1/* Copyright (C) 2002-2020 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <errno.h>
20#include <search.h>
21#include <sys/mman.h>
22#include "semaphoreP.h"
23
24struct walk_closure
25{
26 sem_t *the_sem;
27 struct inuse_sem *rec;
28};
29
30static void
31walker (const void *inodep, VISIT which, void *closure0)
32{
33 struct walk_closure *closure = closure0;
34 struct inuse_sem *nodep = *(struct inuse_sem **) inodep;
35
36 if (nodep->sem == closure->the_sem)
37 closure->rec = nodep;
38}
39
40
41int
42sem_close (sem_t *sem)
43{
44 int result = 0;
45
46 /* Get the lock. */
47 lll_lock (__sem_mappings_lock, LLL_PRIVATE);
48
49 /* Locate the entry for the mapping the caller provided. */
50 struct inuse_sem *rec;
51 {
52 struct walk_closure closure = { .the_sem = sem, .rec = NULL };
53 __twalk_r (__sem_mappings, walker, &closure);
54 rec = closure.rec;
55 }
56 if (rec != NULL)
57 {
58 /* Check the reference counter. If it is going to be zero, free
59 all the resources. */
60 if (--rec->refcnt == 0)
61 {
62 /* Remove the record from the tree. */
63 (void) __tdelete (rec, &__sem_mappings, __sem_search);
64
65 result = munmap (rec->sem, sizeof (sem_t));
66
67 free (rec);
68 }
69 }
70 else
71 {
72 /* This is no valid semaphore. */
73 result = -1;
74 __set_errno (EINVAL);
75 }
76
77 /* Release the lock. */
78 lll_unlock (__sem_mappings_lock, LLL_PRIVATE);
79
80 return result;
81}
82