1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
/* Copyright (C) 2002-2020 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
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <search.h>
#include <sys/mman.h>
#include "semaphoreP.h"
struct walk_closure
{
sem_t *the_sem;
struct inuse_sem *rec;
};
static void
walker (const void *inodep, VISIT which, void *closure0)
{
struct walk_closure *closure = closure0;
struct inuse_sem *nodep = *(struct inuse_sem **) inodep;
if (nodep->sem == closure->the_sem)
closure->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. */
struct inuse_sem *rec;
{
struct walk_closure closure = { .the_sem = sem, .rec = NULL };
__twalk_r (__sem_mappings, walker, &closure);
rec = closure.rec;
}
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;
}
|
