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 "osi/include/semaphore.h" 22 23 #include <assert.h> 24 #include <errno.h> 25 #include <fcntl.h> 26 #include <malloc.h> 27 #include <string.h> 28 #include <sys/eventfd.h> 29 #include <unistd.h> 30 31 #include "osi/include/allocator.h" 32 #include "osi/include/log.h" 33 #include "osi/include/osi.h" 34 35 #if !defined(EFD_SEMAPHORE) 36 # define EFD_SEMAPHORE (1 << 0) 37 #endif 38 39 struct semaphore_t { 40 int fd; 41 }; 42 semaphore_new(unsigned int value)43 semaphore_t *semaphore_new(unsigned int value) { 44 semaphore_t *ret = osi_malloc(sizeof(semaphore_t)); 45 ret->fd = eventfd(value, EFD_SEMAPHORE); 46 if (ret->fd == INVALID_FD) { 47 LOG_ERROR(LOG_TAG, "%s unable to allocate semaphore: %s", __func__, strerror(errno)); 48 osi_free(ret); 49 ret = NULL; 50 } 51 return ret; 52 } 53 semaphore_free(semaphore_t * semaphore)54 void 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 semaphore_wait(semaphore_t * semaphore)63 void semaphore_wait(semaphore_t *semaphore) { 64 assert(semaphore != NULL); 65 assert(semaphore->fd != INVALID_FD); 66 67 eventfd_t value; 68 if (eventfd_read(semaphore->fd, &value) == -1) 69 LOG_ERROR(LOG_TAG, "%s unable to wait on semaphore: %s", __func__, strerror(errno)); 70 } 71 semaphore_try_wait(semaphore_t * semaphore)72 bool 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(LOG_TAG, "%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(LOG_TAG, "%s unable to set O_NONBLOCK for semaphore fd: %s", __func__, strerror(errno)); 83 return false; 84 } 85 86 bool rc = true; 87 eventfd_t value; 88 if (eventfd_read(semaphore->fd, &value) == -1) 89 rc = false; 90 91 if (fcntl(semaphore->fd, F_SETFL, flags) == -1) 92 LOG_ERROR(LOG_TAG, "%s unable to restore flags for semaphore fd: %s", __func__, strerror(errno)); 93 return rc; 94 } 95 semaphore_post(semaphore_t * semaphore)96 void semaphore_post(semaphore_t *semaphore) { 97 assert(semaphore != NULL); 98 assert(semaphore->fd != INVALID_FD); 99 100 if (eventfd_write(semaphore->fd, 1ULL) == -1) 101 LOG_ERROR(LOG_TAG, "%s unable to post to semaphore: %s", __func__, strerror(errno)); 102 } 103 semaphore_get_fd(const semaphore_t * semaphore)104 int semaphore_get_fd(const semaphore_t *semaphore) { 105 assert(semaphore != NULL); 106 assert(semaphore->fd != INVALID_FD); 107 return semaphore->fd; 108 } 109