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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . O S _ L I B --
-- --
-- S p e c --
-- --
-- Copyright (C) 1995-2011, 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. --
-- --
------------------------------------------------------------------------------
-- Operating system interface facilities
-- This package contains types and procedures for interfacing to the
-- underlying OS. It is used by the GNAT compiler and by tools associated
-- with the GNAT compiler, and therefore works for the various operating
-- systems to which GNAT has been ported. This package will undoubtedly grow
-- as new services are needed by various tools.
-- This package tends to use fairly low-level Ada in order to not bring in
-- large portions of the RTL. For example, functions return access to string
-- as part of avoiding functions returning unconstrained types.
-- Except where specifically noted, these routines are portable across all
-- GNAT implementations on all supported operating systems.
-- Note: this package is in the System hierarchy so that it can be directly
-- be used by other predefined packages. User access to this package is via
-- a renaming of this package in GNAT.OS_Lib (file g-os_lib.ads).
pragma Compiler_Unit;
with System;
with System.Strings;
package System.OS_Lib is
pragma Elaborate_Body (OS_Lib);
-----------------------
-- String Operations --
-----------------------
-- These are reexported from package Strings (which was introduced to
-- avoid different packages declaring different types unnecessarily).
-- See package System.Strings for details.
subtype String_Access is Strings.String_Access;
function "=" (Left, Right : String_Access) return Boolean
renames Strings."=";
procedure Free (X : in out String_Access) renames Strings.Free;
subtype String_List is Strings.String_List;
function "=" (Left, Right : String_List) return Boolean
renames Strings."=";
function "&" (Left : String_Access; Right : String_Access)
return String_List renames Strings."&";
function "&" (Left : String_Access; Right : String_List)
return String_List renames Strings."&";
function "&" (Left : String_List; Right : String_Access)
return String_List renames Strings."&";
function "&" (Left : String_List; Right : String_List)
return String_List renames Strings."&";
subtype String_List_Access is Strings.String_List_Access;
function "=" (Left, Right : String_List_Access) return Boolean
renames Strings."=";
procedure Free (Arg : in out String_List_Access)
renames Strings.Free;
---------------------
-- Time/Date Stuff --
---------------------
type OS_Time is private;
-- The OS's notion of time is represented by the private type OS_Time.
-- This is the type returned by the File_Time_Stamp functions to obtain
-- the time stamp of a specified file. Functions and a procedure (modeled
-- after the similar subprograms in package Calendar) are provided for
-- extracting information from a value of this type. Although these are
-- called GM, the intention is not that they provide GMT times in all
-- cases but rather the actual (time-zone independent) time stamp of the
-- file (of course in Unix systems, this *is* in GMT form).
Invalid_Time : constant OS_Time;
-- A special unique value used to flag an invalid time stamp value
subtype Year_Type is Integer range 1900 .. 2099;
subtype Month_Type is Integer range 1 .. 12;
subtype Day_Type is Integer range 1 .. 31;
subtype Hour_Type is Integer range 0 .. 23;
subtype Minute_Type is Integer range 0 .. 59;
subtype Second_Type is Integer range 0 .. 59;
-- Declarations similar to those in Calendar, breaking down the time
function Current_Time return OS_Time;
-- Return the system clock value as OS_Time
function GM_Year (Date : OS_Time) return Year_Type;
function GM_Month (Date : OS_Time) return Month_Type;
function GM_Day (Date : OS_Time) return Day_Type;
function GM_Hour (Date : OS_Time) return Hour_Type;
function GM_Minute (Date : OS_Time) return Minute_Type;
function GM_Second (Date : OS_Time) return Second_Type;
-- Functions to extract information from OS_Time value
function "<" (X, Y : OS_Time) return Boolean;
function ">" (X, Y : OS_Time) return Boolean;
function ">=" (X, Y : OS_Time) return Boolean;
function "<=" (X, Y : OS_Time) return Boolean;
-- Basic comparison operators on OS_Time with obvious meanings. Note that
-- these have Intrinsic convention, so for example it is not permissible
-- to create accesses to any of these functions.
procedure GM_Split
(Date : OS_Time;
Year : out Year_Type;
Month : out Month_Type;
Day : out Day_Type;
Hour : out Hour_Type;
Minute : out Minute_Type;
Second : out Second_Type);
-- Analogous to the Split routine in Ada.Calendar, takes an OS_Time and
-- provides a representation of it as a set of component parts, to be
-- interpreted as a date point in UTC.
----------------
-- File Stuff --
----------------
-- These routines give access to the open/creat/close/read/write level of
-- I/O routines in the typical C library (these functions are not part of
-- the ANSI C standard, but are typically available in all systems). See
-- also package Interfaces.C_Streams for access to the stream level
-- routines.
