1/****************************************************************************** 2 * 3 * Copyright (C) 2014 Google, Inc. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 19#define LOG_TAG "bt_osi_semaphore" 20 21#include <assert.h> 22#include <errno.h> 23#include <fcntl.h> 24#include <malloc.h> 25#include <string.h> 26#include <sys/eventfd.h> 27 28#include "osi/include/allocator.h" 29#include "osi/include/osi.h" 30#include "osi/include/log.h" 31#include "osi/include/semaphore.h" 32 33#if !defined(EFD_SEMAPHORE) 34# define EFD_SEMAPHORE (1 << 0) 35#endif 36 37struct semaphore_t { 38 int fd; 39}; 40 41semaphore_t *semaphore_new(unsigned int value) { 42 semaphore_t *ret = osi_malloc(sizeof(semaphore_t)); 43 if (ret) { 44 ret->fd = eventfd(value, EFD_SEMAPHORE); 45 if (ret->fd == INVALID_FD) { 46 LOG_ERROR("%s unable to allocate semaphore: %s", __func__, strerror(errno)); 47 osi_free(ret); 48 ret = NULL; 49 } 50 } 51 return ret; 52} 53 54void semaphore_free(semaphore_t *semaphore) { 55 if (!semaphore) 56 return; 57 58 if (semaphore->fd != INVALID_FD) 59 close(semaphore->fd); 60 osi_free(semaphore); 61} 62 63void semaphore_wait(semaphore_t *semaphore) { 64 assert(semaphore != NULL); 65 assert(semaphore->fd != INVALID_FD); 66 67 uint64_t value; 68 if (eventfd_read(semaphore->fd, &value) == -1) 69 LOG_ERROR("%s unable to wait on semaphore: %s", __func__, strerror(errno)); 70} 71 72bool semaphore_try_wait(semaphore_t *semaphore) { 73 assert(semaphore != NULL); 74 assert(semaphore->fd != INVALID_FD); 75 76 int flags = fcntl(semaphore->fd, F_GETFL); 77 if (flags == -1) { 78 LOG_ERROR("%s unable to get flags for semaphore fd: %s", __func__, strerror(errno)); 79 return false; 80 } 81 if (fcntl(semaphore->fd, F_SETFL, flags | O_NONBLOCK) == -1) { 82 LOG_ERROR("%s unable to set O_NONBLOCK for semaphore fd: %s", __func__, strerror(errno)); 83 return false; 84 } 85 86 eventfd_t value; 87 if (eventfd_read(semaphore->fd, &value) == -1) 88 return false; 89 90 if (fcntl(semaphore->fd, F_SETFL, flags) == -1) 91 LOG_ERROR("%s unable to resetore flags for semaphore fd: %s", __func__, strerror(errno)); 92 return true; 93} 94 95void semaphore_post(semaphore_t *semaphore) { 96 assert(semaphore != NULL); 97 assert(semaphore->fd != INVALID_FD); 98 99 if (eventfd_write(semaphore->fd, 1ULL) == -1) 100 LOG_ERROR("%s unable to post to semaphore: %s", __func__, strerror(errno)); 101} 102 103int semaphore_get_fd(const semaphore_t *semaphore) { 104 assert(semaphore != NULL); 105 assert(semaphore->fd != INVALID_FD); 106 return semaphore->fd; 107} 108