gcc/ada/s-os_lib.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                        S Y S T E M . O S _ L I B                         --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1995-2008, 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 2,  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.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  19 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  20 -- Boston, MA 02110-1301, USA.                                              --
  21 --                                                                          --
  22 -- As a special exception,  if other files  instantiate  generics from this --
  23 -- unit, or you link  this unit with other files  to produce an executable, --
  24 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  25 -- covered  by the  GNU  General  Public  License.  This exception does not --
  26 -- however invalidate  any other reasons why  the executable file  might be --
  27 -- covered by the  GNU Public License.                                      --
  28 --                                                                          --
  29 -- GNAT was originally developed  by the GNAT team at  New York University. --
  30 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  31 --                                                                          --
  32 ------------------------------------------------------------------------------
  33
  34 --  Operating system interface facilities
  35
  36 --  This package contains types and procedures for interfacing to the
  37 --  underlying OS. It is used by the GNAT compiler and by tools associated
  38 --  with the GNAT compiler, and therefore works for the various operating
  39 --  systems to which GNAT has been ported. This package will undoubtedly grow
  40 --  as new services are needed by various tools.
  41
  42 --  This package tends to use fairly low-level Ada in order to not bring in
  43 --  large portions of the RTL. For example, functions return access to string
  44 --  as part of avoiding functions returning unconstrained types.
  45
  46 --  Except where specifically noted, these routines are portable across all
  47 --  GNAT implementations on all supported operating systems.
  48
  49 --  Note: this package is in the System hierarchy so that it can be directly
  50 --  be used by other predefined packages. User access to this package is via
  51 --  a renaming of this package in GNAT.OS_Lib (file g-os_lib.ads).
  52
  53 pragma Warnings (Off);
  54 pragma Compiler_Unit;
  55 pragma Warnings (On);
  56
  57 with System;
  58 with System.Strings;
  59
  60 package System.OS_Lib is
  61    pragma Elaborate_Body (OS_Lib);
  62
  63    -----------------------
  64    -- String Operations --
  65    -----------------------
  66
  67    --  These are reexported from package Strings (which was introduced to
  68    --  avoid different packages declaring different types unnecessarily).
  69    --  See package System.Strings for details.
  70
  71    subtype String_Access is Strings.String_Access;
  72
  73    function "=" (Left, Right : String_Access) return Boolean
  74      renames Strings."=";
  75
  76    procedure Free (X : in out String_Access) renames Strings.Free;
  77
  78    subtype String_List is Strings.String_List;
  79
  80    function "=" (Left, Right : String_List) return Boolean
  81      renames Strings."=";
  82
  83    function "&" (Left : String_Access; Right : String_Access)
  84      return String_List renames Strings."&";
  85    function "&" (Left : String_Access; Right : String_List)
  86      return String_List renames Strings."&";
  87    function "&" (Left : String_List; Right : String_Access)
  88      return String_List renames Strings."&";
  89    function "&" (Left : String_List; Right : String_List)
  90      return String_List renames Strings."&";
  91
  92    subtype String_List_Access is Strings.String_List_Access;
  93
  94    function "=" (Left, Right : String_List_Access) return Boolean
  95      renames Strings."=";
  96
  97    procedure Free (Arg : in out String_List_Access)
  98      renames Strings.Free;
  99
 100    ---------------------
 101    -- Time/Date Stuff --
 102    ---------------------
 103
 104    type OS_Time is private;
 105    --  The OS's notion of time is represented by the private type OS_Time.
 106    --  This is the type returned by the File_Time_Stamp functions to obtain
 107    --  the time stamp of a specified file. Functions and a procedure (modeled
 108    --  after the similar subprograms in package Calendar) are provided for
 109    --  extracting information from a value of this type. Although these are
 110    --  called GM, the intention is not that they provide GMT times in all
 111    --  cases but rather the actual (time-zone independent) time stamp of the
 112    --  file (of course in Unix systems, this *is* in GMT form).
 113
 114    Invalid_Time : constant OS_Time;
 115    --  A special unique value used to flag an invalid time stamp value
 116
 117    subtype Year_Type   is Integer range 1900 .. 2099;
 118    subtype Month_Type  is Integer range    1 ..   12;
 119    subtype Day_Type    is Integer range    1 ..   31;
 120    subtype Hour_Type   is Integer range    0 ..   23;
 121    subtype Minute_Type is Integer range    0 ..   59;
 122    subtype Second_Type is Integer range    0 ..   59;
 123    --  Declarations similar to those in Calendar, breaking down the time
 124
 125    function Current_Time return OS_Time;
 126    --  Return the system clock value as OS_Time
 127
 128    function GM_Year    (Date : OS_Time) return Year_Type;
 129    function GM_Month   (Date : OS_Time) return Month_Type;
 130    function GM_Day     (Date : OS_Time) return Day_Type;
 131    function GM_Hour    (Date : OS_Time) return Hour_Type;
 132    function GM_Minute  (Date : OS_Time) return Minute_Type;
 133    function GM_Second  (Date : OS_Time) return Second_Type;
 134    --  Functions to extract information from OS_Time value
 135
 136    function "<"  (X, Y : OS_Time) return Boolean;
 137    function ">"  (X, Y : OS_Time) return Boolean;
 138    function ">=" (X, Y : OS_Time) return Boolean;
 139    function "<=" (X, Y : OS_Time) return Boolean;
 140    --  Basic comparison operators on OS_Time with obvious meanings. Note that
 141    --  these have Intrinsic convention, so for example it is not permissible
 142    --  to create accesses to any of these functions.
