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       1             : /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* This Source Code Form is subject to the terms of the Mozilla Public
       3             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       4             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       5             : 
       6             : /*
       7             :  * File: pripcsem.h
       8             :  *
       9             :  * Description: named semaphores for interprocess
      10             :  * synchronization
      11             :  *
      12             :  * Unrelated processes obtain access to a shared semaphore
      13             :  * by specifying its name.
      14             :  *
      15             :  * Our goal is to support named semaphores on at least
      16             :  * Unix and Win32 platforms.  The implementation will use
      17             :  * one of the three native semaphore APIs: POSIX, System V,
      18             :  * and Win32.
      19             :  *
      20             :  * Because POSIX named semaphores have kernel persistence,
      21             :  * we are forced to have a delete function in this API.
      22             :  */
      23             : 
      24             : #ifndef pripcsem_h___
      25             : #define pripcsem_h___
      26             : 
      27             : #include "prtypes.h"
      28             : #include "prio.h"
      29             : 
      30             : PR_BEGIN_EXTERN_C
      31             : 
      32             : /*
      33             :  * PRSem is an opaque structure that represents a named
      34             :  * semaphore.
      35             :  */
      36             : typedef struct PRSem PRSem;
      37             : 
      38             : /*
      39             :  * PR_OpenSemaphore --
      40             :  *
      41             :  * Create or open a named semaphore with the specified name.
      42             :  * A handle to the semaphore is returned.
      43             :  *
      44             :  * If the named semaphore doesn't exist and the PR_SEM_CREATE
      45             :  * flag is specified, the named semaphore is created.  The
      46             :  * created semaphore needs to be removed from the system with
      47             :  * a PR_DeleteSemaphore call.
      48             :  *
      49             :  * If PR_SEM_CREATE is specified, the third argument is the
      50             :  * access permission bits of the new semaphore (same
      51             :  * interpretation as the mode argument to PR_Open) and the
      52             :  * fourth argument is the initial value of the new semaphore.
      53             :  * If PR_SEM_CREATE is not specified, the third and fourth
      54             :  * arguments are ignored.
      55             :  */
      56             : 
      57             : #define PR_SEM_CREATE 0x1  /* create if not exist */
      58             : #define PR_SEM_EXCL   0x2  /* fail if already exists */
      59             : 
      60           0 : NSPR_API(PRSem *) PR_OpenSemaphore(
      61             :     const char *name, PRIntn flags, PRIntn mode, PRUintn value);
      62             : 
      63             : /*
      64             :  * PR_WaitSemaphore --
      65             :  *
      66             :  * If the value of the semaphore is > 0, decrement the value and return.
      67             :  * If the value is 0, sleep until the value becomes > 0, then decrement
      68             :  * the value and return.
      69             :  *
      70             :  * The "test and decrement" operation is performed atomically.
      71             :  */
      72             : 
      73           0 : NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);
      74             : 
      75             : /*
      76             :  * PR_PostSemaphore --
      77             :  *
      78             :  * Increment the value of the named semaphore by 1.
      79             :  */
      80             : 
      81           0 : NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem);
      82             : 
      83             : /*
      84             :  * PR_CloseSemaphore --
      85             :  *
      86             :  * Close a named semaphore handle.
      87             :  */
      88             : 
      89           0 : NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem);
      90             : 
      91             : /*
      92             :  * PR_DeleteSemaphore --
      93             :  *
      94             :  * Remove a named semaphore from the system.
      95             :  */
      96             : 
      97           0 : NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name);
      98             : 
      99             : PR_END_EXTERN_C
     100             : 
     101             : #endif /* pripcsem_h___ */