Linux debugging

Check our new training course

Linux debugging, tracing, profiling & perf. analysis

Check our new training course
with Creative Commons CC-BY-SA
lecture and lab materials

Bootlin logo

Elixir Cross Referencer

  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
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
/*
Copyright (c) 2001-2006, Gerrit Pape
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

   1. Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.
   2. Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
   3. The name of the author may not be used to endorse or promote products
      derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

/* Taken from http://smarden.sunsite.dk/runit/sv.8.html:

sv - control and manage services monitored by runsv

sv [-v] [-w sec] command services
/etc/init.d/service [-w sec] command

The sv program reports the current status and controls the state of services
monitored by the runsv(8) supervisor.

services consists of one or more arguments, each argument naming a directory
service used by runsv(8). If service doesn't start with a dot or slash,
it is searched in the default services directory /var/service/, otherwise
relative to the current directory.

command is one of up, down, status, once, pause, cont, hup, alarm, interrupt,
1, 2, term, kill, or exit, or start, stop, restart, shutdown, force-stop,
force-reload, force-restart, force-shutdown.

The sv program can be sym-linked to /etc/init.d/ to provide an LSB init
script interface. The service to be controlled then is specified by the
base name of the "init script".

status
    Report the current status of the service, and the appendant log service
    if available, to standard output.
up
    If the service is not running, start it. If the service stops, restart it.
down
    If the service is running, send it the TERM signal, and the CONT signal.
    If ./run exits, start ./finish if it exists. After it stops, do not
    restart service.
once
    If the service is not running, start it. Do not restart it if it stops.
pause cont hup alarm interrupt quit 1 2 term kill
    If the service is running, send it the STOP, CONT, HUP, ALRM, INT, QUIT,
    USR1, USR2, TERM, or KILL signal respectively.
exit
    If the service is running, send it the TERM signal, and the CONT signal.
    Do not restart the service. If the service is down, and no log service
    exists, runsv(8) exits. If the service is down and a log service exists,
    send the TERM signal to the log service. If the log service is down,
    runsv(8) exits. This command is ignored if it is given to an appendant
    log service.

sv actually looks only at the first character of above commands.

Commands compatible to LSB init script actions:

status
    Same as status.
start
    Same as up, but wait up to 7 seconds for the command to take effect.
    Then report the status or timeout. If the script ./check exists in
    the service directory, sv runs this script to check whether the service
    is up and available; it's considered to be available if ./check exits
    with 0.
stop
    Same as down, but wait up to 7 seconds for the service to become down.
    Then report the status or timeout.
restart
    Send the commands term, cont, and up to the service, and wait up to
    7 seconds for the service to restart. Then report the status or timeout.
    If the script ./check exists in the service directory, sv runs this script
    to check whether the service is up and available again; it's considered
    to be available if ./check exits with 0.
shutdown
    Same as exit, but wait up to 7 seconds for the runsv(8) process
    to terminate. Then report the status or timeout.
force-stop
    Same as down, but wait up to 7 seconds for the service to become down.
    Then report the status, and on timeout send the service the kill command.
force-reload
    Send the service the term and cont commands, and wait up to
    7 seconds for the service to restart. Then report the status,
    and on timeout send the service the kill command.
force-restart
    Send the service the term, cont and up commands, and wait up to
    7 seconds for the service to restart. Then report the status, and
    on timeout send the service the kill command. If the script ./check
    exists in the service directory, sv runs this script to check whether
    the service is up and available again; it's considered to be available
    if ./check exits with 0.
force-shutdown
    Same as exit, but wait up to 7 seconds for the runsv(8) process to
    terminate. Then report the status, and on timeout send the service
    the kill command.

Additional Commands

check
    Check for the service to be in the state that's been requested. Wait up to
    7 seconds for the service to reach the requested state, then report
    the status or timeout. If the requested state of the service is up,
    and the script ./check exists in the service directory, sv runs
    this script to check whether the service is up and running;
    it's considered to be up if ./check exits with 0.