-- Note on file names. If a file name is passed as type String in any of
-- the following specifications, then the name is a normal Ada string and
-- need not be NUL-terminated. However, a trailing NUL character is
-- permitted, and will be ignored (more accurately, the NUL and any
-- characters that follow it will be ignored).
type File_Descriptor is new Integer;
-- Corresponds to the int file handle values used in the C routines
Standin : constant File_Descriptor := 0;
Standout : constant File_Descriptor := 1;
Standerr : constant File_Descriptor := 2;
-- File descriptors for standard input output files
Invalid_FD : constant File_Descriptor := -1;
-- File descriptor returned when error in opening/creating file;
type Mode is (Binary, Text);
for Mode'Size use Integer'Size;
for Mode use (Binary => 0, Text => 1);
-- Used in all the Open and Create calls to specify if the file is to be
-- opened in binary mode or text mode. In systems like Unix, this has no
-- effect, but in systems capable of text mode translation, the use of
-- Text as the mode parameter causes the system to do CR/LF translation
-- and also to recognize the DOS end of file character on input. The use
-- of Text where appropriate allows programs to take a portable Unix view
-- of DOS-format files and process them appropriately.
function Open_Read
(Name : String;
Fmode : Mode) return File_Descriptor;
-- Open file Name for reading, returning file descriptor File descriptor
-- returned is Invalid_FD if file cannot be opened.
function Open_Read_Write
(Name : String;
Fmode : Mode) return File_Descriptor;
-- Open file Name for both reading and writing, returning file descriptor.
-- File descriptor returned is Invalid_FD if file cannot be opened.
function Create_File
(Name : String;
Fmode : Mode) return File_Descriptor;
-- Creates new file with given name for writing, returning file descriptor
-- for subsequent use in Write calls. If the file already exists, it is
-- overwritten. File descriptor returned is Invalid_FD if file cannot be
-- successfully created.
function Create_Output_Text_File (Name : String) return File_Descriptor;
-- Creates new text file with given name suitable to redirect standard
-- output, returning file descriptor. File descriptor returned is
-- Invalid_FD if file cannot be successfully created.
function Create_New_File
(Name : String;
Fmode : Mode) return File_Descriptor;
-- Create new file with given name for writing, returning file descriptor
-- for subsequent use in Write calls. This differs from Create_File in
-- that it fails if the file already exists. File descriptor returned is
-- Invalid_FD if the file exists or cannot be created.
Temp_File_Len : constant Integer := 12;
-- Length of name returned by Create_Temp_File call (GNAT-XXXXXX & NUL)
subtype Temp_File_Name is String (1 .. Temp_File_Len);
-- String subtype set by Create_Temp_File
procedure Create_Temp_File
(FD : out File_Descriptor;
Name : out Temp_File_Name);
-- Create and open for writing a temporary file in the current working
-- directory. The name of the file and the File Descriptor are returned.
-- The File Descriptor returned is Invalid_FD in the case of failure. No
-- mode parameter is provided. Since this is a temporary file, there is no
-- point in doing text translation on it.
--
-- On some operating systems, the maximum number of temp files that can be
-- created with this procedure may be limited. When the maximum is reached,
-- this procedure returns Invalid_FD. On some operating systems, there may
-- be a race condition between processes trying to create temp files at the
-- same time in the same directory using this procedure.
procedure Create_Temp_File
(FD : out File_Descriptor;
Name : out String_Access);
-- Create and open for writing a temporary file in the current working
-- directory. The name of the file and the File Descriptor are returned.
-- It is the responsibility of the caller to deallocate the access value
-- returned in Name.
--
-- The file is opened in binary mode (no text translation).
--
-- This procedure will always succeed if the current working directory is
-- writable. If the current working directory is not writable, then
-- Invalid_FD is returned for the file descriptor and null for the Name.
-- There is no race condition problem between processes trying to create
-- temp files at the same time in the same directory.
procedure Create_Temp_Output_File
(FD : out File_Descriptor;
Name : out String_Access);
-- Create and open for writing a temporary file in the current working
-- directory suitable to redirect standard output. The name of the file and
-- the File Descriptor are returned. It is the responsibility of the caller
-- to deallocate the access value returned in Name.
--
-- The file is opened in text mode
--
-- This procedure will always succeed if the current working directory is
-- writable. If the current working directory is not writable, then
-- Invalid_FD is returned for the file descriptor and null for the Name.
