1 /*
2 * Copyright (C) 2010 Red Hat, Inc.
3 *
4 * Author: Angus Salkeld <asalkeld@redhat.com>
5 *
6 * This file is part of libqb.
7 *
8 * libqb is free software: you can redistribute it and/or modify
9 * it under the terms of the GNU Lesser General Public License as published by
10 * the Free Software Foundation, either version 2.1 of the License, or
11 * (at your option) any later version.
12 *
13 * libqb is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public License
19 * along with libqb. If not, see <http://www.gnu.org/licenses/>.
20 */
21 #ifndef _RINGBUFFER_H_
22 #define _RINGBUFFER_H_
23
24 #include "os_base.h"
25
26 #ifdef HAVE_SYS_MMAN_H
27 #include <sys/mman.h>
28 #endif /* HAVE_SYS_MMAN_H */
29 #ifdef HAVE_SYS_SEM_H
30 #include <sys/sem.h>
31 #endif
32 #ifdef HAVE_SYS_IPC_H
33 #include <sys/ipc.h>
34 #endif
35 #include "rpl_sem.h"
36 #include "util_int.h"
37 #include <qb/qbatomic.h>
38 #include <qb/qbutil.h>
39 #include <qb/qbrb.h>
40
41 struct qb_ringbuffer_s;
42
43 int32_t qb_rb_sem_create(struct qb_ringbuffer_s *rb, uint32_t flags);
44
45 typedef int32_t(*qb_rb_notifier_post_fn_t) (void * instance, size_t msg_size);
46 typedef ssize_t(*qb_rb_notifier_q_len_fn_t) (void * instance);
47 typedef ssize_t(*qb_rb_notifier_used_fn_t) (void * instance);
48 typedef int32_t(*qb_rb_notifier_timedwait_fn_t) (void * instance,
49 int32_t ms_timeout);
50 typedef int32_t(*qb_rb_notifier_reclaim_fn_t) (void * instance, size_t msg_size);
51 typedef int32_t(*qb_rb_notifier_destroy_fn_t) (void * instance);
52
53 struct qb_rb_notifier {
54 qb_rb_notifier_post_fn_t post_fn;
55 qb_rb_notifier_q_len_fn_t q_len_fn;
56 qb_rb_notifier_used_fn_t space_used_fn;
57 qb_rb_notifier_timedwait_fn_t timedwait_fn;
58 qb_rb_notifier_reclaim_fn_t reclaim_fn;
59 qb_rb_notifier_destroy_fn_t destroy_fn;
60 void *instance;
61 };
62
63 struct qb_ringbuffer_shared_s {
64 volatile uint32_t write_pt;
65 volatile uint32_t read_pt;
66 uint32_t word_size;
67 char hdr_path[PATH_MAX];
68 char data_path[PATH_MAX];
69 int32_t ref_count;
70 rpl_sem_t posix_sem;
71 char user_data[1];
72 } __attribute__ ((aligned(8)));
73
74 struct qb_ringbuffer_s {
75 uint32_t flags;
76 int32_t sem_id;
77 struct qb_ringbuffer_shared_s *shared_hdr;
78 uint32_t *shared_data;
79
80 struct qb_rb_notifier notifier;
81 };
82
83 void qb_rb_force_close(qb_ringbuffer_t * rb);
84
85 /**
86 * Helper to munmap, and conditionally unlink the file or possibly truncate it.
87 * @param rb ringbuffer instance.
88 * @param unlink_it whether the underlying files should be unlinked.
89 * @param truncate_fallback whether to truncate the files when unlink fails.
90 * @return 0 (success) or -errno
91 */
92 int32_t qb_rb_close_helper(struct qb_ringbuffer_s * rb, int32_t unlink_it,
93 int32_t truncate_fallback);
94
95 qb_ringbuffer_t *qb_rb_open_2(const char *name, size_t size, uint32_t flags,
96 size_t shared_user_data_size,
97 struct qb_rb_notifier *notifier);
98
99
100 #ifndef HAVE_SEMUN
101 union semun {
102 int32_t val;
103 struct semid_ds *buf;
104 unsigned short int *array;
105 struct seminfo *__buf;
106 };
107 #endif /* HAVE_SEMUN */
108
109
110 /* This function is to be used to "decorate" argument (with an extra
111 reference level added) to qb_rb_{force_,}_close() so as to avoid trivial
112 IPC API misuses such as recv-after-close rather than avoiding races in
113 multi-threaded applications (although it partially helps there, too);
114 it's debatable whether that should be fixed at higher level in ipc[cs].c */
115 static inline struct qb_ringbuffer_s *
qb_rb_lastref_and_ret(struct qb_ringbuffer_s ** rb)116 qb_rb_lastref_and_ret(struct qb_ringbuffer_s ** rb)
117 {
118 struct qb_ringbuffer_s *rb_res = *rb;
119
120 if (rb_res == NULL) {
121 return NULL;
122 }
123 *rb = NULL;
124 /* qb_rb_close will get rid of this "last reference" */
125 qb_atomic_int_set(&rb_res->shared_hdr->ref_count, 1);
126
127 return rb_res;
128 }
129
130 #endif /* _RINGBUFFER_H_ */
131