1 /******************************************************************************
2 *
3 * Copyright 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/semaphore.h"
22
23 #include <bluetooth/log.h>
24 #include <fcntl.h>
25 #include <malloc.h>
26 #include <string.h>
27 #include <sys/eventfd.h>
28 #include <unistd.h>
29
30 #include "osi/include/allocator.h"
31 #include "osi/include/osi.h"
32
33 #if !defined(EFD_SEMAPHORE)
34 #define EFD_SEMAPHORE (1 << 0)
35 #endif
36
37 using namespace bluetooth;
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 = static_cast<semaphore_t*>(osi_malloc(sizeof(semaphore_t)));
45 ret->fd = eventfd(value, EFD_SEMAPHORE);
46 if (ret->fd == INVALID_FD) {
47 log::error("unable to allocate semaphore: {}", 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
59 if (semaphore->fd != INVALID_FD) {
60 close(semaphore->fd);
61 }
62 osi_free(semaphore);
63 }
64
semaphore_wait(semaphore_t * semaphore)65 void semaphore_wait(semaphore_t* semaphore) {
66 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
67 log::assert_that(semaphore->fd != INVALID_FD, "assert failed: semaphore->fd != INVALID_FD");
68
69 eventfd_t value;
70 if (eventfd_read(semaphore->fd, &value) == -1) {
71 log::error("unable to wait on semaphore: {}", strerror(errno));
72 }
73 }
74
semaphore_try_wait(semaphore_t * semaphore)75 bool semaphore_try_wait(semaphore_t* semaphore) {
76 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
77 log::assert_that(semaphore->fd != INVALID_FD, "assert failed: semaphore->fd != INVALID_FD");
78
79 int flags = fcntl(semaphore->fd, F_GETFL);
80 if (flags == -1) {
81 log::error("unable to get flags for semaphore fd: {}", strerror(errno));
82 return false;
83 }
84 if (fcntl(semaphore->fd, F_SETFL, flags | O_NONBLOCK) == -1) {
85 log::error("unable to set O_NONBLOCK for semaphore fd: {}", strerror(errno));
86 return false;
87 }
88
89 bool rc = true;
90 eventfd_t value;
91 if (eventfd_read(semaphore->fd, &value) == -1) {
92 rc = false;
93 }
94
95 if (fcntl(semaphore->fd, F_SETFL, flags) == -1) {
96 log::error("unable to restore flags for semaphore fd: {}", strerror(errno));
97 }
98 return rc;
99 }
100
semaphore_post(semaphore_t * semaphore)101 void semaphore_post(semaphore_t* semaphore) {
102 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
103 log::assert_that(semaphore->fd != INVALID_FD, "assert failed: semaphore->fd != INVALID_FD");
104
105 if (eventfd_write(semaphore->fd, 1ULL) == -1) {
106 log::error("unable to post to semaphore: {}", strerror(errno));
107 }
108 }
109
semaphore_get_fd(const semaphore_t * semaphore)110 int semaphore_get_fd(const semaphore_t* semaphore) {
111 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
112 log::assert_that(semaphore->fd != INVALID_FD, "assert failed: semaphore->fd != INVALID_FD");
113 return semaphore->fd;
114 }
115