summaryrefslogtreecommitdiff
path: root/sysklogd/syslogd.c
blob: 33203697d37373b90553de27f6145cb7d207e8a8 (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
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
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
/* vi: set sw=4 ts=4: */
/*
 * Mini syslogd implementation for busybox
 *
 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
 *
 * Copyright (C) 2000 by Karl M. Hegbloom <karlheg@debian.org>
 *
 * "circular buffer" Copyright (C) 2001 by Gennady Feldman <gfeldman@gena01.com>
 *
 * Maintainer: Gennady Feldman <gfeldman@gena01.com> as of Mar 12, 2001
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 */

/*
 * Done in syslogd_and_logger.c:
#include "libbb.h"
#define SYSLOG_NAMES
#define SYSLOG_NAMES_CONST
#include <syslog.h>
*/

#include <sys/un.h>
#include <sys/uio.h>

#if ENABLE_FEATURE_REMOTE_LOG
#include <netinet/in.h>
#endif

#if ENABLE_FEATURE_IPC_SYSLOG
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#endif


#define DEBUG 0

/* MARK code is not very useful, is bloat, and broken:
 * can deadlock if alarmed to make MARK while writing to IPC buffer
 * (semaphores are down but do_mark routine tries to down them again) */
#undef SYSLOGD_MARK

/* Write locking does not seem to be useful either */
#undef SYSLOGD_WRLOCK

enum {
	MAX_READ = 256,
	DNS_WAIT_SEC = 2 * 60,
};

/* Semaphore operation structures */
struct shbuf_ds {
	int32_t size;   /* size of data - 1 */
	int32_t tail;   /* end of message list */
	char data[1];   /* data/messages */
};

#if ENABLE_FEATURE_REMOTE_LOG
typedef struct {
	int remoteFD;
	unsigned last_dns_resolve;
	len_and_sockaddr *remoteAddr;
	const char *remoteHostname;
} remoteHost_t;
#endif

/* Allows us to have smaller initializer. Ugly. */
#define GLOBALS \
	const char *logFilePath;                \
	int logFD;                              \
	/* interval between marks in seconds */ \
	/*int markInterval;*/                   \
	/* level of messages to be logged */    \
	int logLevel;                           \
IF_FEATURE_ROTATE_LOGFILE( \
	/* max size of file before rotation */  \
	unsigned logFileSize;                   \
	/* number of rotated message files */   \
	unsigned logFileRotate;                 \
	unsigned curFileSize;                   \
	smallint isRegular;                     \
) \
IF_FEATURE_IPC_SYSLOG( \
	int shmid; /* ipc shared memory id */   \
	int s_semid; /* ipc semaphore id */     \
	int shm_size;                           \
	struct sembuf SMwup[1];                 \
	struct sembuf SMwdn[3];                 \
)

struct init_globals {
	GLOBALS
};

struct globals {
	GLOBALS

#if ENABLE_FEATURE_REMOTE_LOG
	llist_t *remoteHosts;
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
	struct shbuf_ds *shbuf;
#endif
	time_t last_log_time;
	/* localhost's name. We print only first 64 chars */
	char *hostname;

	/* We recv into recvbuf... */
	char recvbuf[MAX_READ * (1 + ENABLE_FEATURE_SYSLOGD_DUP)];
	/* ...then copy to parsebuf, escaping control chars */
	/* (can grow x2 max) */
	char parsebuf[MAX_READ*2];
	/* ...then sprintf into printbuf, adding timestamp (15 chars),
	 * host (64), fac.prio (20) to the message */
	/* (growth by: 15 + 64 + 20 + delims = ~110) */
	char printbuf[MAX_READ*2 + 128];
};

static const struct init_globals init_data = {
	.logFilePath = "/var/log/messages",
	.logFD = -1,
#ifdef SYSLOGD_MARK
	.markInterval = 20 * 60,
#endif
	.logLevel = 8,
#if ENABLE_FEATURE_ROTATE_LOGFILE
	.logFileSize = 200 * 1024,
	.logFileRotate = 1,
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
	.shmid = -1,
	.s_semid = -1,
	.shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024), // default shm size
	.SMwup = { {1, -1, IPC_NOWAIT} },
	.SMwdn = { {0, 0}, {1, 0}, {1, +1} },
#endif
};

