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20263082 LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2011 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU General Public License as published by | |
10 | the Free Software Foundation; either version 2 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <stdbool.h> | |
23 | #include <assert.h> | |
24 | #include <sys/epoll.h> | |
25 | #include <string.h> | |
26 | #include <errno.h> | |
27 | #include <sys/timerfd.h> | |
28 | #include <unistd.h> | |
29 | ||
30 | #include "dbus-loop.h" | |
31 | #include "dbus-common.h" | |
32 | #include "util.h" | |
33 | ||
34 | /* Minimal implementation of the dbus loop which integrates all dbus | |
35 | * events into a single epoll fd which we can triviall integrate with | |
36 | * other loops. Note that this is not used in the main systemd daemon | |
37 | * since we run a more elaborate mainloop there. */ | |
38 | ||
39 | typedef struct EpollData { | |
40 | int fd; | |
41 | void *object; | |
42 | bool is_timeout:1; | |
43 | bool fd_is_dupped:1; | |
44 | } EpollData; | |
45 | ||
46 | static dbus_bool_t add_watch(DBusWatch *watch, void *data) { | |
47 | EpollData *e; | |
48 | struct epoll_event ev; | |
49 | ||
50 | assert(watch); | |
51 | ||
52 | e = new0(EpollData, 1); | |
53 | if (!e) | |
54 | return FALSE; | |
55 | ||
56 | e->fd = dbus_watch_get_unix_fd(watch); | |
57 | e->object = watch; | |
58 | e->is_timeout = false; | |
59 | ||
60 | zero(ev); | |
61 | ev.events = bus_flags_to_events(watch); | |
62 | ev.data.ptr = e; | |
63 | ||
64 | if (epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_ADD, e->fd, &ev) < 0) { | |
65 | ||
66 | if (errno != EEXIST) { | |
67 | free(e); | |
68 | return FALSE; | |
69 | } | |
70 | ||
71 | /* Hmm, bloody D-Bus creates multiple watches on the | |
72 | * same fd. epoll() does not like that. As a dirty | |
73 | * hack we simply dup() the fd and hence get a second | |
74 | * one we can safely add to the epoll(). */ | |
75 | ||
76 | e->fd = dup(e->fd); | |
77 | if (e->fd < 0) { | |
78 | free(e); | |
79 | return FALSE; | |
80 | } | |
81 | ||
82 | if (epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_ADD, e->fd, &ev) < 0) { | |
83 | close_nointr_nofail(e->fd); | |
84 | free(e); | |
85 | return FALSE; | |
86 | } | |
87 | ||
88 | e->fd_is_dupped = true; | |
89 | } | |
90 | ||
91 | dbus_watch_set_data(watch, e, NULL); | |
92 | ||
93 | return TRUE; | |
94 | } | |
95 | ||
96 | static void remove_watch(DBusWatch *watch, void *data) { | |
97 | EpollData *e; | |
98 | ||
99 | assert(watch); | |
100 | ||
101 | e = dbus_watch_get_data(watch); | |
102 | if (!e) | |
103 | return; | |
104 | ||
105 | assert_se(epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_DEL, e->fd, NULL) >= 0); | |
106 | ||
107 | if (e->fd_is_dupped) | |
108 | close_nointr_nofail(e->fd); | |
109 | ||
110 | free(e); | |
111 | } | |
112 | ||
113 | static void toggle_watch(DBusWatch *watch, void *data) { | |
114 | EpollData *e; | |
115 | struct epoll_event ev; | |
116 | ||
117 | assert(watch); | |
118 | ||
119 | e = dbus_watch_get_data(watch); | |
120 | if (!e) | |
121 | return; | |
122 | ||
123 | zero(ev); | |
124 | ev.events = bus_flags_to_events(watch); | |
125 | ev.data.ptr = e; | |
126 | ||
127 | assert_se(epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_MOD, e->fd, &ev) == 0); | |
128 | } | |
129 | ||
130 | static int timeout_arm(EpollData *e) { | |
131 | struct itimerspec its; | |
132 | ||
133 | assert(e); | |
134 | assert(e->is_timeout); | |
