control string for Open. ----------------------- -- Local Subprograms -- ----------------------- procedure Free_String is new Unchecked_Deallocation (String, Pstring); subtype Fopen_String is String (1 .. 4); -- Holds open string (longest is "w+b" & nul) procedure Fopen_Mode (Mode : File_Mode; Text : Boolean; Creat : Boolean; Amethod : Character; Fopstr : out Fopen_String); -- Determines proper open mode for a file to be opened in the given -- Ada mode. Text is true for a text file and false otherwise, and -- Creat is true for a create call, and False for an open call. The -- value stored in Fopstr is a nul-terminated string suitable for a -- call to fopen or freopen. Amethod is the character designating -- the access method from the Access_Method field of the FCB. --------------------- -- Check_File_Open -- --------------------- procedure Check_File_Open (File : AFCB_Ptr) is begin if File = null then raise Status_Error; end if; end Check_File_Open; ---------------- -- Append_Set -- ---------------- procedure Append_Set (File : AFCB_Ptr) is begin if File.Mode = Append_File then if fseek (File.Stream, 0, SEEK_END) /= 0 then raise Device_Error; end if; end if; end Append_Set; ---------------- -- Chain_File -- ---------------- procedure Chain_File (File : AFCB_Ptr) is begin File.Next := Open_Files; File.Prev := null; Open_Files := File; if File.Next /= null then File.Next.Prev := File; end if; end Chain_File; ----------------------- -- Check_Read_Status -- ----------------------- procedure Check_Read_Status (File : AFCB_Ptr) is begin if File = null then raise Status_Error; elsif File.Mode > Inout_File then raise Mode_Error; end if; end Check_Read_Status; ------------------------ -- Check_Write_Status -- ------------------------ procedure Check_Write_Status (File : AFCB_Ptr) is begin if File = null then raise Status_Error; elsif File.Mode = In_File then raise Mode_Error; end if; end Check_Write_Status; ----------- -- Close -- ----------- procedure Close (File : in out AFCB_Ptr) is Close_Status : int := 0; Dup_Strm : Boolean := False; begin Check_File_Open (File); AFCB_Close (File); -- Sever the association between the given file and its associated -- external file. The given file is left closed. Do not perform system -- closes on the standard input, output and error files and also do -- not attempt to close a stream that does not exist (signalled by a -- null stream value -- happens in some error situations). if not File.Is_System_File and then File.Stream /= NULL_Stream then -- Do not do an fclose if this is a shared file and there is -- at least one other instance of the stream that is open. if File.Shared_Status = Yes then declare P : AFCB_Ptr; begin P := Open_Files; while P /= null loop if P /= File and then File.Stream = P.Stream then Dup_Strm := True; exit; end if; P := P.Next; end loop; end; end if; -- Do the fclose unless this was a duplicate in the shared case if not Dup_Strm then Close_Status := fclose (File.Stream); end if; end if; -- Dechain file from list of open files and then free the storage -- Since this is a global data structure, we have to protect against -- multiple tasks attempting to access this list. -- Note that we do not use an exception handler to unlock here since -- no exception can occur inside the lock/unlock pair. SSL.Lock_Task.all; if File.Prev = null then Open_Files := File.Next; else File.Prev.Next := File.Next; end if; if File.Next /= null then File.Next.Prev := File.Prev; end if; SSL.Unlock_Task.all; -- Deallocate some parts of the file structure that were kept in heap -- storage with the exception of system files (standard input, output -- and error) since they had some information allocated in the stack. if not File.Is_System_File then Free_String (File.Name); Free_String (File.Form); AFCB_Free (File); end if; File := null; if Close_Status /= 0 then raise Device_Error; end if; end Close; ------------ -- Delete -- ------------ procedure Delete (File : in out AFCB_Ptr) is begin Check_File_Open (File); if not File.Is_Regular_File then raise Use_Error; end if; declare Filename : aliased constant String := File.Name.all; begin Close (File); if unlink (Filename'Address) = -1 then raise Use_Error; end if; end; end Delete; ----------------- -- End_Of_File -- ----------------- function End_Of_File (File : AFCB_Ptr) return Boolean is begin Check_File_Open (File); if feof (File.Stream) /= 0 then return True; else Check_Read_Status (File); if ungetc (fgetc (File.Stream), File.Stream) = EOF then clearerr (File.Stream); return True; else return False; end if; end if; end End_Of_File; -------------- -- Finalize -- -------------- -- Note: we do not need to worry about locking against multiple task -- access in this routine, since it is called only from the environment -- task just before terminating execution. procedure Finalize (V : in out File_IO_Clean_Up_Type) is Discard : int; Fptr1 : AFCB_Ptr; Fptr2 : AFCB_Ptr; begin -- First close all open files (the slightly complex form of this loop -- is required because Close as a side effect nulls out its argument) Fptr1 := Open_Files; while Fptr1 /= null loop Fptr2 := Fptr1.Next; Close (Fptr1); Fptr1 := Fptr2; end loop; -- Now unlink all temporary files. We do not bother to free the -- blocks because we are just about to terminate the program. We -- also ignore any errors while attempting these unlink operations. while Temp_Files /= null loop Discard := unlink (Temp_Files.Name'Address); Temp_Files := Temp_Files.Next; end loop; end Finalize; ----------- -- Flush -- ----------- procedure Flush (File : AFCB_Ptr) is begin Check_Write_Status (File); if fflush (File.Stream) = 0 then return; else raise Device_Error; end if; end Flush; ---------------- -- Fopen_Mode -- ---------------- -- The fopen mode to be used is shown by the following table: -- OPEN CREATE -- Append_File "r+" "w+" -- In_File "r" "w+" -- Out_File (Direct_IO) "r+" "w" -- Out_File (all others) "w" "w" -- Inout_File "r+" "w+" -- Note: we do not use "a" or "a+" for Append_File, since this would not -- work in the case of stream files, where even if in append file mode, -- you can reset to earlier points in the file. The caller must use the -- Append_Set routine to deal with the necessary positioning. -- Note: in several cases, the fopen mode used allows reading and -- writing, but the setting of the Ada mode is more restrictive. For -- instance, Create in In_File mode uses "w+" which allows writing, -- but the Ada mode In_File will cause any write operations to be -- rejected with Mode_Error in any case. -- Note: for the Out_File/Open cases for other than the Direct_IO case, -- an initial call will be made by the caller to first open the file in -- "r" mode to be sure that it exists. The real open, in "w" mode, will -- then destroy this file. This is peculiar, but that's what Ada semantics -- require and the ACVT tests insist on! -- If text file translation is required, then either b or t is -- added to the mode, depending on the setting of Text. procedure Fopen_Mode (Mode : File_Mode; Text : Boolean; Creat : Boolean; Amethod : Character; Fopstr : out Fopen_String) is Fptr : Positive; begin case Mode is when In_File => if Creat then Fopstr (1) := 'w'; Fopstr (2) := '+'; Fptr := 3; else Fopstr (1) := 'r'; Fptr := 2; end if; when Out_File => if Amethod = 'D' and not Creat then Fopstr (1) := 'r'; Fopstr (2) := '+'; Fptr := 3; else Fopstr (1) := 'w'; Fptr := 2; end if; when Inout_File | Append_File => if Creat then Fopstr (1) := 'w'; else Fopstr (1) := 'r'; end