#define G (*ptr_to_globals)
#define INIT_G() do { \
	SET_PTR_TO_GLOBALS(memcpy(xzalloc(sizeof(G)), &init_data, sizeof(init_data))); \
} while (0)


/* Options */
enum {
	OPTBIT_mark = 0, // -m
	OPTBIT_nofork, // -n
	OPTBIT_outfile, // -O
	OPTBIT_loglevel, // -l
	OPTBIT_small, // -S
	IF_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize   ,)	// -s
	IF_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt  ,)	// -b
	IF_FEATURE_REMOTE_LOG(    OPTBIT_remotelog  ,)	// -R
	IF_FEATURE_REMOTE_LOG(    OPTBIT_locallog   ,)	// -L
	IF_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,)	// -C
	IF_FEATURE_SYSLOGD_DUP(   OPTBIT_dup        ,)	// -D

	OPT_mark        = 1 << OPTBIT_mark    ,
	OPT_nofork      = 1 << OPTBIT_nofork  ,
	OPT_outfile     = 1 << OPTBIT_outfile ,
	OPT_loglevel    = 1 << OPTBIT_loglevel,
	OPT_small       = 1 << OPTBIT_small   ,
	OPT_filesize    = IF_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize   )) + 0,
	OPT_rotatecnt   = IF_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt  )) + 0,
	OPT_remotelog   = IF_FEATURE_REMOTE_LOG(    (1 << OPTBIT_remotelog  )) + 0,
	OPT_locallog    = IF_FEATURE_REMOTE_LOG(    (1 << OPTBIT_locallog   )) + 0,
	OPT_circularlog = IF_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
	OPT_dup         = IF_FEATURE_SYSLOGD_DUP(   (1 << OPTBIT_dup        )) + 0,
};
#define OPTION_STR "m:nO:l:S" \
	IF_FEATURE_ROTATE_LOGFILE("s:" ) \
	IF_FEATURE_ROTATE_LOGFILE("b:" ) \
	IF_FEATURE_REMOTE_LOG(    "R:" ) \
	IF_FEATURE_REMOTE_LOG(    "L"  ) \
	IF_FEATURE_IPC_SYSLOG(    "C::") \
	IF_FEATURE_SYSLOGD_DUP(   "D"  )
#define OPTION_DECL *opt_m, *opt_l \
	IF_FEATURE_ROTATE_LOGFILE(,*opt_s) \
	IF_FEATURE_ROTATE_LOGFILE(,*opt_b) \
	IF_FEATURE_IPC_SYSLOG(    ,*opt_C = NULL)
#define OPTION_PARAM &opt_m, &G.logFilePath, &opt_l \
	IF_FEATURE_ROTATE_LOGFILE(,&opt_s) \
	IF_FEATURE_ROTATE_LOGFILE(,&opt_b) \
	IF_FEATURE_REMOTE_LOG(	  ,&remoteAddrList) \
	IF_FEATURE_IPC_SYSLOG(    ,&opt_C)


/* circular buffer variables/structures */
#if ENABLE_FEATURE_IPC_SYSLOG

#if CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE < 4
#error Sorry, you must set the syslogd buffer size to at least 4KB.
#error Please check CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE
#endif

/* our shared key (syslogd.c and logread.c must be in sync) */
enum { KEY_ID = 0x414e4547 }; /* "GENA" */

static void ipcsyslog_cleanup(void)
{
	if (G.shmid != -1) {
		shmdt(G.shbuf);
	}
	if (G.shmid != -1) {
		shmctl(G.shmid, IPC_RMID, NULL);
	}
	if (G.s_semid != -1) {
		semctl(G.s_semid, 0, IPC_RMID, 0);
	}
}

static void ipcsyslog_init(void)
{
	if (DEBUG)
		printf("shmget(%x, %d,...)\n", (int)KEY_ID, G.shm_size);

	G.shmid = shmget(KEY_ID, G.shm_size, IPC_CREAT | 0644);
	if (G.shmid == -1) {
		bb_perror_msg_and_die("shmget");
	}

	G.shbuf = shmat(G.shmid, NULL, 0);
	if (G.shbuf == (void*) -1L) { /* shmat has bizarre error return */
		bb_perror_msg_and_die("shmat");
	}

	memset(G.shbuf, 0, G.shm_size);
	G.shbuf->size = G.shm_size - offsetof(struct shbuf_ds, data) - 1;
	/*G.shbuf->tail = 0;*/