-- There is no race condition problem between processes trying to create
-- temp files at the same time in the same directory.
procedure Close (FD : File_Descriptor; Status : out Boolean);
-- Close file referenced by FD. Status is False if the underlying service
-- failed. Reasons for failure include: disk full, disk quotas exceeded
-- and invalid file descriptor (the file may have been closed twice).
procedure Close (FD : File_Descriptor);
-- Close file referenced by FD. This form is used when the caller wants to
-- ignore any possible error (see above for error cases).
procedure Set_Close_On_Exec
(FD : File_Descriptor;
Close_On_Exec : Boolean;
Status : out Boolean);
-- When Close_On_Exec is True, mark FD to be closed automatically when new
-- program is executed by the calling process (i.e. prevent FD from being
-- inherited by child processes). When Close_On_Exec is False, mark FD to
-- not be closed on exec (i.e. allow it to be inherited). Status is False
-- if the operation could not be performed.
procedure Delete_File (Name : String; Success : out Boolean);
-- Deletes file. Success is set True or False indicating if the delete is
-- successful.
procedure Rename_File
(Old_Name : String;
New_Name : String;
Success : out Boolean);
-- Rename a file. Success is set True or False indicating if the rename is
-- successful or not.
-- The following defines the mode for the Copy_File procedure below. Note
-- that "time stamps and other file attributes" in the descriptions below
-- refers to the creation and last modification times, and also the file
-- access (read/write/execute) status flags.
type Copy_Mode is
(Copy,
-- Copy the file. It is an error if the target file already exists. The
-- time stamps and other file attributes are preserved in the copy.
Overwrite,
-- If the target file exists, the file is replaced otherwise the file
-- is just copied. The time stamps and other file attributes are
-- preserved in the copy.
Append);
-- If the target file exists, the contents of the source file is
-- appended at the end. Otherwise the source file is just copied. The
-- time stamps and other file attributes are preserved if the
-- destination file does not exist.
type Attribute is
(Time_Stamps,
-- Copy time stamps from source file to target file. All other
-- attributes are set to normal default values for file creation.
Full,
-- All attributes are copied from the source file to the target file.
-- This includes the timestamps, and for example also includes
-- read/write/execute attributes in Unix systems.
None);
-- No attributes are copied. All attributes including the time stamp
-- values are set to normal default values for file creation.
-- Note: The default is Time_Stamps, which corresponds to the normal
-- default on Windows style systems. Full corresponds to the typical
-- effect of "cp -p" on Unix systems, and None corresponds to the typical
-- effect of "cp" on Unix systems.
-- Note: Time_Stamps and Full are not supported on VMS and VxWorks 5
procedure Copy_File
(Name : String;
Pathname : String;
Success : out Boolean;
Mode : Copy_Mode := Copy;
Preserve : Attribute := Time_Stamps);
-- Copy a file. Name must designate a single file (no wild cards allowed).
-- Pathname can be a filename or directory name. In the latter case Name
-- is copied into the directory preserving the same file name. Mode
-- defines the kind of copy, see above with the default being a normal
-- copy in which the target file must not already exist. Success is set to
-- True or False indicating if the copy is successful (depending on the
-- specified Mode).
--
-- Note: this procedure is only supported to a very limited extent on VMS.
-- The only supported mode is Overwrite, and the only supported value for
-- Preserve is None, resulting in the default action which for Overwrite
-- is to leave attributes unchanged. Furthermore, the copy only works for
-- simple text files.
procedure Copy_Time_Stamps (Source, Dest : String; Success : out Boolean);
-- Copy Source file time stamps (last modification and last access time
-- stamps) to Dest file. Source and Dest must be valid filenames,
-- furthermore Dest must be writable. Success will be set to True if the
-- operation was successful and False otherwise.
--
-- Note: this procedure is not supported on VMS and VxWorks 5. On these
-- platforms, Success is always set to False.
function Read
(FD : File_Descriptor;
A : System.Address;
N : Integer) return Integer;
-- Read N bytes to address A from file referenced by FD. Returned value is
-- count of bytes actually read, which can be less than N at EOF.
function Write
(FD : File_Descriptor;
A : System.Address;
N : Integer) return Integer;
-- Write N bytes from address A to file referenced by FD. The returned
-- value is the number of bytes written, which can be less than N if a
-- disk full condition was detected.