if; Fopstr (2) := '+'; Fptr := 3; end case; -- If text_translation_required is true then we need to append -- either a t or b to the string to get the right mode if text_translation_required then if Text then Fopstr (Fptr) := 't'; else Fopstr (Fptr) := 'b'; end if; Fptr := Fptr + 1; end if; Fopstr (Fptr) := ASCII.NUL; end Fopen_Mode; ---------- -- Form -- ---------- function Form (File : in AFCB_Ptr) return String is begin if File = null then raise Status_Error; else return File.Form.all (1 .. File.Form'Length - 1); end if; end Form; ------------------ -- Form_Boolean -- ------------------ function Form_Boolean (Form : String; Keyword : String; Default : Boolean) return Boolean is V1, V2 : Natural; begin Form_Parameter (Form, Keyword, V1, V2); if V1 = 0 then return Default; elsif Form (V1) = 'y' then return True; elsif Form (V1) = 'n' then return False; else raise Use_Error; end if; end Form_Boolean; ------------------ -- Form_Integer -- ------------------ function Form_Integer (Form : String; Keyword : String; Default : Integer) return Integer is V1, V2 : Natural; V : Integer; begin Form_Parameter (Form, Keyword, V1, V2); if V1 = 0 then return Default; else V := 0; for J in V1 .. V2 loop if Form (J) not in '0' .. '9' then raise Use_Error; else V := V * 10 + Character'Pos (Form (J)) - Character'Pos ('0'); end if; if V > 999_999 then raise Use_Error; end if; end loop; return V; end if; end Form_Integer; -------------------- -- Form_Parameter -- -------------------- procedure Form_Parameter (Form : String; Keyword : String; Start : out Natural; Stop : out Natural) is Klen : constant Integer := Keyword'Length; -- Start of processing for Form_Parameter begin for J in Form'First + Klen .. Form'Last - 1 loop if Form (J) = '=' and then Form (J - Klen .. J - 1) = Keyword then Start := J + 1; Stop := Start - 1; while Form (Stop + 1) /= ASCII.NUL and then Form (Stop + 1) /= ',' loop Stop := Stop + 1; end loop; return; end if; end loop; Start := 0; end Form_Parameter; ------------- -- Is_Open -- ------------- function Is_Open (File : in AFCB_Ptr) return Boolean is begin return (File /= null); end Is_Open; ---------- -- Mode -- ---------- function Mode (File : in AFCB_Ptr) return File_Mode is begin if File = null then raise Status_Error; else return File.Mode; end if; end Mode; ---------- -- Name -- ---------- function Name (File : in AFCB_Ptr) return String is begin if File = null then raise Status_Error; else return File.Name.all (1 .. File.Name'Length - 1); end if; end Name; ---------- -- Open -- ---------- procedure Open (File_Ptr : in out AFCB_Ptr; Dummy_FCB : in out AFCB'Class; Mode : File_Mode; Name : String; Form : String; Amethod : Character; Creat : Boolean; Text : Boolean; C_Stream : FILEs := NULL_Stream) is Stream : FILEs := C_Stream; -- Stream which we open in response to this request Shared : Shared_Status_Type; -- Setting of Shared_Status field for file Fopstr : aliased Fopen_String; -- Mode string used in fopen call Formstr : aliased String (1 .. Form'Length + 1); -- Form string with ASCII.NUL appended, folded to lower case Tempfile : constant Boolean := (Name'Length = 0); -- Indicates temporary file case Namelen : constant Integer := Integer'Max (L_tmpnam, Name'Length); -- Length required for file name, not including final ASCII.NUL Namestr : aliased String (1 .. Namelen + 1); -- Name as given or temporary file name with ASCII.NUL appended Fullname : aliased String (1 .. max_path_len + 1); -- Full name (as required for Name function, and as stored in the -- control block in the Name field) with ASCII.NUL appended. Full_Name_Len : Integer; -- Length of name actually stored in Fullname begin if File_Ptr /= null then raise Status_Error; end if; -- Acquire form string, setting required NUL terminator Formstr (1 .. Form'Length) := Form; Formstr (Formstr'Last) := ASCII.NUL; -- Convert form string to lower case for J in Formstr'Range loop if Formstr (J) in 'A' .. 