	// we'll trust the OS to set initial semval to 0 (let's hope)
	G.s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023);
	if (G.s_semid == -1) {
		if (errno == EEXIST) {
			G.s_semid = semget(KEY_ID, 2, 0);
			if (G.s_semid != -1)
				return;
		}
		bb_perror_msg_and_die("semget");
	}
}

/* Write message to shared mem buffer */
static void log_to_shmem(const char *msg, int len)
{
	int old_tail, new_tail;

	if (semop(G.s_semid, G.SMwdn, 3) == -1) {
		bb_perror_msg_and_die("SMwdn");
	}

	/* Circular Buffer Algorithm:
	 * --------------------------
	 * tail == position where to store next syslog message.
	 * tail's max value is (shbuf->size - 1)
	 * Last byte of buffer is never used and remains NUL.
	 */
	len++; /* length with NUL included */
 again:
	old_tail = G.shbuf->tail;
	new_tail = old_tail + len;
	if (new_tail < G.shbuf->size) {
		/* store message, set new tail */
		memcpy(G.shbuf->data + old_tail, msg, len);
		G.shbuf->tail = new_tail;
	} else {
		/* k == available buffer space ahead of old tail */
		int k = G.shbuf->size - old_tail;
		/* copy what fits to the end of buffer, and repeat */
		memcpy(G.shbuf->data + old_tail, msg, k);
		msg += k;
		len -= k;
		G.shbuf->tail = 0;
		goto again;
	}
	if (semop(G.s_semid, G.SMwup, 1) == -1) {
		bb_perror_msg_and_die("SMwup");
	}
	if (DEBUG)
		printf("tail:%d\n", G.shbuf->tail);
}
#else
void ipcsyslog_cleanup(void);
void ipcsyslog_init(void);
void log_to_shmem(const char *msg);
#endif /* FEATURE_IPC_SYSLOG */


/* Print a message to the log file. */
static void log_locally(time_t now, char *msg)
{
#ifdef SYSLOGD_WRLOCK
	struct flock fl;
#endif
	int len = strlen(msg);

#if ENABLE_FEATURE_IPC_SYSLOG
	if ((option_mask32 & OPT_circularlog) && G.shbuf) {
		log_to_shmem(msg, len);
		return;
	}
#endif
	if (G.logFD >= 0) {
		/* Reopen log file every second. This allows admin
		 * to delete the file and not worry about restarting us.
		 * This costs almost nothing since it happens
		 * _at most_ once a second.
		 */
		if (!now)
			now = time(NULL);
		if (G.last_log_time != now) {
			G.last_log_time = now;
			close(G.logFD);
			goto reopen;
		}
	} else {
 reopen:
		G.logFD = open(G.logFilePath, O_WRONLY | O_CREAT
					| O_NOCTTY | O_APPEND | O_NONBLOCK,
					0666);
		if (G.logFD < 0) {
			/* cannot open logfile? - print to /dev/console then */
			int fd = device_open(DEV_CONSOLE, O_WRONLY | O_NOCTTY | O_NONBLOCK);
			if (fd < 0)
				fd = 2; /* then stderr, dammit */
			full_write(fd, msg, len);
			if (fd != 2)
				close(fd);
			return;
		}
#if ENABLE_FEATURE_ROTATE_LOGFILE
		{
			struct stat statf;
			G.isRegular = (fstat(G.logFD, &statf) == 0 && S_ISREG(statf.st_mode));
			/* bug (mostly harmless): can wrap around if file > 4gb */
			G.curFileSize = statf.st_size;
		}
#endif
	}

#ifdef SYSLOGD_WRLOCK
	fl.l_whence = SEEK_SET;
	fl.l_start = 0;
	fl.l_len = 1;
	fl.l_type = F_WRLCK;
	fcntl(G.logFD, F_SETLKW, &fl);
#endif

