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9fd92637 DG |
1 | /* |
2 | * Copyright (C) 2013 - David Goulet <dgoulet@efficios.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify it | |
5 | * under the terms of the GNU General Public License, version 2 only, as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
11 | * more details. | |
12 | * | |
13 | * You should have received a copy of the GNU General Public License along with | |
14 | * this program; if not, write to the Free Software Foundation, Inc., 51 | |
15 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
16 | */ | |
17 | ||
18 | #define _GNU_SOURCE | |
19 | #include <assert.h> | |
20 | #include <fcntl.h> | |
21 | #include <unistd.h> | |
22 | ||
23 | #include <common/common.h> | |
24 | ||
25 | #include "pipe.h" | |
26 | ||
27 | /* | |
28 | * Lock read side of a pipe. | |
29 | */ | |
30 | static void lock_read_side(struct lttng_pipe *pipe) | |
31 | { | |
32 | pthread_mutex_lock(&pipe->read_mutex); | |
33 | } | |
34 | ||
35 | /* | |
36 | * Unlock read side of a pipe. | |
37 | */ | |
38 | static void unlock_read_side(struct lttng_pipe *pipe) | |
39 | { | |
40 | pthread_mutex_unlock(&pipe->read_mutex); | |
41 | } | |
42 | ||
43 | /* | |
44 | * Lock write side of a pipe. | |
45 | */ | |
46 | static void lock_write_side(struct lttng_pipe *pipe) | |
47 | { | |
48 | pthread_mutex_lock(&pipe->write_mutex); | |
49 | } | |
50 | ||
51 | /* | |
52 | * Unlock write side of a pipe. | |
53 | */ | |
54 | static void unlock_write_side(struct lttng_pipe *pipe) | |
55 | { | |
56 | pthread_mutex_unlock(&pipe->write_mutex); | |
57 | } | |
58 | ||
59 | /* | |
60 | * Internal function. Close read side of pipe WITHOUT locking the mutex. | |
61 | * | |
62 | * Return 0 on success else a negative errno from close(2). | |
63 | */ | |
64 | static int _pipe_read_close(struct lttng_pipe *pipe) | |
65 | { | |
66 | int ret, ret_val = 0; | |
67 | ||
68 | assert(pipe); | |
69 | ||
70 | if (!lttng_pipe_is_read_open(pipe)) { | |
71 | goto end; | |
72 | } | |
73 | ||
74 | do { | |
75 | ret = close(pipe->fd[0]); | |
76 | } while (ret < 0 && errno == EINTR); | |
77 | if (ret < 0) { | |
78 | PERROR("close lttng read pipe"); | |
79 | ret_val = -errno; | |
80 | } | |
81 | pipe->r_state = LTTNG_PIPE_STATE_CLOSED; | |
82 | ||
83 | end: | |
84 | return ret_val; | |
85 | } | |
86 | ||
87 | /* | |
88 | * Internal function. Close write side of pipe WITHOUT locking the mutex. | |
89 | * | |
90 | * Return 0 on success else a negative errno from close(2). | |
91 | */ | |
92 | static int _pipe_write_close(struct lttng_pipe *pipe) | |
93 | { | |
94 | int ret, ret_val = 0; | |
95 | ||
96 | assert(pipe); | |
97 | ||
98 | if (!lttng_pipe_is_write_open(pipe)) { | |
99 | goto end; | |
100 | } | |
101 | ||
102 | do { | |
103 | ret = close(pipe->fd[1]); | |
104 | } while (ret < 0 && errno == EINTR); | |
105 | if (ret < 0) { | |
106 | PERROR("close lttng write pipe"); | |
107 | ret_val = -errno; | |
108 | } | |
109 | pipe->w_state = LTTNG_PIPE_STATE_CLOSED; | |
110 | ||
111 | end: | |
112 | return ret_val; | |
113 | } | |
114 | ||
115 | ||
116 | /* | |
117 | * Open a new lttng pipe and set flags using fcntl(). | |
118 | * | |
119 | * Return a newly allocated lttng pipe on success or else NULL. | |
120 | */ | |
121 | struct lttng_pipe *lttng_pipe_open(int flags) | |
122 | { | |
123 | int ret; | |
124 | struct lttng_pipe *p; | |
125 | ||
126 | p = zmalloc(sizeof(*p)); | |
127 | if (!p) { | |
128 | PERROR("zmalloc pipe open"); | |
129 | goto error; | |
130 | } | |
131 | ||
132 | ret = pipe(p->fd); | |
133 | if (ret < 0) { | |
134 | PERROR("lttng pipe"); | |
135 | goto error; | |
136 | } | |
137 | ||
138 | if (flags) { | |
139 | int i; | |
140 | ||
141 | for (i = 0; i < 2; i++) { | |
142 | ret = fcntl(p->fd[i], F_SETFD, flags); | |
143 | if (ret < 0) { | |
144 | PERROR("fcntl lttng pipe %d", flags); | |
145 | goto error; | |
146 | } | |
147 | } | |
148 | } | |
149 | ||
150 | pthread_mutex_init(&p->read_mutex, NULL); | |
151 | pthread_mutex_init(&p->write_mutex, NULL); | |
152 | p->r_state = LTTNG_PIPE_STATE_OPENED; | |
153 | p->w_state = LTTNG_PIPE_STATE_OPENED; | |
154 | p->flags = flags; | |
155 | ||
156 | return p; | |
157 | ||
