sysklogd/syslogd.c - codeaurora/busybox - Gitiles

 /* 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.
  */

 #include "busybox.h"
 #include <paths.h>
 #include <sys/un.h>

 /* SYSLOG_NAMES defined to pull some extra junk from syslog.h */
 #define SYSLOG_NAMES
 #include <sys/syslog.h>
 #include <sys/uio.h>

 #define DEBUG 0

 /* Path to the unix socket */
 static char *dev_log_name;

 /* Path for the file where all log messages are written */
 static const char *logFilePath = "/var/log/messages";
 static int logFD = -1;

 /* interval between marks in seconds */
 static int markInterval = 20 * 60;

 /* level of messages to be locally logged */
 static int logLevel = 8;

 /* localhost's name */
 static char localHostName[64];

 #if ENABLE_FEATURE_ROTATE_LOGFILE
 /* max size of message file before being rotated */
 static unsigned logFileSize = 200 * 1024;
 /* number of rotated message files */
 static unsigned logFileRotate = 1;
 static unsigned curFileSize;
 static smallint isRegular;
 #endif

 #if ENABLE_FEATURE_REMOTE_LOG
 #include <netinet/in.h>
 /* udp socket for logging to remote host */
 static int remoteFD = -1;
 static len_and_sockaddr* remoteAddr;
 #endif

 /* We are using bb_common_bufsiz1 for buffering: */
 enum { MAX_READ = (BUFSIZ/6) & ~0xf };
 /* We recv into RECVBUF... (size: MAX_READ ~== BUFSIZ/6) */
 #define RECVBUF  bb_common_bufsiz1
 /* ...then copy to PARSEBUF, escaping control chars */
 /* (can grow x2 max ~== BUFSIZ/3) */
 #define PARSEBUF (bb_common_bufsiz1 + MAX_READ)
 /* ...then sprintf into PRINTBUF, adding timestamp (15 chars),
  * host (64), fac.prio (20) to the message */
 /* (growth by: 15 + 64 + 20 + delims = ~110) */
 #define PRINTBUF (bb_common_bufsiz1 + 3*MAX_READ)
 /* totals: BUFSIZ == BUFSIZ/6 + BUFSIZ/3 + (BUFSIZ/3+BUFSIZ/6)
  * -- we have BUFSIZ/6 extra at the ent of PRINTBUF
  * which covers needed ~110 extra bytes (and much more) */


 /* Options */
 enum {
 	OPTBIT_mark = 0, // -m
 	OPTBIT_nofork, // -n
 	OPTBIT_outfile, // -O
 	OPTBIT_loglevel, // -l
 	OPTBIT_small, // -S
 	USE_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize   ,)	// -s
 	USE_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt  ,)	// -b
 	USE_FEATURE_REMOTE_LOG(    OPTBIT_remote     ,)	// -R
 	USE_FEATURE_REMOTE_LOG(    OPTBIT_localtoo   ,)	// -L
 	USE_FEATURE_IPC_SYSLOG(    OPTBIT_circularlog,)	// -C

 	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    = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize   )) + 0,
 	OPT_rotatecnt   = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt  )) + 0,
 	OPT_remotelog   = USE_FEATURE_REMOTE_LOG(    (1 << OPTBIT_remote     )) + 0,
 	OPT_locallog    = USE_FEATURE_REMOTE_LOG(    (1 << OPTBIT_localtoo   )) + 0,
 	OPT_circularlog = USE_FEATURE_IPC_SYSLOG(    (1 << OPTBIT_circularlog)) + 0,
 };
 #define OPTION_STR "m:nO:l:S" \
 	USE_FEATURE_ROTATE_LOGFILE("s:" ) \
 	USE_FEATURE_ROTATE_LOGFILE("b:" ) \
 	USE_FEATURE_REMOTE_LOG(    "R:" ) \
 	USE_FEATURE_REMOTE_LOG(    "L"  ) \
 	USE_FEATURE_IPC_SYSLOG(    "C::")
 #define OPTION_DECL *opt_m, *opt_l \
 	USE_FEATURE_ROTATE_LOGFILE(,*opt_s) \
 	USE_FEATURE_ROTATE_LOGFILE(,*opt_b) \
 	USE_FEATURE_REMOTE_LOG(    ,*opt_R) \
 	USE_FEATURE_IPC_SYSLOG(    ,*opt_C = NULL)
 #define OPTION_PARAM &opt_m, &logFilePath, &opt_l \
 	USE_FEATURE_ROTATE_LOGFILE(,&opt_s) \
 	USE_FEATURE_ROTATE_LOGFILE(,&opt_b) \
 	USE_FEATURE_REMOTE_LOG(    ,&opt_R) \
 	USE_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

