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 <base/logging.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 "check.h"
32 #include "osi/include/allocator.h"
33 #include "osi/include/log.h"
34 #include "osi/include/osi.h"
35
36 #if !defined(EFD_SEMAPHORE)
37 #define EFD_SEMAPHORE (1 << 0)
38 #endif
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("%s unable to allocate semaphore: %s", __func__, 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 CHECK(semaphore != NULL);
64 CHECK(semaphore->fd != INVALID_FD);
65
66 eventfd_t value;
67 if (eventfd_read(semaphore->fd, &value) == -1)
68 LOG_ERROR("%s unable to wait on semaphore: %s", __func__, strerror(errno));
69 }
70
semaphore_try_wait(semaphore_t * semaphore)71 bool semaphore_try_wait(semaphore_t* semaphore) {
72 CHECK(semaphore != NULL);
73 CHECK(semaphore->fd != INVALID_FD);
74
75 int flags = fcntl(semaphore->fd, F_GETFL);
76 if (flags == -1) {
77 LOG_ERROR("%s unable to get flags for semaphore fd: %s", __func__,
78 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__,
83 strerror(errno));
84 return false;
85 }
86
87 bool rc = true;
88 eventfd_t value;
89 if (eventfd_read(semaphore->fd, &value) == -1) rc = false;
90
91 if (fcntl(semaphore->fd, F_SETFL, flags) == -1)
92 LOG_ERROR("%s unable to restore flags for semaphore fd: %s", __func__,
93 strerror(errno));
94 return rc;
95 }
96
semaphore_post(semaphore_t * semaphore)97 void semaphore_post(semaphore_t* semaphore) {
98 CHECK(semaphore != NULL);
99 CHECK(semaphore->fd != INVALID_FD);
100
101 if (eventfd_write(semaphore->fd, 1ULL) == -1)
102 LOG_ERROR("%s unable to post to semaphore: %s", __func__, strerror(errno));
103 }
104
semaphore_get_fd(const semaphore_t * semaphore)105 int semaphore_get_fd(const semaphore_t* semaphore) {
106 CHECK(semaphore != NULL);
107 CHECK(semaphore->fd != INVALID_FD);
108 return semaphore->fd;
109 }
110