Notify handle

man/syslog.conf.5

@@ -105,6 +105,17 @@ cron or a separate log rotate daemon.
 Comments, lines starting with a hash mark ('#'), and empty lines are
 ignored.  If an error occurs during parsing the whole line is ignored.
 .Pp
+The special keyword
+.Em notify
+specifies the path to an executable program which will get called
+whenever a log file has been rotated, with the name of the file, less
+its rotation suffix
+.Ql .0 ,
+as an argument.
+For example:
+.Ql notify /sbin/on-log-rotate.sh .
+Any number of notifiers may be installed.
+.Pp
 A special
 .Em include
 keyword can be used to include all files with names ending in '.conf'

src/syslogd.c

@@ -147,6 +147,11 @@ static int	  KeepKernTime;		  /* Keep kernel timestamp, evern after initial read
 static off_t	  RotateSz = 0;		  /* Max file size (bytes) before rotating, disabled by default */
 static int	  RotateCnt = 5;	  /* Max number (count) of log files to keep, set with -c <NUM> */
 
+/*
+ * List of notifiers
+ */
+static SIMPLEQ_HEAD(notifiers, notifier) nothead = SIMPLEQ_HEAD_INITIALIZER(nothead);
+
 /*
  * List of peers and sockets for binding.
  */
@@ -180,9 +185,12 @@ static void signal_init(void);
 static void boot_time_init(void);
 static void init(void);
 static int  strtobytes(char *arg);
-static int  cfparse(FILE *fp, struct files *newf);
+static int  cfparse(FILE *fp, struct files *newf, struct notifiers *newn);
 int         decode(char *name, struct _code *codetab);
 static void logit(char *, ...);
+static void notifier_add(struct notifiers *newn, const char *program);
+static void notifier_invoke(const char *logfile);
+static void notifier_free_all(void);
 void        reload(int);
 static int  validate(struct sockaddr *sa, const char *hname);
 static int	waitdaemon(int);
@@ -1604,6 +1612,9 @@ void logrotate(struct filed *f)
 				ERR("Failed re-opening log file %s after rotation", f->f_un.f_fname);
 				return;
 			}
+
+			if (!SIMPLEQ_EMPTY(&nothead))
+				notifier_invoke(f->f_un.f_fname);
 		}
 		ftruncate(f->f_file, 0);
 	}
@@ -2455,6 +2466,7 @@ static void boot_time_init(void)
 static void init(void)
 {
 	static int once = 1;
+	struct notifiers newn = SIMPLEQ_HEAD_INITIALIZER(newn);
 	struct filed *f;
 	struct files newf = SIMPLEQ_HEAD_INITIALIZER(newf);
 	FILE *fp;
@@ -2538,7 +2550,7 @@ static void init(void)
 		}
 	}
 
-	if (cfparse(fp, &newf)) {
+	if (cfparse(fp, &newf, &newn)) {
 		fclose(fp);
 		return;
 	}
@@ -2548,11 +2560,27 @@ static void init(void)
 	 * Close all open log files.
 	 */
 	close_open_log_files();
+
 	fhead = newf;
 
+	/*
+	 * Free all notifiers
+	 */
+	notifier_free_all();
+
+	nothead = newn;
+
 	Initialized = 1;
 
 	if (Debug) {
+		if (!SIMPLEQ_EMPTY(&nothead)) {
+			struct notifier *np;
+
+			SIMPLEQ_FOREACH(np, &nothead, n_link)
+				printf("notify %s\n", np->n_program);
+			printf("\n");
+		}
+
 		SIMPLEQ_FOREACH(f, &fhead, f_link) {
 			if (f->f_type == F_UNUSED)
 				continue;
@@ -2923,7 +2951,7 @@ static struct filed *cfline(char *line)
 /*
  * Parse .conf file and append to list
  */
-static int cfparse(FILE *fp, struct files *newf)
+static int cfparse(FILE *fp, struct files *newf, struct notifiers *newn)
 {
 	struct filed *f;
 	char  cbuf[BUFSIZ];
@@ -2988,13 +3016,18 @@ static int cfparse(FILE *fp, struct files *newf)
 				}
 
 				logit("Parsing %s ...", gl.gl_pathv[i]);
-				cfparse(fpi, newf);
+				cfparse(fpi, newf, newn);
 				fclose(fpi);
 			}
 			globfree(&gl);
 			continue;
 		}
 
+		if (!strncmp(cbuf, "notify", 6)) {
+			notifier_add(newn, &cbuf[6]);
+			continue;
+		}
+
 		f = cfline(cbuf);
 		if (!f)
 			continue;
@@ -3337,6 +3370,70 @@ static void logit(char *fmt, ...)
 	fflush(stdout);
 }
 
