gcc/ada/libgnat/s-fileio.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
   4 --                                                                          --
   5 --                       S Y S T E M . F I L E _ I O                        --
   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 provides support for the routines described in (RM A.8.2)
  33 --  which are common to Text_IO, Direct_IO, Sequential_IO and Stream_IO.
  34
  35 with Interfaces.C_Streams;
  36
  37 with System.File_Control_Block;
  38
  39 package System.File_IO is
  40    pragma Preelaborate;
  41
  42    package FCB renames System.File_Control_Block;
  43    package ICS renames Interfaces.C_Streams;
  44
  45    ---------------------
  46    -- File Management --
  47    ---------------------
  48
  49    procedure Open
  50      (File_Ptr  : in out FCB.AFCB_Ptr;
  51       Dummy_FCB : FCB.AFCB'Class;
  52       Mode      : FCB.File_Mode;
  53       Name      : String;
  54       Form      : String;
  55       Amethod   : Character;
  56       Creat     : Boolean;
  57       Text      : Boolean;
  58       C_Stream  : ICS.FILEs := ICS.NULL_Stream);
  59    --  This routine is used for both Open and Create calls:
  60    --
  61    --    File_Ptr is the file type, which must be null on entry
  62    --    (i.e. the file must be closed before the call).
  63    --
  64    --    Dummy_FCB is a default initialized file control block of appropriate
  65    --    type. Note that the tag of this record indicates the type and length
  66    --    of the control block. This control block is used only for the purpose
  67    --    of providing the controlling argument for calling the write version
  68    --    of Allocate_AFCB. It has no other purpose, and its fields are never
  69    --    read or written.
  70    --
  71    --    Mode is the required mode
  72    --
  73    --    Name is the file name, with a null string indicating that a temporary
  74    --    file is to be created (only permitted in create mode, not open mode).
  75    --
  76    --    Creat is True for a create call, and false for an open call
  77    --
  78    --    Text is set True to open the file in text mode (w+t or r+t) instead
  79    --    of the usual binary mode open (w+b or r+b).
  80    --
  81    --    Form is the form string given in the open or create call, this is
  82    --    stored in the AFCB.
  83    --
  84    --    Amethod indicates the access method:
  85    --
  86    --      D = Direct_IO
  87    --      Q = Sequential_IO
  88    --      S = Stream_IO
  89    --      T = Text_IO
  90    --      W = Wide_Text_IO
  91    --      ??? Wide_Wide_Text_IO ???
  92    --
  93    --    C_Stream is left at its default value for the normal case of an
  94    --    Open or Create call as defined in the RM. The only time this is
  95    --    non-null is for the Open call from Ada.xxx_IO.C_Streams.Open.
  96    --
  97    --  On return, if the open/create succeeds, then the fields of File are
  98    --  filled in, and this value is copied to the heap. File_Ptr points to
  99    --  this allocated file control block. If the open/create fails, then the
 100    --  fields of File are undefined, and File_Ptr is unchanged.
 101
 102    procedure Close (File_Ptr : access FCB.AFCB_Ptr);
 103    --  The file is closed, all storage associated with it is released, and
 104    --  File is set to null. Note that this routine calls AFCB_Close to perform
 105    --  any specialized close actions, then closes the file at the system level,
 106    --  then frees the mode and form strings, and finally calls AFCB_Free to
 107    --  free the file control block itself, setting File.all to null. Note that
 108    --  for this assignment to be done in all cases, including those where
 109    --  an exception is raised, we can't use an IN OUT parameter (which would
 110    --  not be copied back in case of abnormal return).
 111
 112    procedure Delete (File_Ptr : access FCB.AFCB_Ptr);
 113    --  The indicated file is unlinked
 114
 115    procedure Reset (File_Ptr : access FCB.AFCB_Ptr; Mode : FCB.File_Mode);
 116    --  The file is reset, and the mode changed as indicated
 117
 118    procedure Reset (File_Ptr : access FCB.AFCB_Ptr);
 119    --  The files is reset, and the mode is unchanged
 120
 121    function Mode (File : FCB.AFCB_Ptr) return FCB.File_Mode;
 122    --  Returns the mode as supplied by create, open or reset
 123
 124    function Name (File : FCB.AFCB_Ptr) return String;
 125    --  Returns the file name as supplied by Open or Create. Raises Use_Error
 126    --  if used with temporary files or standard files.
 127
 128    function Form (File : FCB.AFCB_Ptr) return String;
 129    --  Returns the form as supplied by create, open or reset The string is
 130    --  normalized to all lower case letters.
 131
 132    function Is_Open (File : FCB.AFCB_Ptr) return Boolean;
 133    --  Determines if file is open or not
 134
 135    ----------------------
 136    -- Utility Routines --
 137    ----------------------
 138
 139    --  Some internal routines not defined in A.8.2. These are routines which
 140    --  provide required common functionality shared by separate packages.
 141
 142    procedure Chain_File (File : FCB.AFCB_Ptr);
 143    --  Used to chain the given file into the list of open files. Normally this
 144    --  is done implicitly by Open. Chain_File is used for the special cases of
 145    --  the system files defined by Text_IO (stdin, stdout, stderr) which are
 146    --  not opened in the normal manner. Note that the caller is responsible
 147    --  for task lock out to protect the global data structures if this is
 148    --  necessary (it is needed for the calls from within this unit itself,
 149    --  but not required for the calls from Text_IO and [Wide_]Wide_Text_IO
 150    --  that are made during elaboration of the environment task).
