The Tor Browser: nsprpub/pr/include/pripcsem.h@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     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/. */

     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  */

    24 #ifndef pripcsem_h___

    25 #define pripcsem_h___

    27 #include "prtypes.h"

    28 #include "prio.h"

    30 PR_BEGIN_EXTERN_C

    32 /*

    33  * PRSem is an opaque structure that represents a named

    34  * semaphore.

    35  */

    36 typedef struct PRSem PRSem;

    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  */

    57 #define PR_SEM_CREATE 0x1  /* create if not exist */

    58 #define PR_SEM_EXCL   0x2  /* fail if already exists */

    60 NSPR_API(PRSem *) PR_OpenSemaphore(

    61     const char *name, PRIntn flags, PRIntn mode, PRUintn value);

    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  */

    73 NSPR_API(PRStatus) PR_WaitSemaphore(PRSem *sem);

    75 /*

    76  * PR_PostSemaphore --

    77  *

    78  * Increment the value of the named semaphore by 1.

    79  */

    81 NSPR_API(PRStatus) PR_PostSemaphore(PRSem *sem);

    83 /*

    84  * PR_CloseSemaphore --

    85  *

    86  * Close a named semaphore handle.

    87  */

    89 NSPR_API(PRStatus) PR_CloseSemaphore(PRSem *sem);

    91 /*

    92  * PR_DeleteSemaphore --

    93  *

    94  * Remove a named semaphore from the system.

    95  */

    97 NSPR_API(PRStatus) PR_DeleteSemaphore(const char *name);

    99 PR_END_EXTERN_C

   101 #endif /* pripcsem_h___ */

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