#if ENABLE_FEATURE_ROTATE_LOGFILE
	if (G.logFileSize && G.isRegular && G.curFileSize > G.logFileSize) {
		if (G.logFileRotate) { /* always 0..99 */
			int i = strlen(G.logFilePath) + 3 + 1;
			char oldFile[i];
			char newFile[i];
			i = G.logFileRotate - 1;
			/* rename: f.8 -> f.9; f.7 -> f.8; ... */
			while (1) {
				sprintf(newFile, "%s.%d", G.logFilePath, i);
				if (i == 0) break;
				sprintf(oldFile, "%s.%d", G.logFilePath, --i);
				/* ignore errors - file might be missing */
				rename(oldFile, newFile);
			}
			/* newFile == "f.0" now */
			rename(G.logFilePath, newFile);
#ifdef SYSLOGD_WRLOCK
			fl.l_type = F_UNLCK;
			fcntl(G.logFD, F_SETLKW, &fl);
#endif
			close(G.logFD);
			goto reopen;
		}
		ftruncate(G.logFD, 0);
	}
	G.curFileSize +=
#endif
			full_write(G.logFD, msg, len);
#ifdef SYSLOGD_WRLOCK
	fl.l_type = F_UNLCK;
	fcntl(G.logFD, F_SETLKW, &fl);
#endif
}

static void parse_fac_prio_20(int pri, char *res20)
{
	const CODE *c_pri, *c_fac;

	if (pri != 0) {
		c_fac = facilitynames;
		while (c_fac->c_name) {
			if (c_fac->c_val != (LOG_FAC(pri) << 3)) {
				c_fac++;
				continue;
			}
			/* facility is found, look for prio */
			c_pri = prioritynames;
			while (c_pri->c_name) {
				if (c_pri->c_val != LOG_PRI(pri)) {
					c_pri++;
					continue;
				}
				snprintf(res20, 20, "%s.%s",
						c_fac->c_name, c_pri->c_name);
				return;
			}
			/* prio not found, bail out */
			break;
		}
		snprintf(res20, 20, "<%d>", pri);
	}
}

/* len parameter is used only for "is there a timestamp?" check.
 * NB: some callers cheat and supply len==0 when they know
 * that there is no timestamp, short-circuiting the test. */
static void timestamp_and_log(int pri, char *msg, int len)
{
	char *timestamp;
	time_t now;

	/* Jan 18 00:11:22 msg... */
	/* 01234567890123456 */
	if (len < 16 || msg[3] != ' ' || msg[6] != ' '
	 || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
	) {
		time(&now);
		timestamp = ctime(&now) + 4; /* skip day of week */
	} else {
		now = 0;
		timestamp = msg;
		msg += 16;
	}
	timestamp[15] = '\0';

	if (option_mask32 & OPT_small)
		sprintf(G.printbuf, "%s %s\n", timestamp, msg);
	else {
		char res[20];
		parse_fac_prio_20(pri, res);
		sprintf(G.printbuf, "%s %.64s %s %s\n", timestamp, G.hostname, res, msg);
	}

	/* Log message locally (to file or shared mem) */
	log_locally(now, G.printbuf);
}

static void timestamp_and_log_internal(const char *msg)
{
	/* -L, or no -R */
	if (ENABLE_FEATURE_REMOTE_LOG && !(option_mask32 & OPT_locallog))
		return;
	timestamp_and_log(LOG_SYSLOG | LOG_INFO, (char*)msg, 0);
}

/* tmpbuf[len] is a NUL byte (set by caller), but there can be other,
 * embedded NULs. Split messages on each of these NULs, parse prio,
 * escape control chars and log each locally. */
static void split_escape_and_log(char *tmpbuf, int len)
{
	char *p = tmpbuf;

	tmpbuf += len;
	while (p < tmpbuf) {
		char c;
		char *q = G.parsebuf;
		int pri = (LOG_USER | LOG_NOTICE);

		if (*p == '<') {
			/* Parse the magic priority number */
			pri = bb_strtou(p + 1, &p, 10);
			if (*p == '>')
				p++;
			if (pri & ~(LOG_FACMASK | LOG_PRIMASK))
				pri = (LOG_USER | LOG_NOTICE);
		}

		while ((c = *p++)) {
			if (c == '\n')
				c = ' ';
			if (!(c & ~0x1f) && c != '\t') {
				*q++ = '^';
				c += '@'; /* ^@, ^A, ^B... */
			}
			*q++ = c;
		}
		*q = '\0';