Options

-v
    wait up to 7 seconds for the command to take effect.
    Then report the status or timeout.
-w sec
    Override the default timeout of 7 seconds with sec seconds. Implies -v.

Environment

SVDIR
    The environment variable $SVDIR overrides the default services directory
    /var/service.
SVWAIT
    The environment variable $SVWAIT overrides the default 7 seconds to wait
    for a command to take effect. It is overridden by the -w option.

Exit Codes
    sv exits 0, if the command was successfully sent to all services, and,
    if it was told to wait, the command has taken effect to all services.

    For each service that caused an error (e.g. the directory is not
    controlled by a runsv(8) process, or sv timed out while waiting),
    sv increases the exit code by one and exits non zero. The maximum
    is 99. sv exits 100 on error.
*/

/* Busyboxed by Denis Vlasenko <vda.linux@googlemail.com> */
/* TODO: depends on runit_lib.c - review and reduce/eliminate */

#include <sys/poll.h>
#include <sys/file.h>
#include "libbb.h"
#include "runit_lib.h"

struct globals {
	const char *acts;
	char **service;
	unsigned rc;
/* "Bernstein" time format: unix + 0x400000000000000aULL */
	uint64_t tstart, tnow;
	svstatus_t svstatus;
};
#define G (*(struct globals*)&bb_common_bufsiz1)
#define acts         (G.acts        )
#define service      (G.service     )
#define rc           (G.rc          )
#define tstart       (G.tstart      )
#define tnow         (G.tnow        )
#define svstatus     (G.svstatus    )
#define INIT_G() do { } while (0)


static void fatal_cannot(const char *m1) ATTRIBUTE_NORETURN;
static void fatal_cannot(const char *m1)
{
	bb_perror_msg("fatal: cannot %s", m1);
	_exit(151);
}

static void out(const char *p, const char *m1)
{
	printf("%s%s: %s", p, *service, m1);
	if (errno) {
		printf(": %s", strerror(errno));
	}
	bb_putchar('\n'); /* will also flush the output */
}

#define WARN    "warning: "
#define OK      "ok: "

static void fail(const char *m1)
{
	++rc;
	out("fail: ", m1);
}
static void failx(const char *m1)
{
	errno = 0;
	fail(m1);
}
static void warn(const char *m1)
{
	++rc;
	/* "warning: <service>: <m1>\n" */
	out("warning: ", m1);
}
static void ok(const char *m1)
{
	errno = 0;
	out(OK, m1);
}

static int svstatus_get(void)
{
	int fd, r;

	fd = open_write("supervise/ok");
	if (fd == -1) {
		if (errno == ENODEV) {
			*acts == 'x' ? ok("runsv not running")
			             : failx("runsv not running");
			return 0;
		}
		warn("cannot open supervise/ok");
		return -1;
	}
	close(fd);
	fd = open_read("supervise/status");
	if (fd == -1) {
		warn("cannot open supervise/status");
		return -1;
	}
	r = read(fd, &svstatus, 20);
	close(fd);
	switch (r) {
	case 20:
		break;
	case -1:
		warn("cannot read supervise/status");
		return -1;
	default:
		errno = 0;
		warn("cannot read supervise/status: bad format");
		return -1;
	}
	return 1;
}

static unsigned svstatus_print(const char *m)
{
	int diff;
	int pid;
	int normallyup = 0;
	struct stat s;
	uint64_t timestamp;

	if (stat("down", &s) == -1) {
		if (errno != ENOENT) {
			bb_perror_msg(WARN"cannot stat %s/down", *service);
			return 0;
		}
		normallyup = 1;
	}
	pid = SWAP_LE32(svstatus.pid_le32);
	timestamp = SWAP_BE64(svstatus.time_be64);
	if (pid) {
		switch (svstatus.run_or_finish) {
		case 1: printf("run: "); break;
		case 2: printf("finish: "); break;
		}
		printf("%s: (pid %d) ", m, pid);
	} else {
		printf("down: %s: ", m);
	}
	diff = tnow - timestamp;
	printf("%us", (diff < 0 ? 0 : diff));
	if (pid) {
		if (!normallyup) printf(", normally down");
		if (svstatus.paused) printf(", paused");
		if (svstatus.want == 'd') printf(", want down");
		if (svstatus.got_term) printf(", got TERM");
	} else {
		if (normallyup) printf(", normally up");
		if (svstatus.want == 'u') printf(", want up");
	}
	return pid ? 1 : 2;
}

