aboutsummaryrefslogtreecommitdiff
path: root/sysklogd/syslogd.c
blob: 2053cb146ca7521a2855872db1e77f1353eda02f (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
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
/* 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 GPLv2 or later, see file LICENSE in this source tree.
 */

//usage:#define syslogd_trivial_usage
//usage:       "[OPTIONS]"
//usage:#define syslogd_full_usage "\n\n"
//usage:       "System logging utility\n"
//usage:	IF_NOT_FEATURE_SYSLOGD_CFG(
//usage:       "(this version of syslogd ignores /etc/syslog.conf)\n"
//usage:	)
//usage:     "\n	-n		Run in foreground"
//usage:     "\n	-O FILE		Log to FILE (default:/var/log/messages)"
//usage:     "\n	-l N		Log only messages more urgent than prio N (1-8)"
//usage:     "\n	-S		Smaller output"
//usage:	IF_FEATURE_ROTATE_LOGFILE(
//usage:     "\n	-s SIZE		Max size (KB) before rotation (default:200KB, 0=off)"
//usage:     "\n	-b N		N rotated logs to keep (default:1, max=99, 0=purge)"
//usage:	)
//usage:	IF_FEATURE_REMOTE_LOG(
//usage:     "\n	-R HOST[:PORT]	Log to IP or hostname on PORT (default PORT=514/UDP)"
//usage:     "\n	-L		Log locally and via network (default is network only if -R)"
//usage:	)
//usage:	IF_FEATURE_SYSLOGD_DUP(
//usage:     "\n	-D		Drop duplicates"
//usage:	)
//usage:	IF_FEATURE_IPC_SYSLOG(
/* NB: -Csize shouldn't have space (because size is optional) */
//usage:     "\n	-C[size_kb]	Log to shared mem buffer (use logread to read it)"
//usage:	)
//usage:	IF_FEATURE_SYSLOGD_CFG(
//usage:     "\n	-f FILE		Use FILE as config (default:/etc/syslog.conf)"
//usage:	)
/* //usage:  "\n	-m MIN		Minutes between MARK lines (default:20, 0=off)" */
//usage:	IF_FEATURE_KMSG_SYSLOG(
//usage:     "\n	-K		Log to kernel printk buffer (use dmesg to read it)"
//usage:	)
//usage:
//usage:#define syslogd_example_usage
//usage:       "$ syslogd -R masterlog:514\n"
//usage:       "$ syslogd -R 192.168.1.1:601\n"

/*
 * 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 = CONFIG_FEATURE_SYSLOGD_READ_BUFFER_SIZE,
	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

typedef struct logFile_t {
	const char *path;
	int fd;
#if ENABLE_FEATURE_ROTATE_LOGFILE
	unsigned size;
	uint8_t isRegular;
#endif
} logFile_t;

#if ENABLE_FEATURE_SYSLOGD_CFG
typedef struct logRule_t {
	uint8_t enabled_facility_priomap[LOG_NFACILITIES];
	struct logFile_t *file;
	struct logRule_t *next;
} logRule_t;
#endif

/* Allows us to have smaller initializer. Ugly. */
#define GLOBALS \
	logFile_t logFile;                      \
	/* 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;                 \
) \
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];                 \
) \
IF_FEATURE_SYSLOGD_CFG( \
	logRule_t *log_rules; \
) \
IF_FEATURE_KMSG_SYSLOG( \
	int kmsgfd; \
	int primask; \
)

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 = {
	.logFile = {
		.path = "/var/log/messages",
		.fd = -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
	IF_FEATURE_SYSLOGD_CFG(   OPTBIT_cfg        ,)	// -f
	IF_FEATURE_KMSG_SYSLOG(   OPTBIT_kmsg       ,)	// -K

