Support for logging to a file/stdout using syslog API

Signed-off-by: Joachim Nilsson <troglobit@gmail.com>

man/logger.1

@@ -40,18 +40,29 @@
 .Op Ar MESSAGE
 .Sh DESCRIPTIOMN
 .Nm
-can be used to send messages to the system log from a UNIX shell, or
+can be used to log messages to the system log daemon from a UNIX shell,
-script.
+or script.  Optionally a stand-alone log file can be used, which is the
+automatically log rotated.  Without a
+.Ar MESSAGE
+argument
+.Nm
+reads input from
+.Ar stdin .
 .Sh OPTIONS
 This program follows the usual UNIX command line syntax:
 .Bl -tag -width Ds
 .It Fl f Ar FILE
 Log file to write messages to, instead of syslog daemon.
+.Nm
+accepts
+.Fl f-
+as an alias for
+.Ar stdout .
 .It Fl h
 Show program help.
 .It Fl p Ar PRIO
 Priority, numeric or
-.Ar facility.level
+.Ar facility.severity
 pair.
 .It Fl r Ar SIZE:NUM
 Controls log file rotation.
@@ -69,7 +80,15 @@ Show program version.
 .It Ar MESSAGE
 Log message to write.  Remember to use single/double qoutes if calling
 .Nm
-from a shell prompt due to expansion the shell does.
+from a shell prompt due to expansion the shell does.  If no message is
+given
+.Nm
+will read from
+.Ar stdin
+until EOF.  In this mode every new row (newline separated) is converted
+into an independent
+.Xr syslog 3
+call.
 .El
 .Sh EXAMPLES
 .Bd -unfilled -offset left

src/logger.c

@@ -29,7 +29,9 @@
  * SUCH DAMAGE.
  */
 
-#include <config.h>
+#include "config.h"
+
+#include <err.h>
 #include <errno.h>
 #include <getopt.h>
 #include <stdio.h>
@@ -42,7 +44,7 @@
 #include "compat.h"
 
 static const char version_info[] = PACKAGE_NAME " v" PACKAGE_VERSION;
-
+static struct syslog_data log    = SYSLOG_DATA_INIT;
 
 static int create(char *path, mode_t mode, uid_t uid, gid_t gid)
 {
@@ -113,6 +115,7 @@ static int checksz(FILE *fp, off_t sz)
 {
 	struct stat st;
 
+	fsync(fileno(fp));
 	if (sz <= 0)
 		return 0;
 
@@ -124,49 +127,20 @@ static int checksz(FILE *fp, off_t sz)
 	return 0;
 }
 
-static int logit(int level, char *buf, size_t len)
+char *chomp(char *str)
 {
-	if (buf[0]) {
+        char *p;
-		syslog(level, "%s", buf);
+
-		return 0;
+        if (!str || strlen(str) < 1) {
+                errno = EINVAL;
+                return NULL;
         }
 
-	while ((fgets(buf, len, stdin)))
+        p = str + strlen(str) - 1;
-		syslog(level, "%s", buf);
+        while (p >= str && *p == '\n')
+                *p-- = 0;
 
-	return 0;
+        return str;
-}
-
-static int flogit(char *logfile, int num, off_t sz, char *buf, size_t len)
-{
-	FILE *fp;
-
-reopen:
-	fp = fopen(logfile, "a");
-	if (!fp) {
-		syslog(LOG_ERR | LOG_PERROR, "Failed opening %s: %s", logfile, strerror(errno));
-		return 1;
-	}
-
-	if (buf[0]) {
-		fprintf(fp, "%s\n", buf);
-		fsync(fileno(fp));
-		if (checksz(fp, sz))
-			return logrotate(logfile, num, sz);
-	} else {
-		while ((fgets(buf, len, stdin))) {
-			fputs(buf, fp);
-			fsync(fileno(fp));
-
-			if (checksz(fp, sz)) {
-				logrotate(logfile, num, sz);
-				buf[0] = 0;
-				goto reopen;
-			}
-		}
-	}
-
-	return fclose(fp);
 }
 
 static int parse_prio(char *arg, int *f, int *l)
@@ -178,21 +152,23 @@ static int parse_prio(char *arg, int *f, int *l)
 		*ptr++ = 0;
 
 		for (int i = 0; facilitynames[i].c_name; i++) {
-			if (!strcmp(facilitynames[i].c_name, arg)) {
+			if (strcmp(facilitynames[i].c_name, arg))
+				continue;
+
 			*f = facilitynames[i].c_val;
 			break;
 		}
-		}
 
 		arg = ptr;
 	}
 
 	for (int i = 0; prioritynames[i].c_name; i++) {
-		if (!strcmp(prioritynames[i].c_name, arg)) {
+		if (strcmp(prioritynames[i].c_name, arg))
+			continue;
+
 		*l = prioritynames[i].c_val;
 		break;
 	}
-	}
 