Seek_Cur : constant := 1;
Seek_End : constant := 2;
Seek_Set : constant := 0;
-- Used to indicate origin for Lseek call
procedure Lseek
(FD : File_Descriptor;
offset : Long_Integer;
origin : Integer);
pragma Import (C, Lseek, "__gnat_lseek");
-- Sets the current file pointer to the indicated offset value, relative
-- to the current position (origin = SEEK_CUR), end of file (origin =
-- SEEK_END), or start of file (origin = SEEK_SET).
function File_Length (FD : File_Descriptor) return Long_Integer;
pragma Import (C, File_Length, "__gnat_file_length");
-- Get length of file from file descriptor FD
function File_Time_Stamp (Name : String) return OS_Time;
-- Given the name of a file or directory, Name, obtains and returns the
-- time stamp. This function can be used for an unopened file. Returns
-- Invalid_Time is Name doesn't correspond to an existing file.
function File_Time_Stamp (FD : File_Descriptor) return OS_Time;
-- Get time stamp of file from file descriptor FD Returns Invalid_Time is
-- FD doesn't correspond to an existing file.
function Normalize_Pathname
(Name : String;
Directory : String := "";
Resolve_Links : Boolean := True;
Case_Sensitive : Boolean := True) return String;
-- Returns a file name as an absolute path name, resolving all relative
-- directories, and symbolic links. The parameter Directory is a fully
-- resolved path name for a directory, or the empty string (the default).
-- Name is the name of a file, which is either relative to the given
-- directory name, if Directory is non-null, or to the current working
-- directory if Directory is null. The result returned is the normalized
-- name of the file. For most cases, if two file names designate the same
-- file through different paths, Normalize_Pathname will return the same
-- canonical name in both cases. However, there are cases when this is not
-- true; for example, this is not true in Unix for two hard links
-- designating the same file.
--
-- On Windows, the returned path will start with a drive letter except
-- when Directory is not empty and does not include a drive letter. If
-- Directory is empty (the default) and Name is a relative path or an
-- absolute path without drive letter, the letter of the current drive
-- will start the returned path. If Case_Sensitive is True (the default),
-- then this drive letter will be forced to upper case ("C:\...").
--
-- If Resolve_Links is set to True, then the symbolic links, on systems
-- that support them, will be fully converted to the name of the file or
-- directory pointed to. This is slightly less efficient, since it
-- requires system calls.
--
-- If Name cannot be resolved or is null on entry (for example if there is
-- symbolic link circularity, e.g. A is a symbolic link for B, and B is a
-- symbolic link for A), then Normalize_Pathname returns an empty string.
--
-- In VMS, if Name follows the VMS syntax file specification, it is first
-- converted into Unix syntax. If the conversion fails, Normalize_Pathname
-- returns an empty string.
--
-- For case-sensitive file systems, the value of Case_Sensitive parameter
-- is ignored. For file systems that are not case-sensitive, such as
-- Windows and OpenVMS, if this parameter is set to False, then the file
-- and directory names are folded to lower case. This allows checking
-- whether two files are the same by applying this function to their names
-- and comparing the results. If Case_Sensitive is set to True, this
-- function does not change the casing of file and directory names.
function Is_Absolute_Path (Name : String) return Boolean;
-- Returns True if Name is an absolute path name, i.e. it designates a
-- file or directory absolutely rather than relative to another directory.
function Is_Regular_File (Name : String) return Boolean;
-- Determines if the given string, Name, is the name of an existing
-- regular file. Returns True if so, False otherwise. Name may be an
-- absolute path name or a relative path name, including a simple file
-- name. If it is a relative path name, it is relative to the current
-- working directory.
function Is_Directory (Name : String) return Boolean;
-- Determines if the given string, Name, is the name of a directory.
-- Returns True if so, False otherwise. Name may be an absolute path
-- name or a relative path name, including a simple file name. If it is
-- a relative path name, it is relative to the current working directory.
function Is_Readable_File (Name : String) return Boolean;
-- Determines if the given string, Name, is the name of an existing file
-- that is readable. Returns True if so, False otherwise. Note that this
-- function simply interrogates the file attributes (e.g. using the C
-- function stat), so it does not indicate a situation in which a file may
-- not actually be readable due to some other process having exclusive
-- access.
function Is_Executable_File (Name : String) return Boolean;
-- Determines if the given string, Name, is the name of an existing file
-- that is executable. Returns True if so, False otherwise. Note that this
-- function simply interrogates the file attributes (e.g. using the C
-- function stat), so it does not indicate a situation in which a file may
-- not actually be readable due to some other process having exclusive
-- access.
function Is_Writable_File (Name : String) return Boolean;
-- Determines if the given string, Name, is the name of an existing file
-- that is writable. Returns True if so, False otherwise. Note that this
-- function simply interrogates the file attributes (e.g. using the C
-- function stat), so it does not indicate a situation in which a file may
-- not actually be writeable due to some other process having exclusive
-- access.
function Is_Symbolic_Link (Name : String) return Boolean;
-- Determines if the given string, Name, is the path of a symbolic link on
-- systems that support it. Returns True if so, False if the path is not a
-- symbolic link or if the system does not support symbolic links.