158 | error: | |
159 | lttng_pipe_destroy(p); | |
160 | return NULL; | |
161 | } | |
162 | ||
163 | /* | |
164 | * Close read side of a lttng pipe. | |
165 | * | |
166 | * Return 0 on success else a negative value. | |
167 | */ | |
168 | int lttng_pipe_read_close(struct lttng_pipe *pipe) | |
169 | { | |
170 | int ret; | |
171 | ||
172 | assert(pipe); | |
173 | ||
174 | /* Handle read side first. */ | |
175 | lock_read_side(pipe); | |
176 | ret = _pipe_read_close(pipe); | |
177 | unlock_read_side(pipe); | |
178 | ||
179 | return ret; | |
180 | } | |
181 | ||
182 | /* | |
183 | * Close write side of a lttng pipe. | |
184 | * | |
185 | * Return 0 on success else a negative value. | |
186 | */ | |
187 | int lttng_pipe_write_close(struct lttng_pipe *pipe) | |
188 | { | |
189 | int ret; | |
190 | ||
191 | assert(pipe); | |
192 | ||
193 | lock_write_side(pipe); | |
194 | ret = _pipe_write_close(pipe); | |
195 | unlock_write_side(pipe); | |
196 | ||
197 | return ret; | |
198 | } | |
199 | ||
200 | /* | |
201 | * Close both read and write side of a lttng pipe. | |
202 | * | |
203 | * Return 0 on success else a negative value. | |
204 | */ | |
205 | int lttng_pipe_close(struct lttng_pipe *pipe) | |
206 | { | |
207 | int ret, ret_val = 0; | |
208 | ||
209 | assert(pipe); | |
210 | ||
211 | ret = lttng_pipe_read_close(pipe); | |
212 | if (ret < 0) { | |
213 | ret_val = ret; | |
214 | } | |
215 | ||
216 | ret = lttng_pipe_write_close(pipe); | |
217 | if (ret < 0) { | |
218 | ret_val = ret; | |
219 | } | |
220 | ||
221 | return ret_val; | |
222 | } | |
223 | ||
224 | /* | |
225 | * Close and destroy a lttng pipe object. Finally, pipe is freed. | |
226 | */ | |
227 | void lttng_pipe_destroy(struct lttng_pipe *pipe) | |
228 | { | |
229 | int ret; | |
230 | ||
231 | if (!pipe) { | |
232 | return; | |
233 | } | |
234 | ||
235 | /* | |
236 | * Destroy should *never* be called with a locked mutex. These must always | |
237 | * succeed so we unlock them after the close pipe below. | |
238 | */ | |
239 | ret = pthread_mutex_trylock(&pipe->read_mutex); | |
240 | assert(!ret); | |
241 | ret = pthread_mutex_trylock(&pipe->write_mutex); | |
242 | assert(!ret); | |
243 | ||
244 | /* Close pipes WITHOUT trying to lock the pipes. */ | |
245 | (void) _pipe_read_close(pipe); | |
246 | (void) _pipe_write_close(pipe); | |
247 | ||
248 | unlock_read_side(pipe); | |
249 | unlock_write_side(pipe); | |
250 | ||
251 | (void) pthread_mutex_destroy(&pipe->read_mutex); | |
252 | (void) pthread_mutex_destroy(&pipe->write_mutex); | |
253 | ||
254 | free(pipe); | |
255 | } | |
256 | ||
257 | /* | |
258 | * Read on a lttng pipe and put the data in buf of at least size count. | |
259 | * | |
6cd525e8 MD |
260 | * Return "count" on success. Return < count on error. errno can be used |
261 | * to check the actual error. | |
9fd92637 DG |
262 | */ |
263 | ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count) | |
264 | { | |
6cd525e8 | 265 | ssize_t ret; |
9fd92637 DG |
266 | |
267 | assert(pipe); | |
268 | assert(buf); | |
269 | ||
270 | lock_read_side(pipe); | |
9fd92637 | 271 | if (!lttng_pipe_is_read_open(pipe)) { |
6cd525e8 MD |
272 | ret = -1; |
273 | errno = EBADF; | |
9fd92637 DG |
274 | goto error; |
275 | } | |
6cd525e8 | 276 | ret = lttng_read(pipe->fd[0], buf, count); |
9fd92637 DG |
277 | error: |
278 | unlock_read_side(pipe); | |
279 | return ret; | |
280 | } | |
281 | ||
282 | /* | |
283 | * Write on a lttng pipe using the data in buf and size of count. | |
284 | * | |
6cd525e8 MD |
285 | * Return "count" on success. Return < count on error. errno can be used |
286 | * to check the actual error. | |
9fd92637 DG |
287 | */ |
288 | ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf, | |
289 | size_t count) | |
290 | { | |
6cd525e8 | 291 | ssize_t ret; |
9fd92637 DG |
292 | |
293 | assert(pipe); | |
294 | assert(buf); | |
295 | ||
296 | lock_write_side(pipe); | |
9fd92637 | 297 | if (!lttng_pipe_is_write_open(pipe)) { |
6cd525e8 MD |
298 | ret = -1; |
299 | errno = EBADF; | |
9fd92637 DG |
300 | goto error; |
301 | } | |
6cd525e8 | 302 | ret = lttng_write(pipe->fd[1], buf, count); |
9fd92637 DG |
303 | error: |
304 | unlock_write_side(pipe); | |
305 | return ret; | |
306 | } |