 143
 144    procedure GM_Split
 145      (Date   : OS_Time;
 146       Year   : out Year_Type;
 147       Month  : out Month_Type;
 148       Day    : out Day_Type;
 149       Hour   : out Hour_Type;
 150       Minute : out Minute_Type;
 151       Second : out Second_Type);
 152    --  Analogous to the Split routine in Ada.Calendar, takes an OS_Time and
 153    --  provides a representation of it as a set of component parts, to be
 154    --  interpreted as a date point in UTC.
 155
 156    ----------------
 157    -- File Stuff --
 158    ----------------
 159
 160    --  These routines give access to the open/creat/close/read/write level of
 161    --  I/O routines in the typical C library (these functions are not part of
 162    --  the ANSI C standard, but are typically available in all systems). See
 163    --  also package Interfaces.C_Streams for access to the stream level
 164    --  routines.
 165
 166    --  Note on file names. If a file name is passed as type String in any of
 167    --  the following specifications, then the name is a normal Ada string and
 168    --  need not be NUL-terminated. However, a trailing NUL character is
 169    --  permitted, and will be ignored (more accurately, the NUL and any
 170    --  characters that follow it will be ignored).
 171
 172    type File_Descriptor is new Integer;
 173    --  Corresponds to the int file handle values used in the C routines
 174
 175    Standin  : constant File_Descriptor := 0;
 176    Standout : constant File_Descriptor := 1;
 177    Standerr : constant File_Descriptor := 2;
 178    --  File descriptors for standard input output files
 179
 180    Invalid_FD : constant File_Descriptor := -1;
 181    --  File descriptor returned when error in opening/creating file;
 182
 183    type Mode is (Binary, Text);
 184    for Mode'Size use Integer'Size;
 185    for Mode use (Binary => 0, Text => 1);
 186    --  Used in all the Open and Create calls to specify if the file is to be
 187    --  opened in binary mode or text mode. In systems like Unix, this has no
 188    --  effect, but in systems capable of text mode translation, the use of
 189    --  Text as the mode parameter causes the system to do CR/LF translation
 190    --  and also to recognize the DOS end of file character on input. The use
 191    --  of Text where appropriate allows programs to take a portable Unix view
 192    --  of DOS-format files and process them appropriately.
 193
 194    function Open_Read
 195      (Name  : String;
 196       Fmode : Mode) return File_Descriptor;
 197    --  Open file Name for reading, returning file descriptor File descriptor
 198    --  returned is Invalid_FD if file cannot be opened.
 199
 200    function Open_Read_Write
 201      (Name  : String;
 202       Fmode : Mode) return File_Descriptor;
 203    --  Open file Name for both reading and writing, returning file descriptor.
 204    --  File descriptor returned is Invalid_FD if file cannot be opened.
 205
 206    function Create_File
 207      (Name  : String;
 208       Fmode : Mode) return File_Descriptor;
 209    --  Creates new file with given name for writing, returning file descriptor
 210    --  for subsequent use in Write calls. File descriptor returned is
 211    --  Invalid_FD if file cannot be successfully created.
 212
 213    function Create_Output_Text_File (Name : String) return File_Descriptor;
 214    --  Creates new text file with given name suitable to redirect standard
 215    --  output, returning file descriptor. File descriptor returned is
 216    --  Invalid_FD if file cannot be successfully created.
 217
 218    function Create_New_File
 219      (Name  : String;
 220       Fmode : Mode) return File_Descriptor;
 221    --  Create new file with given name for writing, returning file descriptor
 222    --  for subsequent use in Write calls. This differs from Create_File in
 223    --  that it fails if the file already exists. File descriptor returned is
 224    --  Invalid_FD if the file exists or cannot be created.
 225
 226    Temp_File_Len : constant Integer := 12;
 227    --  Length of name returned by Create_Temp_File call (GNAT-XXXXXX & NUL)
 228
 229    subtype Temp_File_Name is String (1 .. Temp_File_Len);
 230    --  String subtype set by Create_Temp_File
 231
 232    procedure Create_Temp_File
 233      (FD   : out File_Descriptor;
 234       Name : out Temp_File_Name);
 235    --  Create and open for writing a temporary file in the current working
 236    --  directory. The name of the file and the File Descriptor are returned.
 237    --  The File Descriptor returned is Invalid_FD in the case of failure. No
 238    --  mode parameter is provided. Since this is a temporary file, there is no
 239    --  point in doing text translation on it.
 240    --
 241    --  On some operating systems, the maximum number of temp files that can be
 242    --  created with this procedure may be limited. When the maximum is reached,
 243    --  this procedure returns Invalid_FD. On some operating systems, there may
 244    --  be a race condition between processes trying to create temp files at the
 245    --  same time in the same directory using this procedure.