--
-- A symbolic link is an indirect pointer to a file; its directory entry
-- contains the name of the file to which it is linked. Symbolic links may
-- span file systems and may refer to directories.
procedure Set_Writable (Name : String);
-- Change permissions on the named file to make it writable for its owner
procedure Set_Non_Writable (Name : String);
-- Change permissions on the named file to make it non-writable for its
-- owner. The readable and executable permissions are not modified.
procedure Set_Read_Only (Name : String) renames Set_Non_Writable;
-- This renaming is provided for backwards compatibility with previous
-- versions. The use of Set_Non_Writable is preferred (clearer name).
procedure Set_Executable (Name : String);
-- Change permissions on the named file to make it executable for its owner
procedure Set_Readable (Name : String);
-- Change permissions on the named file to make it readable for its
-- owner.
procedure Set_Non_Readable (Name : String);
-- Change permissions on the named file to make it non-readable for
-- its owner. The writable and executable permissions are not
-- modified.
function Locate_Exec_On_Path
(Exec_Name : String) return String_Access;
-- Try to locate an executable whose name is given by Exec_Name in the
-- directories listed in the environment Path. If the Exec_Name does not
-- have the executable suffix, it will be appended before the search.
-- Otherwise works like Locate_Regular_File below. If the executable is
-- not found, null is returned.
--
-- Note that this function allocates memory for the returned value. This
-- memory needs to be deallocated after use.
function Locate_Regular_File
(File_Name : String;
Path : String) return String_Access;
-- Try to locate a regular file whose name is given by File_Name in the
-- directories listed in Path. If a file is found, its full pathname is
-- returned; otherwise, a null pointer is returned. If the File_Name given
-- is an absolute pathname, then Locate_Regular_File just checks that the
-- file exists and is a regular file. Otherwise, if the File_Name given
-- includes directory information, Locate_Regular_File first checks if the
-- file exists relative to the current directory. If it does not, or if
-- the File_Name given is a simple file name, the Path argument is parsed
-- according to OS conventions, and for each directory in the Path a check
-- is made if File_Name is a relative pathname of a regular file from that
-- directory.
--
-- Note that this function allocates some memory for the returned value.
-- This memory needs to be deallocated after use.
function Get_Debuggable_Suffix return String_Access;
-- Return the debuggable suffix convention. Usually this is the same as
-- the convention for Get_Executable_Suffix. The result is allocated on
-- the heap and should be freed after use to avoid storage leaks.
function Get_Target_Debuggable_Suffix return String_Access;
-- Return the target debuggable suffix convention. Usually this is the same
-- as the convention for Get_Executable_Suffix. The result is allocated on
-- the heap and should be freed after use to avoid storage leaks.
function Get_Executable_Suffix return String_Access;
-- Return the executable suffix convention. The result is allocated on the
-- heap and should be freed after use to avoid storage leaks.
function Get_Object_Suffix return String_Access;
-- Return the object suffix convention. The result is allocated on the heap
-- and should be freed after use to avoid storage leaks.
function Get_Target_Executable_Suffix return String_Access;
-- Return the target executable suffix convention. The result is allocated
-- on the heap and should be freed after use to avoid storage leaks.
function Get_Target_Object_Suffix return String_Access;
-- Return the target object suffix convention. The result is allocated on
-- the heap and should be freed after use to avoid storage leaks.
-- The following section contains low-level routines using addresses to
-- pass file name and executable name. In each routine the name must be
-- Nul-Terminated. For complete documentation refer to the equivalent
-- routine (using String in place of C_File_Name) defined above.
subtype C_File_Name is System.Address;
-- This subtype is used to document that a parameter is the address of a
-- null-terminated string containing the name of a file.
-- All the following functions need comments ???