 151
 152    procedure Check_File_Open (File : FCB.AFCB_Ptr);
 153    --  If the current file is not open, then Status_Error is raised. Otherwise
 154    --  control returns normally (with File pointing to the control block for
 155    --  the open file.
 156
 157    procedure Check_Read_Status (File : FCB.AFCB_Ptr);
 158    --  If the current file is not open, then Status_Error is raised. If the
 159    --  file is open, then the mode is checked to make sure that reading is
 160    --  permitted, and if not Mode_Error is raised, otherwise control returns
 161    --  normally.
 162
 163    procedure Check_Write_Status (File : FCB.AFCB_Ptr);
 164    --  If the current file is not open, then Status_Error is raised. If the
 165    --  file is open, then the mode is checked to ensure that writing is
 166    --  permitted, and if not Mode_Error is raised, otherwise control returns
 167    --  normally.
 168
 169    function End_Of_File (File : FCB.AFCB_Ptr) return Boolean;
 170    --  File must be opened in read mode. True is returned if the stream is
 171    --  currently positioned at the end of file, otherwise False is returned.
 172    --  The position of the stream is not affected.
 173
 174    procedure Flush (File : FCB.AFCB_Ptr);
 175    --  Flushes the stream associated with the given file. The file must be open
 176    --  and in write mode (if not, an appropriate exception is raised)
 177
 178    function Form_Boolean
 179      (Form    : String;
 180       Keyword : String;
 181       Default : Boolean) return Boolean;
 182    --  Searches form string for an entry of the form keyword=xx where xx is
 183    --  either yes/no or y/n. Returns True if yes or y is found, False if no or
 184    --  n is found. If the keyword parameter is not found, returns the value
 185    --  given as Default. May raise Use_Error if a form string syntax error is
 186    --  detected. Keyword and Form must be in lower case.
 187
 188    function Form_Integer
 189      (Form    : String;
 190       Keyword : String;
 191       Default : Integer) return Integer;
 192    --  Searches form string for an entry of the form Keyword=xx where xx is an
 193    --  unsigned decimal integer in the range 0 to 999_999. Returns this integer
 194    --  value if it is found. If the keyword parameter is not found, returns the
 195    --  value given as Default. Raise Use_Error if a form string syntax error is
 196    --  detected. Keyword and Form must be in lower case.
 197
 198    procedure Form_Parameter
 199      (Form    : String;
 200       Keyword : String;
 201       Start   : out Natural;
 202       Stop    : out Natural);
 203    --  Searches form string for an entry of the form Keyword=xx and if found
 204    --  Sets Start and Stop to the first and last characters of xx. Keyword
 205    --  and Form must be in lower case. If no entry matches, then Start and
 206    --  Stop are set to zero on return. Use_Error is raised if a malformed
 207    --  string is detected, but there is no guarantee of full syntax checking.
 208
 209    procedure Read_Buf
 210      (File : FCB.AFCB_Ptr;
 211       Buf  : Address;
 212       Siz  : Interfaces.C_Streams.size_t);
 213    --  Reads Siz bytes from File.Stream into Buf. The caller has checked
 214    --  that the file is open in read mode. Raises an exception if Siz bytes
 215    --  cannot be read (End_Error if no data was read, Data_Error if a partial
 216    --  buffer was read, Device_Error if an error occurs).
 217
 218    procedure Read_Buf
 219      (File  : FCB.AFCB_Ptr;
 220       Buf   : Address;
 221       Siz   : Interfaces.C_Streams.size_t;
 222       Count : out Interfaces.C_Streams.size_t);
 223    --  Reads Siz bytes from File.Stream into Buf. The caller has checked that
 224    --  the file is open in read mode. Device Error is raised if an error
 225    --  occurs. Count is the actual number of bytes read, which may be less
 226    --  than Siz if the end of file is encountered.
 227
 228    procedure Append_Set (File : FCB.AFCB_Ptr);
 229    --  If the mode of the file is Append_File, then the file is positioned at
 230    --  the end of file using fseek, otherwise this call has no effect.
 231
 232    procedure Write_Buf
 233      (File : FCB.AFCB_Ptr;
 234       Buf  : Address;
 235       Siz  : Interfaces.C_Streams.size_t);
 236    --  Writes size_t bytes to File.Stream from Buf. The caller has checked that
 237    --  the file is open in write mode. Raises Device_Error if the complete
 238    --  buffer cannot be written.
 239
 240    procedure Make_Unbuffered (File : FCB.AFCB_Ptr);
 241
 242    procedure Make_Line_Buffered
 243      (File     : FCB.AFCB_Ptr;
 244       Line_Siz : Interfaces.C_Streams.size_t);
 245
 246    procedure Make_Buffered
 247      (File     : FCB.AFCB_Ptr;
 248       Buf_Siz  : Interfaces.C_Streams.size_t);
 249
 250 private
 251    pragma Inline (Check_Read_Status);
 252    pragma Inline (Check_Write_Status);
 253    pragma Inline (Mode);
 254
 255 end System.File_IO;