 #include <sys/ipc.h>
 #include <sys/sem.h>
 #include <sys/shm.h>

 /* our shared key */
 #define KEY_ID ((long)0x414e4547) /* "GENA" */

 // Semaphore operation structures
 static struct shbuf_ds {
 	int32_t size;   // size of data written
 	int32_t head;   // start of message list
 	int32_t tail;   // end of message list
 	char data[1];   // data/messages
 } *shbuf;               // shared memory pointer

 static int shmid = -1;   // ipc shared memory id
 static int s_semid = -1; // ipc semaphore id
 static int shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024);	// default shm size

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

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

 	shmid = shmget(KEY_ID, shm_size, IPC_CREAT | 1023);
 	if (shmid == -1) {
 		bb_perror_msg_and_die("shmget");
 	}

 	shbuf = shmat(shmid, NULL, 0);
 	if (!shbuf) {
 		bb_perror_msg_and_die("shmat");
 	}

 	shbuf->size = shm_size - offsetof(struct shbuf_ds, data);
 	shbuf->head = shbuf->tail = 0;

 	// we'll trust the OS to set initial semval to 0 (let's hope)
 	s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023);
 	if (s_semid == -1) {
 		if (errno == EEXIST) {
 			s_semid = semget(KEY_ID, 2, 0);
 			if (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)
 {
 	/* Why libc insists on these being rw? */
 	static struct sembuf SMwup[1] = { {1, -1, IPC_NOWAIT} };
 	static struct sembuf SMwdn[3] = { {0, 0}, {1, 0}, {1, +1} };

 	int old_tail, new_tail;
 	char *c;

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

 	/* Circular Buffer Algorithm:
 	 * --------------------------
          * tail == position where to store next syslog message.
 	 * head == position of next message to retrieve ("print").
 	 * if head == tail, there is no "unprinted" messages left.
 	 * head is typically advanced by separate "reader" program,
 	 * but if there isn't one, we have to do it ourself.
 	 * messages are NUL-separated.
 	 */
 	len++; /* length with NUL included */
  again:
 	old_tail = shbuf->tail;
 	new_tail = old_tail + len;
 	if (new_tail < shbuf->size) {
 		/* No need to move head if shbuf->head <= old_tail,
 		 * else... */
 		if (old_tail < shbuf->head && shbuf->head <= new_tail) {
 			/* ...need to move head forward */
 			c = memchr(shbuf->data + new_tail, '\0',
 					   shbuf->size - new_tail);
 			if (!c) /* no NUL ahead of us, wrap around */
 				c = memchr(shbuf->data, '\0', old_tail);
 			if (!c) { /* still nothing? point to this msg... */
 				shbuf->head = old_tail;
 			} else {
 				/* convert pointer to offset + skip NUL */
 				shbuf->head = c - shbuf->data + 1;
 			}
 		}
 		/* store message, set new tail */
 		memcpy(shbuf->data + old_tail, msg, len);
 		shbuf->tail = new_tail;
 	} else {
 		/* we need to break up the message and wrap it around */
 		/* k == available buffer space ahead of old tail */
 		int k = shbuf->size - old_tail - 1;
 		if (shbuf->head > old_tail) {
 			/* we are going to overwrite head, need to
 			 * move it out of the way */
 			c = memchr(shbuf->data, '\0', old_tail);
 			if (!c) { /* nothing? point to this msg... */
 				shbuf->head = old_tail;
 			} else { /* convert pointer to offset + skip NUL */
 				shbuf->head = c - shbuf->data + 1;
 			}
 		}
 		/* copy what fits to the end of buffer, and repeat */
 		memcpy(shbuf->data + old_tail, msg, k);
 		msg += k;
 		len -= k;
 		shbuf->tail = 0;
 		goto again;
 	}
 	if (semop(s_semid, SMwup, 1) == -1) {
 		bb_perror_msg_and_die("SMwup");
 	}
 	if (DEBUG)
 		printf("head:%d tail:%d\n", shbuf->head, 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(char *msg)
 {
 	static time_t last;
 	struct flock fl;
 	int len = strlen(msg);