 246
 247    procedure Create_Temp_File
 248      (FD   : out File_Descriptor;
 249       Name : out String_Access);
 250    --  Create and open for writing a temporary file in the current working
 251    --  directory. The name of the file and the File Descriptor are returned.
 252    --  No mode parameter is provided. Since this is a temporary file, there is
 253    --  no point in doing text translation on it. It is the responsibility of
 254    --  the caller to deallocate the access value returned in Name.
 255    --
 256    --  This procedure will always succeed if the current working directory is
 257    --  writable. If the current working directory is not writable, then
 258    --  Invalid_FD is returned for the file descriptor and null for the Name.
 259    --  There is no race condition problem between processes trying to create
 260    --  temp files at the same time in the same directory.
 261
 262    procedure Close (FD : File_Descriptor; Status : out Boolean);
 263    --  Close file referenced by FD. Status is False if the underlying service
 264    --  failed. Reasons for failure include: disk full, disk quotas exceeded
 265    --  and invalid file descriptor (the file may have been closed twice).
 266
 267    procedure Close (FD : File_Descriptor);
 268    --  Close file referenced by FD. This form is used when the caller wants to
 269    --  ignore any possible error (see above for error cases).
 270
 271    procedure Set_Close_On_Exec
 272      (FD            : File_Descriptor;
 273       Close_On_Exec : Boolean;
 274       Status        : out Boolean);
 275    --  When Close_On_Exec is True, mark FD to be closed automatically when new
 276    --  program is executed by the calling process (i.e. prevent FD from being
 277    --  inherited by child processes). When Close_On_Exec is False, mark FD to
 278    --  not be closed on exec (i.e. allow it to be inherited). Status is False
 279    --  if the operation could not be performed.
 280
 281    procedure Delete_File (Name : String; Success : out Boolean);
 282    --  Deletes file. Success is set True or False indicating if the delete is
 283    --  successful.
 284
 285    procedure Rename_File
 286      (Old_Name : String;
 287       New_Name : String;
 288       Success  : out Boolean);
 289    --  Rename a file. Success is set True or False indicating if the rename is
 290    --  successful or not.
 291
 292    --  The following defines the mode for the Copy_File procedure below. Note
 293    --  that "time stamps and other file attributes" in the descriptions below
 294    --  refers to the creation and last modification times, and also the file
 295    --  access (read/write/execute) status flags.
 296
 297    type Copy_Mode is
 298      (Copy,
 299       --  Copy the file. It is an error if the target file already exists. The
 300       --  time stamps and other file attributes are preserved in the copy.
 301
 302       Overwrite,
 303       --  If the target file exists, the file is replaced otherwise the file
 304       --  is just copied. The time stamps and other file attributes are
 305       --  preserved in the copy.
 306
 307       Append);
 308       --  If the target file exists, the contents of the source file is
 309       --  appended at the end. Otherwise the source file is just copied. The
 310       --  time stamps and other file attributes are preserved if the
 311       --  destination file does not exist.
 312
 313    type Attribute is
 314      (Time_Stamps,
 315       --  Copy time stamps from source file to target file. All other
 316       --  attributes are set to normal default values for file creation.
 317
 318       Full,
 319       --  All attributes are copied from the source file to the target file.
 320       --  This includes the timestamps, and for example also includes
 321       --  read/write/execute attributes in Unix systems.
 322
 323       None);
 324       --  No attributes are copied. All attributes including the time stamp
 325       --  values are set to normal default values for file creation.
 326
 327    --  Note: The default is Time_Stamps, which corresponds to the normal
 328    --  default on Windows style systems. Full corresponds to the typical
 329    --  effect of "cp -p" on Unix systems, and None corresponds to the typical
 330    --  effect of "cp" on Unix systems.
 331
 332    --  Note: Time_Stamps and Full are not supported on VMS and VxWorks
 333
 334    procedure Copy_File
 335      (Name     : String;
 336       Pathname : String;
 337       Success  : out Boolean;
 338       Mode     : Copy_Mode := Copy;
 339       Preserve : Attribute := Time_Stamps);
 340    --  Copy a file. Name must designate a single file (no wild cards allowed).
 341    --  Pathname can be a filename or directory name. In the latter case Name
 342    --  is copied into the directory preserving the same file name. Mode
 343    --  defines the kind of copy, see above with the default being a normal
 344    --  copy in which the target file must not already exist. Success is set to
 345    --  True or False indicating if the copy is successful (depending on the
 346    --  specified Mode).
 347    --
 348    --  Note: this procedure is only supported to a very limited extent on VMS.
 349    --  The only supported mode is Overwrite, and the only supported value for
 350    --  Preserve is None, resulting in the default action which for Overwrite
 351    --  is to leave attributes unchanged. Furthermore, the copy only works for
 352    --  simple text files.
 353
 354    procedure Copy_Time_Stamps (Source, Dest : String; Success : out Boolean);
 355    --  Copy Source file time stamps (last modification and last access time
 356    --  stamps) to Dest file. Source and Dest must be valid filenames,
 357    --  furthermore Dest must be writable. Success will be set to True if the
 358    --  operation was successful and False otherwise.
