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------------------------------------------------------------------------------
-- --
-- FLORIST (FSU Implementation of POSIX.5) COMPONENTS --
-- --
-- P O S I X . S E M A P H O R E S --
-- --
-- S p e c --
-- --
-- Copyright (C) 1996-1997 Florida State University --
-- Copyright (C) 1998-2010, AdaCore --
-- --
-- This file is a component of FLORIST, an implementation of the POSIX --
-- Ada bindings for use with the GNAT Ada compiler and the FSU Gnu Ada --
-- Runtime Library (GNARL). --
-- --
-- This package specification contains some text extracted from IEEE STD --
-- 1003.5: 1990, Information Technology -- POSIX Ada Language Interfaces --
-- Part 1: Binding for System Application Program Interface, as amended --
-- by IEEE STD 1003.5b: 1996, Amendment 1: Realtime Extensions, copyright --
-- 1996 by the Institute of Electrical and Electronics Engineers, Inc. --
-- --
-- The package specifications in the IEEE standards cited above represent --
-- only a portion of the documents and are not to be interpreteted --
-- outside the context of the documents. The standards must be used in --
-- conjunction with the package specifications in order to claim --
-- conformance. The IEEE takes no responsibility for and will assume no --
-- liability for damages resulting from the reader's misinterpretation of --
-- said information resulting from its out-of-context nature. To order --
-- copies of the IEEE standards, please contact the IEEE Service Center --
-- at 445 Hoes Lane, PO Box 1331, Piscataway, NJ 08855-1331; via phone at --
-- 1-800-678-IEEE, 908-981-1393; or via fax at 908-981-9667. --
-- --
-- These package specifications are distributed in the hope that they --
-- will be useful, but WITHOUT ANY WARRANTY; without even the implied --
-- warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
------------------------------------------------------------------------------
with POSIX.C,
POSIX.IO,
POSIX.Permissions;
package POSIX.Semaphores is
type Semaphore is limited private;
type Semaphore_Descriptor is private;
procedure Initialize
(Sem : in out Semaphore;
Value : Natural;
Is_Shared : Boolean := False);
function Descriptor_Of (Sem : Semaphore) return Semaphore_Descriptor;
procedure Finalize (Sem : in out Semaphore);
function Open
(Name : POSIX.POSIX_String;
Masked_Signals : POSIX.Signal_Masking := POSIX.RTS_Signals)
return Semaphore_Descriptor;
function Open_Or_Create
(Name : POSIX.POSIX_String;
Permissions : POSIX.Permissions.Permission_Set;
Value : Natural;
Options : POSIX.IO.Open_Option_Set := POSIX.IO.Empty_Set;
Masked_Signals : POSIX.Signal_Masking := POSIX.RTS_Signals)
return Semaphore_Descriptor;
procedure Close (Sem : in out Semaphore_Descriptor);
procedure Unlink_Semaphore (Name : POSIX.POSIX_String);
procedure Wait
(Sem : Semaphore_Descriptor;
Masked_Signals : POSIX.Signal_Masking := POSIX.RTS_Signals);
function Try_Wait (Sem : Semaphore_Descriptor) return Boolean;
procedure Post (Sem : Semaphore_Descriptor);
function Get_Value (Sem : Semaphore_Descriptor) return Integer;
-- .... Change POSIX.5b?
-- The Wait and Try_Wait operations are allowed to be interruptible
-- by a signal, according to the C binding. Here, we have no
-- Masked_Signals parameter. If the system support POSIX threads,
-- we are probably OK, since we will want to keep most signals masked,
-- in all threads but the corresponding handler (if any).
private
-- We rely that type Semaphore will be passed by reference,
-- so that we can use 'Address of a parameter (even an "in" parameter)
-- to get a pointer to the actual object.
-- If there is any danger that it will not be passed by reference,
-- we will need to enclose the "sem_t" value as an aliased component of a
-- record or even of a tagged type.
type Dummy is tagged null record;
type Semaphore is record
Sem : aliased POSIX.C.sem_t;
-- to force by-reference parameter mode:
D : Dummy;
end record;
-- The "access constant" is sometimes a lie, but it allows
-- us to emulate the POSIX C-language interface without violating
-- Ada rules about pointers to variables vs. pointers to constants.
type Semaphore_Descriptor is access constant POSIX.C.sem_t;
pragma Convention (C, Semaphore_Descriptor);
end POSIX.Semaphores;
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