 #if ENABLE_FEATURE_IPC_SYSLOG
 	if ((option_mask32 & OPT_circularlog) && shbuf) {
 		log_to_shmem(msg, len);
 		return;
 	}
 #endif
 	if (logFD >= 0) {
 		time_t cur;
 		time(&cur);
 		if (last != cur) {
 			last = cur; /* reopen log file every second */
 			close(logFD);
 			goto reopen;
 		}
 	} else {
  reopen:
 		logFD = device_open(logFilePath, O_WRONLY | O_CREAT
 					| O_NOCTTY | O_APPEND | O_NONBLOCK);
 		if (logFD < 0) {
 			/* cannot open logfile? - print to /dev/console then */
 			int fd = device_open(_PATH_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;

 		isRegular = (fstat(logFD, &statf) == 0 && (statf.st_mode & S_IFREG));
 		/* bug (mostly harmless): can wrap around if file > 4gb */
 		curFileSize = statf.st_size;
 		}
 #endif
 	}

 	fl.l_whence = SEEK_SET;
 	fl.l_start = 0;
 	fl.l_len = 1;
 	fl.l_type = F_WRLCK;
 	fcntl(logFD, F_SETLKW, &fl);

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

 static void parse_fac_prio_20(int pri, char *res20)
 {
 	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 0 when they know
  * that there is no timestamp, short-cutting the test. */
 static void timestamp_and_log(int pri, char *msg, int len)
 {
 	char *timestamp;

 	if (len < 16 || msg[3] != ' ' || msg[6] != ' '
 	 || msg[9] != ':' || msg[12] != ':' || msg[15] != ' '
 	) {
 		time_t now;
 		time(&now);
 		timestamp = ctime(&now) + 4;
 	} else {
 		timestamp = msg;
 		msg += 16;
 	}
 	timestamp[15] = '\0';

 	/* Log message locally (to file or shared mem) */
 	if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
 		if (LOG_PRI(pri) < logLevel) {
 			if (option_mask32 & OPT_small)
 				sprintf(PRINTBUF, "%s %s\n", timestamp, msg);
 			else {
 				char res[20];
 				parse_fac_prio_20(pri, res);
 				sprintf(PRINTBUF, "%s %s %s %s\n", timestamp, localHostName, res, msg);
 			}
 			log_locally(PRINTBUF);
 		}
 	}
 }

 static void split_escape_and_log(char *tmpbuf, int len)
 {
 	char *p = tmpbuf;

 	tmpbuf += len;
 	while (p < tmpbuf) {
 		char c;
 		char *q = 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)) {
 				*q++ = '^';
 				c += '@'; /* ^@, ^A, ^B... */
 			}
 			*q++ = c;
 		}
 		*q = '\0';
 		/* Now log it */
 		timestamp_and_log(pri, PARSEBUF, q - PARSEBUF);
 	}
 }

 static void quit_signal(int sig)
 {
 	timestamp_and_log(LOG_SYSLOG | LOG_INFO, "syslogd exiting", 0);
 	puts("syslogd exiting");
 	unlink(dev_log_name);
 	if (ENABLE_FEATURE_IPC_SYSLOG)
 		ipcsyslog_cleanup();
 	exit(1);
 }

 static void do_mark(int sig)
 {
 	if (markInterval) {
 		timestamp_and_log(LOG_SYSLOG | LOG_INFO, "-- MARK --", 0);
 		alarm(markInterval);
 	}
 }

 static void do_syslogd(void) ATTRIBUTE_NORETURN;
 static void do_syslogd(void)
 {
 	struct sockaddr_un sunx;
 	socklen_t addr_len;
 	int sock_fd;
 	fd_set fds;

 	/* Set up signal handlers */
 	signal(SIGINT, quit_signal);
 	signal(SIGTERM, quit_signal);
 	signal(SIGQUIT, quit_signal);
 	signal(SIGHUP, SIG_IGN);
 	signal(SIGCHLD, SIG_IGN);
 #ifdef SIGCLD
 	signal(SIGCLD, SIG_IGN);
 #endif
 	signal(SIGALRM, do_mark);
 	alarm(markInterval);

 	dev_log_name = xmalloc_realpath(_PATH_LOG);
 	if (!dev_log_name)
 		dev_log_name = _PATH_LOG;

