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glibc/nptl/sem_close.c
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/* Copyright (C) 2002-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <errno.h> | |
#include <search.h> | |
#include <sys/mman.h> | |
#include "semaphoreP.h" | |
/* Global variables to parametrize the walk function. This works | |
since we always have to use locks. And we have to use the twalk | |
function since the entries are not sorted wrt the mapping | |
address. */ | |
static sem_t *the_sem; | |
static struct inuse_sem *rec; | |
static void | |
walker (const void *inodep, const VISIT which, const int depth) | |
{ | |
struct inuse_sem *nodep = *(struct inuse_sem **) inodep; | |
if (nodep->sem == the_sem) | |
rec = nodep; | |
} | |
int | |
sem_close (sem_t *sem) | |
{ | |
int result = 0; | |
/* Get the lock. */ | |
lll_lock (__sem_mappings_lock, LLL_PRIVATE); | |
/* Locate the entry for the mapping the caller provided. */ | |
rec = NULL; | |
the_sem = sem; | |
__twalk (__sem_mappings, walker); | |
if (rec != NULL) | |
{ | |
/* Check the reference counter. If it is going to be zero, free | |
all the resources. */ | |
if (--rec->refcnt == 0) | |
{ | |
/* Remove the record from the tree. */ | |
(void) __tdelete (rec, &__sem_mappings, __sem_search); | |
result = munmap (rec->sem, sizeof (sem_t)); | |
free (rec); | |
} | |
} | |
else | |
{ | |
/* This is no valid semaphore. */ | |
result = -1; | |
__set_errno (EINVAL); | |
} | |
/* Release the lock. */ | |
lll_unlock (__sem_mappings_lock, LLL_PRIVATE); | |
return result; | |
} |