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 "os/log.h"
31 #include "osi/include/allocator.h"
32 #include "osi/include/osi.h"
33
34 #if !defined(EFD_SEMAPHORE)
35 #define EFD_SEMAPHORE (1 << 0)
36 #endif
37
38 using namespace bluetooth;
39
40 struct semaphore_t {
41 int fd;
42 };
43
semaphore_new(unsigned int value)44 semaphore_t* semaphore_new(unsigned int value) {
45 semaphore_t* ret = static_cast<semaphore_t*>(osi_malloc(sizeof(semaphore_t)));
46 ret->fd = eventfd(value, EFD_SEMAPHORE);
47 if (ret->fd == INVALID_FD) {
48 log::error("unable to allocate semaphore: {}", strerror(errno));
49 osi_free(ret);
50 ret = NULL;
51 }
52 return ret;
53 }
54
semaphore_free(semaphore_t * semaphore)55 void semaphore_free(semaphore_t* semaphore) {
56 if (!semaphore) return;
57
58 if (semaphore->fd != INVALID_FD) close(semaphore->fd);
59 osi_free(semaphore);
60 }
61
semaphore_wait(semaphore_t * semaphore)62 void semaphore_wait(semaphore_t* semaphore) {
63 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
64 log::assert_that(semaphore->fd != INVALID_FD,
65 "assert failed: semaphore->fd != INVALID_FD");
66
67 eventfd_t value;
68 if (eventfd_read(semaphore->fd, &value) == -1)
69 log::error("unable to wait on semaphore: {}", strerror(errno));
70 }
71
semaphore_try_wait(semaphore_t * semaphore)72 bool semaphore_try_wait(semaphore_t* semaphore) {
73 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
74 log::assert_that(semaphore->fd != INVALID_FD,
75 "assert failed: semaphore->fd != INVALID_FD");
76
77 int flags = fcntl(semaphore->fd, F_GETFL);
78 if (flags == -1) {
79 log::error("unable to get flags for semaphore fd: {}", strerror(errno));
80 return false;
81 }
82 if (fcntl(semaphore->fd, F_SETFL, flags | O_NONBLOCK) == -1) {
83 log::error("unable to set O_NONBLOCK for semaphore fd: {}",
84 strerror(errno));
85 return false;
86 }
87
88 bool rc = true;
89 eventfd_t value;
90 if (eventfd_read(semaphore->fd, &value) == -1) rc = false;
91
92 if (fcntl(semaphore->fd, F_SETFL, flags) == -1)
93 log::error("unable to restore flags for semaphore fd: {}", strerror(errno));
94 return rc;
95 }
96
semaphore_post(semaphore_t * semaphore)97 void semaphore_post(semaphore_t* semaphore) {
98 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
99 log::assert_that(semaphore->fd != INVALID_FD,
100 "assert failed: semaphore->fd != INVALID_FD");
101
102 if (eventfd_write(semaphore->fd, 1ULL) == -1)
103 log::error("unable to post to semaphore: {}", strerror(errno));
104 }
105
semaphore_get_fd(const semaphore_t * semaphore)106 int semaphore_get_fd(const semaphore_t* semaphore) {
107 log::assert_that(semaphore != NULL, "assert failed: semaphore != NULL");
108 log::assert_that(semaphore->fd != INVALID_FD,
109 "assert failed: semaphore->fd != INVALID_FD");
110 return semaphore->fd;
111 }
112