	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,
	OPT_cfg         = IF_FEATURE_SYSLOGD_CFG(   (1 << OPTBIT_cfg        )) + 0,
	OPT_kmsg        = IF_FEATURE_KMSG_SYSLOG(   (1 << OPTBIT_kmsg       )) + 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"  ) \
	IF_FEATURE_SYSLOGD_CFG(   "f:" ) \
	IF_FEATURE_KMSG_SYSLOG(   "K"  )
#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) \
	IF_FEATURE_SYSLOGD_CFG(   ,*opt_f = NULL)
#define OPTION_PARAM &opt_m, &(G.logFile.path), &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) \
	IF_FEATURE_SYSLOGD_CFG(   ,&opt_f)


#if ENABLE_FEATURE_SYSLOGD_CFG
static const CODE* find_by_name(char *name, const CODE* c_set)
{
	for (; c_set->c_name; c_set++) {
		if (strcmp(name, c_set->c_name) == 0)
			return c_set;
	}
	return NULL;
}
#endif
static const CODE* find_by_val(int val, const CODE* c_set)
{
	for (; c_set->c_name; c_set++) {
		if (c_set->c_val == val)
			return c_set;
	}
	return NULL;
}

#if ENABLE_FEATURE_SYSLOGD_CFG
static void parse_syslogdcfg(const char *file)
{
	char *t;
	logRule_t **pp_rule;
	/* tok[0] set of selectors */
	/* tok[1] file name */
	/* tok[2] has to be NULL */
	char *tok[3];
	parser_t *parser;

	parser = config_open2(file ? file : "/etc/syslog.conf",
				file ? xfopen_for_read : fopen_for_read);
	if (!parser)
		/* didn't find default /etc/syslog.conf */
		/* proceed as if we built busybox without config support */
		return;

	/* use ptr to ptr to avoid checking whether head was initialized */
	pp_rule = &G.log_rules;
	/* iterate through lines of config, skipping comments */
	while (config_read(parser, tok, 3, 2, "# \t", PARSE_NORMAL | PARSE_MIN_DIE)) {
		char *cur_selector;
		logRule_t *cur_rule;

		/* unexpected trailing token? */
		if (tok[2])
			goto cfgerr;

		cur_rule = *pp_rule = xzalloc(sizeof(*cur_rule));

		cur_selector = tok[0];
		/* iterate through selectors: "kern.info;kern.!err;..." */
		do {
			const CODE *code;
			char *next_selector;
			uint8_t negated_prio; /* "kern.!err" */
			uint8_t single_prio;  /* "kern.=err" */
			uint32_t facmap; /* bitmap of enabled facilities */
			uint8_t primap;  /* bitmap of enabled priorities */
			unsigned i;

			next_selector = strchr(cur_selector, ';');
			if (next_selector)
				*next_selector++ = '\0';

			t = strchr(cur_selector, '.');
			if (!t)
				goto cfgerr;
			*t++ = '\0'; /* separate facility from priority */

			negated_prio = 0;
			single_prio = 0;
			if (*t == '!') {
				negated_prio = 1;
				++t;
			}
			if (*t == '=') {
				single_prio = 1;
				++t;
			}

			/* parse priority */
			if (*t == '*')
				primap = 0xff; /* all 8 log levels enabled */
			else {
				uint8_t priority;
				code = find_by_name(t, prioritynames);
				if (!code)
					goto cfgerr;
				primap = 0;
				priority = code->c_val;
				if (priority == INTERNAL_NOPRI) {
					/* ensure we take "enabled_facility_priomap[fac] &= 0" branch below */
					negated_prio = 1;
				} else {
					priority = 1 << priority;
					do {
						primap |= priority;
						if (single_prio)
							break;
						priority >>= 1;
					} while (priority);
					if (negated_prio)
						primap = ~primap;
				}
			}

			/* parse facility */
			if (*cur_selector == '*')
				facmap = (1<<LOG_NFACILITIES) - 1;
			else {
				char *next_facility;
				facmap = 0;
				t = cur_selector;
				/* iterate through facilities: "kern,daemon.<priospec>" */
				do {
					next_facility = strchr(t, ',');
					if (next_facility)
						*next_facility++ = '\0';
					code = find_by_name(t, facilitynames);
					if (!code)
						goto cfgerr;
					/* "mark" is not a real facility, skip it */
					if (code->c_val != INTERNAL_MARK)
						facmap |= 1<<(LOG_FAC(code->c_val));
					t = next_facility;
				} while (t);
			}