 359    --
 360    --  Note: this procedure is not supported on VMS and VxWorks. On these
 361    --  platforms, Success is always set to False.
 362
 363    function Read
 364      (FD : File_Descriptor;
 365       A  : System.Address;
 366       N  : Integer) return Integer;
 367    --  Read N bytes to address A from file referenced by FD. Returned value is
 368    --  count of bytes actually read, which can be less than N at EOF.
 369
 370    function Write
 371      (FD : File_Descriptor;
 372       A  : System.Address;
 373       N  : Integer) return Integer;
 374    --  Write N bytes from address A to file referenced by FD. The returned
 375    --  value is the number of bytes written, which can be less than N if a
 376    --  disk full condition was detected.
 377
 378    Seek_Cur : constant := 1;
 379    Seek_End : constant := 2;
 380    Seek_Set : constant := 0;
 381    --  Used to indicate origin for Lseek call
 382
 383    procedure Lseek
 384      (FD     : File_Descriptor;
 385       offset : Long_Integer;
 386       origin : Integer);
 387    pragma Import (C, Lseek, "__gnat_lseek");
 388    --  Sets the current file pointer to the indicated offset value, relative
 389    --  to the current position (origin = SEEK_CUR), end of file (origin =
 390    --  SEEK_END), or start of file (origin = SEEK_SET).
 391
 392    function File_Length (FD : File_Descriptor) return Long_Integer;
 393    pragma Import (C, File_Length, "__gnat_file_length");
 394    --  Get length of file from file descriptor FD
 395
 396    function File_Time_Stamp (Name : String) return OS_Time;
 397    --  Given the name of a file or directory, Name, obtains and returns the
 398    --  time stamp. This function can be used for an unopened file. Returns
 399    --  Invalid_Time is Name doesn't correspond to an existing file.
 400
 401    function File_Time_Stamp (FD : File_Descriptor) return OS_Time;
 402    --  Get time stamp of file from file descriptor FD Returns Invalid_Time is
 403    --  FD doesn't correspond to an existing file.
 404
 405    function Normalize_Pathname
 406      (Name           : String;
 407       Directory      : String  := "";
 408       Resolve_Links  : Boolean := True;
 409       Case_Sensitive : Boolean := True) return String;
 410    --  Returns a file name as an absolute path name, resolving all relative
 411    --  directories, and symbolic links. The parameter Directory is a fully
 412    --  resolved path name for a directory, or the empty string (the default).
 413    --  Name is the name of a file, which is either relative to the given
 414    --  directory name, if Directory is non-null, or to the current working
 415    --  directory if Directory is null. The result returned is the normalized
 416    --  name of the file. For most cases, if two file names designate the same
 417    --  file through different paths, Normalize_Pathname will return the same
 418    --  canonical name in both cases. However, there are cases when this is not
 419    --  true; for example, this is not true in Unix for two hard links
 420    --  designating the same file.
 421    --
 422    --  On Windows, the returned path will start with a drive letter except
 423    --  when Directory is not empty and does not include a drive letter. If
 424    --  Directory is empty (the default) and Name is a relative path or an
 425    --  absolute path without drive letter, the letter of the current drive
 426    --  will start the returned path. If Case_Sensitive is True (the default),
 427    --  then this drive letter will be forced to upper case ("C:\...").
 428    --
 429    --  If Resolve_Links is set to True, then the symbolic links, on systems
 430    --  that support them, will be fully converted to the name of the file or
 431    --  directory pointed to. This is slightly less efficient, since it
 432    --  requires system calls.
 433    --
 434    --  If Name cannot be resolved or is null on entry (for example if there is
 435    --  symbolic link circularity, e.g. A is a symbolic link for B, and B is a
 436    --  symbolic link for A), then Normalize_Pathname returns an empty  string.
 437    --
 438    --  In VMS, if Name follows the VMS syntax file specification, it is first
 439    --  converted into Unix syntax. If the conversion fails, Normalize_Pathname
 440    --  returns an empty string.
 441    --
 442    --  For case-sensitive file systems, the value of Case_Sensitive parameter
 443    --  is ignored. For file systems that are not case-sensitive, such as
 444    --  Windows and OpenVMS, if this parameter is set to False, then the file
 445    --  and directory names are folded to lower case. This allows checking
 446    --  whether two files are the same by applying this function to their names
 447    --  and comparing the results. If Case_Sensitive is set to True, this
 448    --  function does not change the casing of file and directory names.
 449
 450    function Is_Absolute_Path (Name : String) return Boolean;
 451    --  Returns True if Name is an absolute path name, i.e. it designates a
 452    --  file or directory absolutely rather than relative to another directory.
 453
 454    function Is_Regular_File (Name : String) return Boolean;
 455    --  Determines if the given string, Name, is the name of an existing
 456    --  regular file. Returns True if so, False otherwise. Name may be an
 457    --  absolute path name or a relative path name, including a simple file
 458    --  name. If it is a relative path name, it is relative to the current
 459    --  working directory.
 460
 461    function Is_Directory (Name : String) return Boolean;
 462    --  Determines if the given string, Name, is the name of a directory.
 463    --  Returns True if so, False otherwise. Name may be an absolute path
 464    --  name or a relative path name, including a simple file name. If it is
 465    --  a relative path name, it is relative to the current working directory.