function Open_Read
(Name : C_File_Name;
Fmode : Mode) return File_Descriptor;
function Open_Read_Write
(Name : C_File_Name;
Fmode : Mode) return File_Descriptor;
function Create_File
(Name : C_File_Name;
Fmode : Mode) return File_Descriptor;
function Create_New_File
(Name : C_File_Name;
Fmode : Mode) return File_Descriptor;
procedure Delete_File (Name : C_File_Name; Success : out Boolean);
procedure Rename_File
(Old_Name : C_File_Name;
New_Name : C_File_Name;
Success : out Boolean);
procedure Copy_File
(Name : C_File_Name;
Pathname : C_File_Name;
Success : out Boolean;
Mode : Copy_Mode := Copy;
Preserve : Attribute := Time_Stamps);
procedure Copy_Time_Stamps
(Source, Dest : C_File_Name;
Success : out Boolean);
function File_Time_Stamp (Name : C_File_Name) return OS_Time;
-- Returns Invalid_Time is Name doesn't correspond to an existing file
function Is_Regular_File (Name : C_File_Name) return Boolean;
function Is_Directory (Name : C_File_Name) return Boolean;
function Is_Readable_File (Name : C_File_Name) return Boolean;
function Is_Executable_File (Name : C_File_Name) return Boolean;
function Is_Writable_File (Name : C_File_Name) return Boolean;
function Is_Symbolic_Link (Name : C_File_Name) return Boolean;
function Locate_Regular_File
(File_Name : C_File_Name;
Path : C_File_Name) return String_Access;
------------------
-- Subprocesses --
------------------
subtype Argument_List is String_List;
-- Type used for argument list in call to Spawn. The lower bound of the
-- array should be 1, and the length of the array indicates the number of
-- arguments.
subtype Argument_List_Access is String_List_Access;
-- Type used to return Argument_List without dragging in secondary stack.
-- Note that there is a Free procedure declared for this subtype which
-- frees the array and all referenced strings.
procedure Normalize_Arguments (Args : in out Argument_List);
-- Normalize all arguments in the list. This ensure that the argument list
-- is compatible with the running OS and will works fine with Spawn and
-- Non_Blocking_Spawn for example. If Normalize_Arguments is called twice
-- on the same list it will do nothing the second time. Note that Spawn
-- and Non_Blocking_Spawn call Normalize_Arguments automatically, but
-- since there is a guarantee that a second call does nothing, this
-- internal call will have no effect if Normalize_Arguments is called
-- before calling Spawn. The call to Normalize_Arguments assumes that the
-- individual referenced arguments in Argument_List are on the heap, and
-- may free them and reallocate if they are modified.
procedure Spawn
(Program_Name : String;
Args : Argument_List;
Success : out Boolean);
-- This procedure spawns a program with a given list of arguments. The
-- first parameter of is the name of the executable. The second parameter
-- contains the arguments to be passed to this program. Success is False
-- if the named program could not be spawned or its execution completed
-- unsuccessfully. Note that the caller will be blocked until the
-- execution of the spawned program is complete. For maximum portability,
-- use a full path name for the Program_Name argument. On some systems
-- (notably Unix systems) a simple file name may also work (if the
-- executable can be located in the path).
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
--
-- Note: Arguments in Args that contain spaces and/or quotes such as
-- "--GCC=gcc -v" or "--GCC=""gcc -v""" are not portable across all
-- operating systems, and would not have the desired effect if they were
-- passed directly to the operating system. To avoid this problem, Spawn
-- makes an internal call to Normalize_Arguments, which ensures that such
-- arguments are modified in a manner that ensures that the desired effect
-- is obtained on all operating systems. The caller may call
-- Normalize_Arguments explicitly before the call (e.g. to print out the
-- exact form of arguments passed to the operating system). In this case
-- the guarantee a second call to Normalize_Arguments has no effect
-- ensures that the internal call will not affect the result. Note that
-- the implicit call to Normalize_Arguments may free and reallocate some
-- of the individual arguments.
--
-- This function will always set Success to False under VxWorks and other
-- similar operating systems which have no notion of the concept of
-- dynamically executable file. Otherwise Success is set True if the exit
-- status of the spawned process is zero.
function Spawn
(Program_Name : String;
Args : Argument_List) return Integer;
-- Similar to the above procedure, but returns the actual status returned
-- by the operating system, or -1 under VxWorks and any other similar
-- operating systems which have no notion of separately spawnable programs.
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
procedure Spawn
(Program_Name : String;
Args : Argument_List;
Output_File_Descriptor : File_Descriptor;
Return_Code : out Integer;
Err_To_Out : Boolean := True);
-- Similar to the procedure above, but redirects the output to the file
-- designated by Output_File_Descriptor. If Err_To_Out is True, then the
-- Standard Error output is also redirected.
-- Return_Code is set to the status code returned by the operating system
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
procedure Spawn
(Program_Name : String;
Args : Argument_List;
Output_File : String;
Success : out Boolean;
Return_Code : out Integer;
Err_To_Out : Boolean := True);
-- Similar to the procedure above, but saves the output of the command to
-- a file with the name Output_File.
--
-- Success is set to True if the command is executed and its output
-- successfully written to the file. If Success is True, then Return_Code
-- will be set to the status code returned by the operating system.
