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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
|
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
This file is part of systemd.
Copyright 2011 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdbool.h>
#include <assert.h>
#include <sys/epoll.h>
#include <string.h>
#include <errno.h>
#include <sys/timerfd.h>
#include <unistd.h>
#include "dbus-loop.h"
#include "dbus-common.h"
#include "util.h"
/* Minimal implementation of the dbus loop which integrates all dbus
* events into a single epoll fd which we can triviall integrate with
* other loops. Note that this is not used in the main systemd daemon
* since we run a more elaborate mainloop there. */
typedef struct EpollData {
int fd;
void *object;
bool is_timeout:1;
bool fd_is_dupped:1;
} EpollData;
static dbus_bool_t add_watch(DBusWatch *watch, void *data) {
EpollData _cleanup_free_ *e = NULL;
struct epoll_event ev = { .data.ptr = e };
assert(watch);
e = new0(EpollData, 1);
if (!e)
return FALSE;
e->fd = dbus_watch_get_unix_fd(watch);
e->object = watch;
e->is_timeout = false;
ev.events = bus_flags_to_events(watch);
if (epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_ADD, e->fd, &ev) < 0) {
if (errno != EEXIST)
return FALSE;
/* Hmm, bloody D-Bus creates multiple watches on the
* same fd. epoll() does not like that. As a dirty
* hack we simply dup() the fd and hence get a second
* one we can safely add to the epoll(). */
e->fd = dup(e->fd);
if (e->fd < 0)
return FALSE;
if (epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_ADD, e->fd, &ev) < 0) {
close_nointr_nofail(e->fd);
return FALSE;
}
e->fd_is_dupped = true;
}
dbus_watch_set_data(watch, e, NULL);
e = NULL; /* prevent freeing */
return TRUE;
}
static void remove_watch(DBusWatch *watch, void *data) {
EpollData _cleanup_free_ *e = NULL;
assert(watch);
e = dbus_watch_get_data(watch);
if (!e)
return;
assert_se(epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_DEL, e->fd, NULL) >= 0);
if (e->fd_is_dupped)
close_nointr_nofail(e->fd);
}
static void toggle_watch(DBusWatch *watch, void *data) {
EpollData *e;
struct epoll_event ev = {};
assert(watch);
e = dbus_watch_get_data(watch);
if (!e)
return;
ev.data.ptr = e;
ev.events = bus_flags_to_events(watch);
assert_se(epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_MOD, e->fd, &ev) == 0);
}
static int timeout_arm(EpollData *e) {
struct itimerspec its = {};
assert(e);
assert(e->is_timeout);
if (dbus_timeout_get_enabled(e->object)) {
timespec_store(&its.it_value, dbus_timeout_get_interval(e->object) * USEC_PER_MSEC);
its.it_interval = its.it_value;
}
if (timerfd_settime(e->fd, 0, &its, NULL) < 0)
return -errno;
return 0;
}
static dbus_bool_t add_timeout(DBusTimeout *timeout, void *data) {
EpollData *e;
struct epoll_event ev = {};
assert(timeout);
e = new0(EpollData, 1);
if (!e)
return FALSE;
e->fd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK|TFD_CLOEXEC);
if (e->fd < 0)
goto fail;
e->object = timeout;
e->is_timeout = true;
if (timeout_arm(e) < 0)
goto fail;
ev.events = EPOLLIN;
ev.data.ptr = e;
if (epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_ADD, e->fd, &ev) < 0)
goto fail;
dbus_timeout_set_data(timeout, e, NULL);
return TRUE;
fail:
if (e->fd >= 0)
close_nointr_nofail(e->fd);
free(e);
return FALSE;
}
static void remove_timeout(DBusTimeout *timeout, void *data) {
EpollData _cleanup_free_ *e = NULL;
assert(timeout);
e = dbus_timeout_get_data(timeout);
if (!e)
return;
assert_se(epoll_ctl(PTR_TO_INT(data), EPOLL_CTL_DEL, e->fd, NULL) >= 0);
close_nointr_nofail(e->fd);
}
static void toggle_timeout(DBusTimeout *timeout, void *data) {
EpollData *e;
int r;
assert(timeout);
e = dbus_timeout_get_data(timeout);
if (!e)
return;
r = timeout_arm(e);
if (r < 0)
log_error("Failed to rearm timer: %s", strerror(-r));
}
int bus_loop_open(DBusConnection *c) {
int fd;
assert(c);
fd = epoll_create1(EPOLL_CLOEXEC);
if (fd < 0)
return -errno;
if (!dbus_connection_set_watch_functions(c, add_watch, remove_watch, toggle_watch, INT_TO_PTR(fd), NULL) ||
!dbus_connection_set_timeout_functions(c, add_timeout, remove_timeout, toggle_timeout, INT_TO_PTR(fd), NULL)) {
close_nointr_nofail(fd);
return -ENOMEM;
}
return fd;
}
int bus_loop_dispatch(int fd) {
int n;
struct epoll_event event = {};
EpollData *d;
assert(fd >= 0);
n = epoll_wait(fd, &event, 1, 0);
if (n < 0)
return errno == EAGAIN || errno == EINTR ? 0 : -errno;
assert_se(d = event.data.ptr);
if (d->is_timeout) {
DBusTimeout *t = d->object;
if (dbus_timeout_get_enabled(t))
dbus_timeout_handle(t);
} else {
DBusWatch *w = d->object;
if (dbus_watch_get_enabled(w))
dbus_watch_handle(w, bus_events_to_flags(event.events));
}
return 0;
}
|