 466
 467    function Is_Readable_File (Name : String) return Boolean;
 468    --  Determines if the given string, Name, is the name of an existing file
 469    --  that is readable. Returns True if so, False otherwise. Note that this
 470    --  function simply interrogates the file attributes (e.g. using the C
 471    --  function stat), so it does not indicate a situation in which a file may
 472    --  not actually be readable due to some other process having exclusive
 473    --  access.
 474
 475    function Is_Executable_File (Name : String) return Boolean;
 476    --  Determines if the given string, Name, is the name of an existing file
 477    --  that is executable. Returns True if so, False otherwise. Note that this
 478    --  function simply interrogates the file attributes (e.g. using the C
 479    --  function stat), so it does not indicate a situation in which a file may
 480    --  not actually be readable due to some other process having exclusive
 481    --  access.
 482
 483    function Is_Writable_File (Name : String) return Boolean;
 484    --  Determines if the given string, Name, is the name of an existing file
 485    --  that is writable. Returns True if so, False otherwise. Note that this
 486    --  function simply interrogates the file attributes (e.g. using the C
 487    --  function stat), so it does not indicate a situation in which a file may
 488    --  not actually be writeable due to some other process having exclusive
 489    --  access.
 490
 491    function Is_Symbolic_Link (Name : String) return Boolean;
 492    --  Determines if the given string, Name, is the path of a symbolic link on
 493    --  systems that support it. Returns True if so, False if the path is not a
 494    --  symbolic link or if the system does not support symbolic links.
 495    --
 496    --  A symbolic link is an indirect pointer to a file; its directory entry
 497    --  contains the name of the file to which it is linked. Symbolic links may
 498    --  span file systems and may refer to directories.
 499
 500    procedure Set_Writable (Name : String);
 501    --  Change permissions on the named file to make it writable for its owner
 502
 503    procedure Set_Non_Writable (Name : String);
 504    --  Change permissions on the named file to make it non-writable for its
 505    --  owner. The readable and executable permissions are not modified.
 506
 507    procedure Set_Read_Only (Name : String) renames Set_Non_Writable;
 508    --  This renaming is provided for backwards compatibility with previous
 509    --  versions. The use of Set_Non_Writable is preferred (clearer name).
 510
 511    procedure Set_Executable (Name : String);
 512    --  Change permissions on the named file to make it executable for its owner
 513
 514    procedure Set_Readable (Name : String);
 515    --  Change permissions on the named file to make it readable for its
 516    --  owner.
 517
 518    procedure Set_Non_Readable (Name : String);
 519    --  Change permissions on the named file to make it non-readable for
 520    --  its owner. The writable and executable permissions are not
 521    --  modified.
 522
 523    function Locate_Exec_On_Path
 524      (Exec_Name : String) return String_Access;
 525    --  Try to locate an executable whose name is given by Exec_Name in the
 526    --  directories listed in the environment Path. If the Exec_Name does not
 527    --  have the executable suffix, it will be appended before the search.
 528    --  Otherwise works like Locate_Regular_File below. If the executable is
 529    --  not found, null is returned.
 530    --
 531    --  Note that this function allocates memory for the returned value. This
 532    --  memory needs to be deallocated after use.
 533
 534    function Locate_Regular_File
 535      (File_Name : String;
 536       Path      : String) return String_Access;
 537    --  Try to locate a regular file whose name is given by File_Name in the
 538    --  directories listed in Path. If a file is found, its full pathname is
 539    --  returned; otherwise, a null pointer is returned. If the File_Name given
 540    --  is an absolute pathname, then Locate_Regular_File just checks that the
 541    --  file exists and is a regular file. Otherwise, if the File_Name given
 542    --  includes directory information, Locate_Regular_File first checks if the
 543    --  file exists relative to the current directory. If it does not, or if
 544    --  the File_Name given is a simple file name, the Path argument is parsed
 545    --  according to OS conventions, and for each directory in the Path a check
 546    --  is made if File_Name is a relative pathname of a regular file from that
 547    --  directory.
 548    --
 549    --  Note that this function allocates some memory for the returned value.
 550    --  This memory needs to be deallocated after use.
 551
 552    function Get_Debuggable_Suffix return String_Access;
 553    --  Return the debuggable suffix convention. Usually this is the same as
 554    --  the convention for Get_Executable_Suffix. The result is allocated on
 555    --  the heap and should be freed after use to avoid storage leaks.
 556
 557    function Get_Target_Debuggable_Suffix return String_Access;
 558    --  Return the target debuggable suffix convention. Usually this is the same
 559    --  as the convention for Get_Executable_Suffix. The result is allocated on
 560    --  the heap and should be freed after use to avoid storage leaks.
 561
 562    function Get_Executable_Suffix return String_Access;
 563    --  Return the executable suffix convention. The result is allocated on the
 564    --  heap and should be freed after use to avoid storage leaks.
 565
 566    function Get_Object_Suffix return String_Access;
 567    --  Return the object suffix convention. The result is allocated on the heap
 568    --  and should be freed after use to avoid storage leaks.