'Z' then Formstr (J) := Character'Val (Character'Pos (Formstr (J)) + 32); end if; end loop; -- Acquire setting of shared parameter declare V1, V2 : Natural; begin Form_Parameter (Formstr, "shared", V1, V2); if V1 = 0 then Shared := None; elsif Formstr (V1 .. V2) = "yes" then Shared := Yes; elsif Formstr (V1 .. V2) = "no" then Shared := No; else raise Use_Error; end if; end; -- Remaining processing is done with tasking locked out. This ensures -- that the global data structures (temporary file chain and the open -- file chain) retain their integrity. Locked_Processing : begin SSL.Lock_Task.all; -- If we were given a stream (call from xxx.C_Streams.Open), then set -- full name to null and that is all we have to do in this case so -- skip to end of processing. if Stream /= NULL_Stream then Fullname (1) := ASCII.Nul; Full_Name_Len := 1; -- Normal case of Open or Create else -- If temporary file case, get temporary file name and add -- to the list of temporary files to be deleted on exit. if Tempfile then if not Creat then raise Name_Error; end if; tmpnam (Namestr'Address); if Namestr (1) = ASCII.NUL then raise Use_Error; end if; Temp_Files := new Temp_File_Record'(Name => Namestr, Next => Temp_Files); -- Normal case of non-null name given else Namestr (1 .. Name'Length) := Name; Namestr (Name'Length + 1) := ASCII.NUL; end if; -- Get full name in accordance with the advice of RM A.8.2(22). full_name (Namestr'Address, Fullname'Address); if Fullname (1) = ASCII.NUL then raise Use_Error; end if; for J in Fullname'Range loop if Fullname (J) = ASCII.NUL then Full_Name_Len := J; exit; end if; end loop; -- If Shared=None or Shared=Yes, then check for the existence -- of another file with exactly the same full name. if Shared /= No then declare P : AFCB_Ptr; begin P := Open_Files; while P /= null loop if Fullname (1 .. Full_Name_Len) = P.Name.all then -- If we get a match, and either file has Shared=None, -- then raise Use_Error, since we don't allow two -- files of the same name to be opened unless they -- specify the required sharing mode. if Shared = None or else P.Shared_Status = None then raise Use_Error; -- If both files have Shared=Yes, then we acquire the -- stream from the located file to use as our stream. elsif Shared = Yes and then P.Shared_Status = Yes then Stream := P.Stream; exit; -- Otherwise one of the files has Shared=Yes and one -- has Shared=No. If the current file has Shared=No -- then all is well but we don't want to share any -- other file's stream. If the current file has -- Shared=Yes, we would like to share a stream, but -- not from a file that has Shared=No, so in either -- case we just keep going on the search. else null; end if; end if; P := P.Next; end loop; end; end if; -- Open specified file if we did not find an existing stream if Stream = NULL_Stream then Fopen_Mode (Mode, Text, Creat, Amethod, Fopstr); -- A special case, if we are opening (OPEN case) a file and -- the mode returned by Fopen_Mode is not "r" or "r+", then -- we first make sure that the file exists as required by -- Ada semantics. if Creat = False and then Fopstr (1) /= 'r' then if file_exists (Namestr'Address) = 0 then raise Name_Error; end if; end if; Stream := fopen (Namestr'Address, Fopstr'Address); if Stream = NULL_Stream then if file_exists (Namestr'Address) = 0 then raise Name_Error; else raise Use_Error; end if; end if; end if; end if; -- Stream has been successfully located or opened, so now we are -- committed to completing the opening of the file. Allocate block -- on heap and fill in its fields. File_Ptr := AFCB_Allocate (Dummy_FCB); File_Ptr.Is_Regular_File := (is_regular_file (fileno (Stream)) /= 0); File_Ptr.Is_System_File := False; File_Ptr.Is_Text_File := Text; File_Ptr.Shared_Status := Shared; File_Ptr.Access_Method := Amethod; File_Ptr.Stream := Stream; File_Ptr.Form := new String'(Formstr); File_Ptr.Name := new String'(Fullname (1 .. Full_Name_Len)); File_Ptr.Mode := Mode; File_Ptr.Is_Temporary_File := False; Chain_File (File_Ptr); SSL.Unlock_Task.all; exception when others => SSL.Unlock_Task.all; raise; end Locked_Processing; Append_Set (File_Ptr); end Open; -------------- -- Read_Buf -- -------------- procedure Read_Buf (File : AFCB_Ptr; Buf : Address; Siz : size_t) is Nread : size_t; begin Nread := fread (Buf, 1, Siz, File.Stream); if Nread = Siz then return; elsif ferror (File.Stream) /= 0 then raise Device_Error; elsif Nread = 0 then raise End_Error; else -- 0 < Nread < Siz raise Data_Error; end if; end Read_Buf; procedure Read_Buf (File : AFCB_Ptr; Buf : Address; Siz : in Interfaces.C_Streams.size_t; Count : out Interfaces.C_Streams.size_t) is begin Count := fread (Buf, 1, Siz, File.Stream); if Count = 0 and then ferror (File.Stream) /= 0 then raise Device_Error; end if; end Read_Buf; ----------- -- Reset -- ----------- -- The reset which does not change the mode simply does a rewind. procedure Reset (File : in out AFCB_Ptr) is begin Check_File_Open (File); Reset (File, File.Mode); end Reset; -- The reset with a change in mode is done using freopen, and is -- not permitted except for regular files (since otherwise there -- is no name for the freopen, and in any case it seems meaningless) procedure Reset (File : in out AFCB_Ptr; Mode : in File_Mode) is Fopstr : aliased Fopen_String; begin Check_File_Open (File); -- Change of mode not allowed for shared file or file with no name -- or file that is not a regular file, or for a system file. if File.Shared_Status = Yes or else File.Name'Length <= 1 or else File.Is_System_File or else (not File.Is_Regular_File) then raise Use_Error; -- For In_File or Inout_File for a regular file, we can just do a -- rewind if the mode is unchanged, which is more efficient than -- doing a full reopen. elsif Mode = File.Mode and then Mode <= Inout_File then rewind (File.Stream); -- Here the change of mode is permitted, we do it by reopening the -- file in the new mode and replacing the stream with a new stream. else Fopen_Mode (Mode, File.Is_Text_File, False, File.Access_Method, Fopstr); File.Stream := freopen (File.Name.all'Address, Fopstr'Address, File.Stream); if File.Stream = NULL_Stream then Close (File); raise Use_Error; else File.Mode := Mode; Append_Set (File); end if; end if; end Reset; --------------- -- Write_Buf -- --------------- procedure Write_Buf (File : AFCB_Ptr; Buf : Address; Siz : size_t) is begin -- Note: for most purposes, the Siz and 1 parameters in the fwrite -- call could be reversed, but on VMS, this is a better choice, since -- for some file formats, reversing the parameters results in records -- of one byte each. SSL.Abort_Defer.all; if fwrite (Buf, Siz, 1, File.Stream) /= 1 then if Siz /= 0 then SSL.Abort_Undefer.all; raise Device_Error; end if; end if; SSL.Abort_Undefer.all; end Write_Buf; procedure Make_Unbuffered (File : AFCB_Ptr) is status : Integer; begin status := setvbuf (File.Stream, Null_Address, IONBF, 0); end Make_Unbuffered; procedure Make_Line_Buffered (File : AFCB_Ptr; Line_Siz : Interfaces.C_Streams.size_t) is status : Integer; begin status := setvbuf (File.Stream, Null_Address, IOLBF, Line_Siz); end Make_Line_Buffered; procedure Make_Buffered (File : AFCB_Ptr; Buf_Siz : Interfaces.C_Streams.size_t) is status : Integer; begin status := setvbuf (File.Stream, Null_Address, IOFBF, Buf_Siz); end Make_Buffered; end System.File_IO;