1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
/**
* MIT/X Consortium License
*
* Copyright © 2015 Mattias Andrée <maandree@member.fsf.org>
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#ifndef BUS_H
#define BUS_H
#ifndef _DEFAULT_SOURCE
# define _DEFAULT_SOURCE
#endif
#include <sys/types.h>
/**
* Open the bus for reading only
*/
#define BUS_RDONLY 1
/**
* Open the bus for writing only
*/
#define BUS_WRONLY 0
/**
* Open the bus for both reading and writing only
*/
#define BUS_RDWR 0
/**
* Fail to create bus if its file already exists
*/
#define BUS_EXCL 2
/**
* Fail if interrupted
*/
#define BUS_INTR 4
/**
* The number of bytes in storeable in the shared memory,
* note that this includes the NUL-termination.
* This means that message can be at most one byte smaller.
*/
#define BUS_MEMORY_SIZE 2048
/**
* Bus information
*/
typedef struct bus
{
/**
* The key for the semaphore array
*/
key_t key_sem;
/**
* The key for the
*/
key_t key_shm;
/**
* The ID of the semaphore array
*/
int sem_id;
/**
* The address of the shared memory
*/
char *message;
/**
* Non-zero if and only if `bus_poll` has not been
* called since the last `bus_poll_start`
*/
int first_poll;
} bus_t;
/**
* Create a new bus
*
* @param file The pathname of the bus, `NULL` to create a random one
* @param flags `BUS_EXCL` (if `file` is not `NULL`) to fail if the file
* already exists, otherwise if the file exists, nothing
* will happen;
* `BUS_INTR` to fail if interrupted
* @param out_file Output parameter for the pathname of the bus
* @return 0 on success, -1 on error
*/
int bus_create(const char *file, int flags, char **out_file);
/**
* Remove a bus
*
* @param file The pathname of the bus
* @return 0 on success, -1 on error
*/
int bus_unlink(const char *file);
/**
* Open an existing bus
*
* @param bus Bus information to fill
* @param file The filename of the bus
* @param flags `BUS_RDONLY`, `BUS_WRONLY` or `BUS_RDWR`,
* the value must not be negative
* @return 0 on success, -1 on error
*/
int bus_open(bus_t *bus, const char *file, int flags);
/**
* Close a bus
*
* @param bus Bus information
* @return 0 on success, -1 on error
*/
int bus_close(bus_t *bus);
/**
* Broadcast a message a bus
*
* @param bus Bus information
* @param message The message to write, may not be longer than
* `BUS_MEMORY_SIZE` including the NUL-termination
* @return 0 on success, -1 on error
*/
int bus_write(const bus_t *bus, const char *message);
/**
* Listen (in a loop, forever) for new message on a bus
*
* @param bus Bus information
* @param callback Function to call when a message is received, the
* input parameters will be the read message and
* `user_data` from `bus_read`'s parameter with the
* same name. The message must have been parsed or
* copied when `callback` returns as it may be over
* overridden after that time. `callback` should
* return either of the the values:
* * 0: stop listening
* * 1: continue listening
* * -1: an error has occurred
* However, the function [`bus_read`] will invoke
* `callback` with `message` set to `NULL`one time
* directly after it has started listening on the
* bus. This is to the the program now it can safely
* continue with any action that requires that the
* programs is listening on the bus.
* @return 0 on success, -1 on error
*/
int bus_read(const bus_t *bus, int (*callback)(const char *message, void *user_data), void *user_data);
int bus_poll_start(const bus_t *bus);
int bus_poll_stop(const bus_t *bus);
const char *bus_poll(const bus_t *bus);
#endif
|