 	return 0;
 }
@@ -203,7 +179,7 @@ static int usage(int code)
 	       "\n"
 	       "Write MESSAGE (or stdin) to syslog, or file (with logrotate)\n"
 	       "\n"
-	       "  -p PRIO  Log message priority (numeric or facility.level pair)\n"
+	       "  -p PRIO  Log message priority (numeric or facility.severity pair)\n"
 	       "  -t TAG   Log using the specified tag (defaults to user name)\n"
 	       "  -s       Log to stderr as well as the system log\n"
 	       "\n"
@@ -221,10 +197,12 @@ static int usage(int code)
 
 int main(int argc, char *argv[])
 {
-	int c, rc, num = 5;
+	FILE *fp;
+	int c, num = 5;
 	int facility = LOG_USER;
-	int level = LOG_INFO;
+	int severity = LOG_INFO;
-	int log_opts = LOG_NOWAIT;
+	int log_opts = LOG_NDELAY | LOG_PID;
+	int rotate = 0;
 	off_t size = 200 * 1024;
 	char *ident = NULL, *logfile = NULL;
 	char buf[512] = "";
@@ -236,7 +214,7 @@ int main(int argc, char *argv[])
 			break;
 
 		case 'p':
-			if (parse_prio(optarg, &facility, &level))
+			if (parse_prio(optarg, &facility, &severity))
 				return usage(1);
 			break;
 
@@ -276,14 +254,34 @@ int main(int argc, char *argv[])
 		}
 	}
 
-	openlog(ident, log_opts, facility);
+	if (logfile) {
+		if (strcmp(logfile, "-")) {
+			log_opts |= LOG_NLOG;
+			fp = fopen(logfile, "a");
+			if (!fp)
+				err(1, "Failed opening %s for writing: %m", logfile);
+			rotate = 1;
+		} else {
+			log_opts |= LOG_STDOUT;
+			fp = stdout;
+		}
 
-	if (logfile)
+		log.log_file = fileno(fp);
-		rc = flogit(logfile, num, size, buf, sizeof(buf));
+	}
-	else
-		rc = logit(level, buf, sizeof(buf));
 
-	closelog();
+	openlog_r(ident, log_opts, facility, &log);
 
-	return rc;
+	if (!buf[0]) {
+		while ((fgets(buf, sizeof(buf), stdin)))
+			syslog_r(severity, &log, "%s", chomp(buf));
+	} else
+		syslog_r(severity, &log, "%s", buf);
+
+	closelog_r(&log);
+
+	if (rotate && checksz(fp, size))
+		logrotate(logfile, num, size);
+
+	return 0;
 }
+

src/syslog.c

@@ -40,6 +40,7 @@ __RCSID("$NetBSD: syslog.c,v 1.55 2015/10/26 11:44:30 roy Exp $");
 #include <sys/types.h>
 #include <sys/param.h>
 #include <sys/socket.h>
+#include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/uio.h>
 #include <sys/un.h>
@@ -71,7 +72,8 @@ static mutex_t	syslog_mutex = MUTEX_INITIALIZER;
  * wrapper to catch GLIBC syslog(), which provides this for security measures
  * Note: we only enter here if user includes GLIBC syslog.h
  */
-void __syslog_chk(int pri, int flag __attribute__((unused)), const char *fmt, ...)
+void
+__syslog_chk(int pri, int flag __attribute__((unused)), const char *fmt, ...)
 {
 	va_list ap;
 
@@ -80,6 +82,20 @@ void __syslog_chk(int pri, int flag __attribute__((unused)), const char *fmt, ..
 	va_end(ap);
 }
 
+/*
+ * Used to determine file/socket type of log_file
+ */
+static int
+is_socket(int fd)
+{
+	struct stat st;
+
+	if (fstat(fd, &st) || !S_ISSOCK(st.st_mode))
+		return 0;
+
+	return 1;
+}
+
 /*
  * syslog, vsyslog --
  *	print message on log file; output is intended for syslogd(8).
@@ -186,8 +202,10 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 	char tbuf[TBUF_LEN], fmt_cpy[FMT_LEN], fmt_cat[FMT_LEN] = "";
 	size_t tbuf_left, fmt_left, msgsdlen;
 	char *fmt = fmt_cat;
-	struct iovec iov[7];	/* prog + [ + pid + ]: + fmt + crlf */
+	char dbuf[30];
-	int opened, iovcnt;
+	struct iovec iov[8];	/* date/time + prog + [ + pid + ]: + fmt + crlf */
+	int iovcnt = 0;
+	int opened;
 
 #define INTERNALLOG	LOG_ERR|LOG_CONS|LOG_PERROR|LOG_PID
 	/* Check for invalid bits. */
@@ -219,8 +237,11 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 		tbuf_left -= prlen;				\
 	} while (/*CONSTCOND*/0)
 