 569
 570    function Get_Target_Executable_Suffix return String_Access;
 571    --  Return the target executable suffix convention. The result is allocated
 572    --  on the heap and should be freed after use to avoid storage leaks.
 573
 574    function Get_Target_Object_Suffix return String_Access;
 575    --  Return the target object suffix convention. The result is allocated on
 576    --  the heap and should be freed after use to avoid storage leaks.
 577
 578    --  The following section contains low-level routines using addresses to
 579    --  pass file name and executable name. In each routine the name must be
 580    --  Nul-Terminated. For complete documentation refer to the equivalent
 581    --  routine (using String in place of C_File_Name) defined above.
 582
 583    subtype C_File_Name is System.Address;
 584    --  This subtype is used to document that a parameter is the address of a
 585    --  null-terminated string containing the name of a file.
 586
 587    --  All the following functions need comments ???
 588
 589    function Open_Read
 590      (Name  : C_File_Name;
 591       Fmode : Mode) return File_Descriptor;
 592
 593    function Open_Read_Write
 594      (Name  : C_File_Name;
 595       Fmode : Mode) return File_Descriptor;
 596
 597    function Create_File
 598      (Name  : C_File_Name;
 599       Fmode : Mode) return File_Descriptor;
 600
 601    function Create_New_File
 602      (Name  : C_File_Name;
 603       Fmode : Mode) return File_Descriptor;
 604
 605    procedure Delete_File (Name : C_File_Name; Success : out Boolean);
 606
 607    procedure Rename_File
 608      (Old_Name : C_File_Name;
 609       New_Name : C_File_Name;
 610       Success  : out Boolean);
 611
 612    procedure Copy_File
 613      (Name     : C_File_Name;
 614       Pathname : C_File_Name;
 615       Success  : out Boolean;
 616       Mode     : Copy_Mode := Copy;
 617       Preserve : Attribute := Time_Stamps);
 618
 619    procedure Copy_Time_Stamps
 620      (Source, Dest : C_File_Name;
 621       Success      : out Boolean);
 622
 623    function File_Time_Stamp (Name : C_File_Name) return OS_Time;
 624    --  Returns Invalid_Time is Name doesn't correspond to an existing file
 625
 626    function Is_Regular_File (Name : C_File_Name) return Boolean;
 627    function Is_Directory (Name : C_File_Name) return Boolean;
 628    function Is_Readable_File (Name : C_File_Name) return Boolean;
 629    function Is_Executable_File (Name : C_File_Name) return Boolean;
 630    function Is_Writable_File (Name : C_File_Name) return Boolean;
 631    function Is_Symbolic_Link (Name : C_File_Name) return Boolean;
 632
 633    function Locate_Regular_File
 634      (File_Name : C_File_Name;
 635       Path      : C_File_Name) return String_Access;
 636
 637    ------------------
 638    -- Subprocesses --
 639    ------------------
 640
 641    subtype Argument_List is String_List;
 642    --  Type used for argument list in call to Spawn. The lower bound of the
 643    --  array should be 1, and the length of the array indicates the number of
 644    --  arguments.
 645
 646    subtype Argument_List_Access is String_List_Access;
 647    --  Type used to return Argument_List without dragging in secondary stack.
 648    --  Note that there is a Free procedure declared for this subtype which
 649    --  frees the array and all referenced strings.
 650
 651    procedure Normalize_Arguments (Args : in out Argument_List);
 652    --  Normalize all arguments in the list. This ensure that the argument list
 653    --  is compatible with the running OS and will works fine with Spawn and
 654    --  Non_Blocking_Spawn for example. If Normalize_Arguments is called twice
 655    --  on the same list it will do nothing the second time. Note that Spawn
 656    --  and Non_Blocking_Spawn call Normalize_Arguments automatically, but
 657    --  since there is a guarantee that a second call does nothing, this
 658    --  internal call will have no effect if Normalize_Arguments is called
 659    --  before calling Spawn. The call to Normalize_Arguments assumes that the
 660    --  individual referenced arguments in Argument_List are on the heap, and
 661    --  may free them and reallocate if they are modified.
 662
 663    procedure Spawn
 664      (Program_Name : String;
 665       Args         : Argument_List;
 666       Success      : out Boolean);
 667    --  This procedure spawns a program with a given list of arguments. The
 668    --  first parameter of is the name of the executable. The second parameter
 669    --  contains the arguments to be passed to this program. Success is False
 670    --  if the named program could not be spawned or its execution completed
 671    --  unsuccessfully. Note that the caller will be blocked until the
 672    --  execution of the spawned program is complete. For maximum portability,
 673    --  use a full path name for the Program_Name argument. On some systems
 674    --  (notably Unix systems) a simple file name may also work (if the
 675    --  executable can be located in the path).
 676    --
 677    --  "Spawn" should be avoided in tasking applications, since there are
 678    --  subtle interactions between creating a process and signals/locks
 679    --  that can cause troubles.