			/* merge result with previous selectors */
			for (i = 0; i < LOG_NFACILITIES; ++i) {
				if (!(facmap & (1<<i)))
					continue;
				if (negated_prio)
					cur_rule->enabled_facility_priomap[i] &= primap;
				else
					cur_rule->enabled_facility_priomap[i] |= primap;
			}

			cur_selector = next_selector;
		} while (cur_selector);

		/* check whether current file name was mentioned in previous rules or
		 * as global logfile (G.logFile).
		 */
		if (strcmp(G.logFile.path, tok[1]) == 0) {
			cur_rule->file = &G.logFile;
			goto found;
		}
		/* temporarily use cur_rule as iterator, but *pp_rule still points
		 * to currently processing rule entry.
		 * NOTE: *pp_rule points to the current (and last in the list) rule.
		 */
		for (cur_rule = G.log_rules; cur_rule != *pp_rule; cur_rule = cur_rule->next) {
			if (strcmp(cur_rule->file->path, tok[1]) == 0) {
				/* found - reuse the same file structure */
				(*pp_rule)->file = cur_rule->file;
				cur_rule = *pp_rule;
				goto found;
			}
		}
		cur_rule->file = xzalloc(sizeof(*cur_rule->file));
		cur_rule->file->fd = -1;
		cur_rule->file->path = xstrdup(tok[1]);
 found:
		pp_rule = &cur_rule->next;
	}
	config_close(parser);
	return;

 cfgerr:
	bb_error_msg_and_die("error in '%s' at line %d", file, parser->lineno);
}
#endif

/* 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 old_tail, new_tail;
	int len;

	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 = strlen(msg) + 1; /* 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 */

#if ENABLE_FEATURE_KMSG_SYSLOG
static void kmsg_init(void)
{
	G.kmsgfd = xopen("/dev/kmsg", O_WRONLY);

	/*
	 * kernel < 3.5 expects single char printk KERN_* priority prefix,
	 * from 3.5 onwards the full syslog facility/priority format is supported
	 */
	if (get_linux_version_code() < KERNEL_VERSION(3,5,0))
		G.primask = LOG_PRIMASK;
	else
		G.primask = -1;
}

static void kmsg_cleanup(void)
{
	if (ENABLE_FEATURE_CLEAN_UP)
		close(G.kmsgfd);
}

/* Write message to /dev/kmsg */
static void log_to_kmsg(int pri, const char *msg)
{
	/*
	 * kernel < 3.5 expects single char printk KERN_* priority prefix,
	 * from 3.5 onwards the full syslog facility/priority format is supported
	 */
	pri &= G.primask;

	write(G.kmsgfd, G.printbuf, sprintf(G.printbuf, "<%d>%s\n", pri, msg));
}
#else
void kmsg_init(void);
void kmsg_cleanup(void);
void log_to_kmsg(int pri, const char *msg);
#endif /* FEATURE_KMSG_SYSLOG */

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

	if (log_file->fd >= 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(log_file->fd);
			goto reopen;
		}
	} else {
 reopen:
		log_file->fd = open(log_file->path, O_WRONLY | O_CREAT
					| O_NOCTTY | O_APPEND | O_NONBLOCK,
					0666);
		if (log_file->fd < 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;
			log_file->isRegular = (fstat(log_file->fd, &statf) == 0 && S_ISREG(statf.st_mode));
			/* bug (mostly harmless): can wrap around if file > 4gb */
			log_file->size = 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(log_file->fd, F_SETLKW, &fl);
#endif