+static void notifier_add(struct notifiers *newn, const char *program)
+{
+	while (*program && isspace(*program))
+		++program;
+
+	/* Check whether it is accessible, regardless of TOCTOU */
+	if (!access(program, X_OK)) {
+		struct notifier *np;
+
+		np = calloc(1, sizeof(*np));
+		if (!np) {
+			ERR("Cannot allocate memory for a notify program");
+			return;
+		}
+		np->n_program = strdup(program);
+		if (!np->n_program) {
+			free (np);
+			ERR("Cannot allocate memory for a notify program");
+			return;
+		}
+		SIMPLEQ_INSERT_TAIL(newn, np, n_link);
+	} else
+		logit("notify: non-existing, or not executable program\n");
+}
+
+static void notifier_invoke(const char *logfile)
+{
+	char *argv[3];
+	int childpid;
+	struct notifier *np;
+
+	logit("notify: rotated %s, invoking hooks\n", logfile);
+
+	SIMPLEQ_FOREACH(np, &nothead, n_link) {
+		childpid = fork();
+
+		switch (childpid) {
+		case -1:
+			ERR("Cannot start notifier %s", np->n_program);
+			break;
+		case 0:
+			argv[0] = np->n_program;
+			argv[1] = (char*)logfile;
+			argv[2] = NULL;
+			execv(argv[0], argv);
+			_exit(1);
+		default:
+			logit("notify: forked child pid %d for %s\n",
+				childpid, np->n_program);
+			break;
+		}
+	}
+}
+
+static void notifier_free_all(void)
+{
+	struct notifier *np, *npnext;
+
+	SIMPLEQ_FOREACH_SAFE(np, &nothead, n_link, npnext) {
+		free(np->n_program);
+		free(np);
+	}
+}
+
 /*
  * The following function is resposible for handling a SIGHUP signal.  Since
  * we are now doing mallocs/free as part of init we had better not being

src/syslogd.h

@@ -305,6 +305,14 @@ struct filed {
 	int	 f_rotatesz;
 };
 
+/*
+ * Log rotation notifiers
+ */
+struct notifier {
+	SIMPLEQ_ENTRY(notifier)	 n_link;
+	char			*n_program;
+};
+
 void flog(int pri, char *fmt, ...);
 
 #endif /* SYSKLOGD_SYSLOGD_H_ */

test/Makefile.am

@@ -1,5 +1,5 @@
 EXTRA_DIST       = lib.sh opts.sh
-EXTRA_DIST      += api.sh local.sh unicode.sh remote.sh fwd.sh mark.sh
+EXTRA_DIST      += api.sh local.sh unicode.sh remote.sh fwd.sh mark.sh notify.sh
 CLEANFILES       = *~ *.trs *.log
 TEST_EXTENSIONS  = .sh
 TESTS_ENVIRONMENT= unshare -mrun
@@ -17,5 +17,6 @@ TESTS           += remote.sh
 TESTS           += api.sh
 TESTS           += fwd.sh
 TESTS           += mark.sh
+TESTS           += notify.sh
 
 programs: $(check_PROGRAMS)

test/notify.sh

@@ -0,0 +1,41 @@
+#!/bin/sh
+set -x
+
+if [ x"${srcdir}" = x ]; then
+    srcdir=.
+fi
+. ${srcdir}/lib.sh
+
+[ -x ../src/logger ] || SKIP 'logger missing'
+
+NOT1=${DIR}/${NM}-1.sh
+NOT1STAMP=${DIR}/${NM}-1.stamp
+NOT2=${DIR}/${NM}-2.sh
+NOT2STAMP=${DIR}/${NM}-2.stamp
+
+printf '#!/bin/sh -\necho script 1: $* > '${NOT1STAMP}'\n' > ${NOT1}
+printf '#!/bin/sh -\necho script 2: $* > '${NOT2STAMP}'\n' > ${NOT2}
+chmod 0755 ${NOT1} ${NOT2}
+
+cat <<EOF > ${CONFD}/notifier.conf
+notify      ${NOT1}
+# Match all log messages, store in RC5424 format and rotate every 1 KiB
+*.*       -${LOG}    ;rotate=1k:2,RFC5424
+notify ${NOT2}
+EOF
+
+setup
+
+MSG=01234567890123456789012345678901234567890123456789
+MSG=$MSG$MSG$MSG$MSG$MSG$MSG$MSG$MSG$MSG$MSG
+../src/logger -u ${SOCK} ${MSG}
+../src/logger -u ${SOCK} 1${MSG}
+../src/logger -u ${SOCK} 2${MSG}
+
+if [ -f ${LOG}.0 ] &&
+		grep 'script 1' ${NOT1STAMP} &&
+		grep 'script 2' ${NOT2STAMP}; then
+	OK
+else
+	FAIL 'Notifier did not run.'
+fi