summaryrefslogtreecommitdiff
path: root/udevd.c
blob: 104cb2b9877c92894190b7de93cc6e40637b7e5c (plain)
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
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
/*
 * udevd.c - hotplug event serializer
 *
 * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
 * Copyright (C) 2004 Chris Friesen <chris_friesen@sympatico.ca>
 *
 *
 *	This program is free software; you can redistribute it and/or modify it
 *	under the terms of the GNU General Public License as published by the
 *	Free Software Foundation version 2 of the License.
 *
 *	This program 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
 *	General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License along
 *	with this program; if not, write to the Free Software Foundation, Inc.,
 *	675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <stddef.h>
#include <sys/wait.h>
#include <signal.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/time.h>

#include "list.h"
#include "udev.h"
#include "udev_version.h"
#include "udevd.h"
#include "logging.h"

static int expected_seqnum = 0;
volatile static int children_waiting;
volatile static int msg_q_timeout;

LIST_HEAD(msg_list);
LIST_HEAD(exec_list);
LIST_HEAD(running_list);

static void exec_queue_manager(void);
static void msg_queue_manager(void);

unsigned char logname[42];

int log_ok(void)
{
	return 1;
}

static void msg_dump_queue(void)
{
	struct hotplug_msg *msg;

	list_for_each_entry(msg, &msg_list, list)
		dbg("sequence %d in queue", msg->seqnum);
}

static void msg_dump(struct hotplug_msg *msg)
{
	dbg("sequence %d, '%s', '%s', '%s'",
	    msg->seqnum, msg->action, msg->devpath, msg->subsystem);
}

static struct hotplug_msg *msg_create(void)
{
	struct hotplug_msg *new_msg;

	new_msg = malloc(sizeof(struct hotplug_msg));
	if (new_msg == NULL)
		dbg("error malloc");
	return new_msg;
}

static void run_queue_delete(struct hotplug_msg *msg)
{
	list_del(&msg->list);
	free(msg);
	exec_queue_manager();
}

/* orders the message in the queue by sequence number */
static void msg_queue_insert(struct hotplug_msg *msg)
{
	struct hotplug_msg *loop_msg;

	/* sort message by sequence number into list*/
	list_for_each_entry(loop_msg, &msg_list, list)
		if (loop_msg->seqnum > msg->seqnum)
			break;
	list_add_tail(&msg->list, &loop_msg->list);
	dbg("queued message seq %d", msg->seqnum);

	/* store timestamp of queuing */
	msg->queue_time = time(NULL);

	/* run msg queue manager */
	msg_queue_manager();

	return ;
}

/* forks event and removes event from run queue when finished */
static void udev_run(struct hotplug_msg *msg)
{
	pid_t pid;
	char action[32];
	char devpath[256];
	char *env[] = { action, devpath, NULL };

	snprintf(action, sizeof(action), "ACTION=%s", msg->action);
	snprintf(devpath, sizeof(devpath), "DEVPATH=%s", msg->devpath);

	pid = fork();
	switch (pid) {
	case 0:
		/* child */
		execle(UDEV_BIN, "udev", msg->subsystem, NULL, env);
		dbg("exec of child failed");
		exit(1);
		break;
	case -1:
		dbg("fork of child failed");
		run_queue_delete(msg);
		break;
	default:
		/* get SIGCHLD in main loop */
		dbg("==> exec seq %d [%d] working at '%s'", msg->seqnum, pid, msg->devpath);
		msg->pid = pid;
	}
}

/* returns already running task with devpath */
static struct hotplug_msg *running_with_devpath(struct hotplug_msg *msg)
{
	struct hotplug_msg *loop_msg;
	list_for_each_entry(loop_msg, &running_list, list)
		if (strncmp(loop_msg->devpath, msg->devpath, sizeof(loop_msg->devpath)) == 0)
			return loop_msg;
	return NULL;
}

/* exec queue management routine executes the events and delays events for the same devpath */
static void exec_queue_manager()
{
	struct hotplug_msg *loop_msg;
	struct hotplug_msg *tmp_msg;
	struct hotplug_msg *msg;

	list_for_each_entry_safe(loop_msg, tmp_msg, &exec_list, list) {
		msg = running_with_devpath(loop_msg);
		if (!msg) {
			/* move event to run list */
			list_move_tail(&loop_msg->list, &running_list);
			udev_run(loop_msg);
			dbg("moved seq %d to running list", loop_msg->seqnum);
		} else {
			dbg("delay seq %d, cause seq %d already working on '%s'",
				loop_msg->seqnum, msg->seqnum, msg->devpath);
		}
	}
}

static void msg_move_exec(struct hotplug_msg *msg)
{
	list_move_tail(&msg->list, &exec_list);
	exec_queue_manager();
	expected_seqnum = msg->seqnum+1;
	dbg("moved seq %d to exec, next expected is %d",
		msg->seqnum, expected_seqnum);
}