		/* Now log it */
		if (LOG_PRI(pri) < G.logLevel)
			timestamp_and_log(pri, G.parsebuf, q - G.parsebuf);
	}
}

#ifdef SYSLOGD_MARK
static void do_mark(int sig)
{
	if (G.markInterval) {
		timestamp_and_log_internal("-- MARK --");
		alarm(G.markInterval);
	}
}
#endif

/* Don't inline: prevent struct sockaddr_un to take up space on stack
 * permanently */
static NOINLINE int create_socket(void)
{
	struct sockaddr_un sunx;
	int sock_fd;
	char *dev_log_name;

	memset(&sunx, 0, sizeof(sunx));
	sunx.sun_family = AF_UNIX;

	/* Unlink old /dev/log or object it points to. */
	/* (if it exists, bind will fail) */
	strcpy(sunx.sun_path, "/dev/log");
	dev_log_name = xmalloc_follow_symlinks("/dev/log");
	if (dev_log_name) {
		safe_strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
		free(dev_log_name);
	}
	unlink(sunx.sun_path);

	sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
	xbind(sock_fd, (struct sockaddr *) &sunx, sizeof(sunx));
	chmod("/dev/log", 0666);

	return sock_fd;
}

#if ENABLE_FEATURE_REMOTE_LOG
static int try_to_resolve_remote(remoteHost_t *rh)
{
	if (!rh->remoteAddr) {
		unsigned now = monotonic_sec();

		/* Don't resolve name too often - DNS timeouts can be big */
		if ((now - rh->last_dns_resolve) < DNS_WAIT_SEC)
			return -1;
		rh->last_dns_resolve = now;
		rh->remoteAddr = host2sockaddr(rh->remoteHostname, 514);
		if (!rh->remoteAddr)
			return -1;
	}
	return socket(rh->remoteAddr->u.sa.sa_family, SOCK_DGRAM, 0);
}
#endif

static void do_syslogd(void) NORETURN;
static void do_syslogd(void)
{
	int sock_fd;
#if ENABLE_FEATURE_REMOTE_LOG
	llist_t *item;
#endif
#if ENABLE_FEATURE_SYSLOGD_DUP
	int last_sz = -1;
	char *last_buf;
	char *recvbuf = G.recvbuf;
#else
#define recvbuf (G.recvbuf)
#endif

	/* Set up signal handlers (so that they interrupt read()) */
	signal_no_SA_RESTART_empty_mask(SIGTERM, record_signo);
	signal_no_SA_RESTART_empty_mask(SIGINT, record_signo);
	//signal_no_SA_RESTART_empty_mask(SIGQUIT, record_signo);
	signal(SIGHUP, SIG_IGN);
#ifdef SYSLOGD_MARK
	signal(SIGALRM, do_mark);
	alarm(G.markInterval);
#endif
	sock_fd = create_socket();

	if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
		ipcsyslog_init();
	}

	timestamp_and_log_internal("syslogd started: BusyBox v" BB_VER);

	while (!bb_got_signal) {
		ssize_t sz;

#if ENABLE_FEATURE_SYSLOGD_DUP
		last_buf = recvbuf;
		if (recvbuf == G.recvbuf)
			recvbuf = G.recvbuf + MAX_READ;
		else
			recvbuf = G.recvbuf;
#endif
 read_again:
		sz = read(sock_fd, recvbuf, MAX_READ - 1);
		if (sz < 0) {
			if (!bb_got_signal)
				bb_perror_msg("read from /dev/log");
			break;
		}

		/* Drop trailing '\n' and NULs (typically there is one NUL) */
		while (1) {
			if (sz == 0)
				goto read_again;
			/* man 3 syslog says: "A trailing newline is added when needed".
			 * However, neither glibc nor uclibc do this:
			 * syslog(prio, "test")   sends "test\0" to /dev/log,
			 * syslog(prio, "test\n") sends "test\n\0".
			 * IOW: newline is passed verbatim!
			 * I take it to mean that it's syslogd's job
			 * to make those look identical in the log files. */
			if (recvbuf[sz-1] != '\0' && recvbuf[sz-1] != '\n')
				break;
			sz--;
		}
#if ENABLE_FEATURE_SYSLOGD_DUP
		if ((option_mask32 & OPT_dup) && (sz == last_sz))
			if (memcmp(last_buf, recvbuf, sz) == 0)
				continue;
		last_sz = sz;
#endif
#if ENABLE_FEATURE_REMOTE_LOG
		/* Stock syslogd sends it '\n'-terminated
		 * over network, mimic that */
		recvbuf[sz] = '\n';