 	/* Unlink old /dev/log (or object it points to) */
 	unlink(dev_log_name);

 	memset(&sunx, 0, sizeof(sunx));
 	sunx.sun_family = AF_UNIX;
 	strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
 	sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
 	addr_len = sizeof(sunx.sun_family) + strlen(sunx.sun_path);
 	xbind(sock_fd, (struct sockaddr *) &sunx, addr_len);

 	if (chmod(dev_log_name, 0666) < 0) {
 		bb_perror_msg_and_die("cannot set permission on %s", dev_log_name);
 	}
 	if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
 		ipcsyslog_init();
 	}

 	timestamp_and_log(LOG_SYSLOG | LOG_INFO, "syslogd started: BusyBox v" BB_VER, 0);

 	for (;;) {
 		FD_ZERO(&fds);
 		FD_SET(sock_fd, &fds);

 		if (select(sock_fd + 1, &fds, NULL, NULL, NULL) < 0) {
 			if (errno == EINTR) {
 				/* alarm may have happened */
 				continue;
 			}
 			bb_perror_msg_and_die("select");
 		}

 		if (FD_ISSET(sock_fd, &fds)) {
 			int i;
 			i = recv(sock_fd, RECVBUF, MAX_READ - 1, 0);
 			if (i <= 0)
 				bb_perror_msg_and_die("UNIX socket error");
 			/* TODO: maybe suppress duplicates? */
 #if ENABLE_FEATURE_REMOTE_LOG
 			/* We are not modifying log messages in any way before send */
 			/* Remote site cannot trust _us_ anyway and need to do validation again */
 			if (remoteAddr) {
 				if (-1 == remoteFD) {
 					remoteFD = socket(remoteAddr->sa.sa_family, SOCK_DGRAM, 0);
 				}
 				if (-1 != remoteFD) {
 					/* send message to remote logger, ignore possible error */
 					sendto(remoteFD, RECVBUF, i, MSG_DONTWAIT,
 						&remoteAddr->sa, remoteAddr->len);
 				}
 			}
 #endif
 			RECVBUF[i] = '\0';
 			split_escape_and_log(RECVBUF, i);
 		} /* FD_ISSET() */
 	} /* for */
 }

 int syslogd_main(int argc, char **argv)
 {
 	char OPTION_DECL;
 	char *p;

 	/* do normal option parsing */
 	opt_complementary = "=0"; /* no non-option params */
 	getopt32(argc, argv, OPTION_STR, OPTION_PARAM);
 	if (option_mask32 & OPT_mark) // -m
 		markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
 	//if (option_mask32 & OPT_nofork) // -n
 	//if (option_mask32 & OPT_outfile) // -O
 	if (option_mask32 & OPT_loglevel) // -l
 		logLevel = xatou_range(opt_l, 1, 8);
 	//if (option_mask32 & OPT_small) // -S
 #if ENABLE_FEATURE_ROTATE_LOGFILE
 	if (option_mask32 & OPT_filesize) // -s
 		logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
 	if (option_mask32 & OPT_rotatecnt) // -b
 		logFileRotate = xatou_range(opt_b, 0, 99);
 #endif
 #if ENABLE_FEATURE_REMOTE_LOG
 	if (option_mask32 & OPT_remotelog) { // -R
 		remoteAddr = host2sockaddr(opt_R, 514);
 	}
 	//if (option_mask32 & OPT_locallog) // -L
 #endif
 #if ENABLE_FEATURE_IPC_SYSLOG
 	if ((option_mask32 & OPT_circularlog) && opt_C) // -C
 		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 && !(option_mask32 & OPT_remotelog))
 		option_mask32 |= OPT_locallog;

 	/* Store away localhost's name before the fork */
 	gethostname(localHostName, sizeof(localHostName));
 	p = strchr(localHostName, '.');
 	if (p) {
 		*p = '\0';
 	}

 	if (!(option_mask32 & OPT_nofork)) {
 #ifdef BB_NOMMU
 		vfork_daemon_rexec(0, 1, argc, argv, "-n");
 #else
 		xdaemon(0, 1);
 #endif
 	}
 	umask(0);
 	do_syslogd();
 	/* return EXIT_SUCCESS; */
 }
	/* 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.
	*/