-- Otherwise, Return_Code is undefined.
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
type Process_Id is private;
-- A private type used to identify a process activated by the following
-- non-blocking calls. The only meaningful operation on this type is a
-- comparison for equality.
Invalid_Pid : constant Process_Id;
-- A special value used to indicate errors, as described below
function Pid_To_Integer (Pid : Process_Id) return Integer;
-- Convert a process id to an Integer. Useful for writing hash functions
-- for type Process_Id or to compare two Process_Id (e.g. for sorting).
function Non_Blocking_Spawn
(Program_Name : String;
Args : Argument_List) return Process_Id;
-- This is a non blocking call. The Process_Id of the spawned process is
-- returned. Parameters are to be used as in Spawn. If Invalid_Pid is
-- returned the program could not be spawned.
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
--
-- This function will always return Invalid_Pid under VxWorks, since there
-- is no notion of executables under this OS.
function Non_Blocking_Spawn
(Program_Name : String;
Args : Argument_List;
Output_File_Descriptor : File_Descriptor;
Err_To_Out : Boolean := True) return Process_Id;
-- Similar to the procedure above, but redirects the output to the file
-- designated by Output_File_Descriptor. If Err_To_Out is True, then the
-- Standard Error output is also redirected. Invalid_Pid is returned
-- if the program could not be spawned successfully.
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
--
-- This function will always return Invalid_Pid under VxWorks, since there
-- is no notion of executables under this OS.
function Non_Blocking_Spawn
(Program_Name : String;
Args : Argument_List;
Output_File : String;
Err_To_Out : Boolean := True) return Process_Id;
-- Similar to the procedure above, but saves the output of the command to
-- a file with the name Output_File.
--
-- Success is set to True if the command is executed and its output
-- successfully written to the file. Invalid_Pid is returned if the output
-- file could not be created or if the program could not be spawned
-- successfully.
--
-- Spawning processes from tasking programs is not recommended. See
-- "NOTE: Spawn in tasking programs" below.
--
-- This function will always return Invalid_Pid under VxWorks, since there
-- is no notion of executables under this OS.
procedure Wait_Process (Pid : out Process_Id; Success : out Boolean);
-- Wait for the completion of any of the processes created by previous
-- calls to Non_Blocking_Spawn. The caller will be suspended until one of
-- these processes terminates (normally or abnormally). If any of these
-- subprocesses terminates prior to the call to Wait_Process (and has not
-- been returned by a previous call to Wait_Process), then the call to
-- Wait_Process is immediate. Pid identifies the process that has
-- terminated (matching the value returned from Non_Blocking_Spawn).
-- Success is set to True if this sub-process terminated successfully. If
-- Pid = Invalid_Pid, there were no subprocesses left to wait on.
--
-- This function will always set success to False under VxWorks, since
-- there is no notion of executables under this OS.
function Argument_String_To_List
(Arg_String : String) return Argument_List_Access;
-- Take a string that is a program and its arguments and parse it into an
-- Argument_List. Note that the result is allocated on the heap, and must
-- be freed by the programmer (when it is no longer needed) to avoid
-- memory leaks.
-------------------------------------
-- NOTE: Spawn in Tasking Programs --
-------------------------------------
-- Spawning processes in tasking programs using the above Spawn and
-- Non_Blocking_Spawn subprograms is not recommended, because there are
-- subtle interactions between creating a process and signals/locks that
-- can cause trouble. These issues are not specific to Ada; they depend
-- primarily on the operating system.
-- If you need to spawn processes in a tasking program, you will need to
-- understand the semantics of your operating system, and you are likely to
-- write non-portable code, because operating systems differ in this area.
-- The Spawn and Non_Blocking_Spawn subprograms call the following
-- operating system functions:
-- On Windows: spawnvp (blocking) or CreateProcess (non-blocking)
-- On Solaris: fork1, followed in the child process by execv
-- On other Unix-like systems, and on VMS: fork, followed in the child
-- process by execv.
-- On vxworks, nucleus, and RTX, spawning of processes is not supported
-- For details, look at the functions __gnat_portable_spawn and
-- __gnat_portable_no_block_spawn in adaint.c.
-- You should read the operating-system-specific documentation for the
-- above functions, paying special attention to subtle interactions with
-- threading, signals, locks, and file descriptors. Most of the issues are
-- related to the fact that on Unix, there is a window of time between fork
-- and execv; Windows does not have this problem, because spawning is done
-- in a single operation.
-- On Posix-compliant systems, such as Linux, fork duplicates just the
-- calling thread. (On Solaris, fork1 is the Posix-compliant version of
-- fork.)
