Re-add default size symbols which were erroneously exposed
[lttng-tools.git] / src / common / pipe.c
CommitLineData
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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
6c1c0768 18#define _LGPL_SOURCE
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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 */
30static 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 */
38static 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 */
46static 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 */
54static 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 */
64static 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
83end:
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 */
92static 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
111end:
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 */
a247c6e0 121LTTNG_HIDDEN
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122struct lttng_pipe *lttng_pipe_open(int flags)
123{
124 int ret;
125 struct lttng_pipe *p;
126
127 p = zmalloc(sizeof(*p));
128 if (!p) {
129 PERROR("zmalloc pipe open");
130 goto error;
131 }
132
133 ret = pipe(p->fd);
134 if (ret < 0) {
135 PERROR("lttng pipe");
136 goto error;
137 }
138
139 if (flags) {
140 int i;
141
142 for (i = 0; i < 2; i++) {
143 ret = fcntl(p->fd[i], F_SETFD, flags);
144 if (ret < 0) {
145 PERROR("fcntl lttng pipe %d", flags);
146 goto error;
147 }
148 }
149 }
150
151 pthread_mutex_init(&p->read_mutex, NULL);
152 pthread_mutex_init(&p->write_mutex, NULL);
153 p->r_state = LTTNG_PIPE_STATE_OPENED;
154 p->w_state = LTTNG_PIPE_STATE_OPENED;
155 p->flags = flags;
156
157 return p;
158
159error:
160 lttng_pipe_destroy(p);
161 return NULL;
162}
163
164/*
165 * Close read side of a lttng pipe.
166 *
167 * Return 0 on success else a negative value.
168 */
a247c6e0 169LTTNG_HIDDEN
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170int lttng_pipe_read_close(struct lttng_pipe *pipe)
171{
172 int ret;
173
174 assert(pipe);
175
176 /* Handle read side first. */
177 lock_read_side(pipe);
178 ret = _pipe_read_close(pipe);
179 unlock_read_side(pipe);
180
181 return ret;
182}
183
184/*
185 * Close write side of a lttng pipe.
186 *
187 * Return 0 on success else a negative value.
188 */
a247c6e0 189LTTNG_HIDDEN
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190int lttng_pipe_write_close(struct lttng_pipe *pipe)
191{
192 int ret;
193
194 assert(pipe);
195
196 lock_write_side(pipe);
197 ret = _pipe_write_close(pipe);
198 unlock_write_side(pipe);
199
200 return ret;
201}
202
203/*
204 * Close both read and write side of a lttng pipe.
205 *
206 * Return 0 on success else a negative value.
207 */
a247c6e0 208LTTNG_HIDDEN
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209int lttng_pipe_close(struct lttng_pipe *pipe)
210{
211 int ret, ret_val = 0;
212
213 assert(pipe);
214
215 ret = lttng_pipe_read_close(pipe);
216 if (ret < 0) {
217 ret_val = ret;
218 }
219
220 ret = lttng_pipe_write_close(pipe);
221 if (ret < 0) {
222 ret_val = ret;
223 }
224
225 return ret_val;
226}
227
228/*
229 * Close and destroy a lttng pipe object. Finally, pipe is freed.
230 */
a247c6e0 231LTTNG_HIDDEN
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232void lttng_pipe_destroy(struct lttng_pipe *pipe)
233{
234 int ret;
235
236 if (!pipe) {
237 return;
238 }
239
240 /*
241 * Destroy should *never* be called with a locked mutex. These must always
242 * succeed so we unlock them after the close pipe below.
243 */
244 ret = pthread_mutex_trylock(&pipe->read_mutex);
245 assert(!ret);
246 ret = pthread_mutex_trylock(&pipe->write_mutex);
247 assert(!ret);
248
249 /* Close pipes WITHOUT trying to lock the pipes. */
250 (void) _pipe_read_close(pipe);
251 (void) _pipe_write_close(pipe);
252
253 unlock_read_side(pipe);
254 unlock_write_side(pipe);
255
256 (void) pthread_mutex_destroy(&pipe->read_mutex);
257 (void) pthread_mutex_destroy(&pipe->write_mutex);
258
259 free(pipe);
260}
261
262/*
263 * Read on a lttng pipe and put the data in buf of at least size count.
264 *
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265 * Return "count" on success. Return < count on error. errno can be used
266 * to check the actual error.
9fd92637 267 */
a247c6e0 268LTTNG_HIDDEN
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269ssize_t lttng_pipe_read(struct lttng_pipe *pipe, void *buf, size_t count)
270{
6cd525e8 271 ssize_t ret;
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272
273 assert(pipe);
274 assert(buf);
275
276 lock_read_side(pipe);
9fd92637 277 if (!lttng_pipe_is_read_open(pipe)) {
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278 ret = -1;
279 errno = EBADF;
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280 goto error;
281 }
6cd525e8 282 ret = lttng_read(pipe->fd[0], buf, count);
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283error:
284 unlock_read_side(pipe);
285 return ret;
286}
287
288/*
289 * Write on a lttng pipe using the data in buf and size of count.
290 *
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291 * Return "count" on success. Return < count on error. errno can be used
292 * to check the actual error.
9fd92637 293 */
a247c6e0 294LTTNG_HIDDEN
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295ssize_t lttng_pipe_write(struct lttng_pipe *pipe, const void *buf,
296 size_t count)
297{
6cd525e8 298 ssize_t ret;
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299
300 assert(pipe);
301 assert(buf);
302
303 lock_write_side(pipe);
9fd92637 304 if (!lttng_pipe_is_write_open(pipe)) {
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305 ret = -1;
306 errno = EBADF;
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307 goto error;
308 }
6cd525e8 309 ret = lttng_write(pipe->fd[1], buf, count);
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310error:
311 unlock_write_side(pipe);
312 return ret;
313}
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