#if ENABLE_FEATURE_ROTATE_LOGFILE
	if (G.logFileSize && log_file->isRegular && log_file->size > G.logFileSize) {
		if (G.logFileRotate) { /* always 0..99 */
			int i = strlen(log_file->path) + 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", log_file->path, i);
				if (i == 0) break;
				sprintf(oldFile, "%s.%d", log_file->path, --i);
				/* ignore errors - file might be missing */
				rename(oldFile, newFile);
			}
			/* newFile == "f.0" now */
			rename(log_file->path, newFile);
			/* Incredibly, if F and F.0 are hardlinks, POSIX
			 * _demands_ that rename returns 0 but does not
			 * remove F!!!
			 * (hardlinked F/F.0 pair was observed after
			 * power failure during rename()).
			 * Ensure old file is gone:
			 */
			unlink(log_file->path);
#ifdef SYSLOGD_WRLOCK
			fl.l_type = F_UNLCK;
			fcntl(log_file->fd, F_SETLKW, &fl);
#endif
			close(log_file->fd);
			goto reopen;
		}
		ftruncate(log_file->fd, 0);
	}
	log_file->size +=
#endif
			full_write(log_file->fd, msg, len);
#ifdef SYSLOGD_WRLOCK
	fl.l_type = F_UNLCK;
	fcntl(log_file->fd, F_SETLKW, &fl);
#endif
}

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

	c_fac = find_by_val(LOG_FAC(pri) << 3, facilitynames);
	if (c_fac) {
		c_pri = find_by_val(LOG_PRI(pri), prioritynames);
		if (c_pri) {
			snprintf(res20, 20, "%s.%s", c_fac->c_name, c_pri->c_name);
			return;
		}
	}
	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 (ENABLE_FEATURE_KMSG_SYSLOG && (option_mask32 & OPT_kmsg)) {
		log_to_kmsg(pri, msg);
		return;
	}

	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) */
#if ENABLE_FEATURE_SYSLOGD_CFG
	{
		bool match = 0;
		logRule_t *rule;
		uint8_t facility = LOG_FAC(pri);
		uint8_t prio_bit = 1 << LOG_PRI(pri);

		for (rule = G.log_rules; rule; rule = rule->next) {
			if (rule->enabled_facility_priomap[facility] & prio_bit) {
				log_locally(now, G.printbuf, rule->file);
				match = 1;
			}
		}
		if (match)
			return;
	}
#endif
	if (LOG_PRI(pri) < G.logLevel) {
#if ENABLE_FEATURE_IPC_SYSLOG
		if ((option_mask32 & OPT_circularlog) && G.shbuf) {
			log_to_shmem(G.printbuf);
			return;
		}
#endif
		log_locally(now, G.printbuf, &G.logFile);
	}
}

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 */
		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;

#if ENABLE_FEATURE_SYSTEMD
	if (sd_listen_fds() == 1)
		return SD_LISTEN_FDS_START;
#endif

	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 xsocket(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();
	}

	if (ENABLE_FEATURE_KMSG_SYSLOG && (option_mask32 & OPT_kmsg))
		kmsg_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.
			 * On some errors, close and set remoteFD to -1
			 * so that DNS resolution is retried.
			 */
			if (sendto(rh->remoteFD, recvbuf, sz+1,
					MSG_DONTWAIT | MSG_NOSIGNAL,
					&(rh->remoteAddr->u.sa), rh->remoteAddr->len) == -1
			) {
				switch (errno) {
				case ECONNRESET:
				case ENOTCONN: /* paranoia */
				case EPIPE:
					close(rh->remoteFD);
					rh->remoteFD = -1;
					free(rh->remoteAddr);
					rh->remoteAddr = NULL;
				}
			}
		}
#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");
	remove_pidfile(CONFIG_PID_FILE_PATH "/syslogd.pid");
	if (ENABLE_FEATURE_IPC_SYSLOG)
		ipcsyslog_cleanup();
	if (ENABLE_FEATURE_KMSG_SYSLOG && (option_mask32 & OPT_kmsg))
		kmsg_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;
#if ENABLE_FEATURE_SYSLOGD_CFG
	parse_syslogdcfg(opt_f);
#endif

	/* 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(CONFIG_PID_FILE_PATH "/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