+	if (!(data->log_stat & LOG_NLOG)) {
 		prlen = snprintf(p, tbuf_left, "<%d>1 ", pri);
 		DEC();
+	} else
+		prlen = 0;
 
 	if (gettimeofday(&tv, NULL) != -1) {
 		/* strftime() implies tzset(), localtime_r() doesn't. */
@@ -241,6 +262,13 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 			p[prlen-2] = ':';
 			prlen += 1;
 		}
+
+		if (data->log_stat & (LOG_PERROR|LOG_CONS|LOG_NLOG)) {
+			strftime(dbuf, sizeof(dbuf), "%b %d %Y %T ", &tmnow);
+			iov[iovcnt].iov_base = dbuf;
+			iov[iovcnt].iov_len = strlen(dbuf);
+			iovcnt++;
+		}
 	}
 
 	if (data == &sdata)
@@ -266,8 +294,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 	if (data == &sdata)
 		mutex_unlock(&syslog_mutex);
 
-	if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
+	if (data->log_stat & (LOG_PERROR|LOG_CONS|LOG_NLOG)) {
-		iovcnt = 0;
 		iov[iovcnt].iov_base = p;
 		iov[iovcnt].iov_len = prlen - 1;
 		iovcnt++;
@@ -276,7 +303,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 
 	if (data->log_stat & LOG_PID) {
 		prlen = snprintf(p, tbuf_left, "%d ", getpid());
-		if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
+		if (data->log_stat & (LOG_PERROR|LOG_CONS|LOG_NLOG)) {
 			iov[iovcnt].iov_base = __UNCONST("[");
 			iov[iovcnt].iov_len = 1;
 			iovcnt++;
@@ -289,7 +316,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 		}
 	} else {
 		prlen = snprintf(p, tbuf_left, "- ");
-		if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
+		if (data->log_stat & (LOG_PERROR|LOG_CONS|LOG_NLOG)) {
 			iov[iovcnt].iov_base = __UNCONST(BRCOSP + 1);
 			iov[iovcnt].iov_len = 2;
 			iovcnt++;
@@ -311,7 +338,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 	} else
 		strlcat(fmt_cat, "-", FMT_LEN);
 
-	if (data->log_stat & (LOG_PERROR|LOG_CONS))
+	if (data->log_stat & (LOG_PERROR|LOG_CONS|LOG_NLOG))
 		msgsdlen = strlen(fmt_cat) + 1;
 	else
 		msgsdlen = 0;	/* XXX: GCC */
@@ -354,8 +381,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 	*t = '\0';
 
 	prlen = vsnprintf(p, tbuf_left, fmt_cpy, ap);
-
+	if (data->log_stat & (LOG_PERROR|LOG_CONS|LOG_NLOG)) {
-	if (data->log_stat & (LOG_PERROR|LOG_CONS)) {
 		iov[iovcnt].iov_base = p + msgsdlen;
 		iov[iovcnt].iov_len = prlen - msgsdlen;
 		iovcnt++;
@@ -379,6 +405,21 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 		openlog_unlocked_r(data->log_tag, data->log_stat, 0, data);
 	connectlog_r(data);
 
+	/* Don't write to system log, instead use fd in log_file */
+	if (data->log_stat & LOG_NLOG) {
+		iov[iovcnt].iov_base = __UNCONST(CRLF + 1);
+		iov[iovcnt].iov_len = 1;
+		(void)writev(data->log_file, iov, iovcnt + 1);
+		goto done;
+	}
+
+	/* Log to stdout, usually for debugging syslogp() API */
+	if (data->log_stat & LOG_STDOUT) {
+		strlcat(tbuf, "\n", sizeof(tbuf));
+		write(data->log_file, tbuf, strlen(tbuf));
+		goto done;
+	}
+
 	/*
 	 * If the send() failed, there are two likely scenarios:
 	 *  1) syslogd was restarted
@@ -411,6 +452,7 @@ vsyslogp_r(int pri, struct syslog_data *data, const char *msgid,
 		(void)close(fd);
 	}
 
+done:
 	if (data == &sdata)
 		mutex_unlock(&syslog_mutex);
 
@@ -450,15 +492,19 @@ connectlog_r(struct syslog_data *data)
 	};
 
 	if (data->log_file == -1 || fcntl(data->log_file, F_GETFL, 0) == -1) {
-		if ((data->log_file = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC,
+		data->log_file = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
-		    0)) == -1)
+		if (data->log_file == -1)
 			return;
 		data->log_connected = 0;
 	}
 	if (!data->log_connected) {
-		if (connect(data->log_file,
+		if (!is_socket(data->log_file)) {
-		    (const struct sockaddr *)(const void *)&sun,
+			data->log_connected = 1;
-		    (socklen_t)sizeof(sun)) == -1) {
+			return;
+		}
+
+		if (connect(data->log_file, (const struct sockaddr *)&sun,
+			    sizeof(sun)) == -1) {
 			(void)close(data->log_file);
 			data->log_file = -1;
 		} else