 680    --
 681    --  Note: Arguments in Args that contain spaces and/or quotes such as
 682    --  "--GCC=gcc -v" or "--GCC=""gcc -v""" are not portable across all
 683    --  operating systems, and would not have the desired effect if they were
 684    --  passed directly to the operating system. To avoid this problem, Spawn
 685    --  makes an internal call to Normalize_Arguments, which ensures that such
 686    --  arguments are modified in a manner that ensures that the desired effect
 687    --  is obtained on all operating systems. The caller may call
 688    --  Normalize_Arguments explicitly before the call (e.g. to print out the
 689    --  exact form of arguments passed to the operating system). In this case
 690    --  the guarantee a second call to Normalize_Arguments has no effect
 691    --  ensures that the internal call will not affect the result. Note that
 692    --  the implicit call to Normalize_Arguments may free and reallocate some
 693    --  of the individual arguments.
 694    --
 695    --  This function will always set Success to False under VxWorks and other
 696    --  similar operating systems which have no notion of the concept of
 697    --  dynamically executable file.
 698
 699    function Spawn
 700      (Program_Name : String;
 701       Args         : Argument_List) return Integer;
 702    --  Similar to the above procedure, but returns the actual status returned
 703    --  by the operating system, or -1 under VxWorks and any other similar
 704    --  operating systems which have no notion of separately spawnable programs.
 705    --
 706    --  "Spawn" should not be used in tasking applications.
 707
 708    procedure Spawn
 709      (Program_Name           : String;
 710       Args                   : Argument_List;
 711       Output_File_Descriptor : File_Descriptor;
 712       Return_Code            : out Integer;
 713       Err_To_Out             : Boolean := True);
 714    --  Similar to the procedure above, but redirects the output to the file
 715    --  designated by Output_File_Descriptor. If Err_To_Out is True, then the
 716    --  Standard Error output is also redirected.
 717    --  Return_Code is set to the status code returned by the operating system
 718    --
 719    --  "Spawn" should not be used in tasking applications.
 720
 721    procedure Spawn
 722      (Program_Name : String;
 723       Args         : Argument_List;
 724       Output_File  : String;
 725       Success      : out Boolean;
 726       Return_Code  : out Integer;
 727       Err_To_Out   : Boolean := True);
 728    --  Similar to the procedure above, but saves the output of the command to
 729    --  a file with the name Output_File.
 730    --
 731    --  Success is set to True if the command is executed and its output
 732    --  successfully written to the file. If Success is True, then Return_Code
 733    --  will be set to the status code returned by the operating system.
 734    --  Otherwise, Return_Code is undefined.
 735    --
 736    --  "Spawn" should not be used in tasking applications.
 737
 738    type Process_Id is private;
 739    --  A private type used to identify a process activated by the following
 740    --  non-blocking calls. The only meaningful operation on this type is a
 741    --  comparison for equality.
 742
 743    Invalid_Pid : constant Process_Id;
 744    --  A special value used to indicate errors, as described below
 745
 746    function Pid_To_Integer (Pid : Process_Id) return Integer;
 747    --  Convert a process id to an Integer. Useful for writing hash functions
 748    --  for type Process_Id or to compare two Process_Id (e.g. for sorting).
 749
 750    function Non_Blocking_Spawn
 751      (Program_Name : String;
 752       Args         : Argument_List) return Process_Id;
 753    --  This is a non blocking call. The Process_Id of the spawned process is
 754    --  returned. Parameters are to be used as in Spawn. If Invalid_Pid is
 755    --  returned the program could not be spawned.
 756    --
 757    --  "Non_Blocking_Spawn" should not be used in tasking applications.
 758    --
 759    --  This function will always return Invalid_Pid under VxWorks, since there
 760    --  is no notion of executables under this OS.
 761
 762    function Non_Blocking_Spawn
 763      (Program_Name           : String;
 764       Args                   : Argument_List;
 765       Output_File_Descriptor : File_Descriptor;
 766       Err_To_Out             : Boolean := True) return Process_Id;
 767    --  Similar to the procedure above, but redirects the output to the file
 768    --  designated by Output_File_Descriptor. If Err_To_Out is True, then the
 769    --  Standard Error output is also redirected. Invalid_Pid is returned
 770    --  if the program could not be spawned successfully.
 771    --
 772    --  "Non_Blocking_Spawn" should not be used in tasking applications.
 773    --
 774    --  This function will always return Invalid_Pid under VxWorks, since there
 775    --  is no notion of executables under this OS.
 776
 777    function Non_Blocking_Spawn
 778      (Program_Name : String;
 779       Args         : Argument_List;
 780       Output_File  : String;
 781       Err_To_Out   : Boolean := True) return Process_Id;
 782    --  Similar to the procedure above, but saves the output of the command to
 783    --  a file with the name Output_File.
 784    --
 785    --  Success is set to True if the command is executed and its output
 786    --  successfully written to the file. Invalid_Pid is returned if the output
 787    --  file could not be created or if the program could not be spawned
 788    --  successfully.
 789    --
 790    --  "Non_Blocking_Spawn" should not be used in tasking applications.
 791    --
 792    --  This function will always return Invalid_Pid under VxWorks, since there
 793    --  is no notion of executables under this OS.