135 | ||
136 | zero(its); | |
137 | ||
138 | if (dbus_timeout_get_enabled(e->object)) { | |
139 | timespec_store(&its.it_value, dbus_timeout_get_interval(e->object) * USEC_PER_MSEC); | |
140 | its.it_interval = its.it_value; | |
141 | } | |
142 | ||
143 | if (timerfd_settime(e->fd, 0, &its, NULL) < 0) | |
144 | return -errno; | |
145 | ||
146 | return 0; | |
147 | } | |
148 | ||
149 | static dbus_bool_t add_timeout(DBusTimeout *timeout, void *data) { | |
150 | EpollData *e; | |
151 | struct epoll_event ev; | |
152 | ||
153 | assert(timeout); | |
154 | ||
155 | e = new0(EpollData, 1); | |
156 | if (!e) | |
157 | return FALSE; | |
158 | ||
159 | e->fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC); | |
160 | if (e->fd < 0) | |
161 | goto fail; | |
162 | ||
163 | e->object = timeout; | |
164 | e->is_timeout = true; | |
165 | ||
166 | if (timeout_arm(e) < 0) | |
167 | goto fail; | |
168 | ||
169 | zero(ev); | |
170 | ev.events = EPOLLIN; | |
171 | ev.data.ptr = e; | |
172 | ||
173 | if (epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_ADD, e->fd, &ev) < 0) | |
174 | goto fail; | |
175 | ||
176 | dbus_timeout_set_data(timeout, e, NULL); | |
177 | ||
178 | return TRUE; | |
179 | ||
180 | fail: | |
181 | if (e->fd >= 0) | |
182 | close_nointr_nofail(e->fd); | |
183 | ||
184 | free(e); | |
185 | return FALSE; | |
186 | } | |
187 | ||
188 | static void remove_timeout(DBusTimeout *timeout, void *data) { | |
189 | EpollData *e; | |
190 | ||
191 | assert(timeout); | |
192 | ||
193 | e = dbus_timeout_get_data(timeout); | |
194 | if (!e) | |
195 | return; | |
196 | ||
197 | assert_se(epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_DEL, e->fd, NULL) >= 0); | |
198 | close_nointr_nofail(e->fd); | |
199 | free(e); | |
200 | } | |
201 | ||
202 | static void toggle_timeout(DBusTimeout *timeout, void *data) { | |
203 | EpollData *e; | |
204 | int r; | |
205 | ||
206 | assert(timeout); | |
207 | ||
208 | e = dbus_timeout_get_data(timeout); | |
209 | if (!e) | |
210 | return; | |
211 | ||
212 | r = timeout_arm(e); | |
213 | if (r < 0) | |
214 | log_error("Failed to rearm timer: %s", strerror(-r)); | |
215 | } | |
216 | ||
217 | int bus_loop_open(DBusConnection *c) { | |
218 | int fd; | |
219 | ||
220 | assert(c); | |
221 | ||
222 | fd = epoll_create1(EPOLL_CLOEXEC); | |
223 | if (fd < 0) | |
224 | return -errno; | |
225 | ||
226 | if (!dbus_connection_set_watch_functions(c, add_watch, remove_watch, toggle_watch, INT_TO_PTR(fd), NULL) || | |
227 | !dbus_connection_set_timeout_functions(c, add_timeout, remove_timeout, toggle_timeout, INT_TO_PTR(fd), NULL)) { | |
228 | close_nointr_nofail(fd); | |
229 | return -ENOMEM; | |
230 | } | |
231 | ||
232 | return fd; | |
233 | } | |
234 | ||
235 | int bus_loop_dispatch(int fd) { | |
236 | int n; | |
237 | struct epoll_event event; | |
238 | EpollData *d; | |
239 | ||
240 | assert(fd >= 0); | |
241 | ||
242 | zero(event); | |
243 | ||
244 | n = epoll_wait(fd, &event, 1, 0); | |
245 | if (n < 0) | |
246 | return errno == EAGAIN || errno == EINTR ? 0 : -errno; | |
247 | ||
248 | assert_se(d = event.data.ptr); | |
249 | ||
250 | if (d->is_timeout) { | |
251 | DBusTimeout *t = d->object; | |
252 | ||
253 | if (dbus_timeout_get_enabled(t)) | |
254 | dbus_timeout_handle(t); | |
255 | } else { | |
256 | DBusWatch *w = d->object; | |
257 | ||
258 | if (dbus_watch_get_enabled(w)) | |
259 | dbus_watch_handle(w, bus_events_to_flags(event.events)); | |
260 | } | |
261 | ||
262 | return 0; | |
263 | } |