static int status(const char *unused)
{
	int r;

	r = svstatus_get();
	switch (r) { case -1: case 0: return 0; }

	r = svstatus_print(*service);
	if (chdir("log") == -1) {
		if (errno != ENOENT) {
			printf("; log: "WARN"cannot change to log service directory: %s",
					strerror(errno));
		}
	} else if (svstatus_get()) {
		printf("; ");
		svstatus_print("log");
	}
	bb_putchar('\n'); /* will also flush the output */
	return r;
}

static int checkscript(void)
{
	char *prog[2];
	struct stat s;
	int pid, w;

	if (stat("check", &s) == -1) {
		if (errno == ENOENT) return 1;
		bb_perror_msg(WARN"cannot stat %s/check", *service);
		return 0;
	}
	/* if (!(s.st_mode & S_IXUSR)) return 1; */
	prog[0] = (char*)"./check";
	prog[1] = NULL;
	pid = spawn(prog);
	if (pid <= 0) {
		bb_perror_msg(WARN"cannot %s child %s/check", "run", *service);
		return 0;
	}
	while (wait_pid(&w, pid) == -1) {
		if (errno == EINTR) continue;
		bb_perror_msg(WARN"cannot %s child %s/check", "wait for", *service);
		return 0;
	}
	return !wait_exitcode(w);
}

static int check(const char *a)
{
	int r;
	unsigned pid;
	uint64_t timestamp;

	r = svstatus_get();
	if (r == -1)
		return -1;
	if (r == 0) {
		if (*a == 'x')
			return 1;
		return -1;
	}
	pid = SWAP_LE32(svstatus.pid_le32);
	switch (*a) {
	case 'x':
		return 0;
	case 'u':
		if (!pid || svstatus.run_or_finish != 1) return 0;
		if (!checkscript()) return 0;
		break;
	case 'd':
		if (pid) return 0;
		break;
	case 'c':
		if (pid && !checkscript()) return 0;
		break;
	case 't':
		if (!pid && svstatus.want == 'd') break;
		timestamp = SWAP_BE64(svstatus.time_be64);
		if ((tstart > timestamp) || !pid || svstatus.got_term || !checkscript())
			return 0;
		break;
	case 'o':
		timestamp = SWAP_BE64(svstatus.time_be64);
		if ((!pid && tstart > timestamp) || (pid && svstatus.want != 'd'))
			return 0;
	}
	printf(OK);
	svstatus_print(*service);
	bb_putchar('\n'); /* will also flush the output */
	return 1;
}

static int control(const char *a)
{
	int fd, r;

	if (svstatus_get() <= 0)
		return -1;
	if (svstatus.want == *a)
		return 0;
	fd = open_write("supervise/control");
	if (fd == -1) {
		if (errno != ENODEV)
			warn("cannot open supervise/control");
		else
			*a == 'x' ? ok("runsv not running") : failx("runsv not running");
		return -1;
	}
	r = write(fd, a, strlen(a));
	close(fd);
	if (r != strlen(a)) {
		warn("cannot write to supervise/control");
		return -1;
	}
	return 1;
}

int sv_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int sv_main(int argc, char **argv)
{
	unsigned opt;
	unsigned i, want_exit;
	char *x;
	char *action;
	const char *varservice = "/var/service/";
	unsigned services;
	char **servicex;
	unsigned waitsec = 7;
	smallint kll = 0;
	smallint verbose = 0;
	int (*act)(const char*);
	int (*cbk)(const char*);
	int curdir;

