Support for continuous reading of syslog memory buffers.

Works like ``tail -f'' on a log file.
OK markus@, djm@

2 files changed, 27 insertions, 8 deletions

diff --git a/usr.sbin/syslogc/syslogc.8 b/usr.sbin/syslogc/syslogc.8
index 730bb0242fd..a1769c48b70 100644
--- a/usr.sbin/syslogc/syslogc.8
+++ b/usr.sbin/syslogc/syslogc.8
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: syslogc.8,v 1.4 2005/09/24 02:09:54 djm Exp $
+.\"	$OpenBSD: syslogc.8,v 1.5 2007/01/03 13:25:21 mpf Exp $
 .\"
 .\" Copyright (c) 2004 Damien Miller
 .\"
@@ -21,7 +21,7 @@
 .Nd collect messages from syslog memory buffer
 .Sh SYNOPSIS
 .Nm syslogc
-.Op Fl Ccoq
+.Op Fl Ccfoq
 .Op Fl s Ar reporting_socket
 .Ar logname
 .Nm syslogc
@@ -59,6 +59,12 @@ The options are as follows:
 Request that the log buffer be cleared without reading it.
 .It Fl c
 Request that the log buffer be cleared once it has been read.
+.It Fl f
+Print out the last 10 lines and read from the buffer continuously.
+Like
+.Ar -f
+in
+.Xr tail 1
 .It Fl o
 Check whether the specified log has overflowed.
 If the log has overflowed, then a message will be printed to
@@ -73,6 +79,10 @@ will be appended to its name.
 Specify alternate reporting socket location (the default is
 .Pa /var/run/syslogd.sock ) .
 .El
+.Sh CAVEATS
+The buffer space used for writing logs through the socket is limited.
+Thus it is possible to lose logs when running in continuous mode.
+Losses are reported on standard error.
 .Sh SEE ALSO
 .Xr syslog 3 ,
 .Xr syslog.conf 5 ,
diff --git a/usr.sbin/syslogc/syslogc.c b/usr.sbin/syslogc/syslogc.c
index 7cf6d8c115c..42f54e0b3b3 100644
--- a/usr.sbin/syslogc/syslogc.c
+++ b/usr.sbin/syslogc/syslogc.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: syslogc.c,v 1.11 2005/09/28 08:49:28 stevesk Exp $ */
+/* $OpenBSD: syslogc.c,v 1.12 2007/01/03 13:25:21 mpf Exp $ */
 
 /*
  * Copyright (c) 2004 Damien Miller
@@ -33,7 +33,7 @@
 /*
  * Client protocol NB. all numeric fields in network byte order
  */
-#define CTL_VERSION		0
+#define CTL_VERSION		1
 
 /* Request */
 struct ctl_cmd {
@@ -43,6 +43,7 @@ struct ctl_cmd {
 #define CMD_CLEAR	3	/* Clear log */
 #define CMD_LIST	4	/* List available logs */
 #define CMD_FLAGS	5	/* Query flags only */
+#define CMD_READ_CONT	6	/* Read out log continuously */
 	u_int32_t	cmd;
 	char		logname[MAX_MEMBUF_NAME];
 };
@@ -60,7 +61,7 @@ usage(void)
 {
 	extern char *__progname;
 
-	fprintf(stderr, "Usage: %s [-Ccoq] [-s ctlsock] logname\n", __progname);
+	fprintf(stderr, "Usage: %s [-Ccfhoq] [-s ctlsock] logname\n", __progname);
 	exit(1);
 }
 
@@ -81,7 +82,7 @@ main(int argc, char **argv)
 
 	ctlsock_path = DEFAULT_CTLSOCK;
 	rval = oflag = 0;
-	while ((ch = getopt(argc, argv, "Cchoqs:")) != -1) {
+	while ((ch = getopt(argc, argv, "Ccfhoqs:")) != -1) {
 		switch (ch) {
 		case 'C':
 			cc.cmd = CMD_CLEAR;
@@ -92,6 +93,9 @@ main(int argc, char **argv)
 		case 'h':
 			usage();
 			break;
+		case 'f':
+			cc.cmd = CMD_READ_CONT;
+			break;
 		case 'o':
 			cc.cmd = CMD_FLAGS;
 			oflag = 1;
@@ -149,8 +153,13 @@ main(int argc, char **argv)
 		errx(1, "unsupported syslogd version");
 
 	/* Write out reply */
-	while ((fgets(buf, sizeof(buf), ctlf)) != NULL)
-		fputs(buf, stdout);
+	while ((fgets(buf, sizeof(buf), ctlf)) != NULL) {
+		if (!strcmp(buf, "<ENOBUFS>\n"))
+			fprintf(stderr, "syslogc [%s]: Lines were dropped!\n",
+			    cc.logname);
+		else
+			fputs(buf, stdout);
+	}
 
 	if (oflag && (ntohl(rr.flags) & CTL_HDR_FLAG_OVERFLOW)) {
 		printf("%s has overflowed\n", cc.logname);