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80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
/* Copyright (C) 2002-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <search.h>
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#include <sys/mman.h>
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#include "semaphoreP.h"
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/* Global variables to parametrize the walk function. This works
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since we always have to use locks. And we have to use the twalk
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function since the entries are not sorted wrt the mapping
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address. */
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static sem_t *the_sem;
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static struct inuse_sem *rec;
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static void
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walker (const void *inodep, const VISIT which, const int depth)
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{
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struct inuse_sem *nodep = *(struct inuse_sem **) inodep;
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if (nodep->sem == the_sem)
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rec = nodep;
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}
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int
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sem_close (sem_t *sem)
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{
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int result = 0;
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/* Get the lock. */
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lll_lock (__sem_mappings_lock, LLL_PRIVATE);
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/* Locate the entry for the mapping the caller provided. */
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rec = NULL;
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the_sem = sem;
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__twalk (__sem_mappings, walker);
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if (rec != NULL)
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{
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/* Check the reference counter. If it is going to be zero, free
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all the resources. */
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if (--rec->refcnt == 0)
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{
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/* Remove the record from the tree. */
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(void) __tdelete (rec, &__sem_mappings, __sem_search);
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result = munmap (rec->sem, sizeof (sem_t));
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free (rec);
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}
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}
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else
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{
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/* This is no valid semaphore. */
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result = -1;
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__set_errno (EINVAL);
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}
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/* Release the lock. */
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lll_unlock (__sem_mappings_lock, LLL_PRIVATE);
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return result;
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}
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