/* msg queue management routine handles the timeouts and dispatches the events */
static void msg_queue_manager()
{
	struct hotplug_msg *loop_msg;
	struct hotplug_msg *tmp_msg;
	time_t msg_age = 0;

	dbg("msg queue manager, next expected is %d", expected_seqnum);
recheck:
	list_for_each_entry_safe(loop_msg, tmp_msg, &msg_list, list) {
		/* move event with expected sequence to the exec list */
		if (loop_msg->seqnum == expected_seqnum) {
			msg_move_exec(loop_msg);
			continue;
		}

		/* move event with expired timeout to the exec list */
		msg_age = time(NULL) - loop_msg->queue_time;
		if (msg_age > EVENT_TIMEOUT_SEC-1) {
			msg_move_exec(loop_msg);
			goto recheck;
		} else {
			break;
		}
	}

	msg_dump_queue();

	if (list_empty(&msg_list) == 0) {
		/* set timeout for remaining queued events */
		struct itimerval itv = {{0, 0}, {EVENT_TIMEOUT_SEC - msg_age, 0}};
		dbg("next event expires in %li seconds",
		    EVENT_TIMEOUT_SEC - msg_age);
		setitimer(ITIMER_REAL, &itv, 0);
	}
}

/* receive the msg, do some basic sanity checks, and queue it */
static void handle_msg(int sock)
{
	struct hotplug_msg *msg;
	int retval;

	msg = msg_create();
	if (msg == NULL) {
		dbg("unable to store message");
		return;
	}

	retval = recv(sock, msg, sizeof(struct hotplug_msg), 0);
	if (retval <  0) {
		if (errno != EINTR)
			dbg("unable to receive message");
		return;
	}
	
	if (strncmp(msg->magic, UDEV_MAGIC, sizeof(UDEV_MAGIC)) != 0 ) {
		dbg("message magic '%s' doesn't match, ignore it", msg->magic);
		free(msg);
		return;
	}

	/* if no seqnum is given, we move straight to exec queue */
	if (msg->seqnum == -1) {
		list_add(&msg->list, &exec_list);
		exec_queue_manager();
	} else {
		msg_queue_insert(msg);
	}
}

static void sig_handler(int signum)
{
	switch (signum) {
		case SIGINT:
		case SIGTERM:
			exit(20 + signum);
			break;
		case SIGALRM:
			msg_q_timeout = 1;
			break;
		case SIGCHLD:
			children_waiting = 1;
			break;
		default:
			dbg("unhandled signal");
	}
}

static void udev_done(int pid)
{
	/* find msg associated with pid and delete it */
	struct hotplug_msg *msg;

	list_for_each_entry(msg, &running_list, list) {
		if (msg->pid == pid) {
			dbg("<== exec seq %d came back", msg->seqnum);
			run_queue_delete(msg);
			return;
		}
	}
}

int main(int argc, char *argv[])
{
	int ssock;
	struct sockaddr_un saddr;
	socklen_t addrlen;
	int retval;
	struct sigaction act;

	init_logging("udevd");

	/* set signal handler */
	act.sa_handler = sig_handler;
	sigemptyset (&act.sa_mask);
	act.sa_flags = SA_RESTART;
	sigaction(SIGINT, &act, NULL);
	sigaction(SIGTERM, &act, NULL);

	/* we want these two to interrupt system calls */
	act.sa_flags = 0;
	sigaction(SIGALRM, &act, NULL);
	sigaction(SIGCHLD, &act, NULL);

	memset(&saddr, 0x00, sizeof(saddr));
	saddr.sun_family = AF_LOCAL;
	/* use abstract namespace for socket path */
	strcpy(&saddr.sun_path[1], UDEVD_SOCK_PATH);
	addrlen = offsetof(struct sockaddr_un, sun_path) + strlen(saddr.sun_path+1) + 1;

	ssock = socket(AF_LOCAL, SOCK_DGRAM, 0);
	if (ssock == -1) {
		dbg("error getting socket");
		exit(1);
	}

	/* the bind takes care of ensuring only one copy running */
	retval = bind(ssock, (struct sockaddr *) &saddr, addrlen);
	if (retval < 0) {
		dbg("bind failed\n");
		goto exit;
	}

	while (1) {
		handle_msg(ssock);

		while(msg_q_timeout) {
			msg_q_timeout = 0;
			msg_queue_manager();
		}

		while(children_waiting) {
			children_waiting = 0;
			/* reap all dead children */
			while(1) {
				int pid = waitpid(-1, 0, WNOHANG);
				if ((pid == -1) || (pid == 0))
					break;
				udev_done(pid);
			}
		}
	}
exit:
	close(ssock);
	exit(1);
}