 794
 795    procedure Wait_Process (Pid : out Process_Id; Success : out Boolean);
 796    --  Wait for the completion of any of the processes created by previous
 797    --  calls to Non_Blocking_Spawn. The caller will be suspended until one of
 798    --  these processes terminates (normally or abnormally). If any of these
 799    --  subprocesses terminates prior to the call to Wait_Process (and has not
 800    --  been returned by a previous call to Wait_Process), then the call to
 801    --  Wait_Process is immediate. Pid identifies the process that has
 802    --  terminated (matching the value returned from Non_Blocking_Spawn).
 803    --  Success is set to True if this sub-process terminated successfully. If
 804    --  Pid = Invalid_Pid, there were no subprocesses left to wait on.
 805    --
 806    --  This function will always set success to False under VxWorks, since
 807    --  there is no notion of executables under this OS.
 808
 809    function Argument_String_To_List
 810      (Arg_String : String) return Argument_List_Access;
 811    --  Take a string that is a program and its arguments and parse it into an
 812    --  Argument_List. Note that the result is allocated on the heap, and must
 813    --  be freed by the programmer (when it is no longer needed) to avoid
 814    --  memory leaks.
 815
 816    -------------------
 817    -- Miscellaneous --
 818    -------------------
 819
 820    function Getenv (Name : String) return String_Access;
 821    --  Get the value of the environment variable. Returns an access to the
 822    --  empty string if the environment variable does not exist or has an
 823    --  explicit null value (in some operating systems these are distinct
 824    --  cases, in others they are not; this interface abstracts away that
 825    --  difference. The argument is allocated on the heap (even in the null
 826    --  case), and needs to be freed explicitly when no longer needed to avoid
 827    --  memory leaks.
 828
 829    procedure Setenv (Name : String; Value : String);
 830    --  Set the value of the environment variable Name to Value. This call
 831    --  modifies the current environment, but does not modify the parent
 832    --  process environment. After a call to Setenv, Getenv (Name) will always
 833    --  return a String_Access referencing the same String as Value. This is
 834    --  true also for the null string case (the actual effect may be to either
 835    --  set an explicit null as the value, or to remove the entry, this is
 836    --  operating system dependent). Note that any following calls to Spawn
 837    --  will pass an environment to the spawned process that includes the
 838    --  changes made by Setenv calls. This procedure is not available on VMS.
 839
 840    procedure OS_Exit (Status : Integer);
 841    pragma No_Return (OS_Exit);
 842
 843    --  Exit to OS with given status code (program is terminated). Note that
 844    --  this is abrupt termination. All tasks are immediately terminated. There
 845    --  are no finalization or other Ada-specific cleanup actions performed. On
 846    --  systems with atexit handlers (such as Unix and Windows), atexit handlers
 847    --  are called.
 848
 849    type OS_Exit_Subprogram is access procedure (Status : Integer);
 850
 851    procedure OS_Exit_Default (Status : Integer);
 852    pragma No_Return (OS_Exit_Default);
 853    --  Default implementation of procedure OS_Exit
 854
 855    OS_Exit_Ptr : OS_Exit_Subprogram := OS_Exit_Default'Access;
 856    --  OS_Exit is implemented through this access value. It it then possible to
 857    --  change the implementation of OS_Exit by redirecting OS_Exit_Ptr to an
 858    --  other implementation.
 859
 860    procedure OS_Abort;
 861    pragma Import (C, OS_Abort, "abort");
 862    pragma No_Return (OS_Abort);
 863    --  Exit to OS signalling an abort (traceback or other appropriate
 864    --  diagnostic information should be given if possible, or entry made to
 865    --  the debugger if that is possible).
 866
 867    function Errno return Integer;
 868    pragma Import (C, Errno, "__get_errno");
 869    --  Return the task-safe last error number
 870
 871    procedure Set_Errno (Errno : Integer);
 872    pragma Import (C, Set_Errno, "__set_errno");
 873    --  Set the task-safe error number
 874
 875    Directory_Separator : constant Character;
 876    --  The character that is used to separate parts of a pathname
 877
 878    Path_Separator : constant Character;
 879    --  The character to separate paths in an environment variable value
 880
 881 private
 882    pragma Import (C, Path_Separator, "__gnat_path_separator");
 883    pragma Import (C, Directory_Separator, "__gnat_dir_separator");
 884    pragma Import (C, Current_Time, "__gnat_current_time");
 885
 886    type OS_Time is new Long_Integer;
 887    --  Type used for timestamps in the compiler. This type is used to hold
 888    --  time stamps, but may have a different representation than C's time_t.
 889    --  This type needs to match the declaration of OS_Time in adaint.h.
 890
 891    --  Add pragma Inline statements for comparison operations on OS_Time. It
 892    --  would actually be nice to use pragma Import (Intrinsic) here, but this
 893    --  was not properly supported till GNAT 3.15a, so that would cause
 894    --  bootstrap path problems. To be changed later ???
 895
 896    Invalid_Time : constant OS_Time := -1;
 897    --  This value should match the return value from __gnat_file_time_*
 898
 899    pragma Inline ("<");
 900    pragma Inline (">");
 901    pragma Inline ("<=");
 902    pragma Inline (">=");
 903
 904    type Process_Id is new Integer;
 905    Invalid_Pid : constant Process_Id := -1;
 906
 907 end System.OS_Lib;