	#include "busybox.h"
	#include <paths.h>
	#include <sys/un.h>

	/* SYSLOG_NAMES defined to pull some extra junk from syslog.h */
	#define SYSLOG_NAMES
	#include <sys/syslog.h>
	#include <sys/uio.h>

	#define DEBUG 0

	/* Path to the unix socket */
	static char *dev_log_name;

	/* Path for the file where all log messages are written */
	static const char *logFilePath = "/var/log/messages";
	static int logFD = -1;

	/* interval between marks in seconds */
	static int markInterval = 20 * 60;

	/* level of messages to be locally logged */
	static int logLevel = 8;

	/* localhost's name */
	static char localHostName[64];

	#if ENABLE_FEATURE_ROTATE_LOGFILE
	/* max size of message file before being rotated */
	static unsigned logFileSize = 200 * 1024;
	/* number of rotated message files */
	static unsigned logFileRotate = 1;
	static unsigned curFileSize;
	static smallint isRegular;
	#endif

	#if ENABLE_FEATURE_REMOTE_LOG
	#include <netinet/in.h>
	/* udp socket for logging to remote host */
	static int remoteFD = -1;
	static len_and_sockaddr* remoteAddr;
	#endif

	/* We are using bb_common_bufsiz1 for buffering: */
	enum { MAX_READ = (BUFSIZ/6) & ~0xf };
	/* We recv into RECVBUF... (size: MAX_READ ~== BUFSIZ/6) */
	#define RECVBUF bb_common_bufsiz1
	/* ...then copy to PARSEBUF, escaping control chars */
	/* (can grow x2 max ~== BUFSIZ/3) */
	#define PARSEBUF (bb_common_bufsiz1 + MAX_READ)
	/* ...then sprintf into PRINTBUF, adding timestamp (15 chars),
	* host (64), fac.prio (20) to the message */
	/* (growth by: 15 + 64 + 20 + delims = ~110) */
	#define PRINTBUF (bb_common_bufsiz1 + 3*MAX_READ)
	/* totals: BUFSIZ == BUFSIZ/6 + BUFSIZ/3 + (BUFSIZ/3+BUFSIZ/6)
	* -- we have BUFSIZ/6 extra at the ent of PRINTBUF
	* which covers needed ~110 extra bytes (and much more) */


	/* Options */
	enum {
	OPTBIT_mark = 0, // -m
	OPTBIT_nofork, // -n
	OPTBIT_outfile, // -O
	OPTBIT_loglevel, // -l
	OPTBIT_small, // -S
	USE_FEATURE_ROTATE_LOGFILE(OPTBIT_filesize ,) // -s
	USE_FEATURE_ROTATE_LOGFILE(OPTBIT_rotatecnt ,) // -b
	USE_FEATURE_REMOTE_LOG( OPTBIT_remote ,) // -R
	USE_FEATURE_REMOTE_LOG( OPTBIT_localtoo ,) // -L
	USE_FEATURE_IPC_SYSLOG( OPTBIT_circularlog,) // -C

	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 = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_filesize )) + 0,
	OPT_rotatecnt = USE_FEATURE_ROTATE_LOGFILE((1 << OPTBIT_rotatecnt )) + 0,
	OPT_remotelog = USE_FEATURE_REMOTE_LOG( (1 << OPTBIT_remote )) + 0,
	OPT_locallog = USE_FEATURE_REMOTE_LOG( (1 << OPTBIT_localtoo )) + 0,
	OPT_circularlog = USE_FEATURE_IPC_SYSLOG( (1 << OPTBIT_circularlog)) + 0,
	};
	#define OPTION_STR "m:nO:l:S" \
	USE_FEATURE_ROTATE_LOGFILE("s:" ) \
	USE_FEATURE_ROTATE_LOGFILE("b:" ) \
	USE_FEATURE_REMOTE_LOG( "R:" ) \
	USE_FEATURE_REMOTE_LOG( "L" ) \
	USE_FEATURE_IPC_SYSLOG( "C::")
	#define OPTION_DECL opt_m, opt_l \
	USE_FEATURE_ROTATE_LOGFILE(,*opt_s) \
	USE_FEATURE_ROTATE_LOGFILE(,*opt_b) \
	USE_FEATURE_REMOTE_LOG( ,*opt_R) \
	USE_FEATURE_IPC_SYSLOG( ,*opt_C = NULL)
	#define OPTION_PARAM &opt_m, &logFilePath, &opt_l \
	USE_FEATURE_ROTATE_LOGFILE(,&opt_s) \
	USE_FEATURE_ROTATE_LOGFILE(,&opt_b) \
	USE_FEATURE_REMOTE_LOG( ,&opt_R) \
	USE_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

