| lh | 9ed821d | 2023-04-07 01:36:19 -0700 | [diff] [blame^] | 1 | /* Copyright (C) 2002, 2003 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, write to the Free |
| 17 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 18 | 02111-1307 USA. */ |
| 19 | |
| 20 | #include <errno.h> |
| 21 | #include <search.h> |
| 22 | #include <sys/mman.h> |
| 23 | #include "semaphoreP.h" |
| 24 | |
| 25 | |
| 26 | /* Global variables to parametrize the walk function. This works |
| 27 | since we always have to use locks. And we have to use the twalk |
| 28 | function since the entries are not sorted wrt the mapping |
| 29 | address. */ |
| 30 | static sem_t *the_sem; |
| 31 | static struct inuse_sem *rec; |
| 32 | |
| 33 | static void |
| 34 | walker (const void *inodep, const VISIT which, const int depth) |
| 35 | { |
| 36 | struct inuse_sem *nodep = *(struct inuse_sem **) inodep; |
| 37 | |
| 38 | if (nodep->sem == the_sem) |
| 39 | rec = nodep; |
| 40 | } |
| 41 | |
| 42 | |
| 43 | int |
| 44 | sem_close ( |
| 45 | sem_t *sem) |
| 46 | { |
| 47 | int result = 0; |
| 48 | |
| 49 | /* Get the lock. */ |
| 50 | lll_lock (__sem_mappings_lock, LLL_PRIVATE); |
| 51 | |
| 52 | /* Locate the entry for the mapping the caller provided. */ |
| 53 | rec = NULL; |
| 54 | the_sem = sem; |
| 55 | twalk (__sem_mappings, walker); |
| 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 | } |