Fix epoll not handling signal interruption
[lttng-tools.git] / ltt-sessiond / compat / compat-epoll.c
CommitLineData
5eb91c98
DG
1/*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
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 as published by the Free
6 * Software Foundation; only version 2 of the License.
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., 59 Temple
15 * Place - Suite 330, Boston, MA 02111-1307, USA.
16 */
17
18#include <fcntl.h>
19#include <limits.h>
20#include <stdlib.h>
21#include <sys/types.h>
22#include <sys/stat.h>
23#include <unistd.h>
24
25#include <lttngerr.h>
26
27#include "poll.h"
28
29unsigned int poll_max_size;
30
31/*
32 * Create epoll set and allocate returned events structure.
33 */
34int compat_epoll_create(struct lttng_poll_event *events, int size, int flags)
35{
36 int ret;
37
38 if (events == NULL || size <= 0) {
39 goto error;
40 }
41
42 /* Don't bust the limit here */
43 if (size > poll_max_size) {
44 size = poll_max_size;
45 }
46
47 ret = epoll_create1(flags);
48 if (ret < 0) {
49 /* At this point, every error is fatal */
50 perror("epoll_create1");
51 goto error;
52 }
53
54 events->epfd = ret;
55
56 /* This *must* be freed by using lttng_poll_free() */
57 events->events = zmalloc(size * sizeof(struct epoll_event));
58 if (events->events == NULL) {
59 perror("malloc epoll set");
60 goto error_close;
61 }
62
63 events->events_size = size;
64 events->nb_fd = 0;
65
66 return 0;
67
68error_close:
69 close(events->epfd);
70error:
71 return -1;
72}
73
74/*
75 * Add a fd to the epoll set with requesting events.
76 */
77int compat_epoll_add(struct lttng_poll_event *events, int fd, uint32_t req_events)
78{
79 int ret, new_size;
80 struct epoll_event ev, *ptr;
81
82 if (events == NULL || events->events == NULL || fd < 0) {
83 ERR("Bad compat epoll add arguments");
84 goto error;
85 }
86
87 ev.events = req_events;
88 ev.data.fd = fd;
89
90 ret = epoll_ctl(events->epfd, EPOLL_CTL_ADD, fd, &ev);
91 if (ret < 0) {
92 switch (errno) {
93 case EEXIST:
94 case ENOSPC:
95 case EPERM:
96 /* Print perror and goto end not failing. Show must go on. */
97 perror("epoll_ctl ADD");
98 goto end;
99 default:
100 perror("epoll_ctl ADD fatal");
101 goto error;
102 }
103 }
104
105 events->nb_fd++;
106
107 if (events->nb_fd >= events->events_size) {
108 new_size = 2 * events->events_size;
109 ptr = realloc(events->events, new_size * sizeof(struct epoll_event));
110 if (ptr == NULL) {
111 perror("realloc epoll add");
112 goto error;
113 }
114 events->events = ptr;
115 events->events_size = new_size;
116 }
117
118end:
119 return 0;
120
121error:
122 return -1;
123}
124
125/*
126 * Remove a fd from the epoll set.
127 */
128int compat_epoll_del(struct lttng_poll_event *events, int fd)
129{
130 int ret;
131
132 if (events == NULL || fd < 0) {
133 goto error;
134 }
135
136 ret = epoll_ctl(events->epfd, EPOLL_CTL_DEL, fd, NULL);
137 if (ret < 0) {
138 switch (errno) {
139 case ENOENT:
140 case EPERM:
141 /* Print perror and goto end not failing. Show must go on. */
142 perror("epoll_ctl DEL");
143 goto end;
144 default:
145 perror("epoll_ctl DEL fatal");
146 goto error;
147 }
148 perror("epoll_ctl del");
149 goto error;
150 }
151
152 events->nb_fd--;
153
154end:
155 return 0;
156
157error:
158 return -1;
159}
160
161/*
162 * Wait on epoll set. This is a blocking call of timeout value.
163 */
164int compat_epoll_wait(struct lttng_poll_event *events, int timeout)
165{
166 int ret;
167
168 if (events == NULL || events->events == NULL ||
169 events->events_size < events->nb_fd) {
170 ERR("Wrong arguments in compat_epoll_wait");
171 goto error;
172 }
173
3ada8405
DG
174 do {
175 ret = epoll_wait(events->epfd, events->events, events->nb_fd, timeout);
176 } while (ret == -1 && errno == EINTR);
5eb91c98
DG
177 if (ret < 0) {
178 /* At this point, every error is fatal */
179 perror("epoll_wait");
180 goto error;
181 }
182
183 return ret;
184
185error:
186 return -1;
187}
188
189/*
190 * Setup poll set maximum size.
191 */
192void compat_epoll_set_max_size(void)
193{
194 int ret, fd;
195 char buf[64];
196
197 poll_max_size = LTTNG_POLL_DEFAULT_SIZE;
198
199 fd = open(LTTNG_EPOLL_PROC_PATH, O_RDONLY);
200 if (fd < 0) {
201 return;
202 }
203
204 ret = read(fd, buf, sizeof(buf));
205 if (ret < 0) {
206 perror("read set max size");
207 goto error;
208 }
209
210 poll_max_size = atoi(buf);
211 if (poll_max_size <= 0) {
212 /* Extra precaution */
213 poll_max_size = LTTNG_POLL_DEFAULT_SIZE;
214 }
215
216 DBG("epoll set max size is %d", poll_max_size);
217
218error:
219 close(fd);
220}
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