	#include <sys/ipc.h>
	#include <sys/sem.h>
	#include <sys/shm.h>

	/* our shared key */
	#define KEY_ID ((long)0x414e4547) /* "GENA" */

	// Semaphore operation structures
	static struct shbuf_ds {
	int32_t size; // size of data written
	int32_t head; // start of message list
	int32_t tail; // end of message list
	char data[1]; // data/messages
	} *shbuf; // shared memory pointer

	static int shmid = -1; // ipc shared memory id
	static int s_semid = -1; // ipc semaphore id
	static int shm_size = ((CONFIG_FEATURE_IPC_SYSLOG_BUFFER_SIZE)*1024); // default shm size

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

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

	shmid = shmget(KEY_ID, shm_size, IPC_CREAT \| 1023);
	if (shmid == -1) {
	bb_perror_msg_and_die("shmget");
	}

	shbuf = shmat(shmid, NULL, 0);
	if (!shbuf) {
	bb_perror_msg_and_die("shmat");
	}

	shbuf->size = shm_size - offsetof(struct shbuf_ds, data);
	shbuf->head = shbuf->tail = 0;

	// we'll trust the OS to set initial semval to 0 (let's hope)
	s_semid = semget(KEY_ID, 2, IPC_CREAT \| IPC_EXCL \| 1023);
	if (s_semid == -1) {
	if (errno == EEXIST) {
	s_semid = semget(KEY_ID, 2, 0);
	if (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)
	{
	/* Why libc insists on these being rw? */
	static struct sembuf SMwup[1] = { {1, -1, IPC_NOWAIT} };
	static struct sembuf SMwdn[3] = { {0, 0}, {1, 0}, {1, +1} };

	int old_tail, new_tail;
	char *c;

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

	/* Circular Buffer Algorithm:
	* --------------------------
	* tail == position where to store next syslog message.
	* head == position of next message to retrieve ("print").
	* if head == tail, there is no "unprinted" messages left.
	* head is typically advanced by separate "reader" program,
	* but if there isn't one, we have to do it ourself.
	* messages are NUL-separated.
	*/
	len++; /* length with NUL included */
	again:
	old_tail = shbuf->tail;
	new_tail = old_tail + len;
	if (new_tail < shbuf->size) {
	/* No need to move head if shbuf->head <= old_tail,
	* else... */
	if (old_tail < shbuf->head && shbuf->head <= new_tail) {
	/* ...need to move head forward */
	c = memchr(shbuf->data + new_tail, '\0',
	shbuf->size - new_tail);
	if (!c) /* no NUL ahead of us, wrap around */
	c = memchr(shbuf->data, '\0', old_tail);
	if (!c) { /* still nothing? point to this msg... */
	shbuf->head = old_tail;
	} else {
	/* convert pointer to offset + skip NUL */
	shbuf->head = c - shbuf->data + 1;
	}
	}
	/* store message, set new tail */
	memcpy(shbuf->data + old_tail, msg, len);
	shbuf->tail = new_tail;
	} else {
	/* we need to break up the message and wrap it around */
	/* k == available buffer space ahead of old tail */
	int k = shbuf->size - old_tail - 1;
	if (shbuf->head > old_tail) {
	/* we are going to overwrite head, need to
	* move it out of the way */
	c = memchr(shbuf->data, '\0', old_tail);
	if (!c) { /* nothing? point to this msg... */
	shbuf->head = old_tail;
	} else { /* convert pointer to offset + skip NUL */
	shbuf->head = c - shbuf->data + 1;
	}
	}
	/* copy what fits to the end of buffer, and repeat */
	memcpy(shbuf->data + old_tail, msg, k);
	msg += k;
	len -= k;
	shbuf->tail = 0;
	goto again;
	}
	if (semop(s_semid, SMwup, 1) == -1) {
	bb_perror_msg_and_die("SMwup");
	}
	if (DEBUG)
	printf("head:%d tail:%d\n", shbuf->head, 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(char *msg)
	{
	static time_t last;
	struct flock fl;
	int len = strlen(msg);