	INIT_G();

	xfunc_error_retval = 100;

	x = getenv("SVDIR");
	if (x) varservice = x;
	x = getenv("SVWAIT");
	if (x) waitsec = xatou(x);

	opt = getopt32(argv, "w:v", &x);
	if (opt & 1) waitsec = xatou(x); // -w
	if (opt & 2) verbose = 1; // -v
	argc -= optind;
	argv += optind;
	action = *argv++;
	if (!action || !*argv) bb_show_usage();
	service = argv;
	services = argc - 1;

	tnow = time(0) + 0x400000000000000aULL;
	tstart = tnow;
	curdir = open_read(".");
	if (curdir == -1)
		fatal_cannot("open current directory");

	act = &control;
	acts = "s";
	cbk = &check;

	switch (*action) {
	case 'x':
	case 'e':
		acts = "x";
		if (!verbose) cbk = NULL;
		break;
	case 'X':
	case 'E':
		acts = "x";
		kll = 1;
		break;
	case 'D':
		acts = "d";
		kll = 1;
		break;
	case 'T':
		acts = "tc";
		kll = 1;
		break;
	case 'c':
		if (str_equal(action, "check")) {
			act = NULL;
			acts = "c";
			break;
		}
	case 'u': case 'd': case 'o': case 't': case 'p': case 'h':
	case 'a': case 'i': case 'k': case 'q': case '1': case '2':
		action[1] = '\0';
		acts = action;
		if (!verbose) cbk = NULL;
		break;
	case 's':
		if (str_equal(action, "shutdown")) {
			acts = "x";
			break;
		}
		if (str_equal(action, "start")) {
			acts = "u";
			break;
		}
		if (str_equal(action, "stop")) {
			acts = "d";
			break;
		}
		/* "status" */
		act = &status;
		cbk = NULL;
		break;
	case 'r':
		if (str_equal(action, "restart")) {
			acts = "tcu";
			break;
		}
		bb_show_usage();
	case 'f':
		if (str_equal(action, "force-reload")) {
			acts = "tc";
			kll = 1;
			break;
		}
		if (str_equal(action, "force-restart")) {
			acts = "tcu";
			kll = 1;
			break;
		}
		if (str_equal(action, "force-shutdown")) {
			acts = "x";
			kll = 1;
			break;
		}
		if (str_equal(action, "force-stop")) {
			acts = "d";
			kll = 1;
			break;
		}
	default:
		bb_show_usage();
	}

	servicex = service;
	for (i = 0; i < services; ++i) {
		if ((**service != '/') && (**service != '.')) {
			if (chdir(varservice) == -1)
				goto chdir_failed_0;
		}
		if (chdir(*service) == -1) {
 chdir_failed_0:
			fail("cannot change to service directory");
			goto nullify_service_0;
		}
		if (act && (act(acts) == -1)) {
 nullify_service_0:
			*service = NULL;
		}
		if (fchdir(curdir) == -1)
			fatal_cannot("change to original directory");
		service++;
	}

	if (cbk) while (1) {
		int diff;

		diff = tnow - tstart;
		service = servicex;
		want_exit = 1;
		for (i = 0; i < services; ++i, ++service) {
			if (!*service)
				continue;
			if ((**service != '/') && (**service != '.')) {
				if (chdir(varservice) == -1)
					goto chdir_failed;
			}
			if (chdir(*service) == -1) {
 chdir_failed:
				fail("cannot change to service directory");
				goto nullify_service;
			}
			if (cbk(acts) != 0)
				goto nullify_service;
			want_exit = 0;
			if (diff >= waitsec) {
				printf(kll ? "kill: " : "timeout: ");
				if (svstatus_get() > 0) {
					svstatus_print(*service);
					++rc;
				}
				bb_putchar('\n'); /* will also flush the output */
				if (kll)
					control("k");
 nullify_service:
				*service = NULL;
			}
			if (fchdir(curdir) == -1)
				fatal_cannot("change to original directory");
		}
		if (want_exit) break;
		usleep(420000);
		tnow = time(0) + 0x400000000000000aULL;
	}
	return rc > 99 ? 99 : rc;
}