-- You should avoid using signals while spawning. This includes signals
-- used internally by the Ada run-time system, such as timer signals used
-- to implement delay statements.
-- It is best to spawn any subprocesses very early, before the parent
-- process creates tasks, locks, or installs signal handlers. Certainly
-- avoid doing simultaneous spawns from multiple threads of the same
-- process.
-- There is no problem spawning a subprocess that uses tasking: the
-- problems are caused only by tasking in the parent.
-- If the parent is using tasking, and needs to spawn subprocesses at
-- arbitrary times, one technique is for the parent to spawn (very early)
-- a particular spawn-manager subprocess whose job is to spawn other
-- processes. The spawn-manager avoids tasking. The parent sends messages
-- to the spawn-manager requesting it to spawn processes, using whatever
-- inter-process communication mechanism you like, such as sockets.
-- In short, mixing spawning of subprocesses with tasking is a tricky
-- business, and should be avoided if possible, but if it is necessary,
-- the above guidelines should be followed, and you should beware of
-- portability problems.
-------------------
-- Miscellaneous --
-------------------
function Getenv (Name : String) return String_Access;
-- Get the value of the environment variable. Returns an access to the
-- empty string if the environment variable does not exist or has an
-- explicit null value (in some operating systems these are distinct
-- cases, in others they are not; this interface abstracts away that
-- difference. The argument is allocated on the heap (even in the null
-- case), and needs to be freed explicitly when no longer needed to avoid
-- memory leaks.
procedure Setenv (Name : String; Value : String);
-- Set the value of the environment variable Name to Value. This call
-- modifies the current environment, but does not modify the parent
-- process environment. After a call to Setenv, Getenv (Name) will always
-- return a String_Access referencing the same String as Value. This is
-- true also for the null string case (the actual effect may be to either
-- set an explicit null as the value, or to remove the entry, this is
-- operating system dependent). Note that any following calls to Spawn
-- will pass an environment to the spawned process that includes the
-- changes made by Setenv calls. This procedure is not available on VMS.
procedure OS_Exit (Status : Integer);
pragma No_Return (OS_Exit);
-- Exit to OS with given status code (program is terminated). Note that
-- this is abrupt termination. All tasks are immediately terminated. There
-- are no finalization or other Ada-specific cleanup actions performed. On
-- systems with atexit handlers (such as Unix and Windows), atexit handlers
-- are called.
type OS_Exit_Subprogram is access procedure (Status : Integer);
procedure OS_Exit_Default (Status : Integer);
pragma No_Return (OS_Exit_Default);
-- Default implementation of procedure OS_Exit
OS_Exit_Ptr : OS_Exit_Subprogram := OS_Exit_Default'Access;
-- OS_Exit is implemented through this access value. It it then possible to
-- change the implementation of OS_Exit by redirecting OS_Exit_Ptr to an
-- other implementation.
procedure OS_Abort;
pragma Import (C, OS_Abort, "abort");
pragma No_Return (OS_Abort);
-- Exit to OS signalling an abort (traceback or other appropriate
-- diagnostic information should be given if possible, or entry made to
-- the debugger if that is possible).
function Errno return Integer;
pragma Import (C, Errno, "__get_errno");
-- Return the task-safe last error number
procedure Set_Errno (Errno : Integer);
pragma Import (C, Set_Errno, "__set_errno");
-- Set the task-safe error number
Directory_Separator : constant Character;
-- The character that is used to separate parts of a pathname
Path_Separator : constant Character;
-- The character to separate paths in an environment variable value
private
pragma Import (C, Path_Separator, "__gnat_path_separator");
pragma Import (C, Directory_Separator, "__gnat_dir_separator");
pragma Import (C, Current_Time, "__gnat_current_time");
type OS_Time is
range -(2 ** (Standard'Address_Size - Integer'(1))) ..
+(2 ** (Standard'Address_Size - Integer'(1)) - 1);
-- Type used for timestamps in the compiler. This type is used to hold
-- time stamps, but may have a different representation than C's time_t.
-- This type needs to match the declaration of OS_Time in adaint.h.
-- Add pragma Inline statements for comparison operations on OS_Time. It
-- would actually be nice to use pragma Import (Intrinsic) here, but this
-- was not properly supported till GNAT 3.15a, so that would cause
-- bootstrap path problems. To be changed later ???
Invalid_Time : constant OS_Time := -1;
-- This value should match the return value from __gnat_file_time_*
pragma Inline ("<");
pragma Inline (">");
pragma Inline ("<=");
pragma Inline (">=");
type Process_Id is new Integer;
Invalid_Pid : constant Process_Id := -1;
end System.OS_Lib;