	#if ENABLE_FEATURE_IPC_SYSLOG
	if ((option_mask32 & OPT_circularlog) && shbuf) {
	log_to_shmem(msg, len);
	return;
	}
	#endif
	if (logFD >= 0) {
	time_t cur;
	time(&cur);
	if (last != cur) {
	last = cur; /* reopen log file every second */
	close(logFD);
	goto reopen;
	}
	} else {
	reopen:
	logFD = device_open(logFilePath, O_WRONLY \| O_CREAT
	\| O_NOCTTY \| O_APPEND \| O_NONBLOCK);
	if (logFD < 0) {
	/* cannot open logfile? - print to /dev/console then */
	int fd = device_open(_PATH_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;

	isRegular = (fstat(logFD, &statf) == 0 && (statf.st_mode & S_IFREG));
	/* bug (mostly harmless): can wrap around if file > 4gb */
	curFileSize = statf.st_size;
	}
	#endif
	}

	fl.l_whence = SEEK_SET;
	fl.l_start = 0;
	fl.l_len = 1;
	fl.l_type = F_WRLCK;
	fcntl(logFD, F_SETLKW, &fl);

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

	static void parse_fac_prio_20(int pri, char *res20)
	{
	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 0 when they know
	* that there is no timestamp, short-cutting the test. */
	static void timestamp_and_log(int pri, char *msg, int len)
	{
	char *timestamp;

	if (len < 16 \|\| msg[3] != ' ' \|\| msg[6] != ' '
	\|\| msg[9] != ':' \|\| msg[12] != ':' \|\| msg[15] != ' '
	) {
	time_t now;
	time(&now);
	timestamp = ctime(&now) + 4;
	} else {
	timestamp = msg;
	msg += 16;
	}
	timestamp[15] = '\0';

	/* Log message locally (to file or shared mem) */
	if (!ENABLE_FEATURE_REMOTE_LOG \|\| (option_mask32 & OPT_locallog)) {
	if (LOG_PRI(pri) < logLevel) {
	if (option_mask32 & OPT_small)
	sprintf(PRINTBUF, "%s %s\n", timestamp, msg);
	else {
	char res[20];
	parse_fac_prio_20(pri, res);
	sprintf(PRINTBUF, "%s %s %s %s\n", timestamp, localHostName, res, msg);
	}
	log_locally(PRINTBUF);
	}
	}
	}

	static void split_escape_and_log(char *tmpbuf, int len)
	{
	char *p = tmpbuf;

	tmpbuf += len;
	while (p < tmpbuf) {
	char c;
	char *q = 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)) {
	*q++ = '^';
	c += '@'; /* ^@, ^A, ^B... */
	}
	*q++ = c;
	}
	*q = '\0';
	/* Now log it */
	timestamp_and_log(pri, PARSEBUF, q - PARSEBUF);
	}
	}

	static void quit_signal(int sig)
	{
	timestamp_and_log(LOG_SYSLOG \| LOG_INFO, "syslogd exiting", 0);
	puts("syslogd exiting");
	unlink(dev_log_name);
	if (ENABLE_FEATURE_IPC_SYSLOG)
	ipcsyslog_cleanup();
	exit(1);
	}

	static void do_mark(int sig)
	{
	if (markInterval) {
	timestamp_and_log(LOG_SYSLOG \| LOG_INFO, "-- MARK --", 0);
	alarm(markInterval);
	}
	}

	static void do_syslogd(void) ATTRIBUTE_NORETURN;
	static void do_syslogd(void)
	{
	struct sockaddr_un sunx;
	socklen_t addr_len;
	int sock_fd;
	fd_set fds;

	/* Set up signal handlers */
	signal(SIGINT, quit_signal);
	signal(SIGTERM, quit_signal);
	signal(SIGQUIT, quit_signal);
	signal(SIGHUP, SIG_IGN);
	signal(SIGCHLD, SIG_IGN);
	#ifdef SIGCLD
	signal(SIGCLD, SIG_IGN);
	#endif
	signal(SIGALRM, do_mark);
	alarm(markInterval);

	dev_log_name = xmalloc_realpath(_PATH_LOG);
	if (!dev_log_name)
	dev_log_name = _PATH_LOG;