		/* We are not modifying log messages in any way before send */
		/* Remote site cannot trust _us_ anyway and need to do validation again */
		for (item = G.remoteHosts; item != NULL; item = item->link) {
			remoteHost_t *rh = (remoteHost_t *)item->data;

			if (rh->remoteFD == -1) {
				rh->remoteFD = try_to_resolve_remote(rh);
				if (rh->remoteFD == -1)
					continue;
			}
			/* Send message to remote logger, ignore possible error */
			/* TODO: on some errors, close and set G.remoteFD to -1
			 * so that DNS resolution and connect is retried? */
			sendto(rh->remoteFD, recvbuf, sz+1, MSG_DONTWAIT,
				&(rh->remoteAddr->u.sa), rh->remoteAddr->len);
		}
#endif
		if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
			recvbuf[sz] = '\0'; /* ensure it *is* NUL terminated */
			split_escape_and_log(recvbuf, sz);
		}
	} /* while (!bb_got_signal) */

	timestamp_and_log_internal("syslogd exiting");
	puts("syslogd exiting");
	if (ENABLE_FEATURE_IPC_SYSLOG)
		ipcsyslog_cleanup();
	kill_myself_with_sig(bb_got_signal);
#undef recvbuf
}

int syslogd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int syslogd_main(int argc UNUSED_PARAM, char **argv)
{
	int opts;
	char OPTION_DECL;
#if ENABLE_FEATURE_REMOTE_LOG
	llist_t *remoteAddrList = NULL;
#endif

	INIT_G();

	/* No non-option params, -R can occur multiple times */
	opt_complementary = "=0" IF_FEATURE_REMOTE_LOG(":R::");
	opts = getopt32(argv, OPTION_STR, OPTION_PARAM);
#if ENABLE_FEATURE_REMOTE_LOG
	while (remoteAddrList) {
		remoteHost_t *rh = xzalloc(sizeof(*rh));
		rh->remoteHostname = llist_pop(&remoteAddrList);
		rh->remoteFD = -1;
		rh->last_dns_resolve = monotonic_sec() - DNS_WAIT_SEC - 1;
		llist_add_to(&G.remoteHosts, rh);
	}
#endif

#ifdef SYSLOGD_MARK
	if (opts & OPT_mark) // -m
		G.markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
#endif
	//if (opts & OPT_nofork) // -n
	//if (opts & OPT_outfile) // -O
	if (opts & OPT_loglevel) // -l
		G.logLevel = xatou_range(opt_l, 1, 8);
	//if (opts & OPT_small) // -S
#if ENABLE_FEATURE_ROTATE_LOGFILE
	if (opts & OPT_filesize) // -s
		G.logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
	if (opts & OPT_rotatecnt) // -b
		G.logFileRotate = xatou_range(opt_b, 0, 99);
#endif
#if ENABLE_FEATURE_IPC_SYSLOG
	if (opt_C) // -Cn
		G.shm_size = xatoul_range(opt_C, 4, INT_MAX/1024) * 1024;
#endif

	/* If they have not specified remote logging, then log locally */
	if (ENABLE_FEATURE_REMOTE_LOG && !(opts & OPT_remotelog)) // -R
		option_mask32 |= OPT_locallog;

	/* Store away localhost's name before the fork */
	G.hostname = safe_gethostname();
	*strchrnul(G.hostname, '.') = '\0';

	if (!(opts & OPT_nofork)) {
		bb_daemonize_or_rexec(DAEMON_CHDIR_ROOT, argv);
	}
	//umask(0); - why??
	write_pidfile("/var/run/syslogd.pid");
	do_syslogd();
	/* return EXIT_SUCCESS; */
}

/* Clean up. Needed because we are included from syslogd_and_logger.c */
#undef DEBUG
#undef SYSLOGD_MARK
#undef SYSLOGD_WRLOCK
#undef G
#undef GLOBALS
#undef INIT_G
#undef OPTION_STR
#undef OPTION_DECL
#undef OPTION_PARAM