Arnd Ben Otto writes:

Hi Eric

I have written a small patch for the Busybox syslogd. With this patch
one can limit the size of the messagfile. As soon as the limit is
reached the syslogd can rotate or purge the messagefile(s) on his own.
There is no necessity to use an external rotatescript.

Even if logread does something similar, its very handy to have some
messagefile after your box crash.

I wrote this patch initial vor BB 0.6x where no cron daemon was avail.
Now I adapted it for the new Version and i hope it is still useful. At
least I still use it :-)

bye
Arnd

include/usage.h

@@ -2214,6 +2214,11 @@
 	"Write all buffered filesystem blocks to disk."
 
 
+#ifdef CONFIG_FEATURE_ROTATE_LOGFILE
+	#define USAGE_ROTATE_LOGFILE(a) a
+#else
+	#define USAGE_ROTATE_LOGFILE(a) 
+#endif
 #ifdef CONFIG_FEATURE_REMOTE_LOG
   #define USAGE_REMOTE_LOG(a) a
 #else
@@ -2234,6 +2239,9 @@
 	"\t-m NUM\t\tInterval between MARK lines (default=20min, 0=off)\n" \
 	"\t-n\t\tRun as a foreground process\n" \
 	"\t-O FILE\t\tUse an alternate log file (default=/var/log/messages)" \
+	USAGE_ROTATE_LOGFILE( \
+	"\n\t-s SIZE\t\tMax size (KB) bevor rotate (default=200KB, 0=off)\n" \
+	"\t-b NUM\t\tNumber of rotated log files (default=1, 0=purge log)") \
 	USAGE_REMOTE_LOG( \
 	"\n\t-R HOST[:PORT]\tLog to IP or hostname on PORT (default PORT=514/UDP)\n" \
 	"\t-L\t\tLog locally and via network logging (default is network only)") \

sysklogd/Config.in

@@ -20,6 +20,14 @@ config CONFIG_SYSLOGD
 	  wrong.  And something almost always will go wrong if
 	  you wait long enough....
 
+config CONFIG_FEATURE_ROTATE_LOGFILE
+	bool "  Rotate message files"
+	default n
+	depends on CONFIG_SYSLOGD
+	help
+	  This enables syslogd to rotate the message files
+	  on his own. No need to use an external rotatescript.
+
 config CONFIG_FEATURE_REMOTE_LOG
 	bool "  Remote Log support"
 	default n

sysklogd/syslogd.c

@@ -58,6 +58,14 @@ static char lfile[MAXPATHLEN];
 
 static const char *logFilePath = __LOG_FILE;
 
+#ifdef CONFIG_FEATURE_ROTATE_LOGFILE
+/* max size of message file bevor being rotated */
+static int logFileSize = 200 * 1024;
+
+/* number of rotated message files */
+static int logFileRotate = 1;
+#endif
+
 /* interval between marks in seconds */
 static int MarkInterval = 20 * 60;
 
@@ -305,6 +313,36 @@ static void message(char *fmt, ...)
 							 O_NONBLOCK)) >= 0) {
 		fl.l_type = F_WRLCK;
 		fcntl(fd, F_SETLKW, &fl);
+#ifdef CONFIG_FEATURE_ROTATE_LOGFILE
+		if ( logFileSize > 0 ) {
+			struct stat statf;
+			int r = fstat(fd, &statf);
+			if( !r && (statf.st_mode & S_IFREG)
+				&& (lseek(fd,0,SEEK_END) > logFileSize) ) {
+				if(logFileRotate > 0) {
+					int i;
+					char oldFile[(strlen(logFilePath)+3)], newFile[(strlen(logFilePath)+3)];
+					for(i=logFileRotate-1;i>0;i--) {
+						sprintf(oldFile, "%s.%d", logFilePath, i-1);
+						sprintf(newFile, "%s.%d", logFilePath, i);
+						rename(oldFile, newFile);
+					}
+					sprintf(newFile, "%s.%d", logFilePath, 0);
+					fl.l_type = F_UNLCK;
+					fcntl (fd, F_SETLKW, &fl);
+					close(fd);
+					rename(logFilePath, newFile);
+					fd = device_open (logFilePath,
+						   O_WRONLY | O_CREAT | O_NOCTTY | O_APPEND |
+						   O_NONBLOCK);
+					fl.l_type = F_WRLCK;
+					fcntl (fd, F_SETLKW, &fl);
+				} else {
+					ftruncate( fd, 0 );
+				}
+			}
+		}
+#endif
 		va_start(arguments, fmt);
 		vdprintf(fd, fmt, arguments);
 		va_end(arguments);
@@ -578,7 +616,7 @@ extern int syslogd_main(int argc, char **argv)
 	char *p;
 
 	/* do normal option parsing */
-	while ((opt = getopt(argc, argv, "m:nO:R:LC::")) > 0) {
+	while ((opt = getopt(argc, argv, "m:nO:s:b:R:LC::")) > 0) {
 		switch (opt) {
 		case 'm':
 			MarkInterval = atoi(optarg) * 60;
@@ -589,6 +627,15 @@ extern int syslogd_main(int argc, char **argv)
 		case 'O':
 			logFilePath = optarg;
 			break;
+#ifdef CONFIG_FEATURE_ROTATE_LOGFILE
+		case 's':
+			logFileSize = atoi(optarg) * 1024;
+			break;
+		case 'b':
+			logFileRotate = atoi(optarg);
+			if( logFileRotate > 99 ) logFileRotate = 99;
+			break;
+#endif
 #ifdef CONFIG_FEATURE_REMOTE_LOG
 		case 'R':
 			RemoteHost = bb_xstrdup(optarg);