	/* Unlink old /dev/log (or object it points to) */
	unlink(dev_log_name);

	memset(&sunx, 0, sizeof(sunx));
	sunx.sun_family = AF_UNIX;
	strncpy(sunx.sun_path, dev_log_name, sizeof(sunx.sun_path));
	sock_fd = xsocket(AF_UNIX, SOCK_DGRAM, 0);
	addr_len = sizeof(sunx.sun_family) + strlen(sunx.sun_path);
	xbind(sock_fd, (struct sockaddr *) &sunx, addr_len);

	if (chmod(dev_log_name, 0666) < 0) {
	bb_perror_msg_and_die("cannot set permission on %s", dev_log_name);
	}
	if (ENABLE_FEATURE_IPC_SYSLOG && (option_mask32 & OPT_circularlog)) {
	ipcsyslog_init();
	}

	timestamp_and_log(LOG_SYSLOG \| LOG_INFO, "syslogd started: BusyBox v" BB_VER, 0);

	for (;;) {
	FD_ZERO(&fds);
	FD_SET(sock_fd, &fds);

	if (select(sock_fd + 1, &fds, NULL, NULL, NULL) < 0) {
	if (errno == EINTR) {
	/* alarm may have happened */
	continue;
	}
	bb_perror_msg_and_die("select");
	}

	if (FD_ISSET(sock_fd, &fds)) {
	int i;
	i = recv(sock_fd, RECVBUF, MAX_READ - 1, 0);
	if (i <= 0)
	bb_perror_msg_and_die("UNIX socket error");
	/* TODO: maybe suppress duplicates? */
	#if ENABLE_FEATURE_REMOTE_LOG
	/* We are not modifying log messages in any way before send */
	/* Remote site cannot trust _us_ anyway and need to do validation again */
	if (remoteAddr) {
	if (-1 == remoteFD) {
	remoteFD = socket(remoteAddr->sa.sa_family, SOCK_DGRAM, 0);
	}
	if (-1 != remoteFD) {
	/* send message to remote logger, ignore possible error */
	sendto(remoteFD, RECVBUF, i, MSG_DONTWAIT,
	&remoteAddr->sa, remoteAddr->len);
	}
	}
	#endif
	RECVBUF[i] = '\0';
	split_escape_and_log(RECVBUF, i);
	} /* FD_ISSET() */
	} /* for */
	}

	int syslogd_main(int argc, char **argv)
	{
	char OPTION_DECL;
	char *p;

	/* do normal option parsing */
	opt_complementary = "=0"; /* no non-option params */
	getopt32(argc, argv, OPTION_STR, OPTION_PARAM);
	if (option_mask32 & OPT_mark) // -m
	markInterval = xatou_range(opt_m, 0, INT_MAX/60) * 60;
	//if (option_mask32 & OPT_nofork) // -n
	//if (option_mask32 & OPT_outfile) // -O
	if (option_mask32 & OPT_loglevel) // -l
	logLevel = xatou_range(opt_l, 1, 8);
	//if (option_mask32 & OPT_small) // -S
	#if ENABLE_FEATURE_ROTATE_LOGFILE
	if (option_mask32 & OPT_filesize) // -s
	logFileSize = xatou_range(opt_s, 0, INT_MAX/1024) * 1024;
	if (option_mask32 & OPT_rotatecnt) // -b
	logFileRotate = xatou_range(opt_b, 0, 99);
	#endif
	#if ENABLE_FEATURE_REMOTE_LOG
	if (option_mask32 & OPT_remotelog) { // -R
	remoteAddr = host2sockaddr(opt_R, 514);
	}
	//if (option_mask32 & OPT_locallog) // -L
	#endif
	#if ENABLE_FEATURE_IPC_SYSLOG
	if ((option_mask32 & OPT_circularlog) && opt_C) // -C
	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 && !(option_mask32 & OPT_remotelog))
	option_mask32 \|= OPT_locallog;

	/* Store away localhost's name before the fork */
	gethostname(localHostName, sizeof(localHostName));
	p = strchr(localHostName, '.');
	if (p) {
	*p = '\0';
	}

	if (!(option_mask32 & OPT_nofork)) {
	#ifdef BB_NOMMU
	vfork_daemon_rexec(0, 1, argc, argv, "-n");
	#else
	xdaemon(0, 1);
	#endif
	}
	umask(0);
	do_syslogd();
	/* return EXIT_SUCCESS; */
	}