Implement the -P option (pidfile)

4 files changed, 39 insertions, 5 deletions

diff --git a/NEWS b/NEWS
index 76215af..04e3a3e 100644
--- a/NEWS
+++ b/NEWS
@@ -1,8 +1,16 @@
-micron -- history of user-visible changes. 2021-04-15
+micron -- history of user-visible changes. 2021-05-06
 See the end of file for copying conditions.
 
 Please send micron bug reports to <gray@gnu.org>
 
+Version 1.2.90 (git)
+
+* New option -P FILE
+
+Writes PID of the running process to FILE.  The file will be removed
+when the program terminates.
+
+
 Version 1.2, 2021-04-15
 
 * Fix cronjob access serialization
diff --git a/configure.ac b/configure.ac
index d8ddcab..066f3c8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -15,7 +15,7 @@
 # with micron. If not, see <http://www.gnu.org/licenses/>. */
 
 AC_PREREQ(2.63)
-AC_INIT([micron],[1.2],[gray@gnu.org.ua])
+AC_INIT([micron],[1.2.90],[gray@gnu.org.ua])
 AC_CONFIG_SRCDIR([src/micron.c])
 AC_CONFIG_AUX_DIR([build-aux])
 AC_CONFIG_HEADER([config.h])
diff --git a/doc/micrond.8 b/doc/micrond.8
index 591a964..5ac2752 100644
--- a/doc/micrond.8
+++ b/doc/micrond.8
@@ -13,7 +13,7 @@
 .\"
 .\" You should have received a copy of the GNU General Public License along
 .\" with micron. If not, see <http://www.gnu.org/licenses/>. */
-.TH MICROND 8 "January 24, 2021" "MICROND" "System Manager's Manual"
+.TH MICROND 8 "May 6, 2021" "MICROND" "System Manager's Manual"
 .SH NAME
 micrond \- a minimal cron implementation
 .SH SYNOPSIS
@@ -23,6 +23,7 @@ micrond \- a minimal cron implementation
  [\fB\-l \fIPRI\fR]\
  [\fB\-m \fIMAILER\fR]\
  [\fB\-o \fIOPTIONS\fR]\
+ [\fB\-P \fIFILE\fR]\
  [\fB\-p \fIDEV\fR]\
  [\fB\-t \fISECONDS\fR]
 .SH DESCRIPTION
@@ -197,6 +198,10 @@ for a discussion of day field semantics.
 See also the \fB_MICRON_DAY_SEMANTICS\fR built-in variable.
 .RE
 .TP
+\fB\-P \fIFILE\fR
+Write the PID of the cron daemon to \fIFILE\fR.  The file will be
+removed when the program terminates.
+.TP
 \fB\-p \fISOCKET\fR
 Send messages to syslog via this socket.  \fISOCKET\fR is either an
 absolute file name of a UNIX socket, or a host name or IPv4 address
diff --git a/src/micrond.c b/src/micrond.c
index 0d0e1e2..bc82493 100644
--- a/src/micrond.c
+++ b/src/micrond.c
@@ -128,7 +128,8 @@ int log_level = LOG_INFO;
 mode_t saved_umask;
 /* Time to wait for all cronjobs to terminate before stopping micrond. */
 unsigned micron_termination_timeout = 60;
-    
+/* Name of the file where to store the PID */
+char *pidfile;
 /* Boolean flag used to filter out @reboot jobs when rescanning. */
 static int running;
 static struct cronjob_options micron_options = {
@@ -265,6 +266,7 @@ usage(void)
     printf("    -m MAILER       set mailer command\n");
     printf("    -N              disable safety checking (for debugging only!)\n");
     printf("    -o OPTS         set crontab options\n");
+    printf("    -P FILE         write the PID of the cron daemon to FILE\n");
     printf("    -p SOCKET       send messages to syslog via this SOCKET\n");
     printf("    -S              log to syslog even if running in foreground\n");
     printf("    -s              log output from cronjobs to syslog\n");
@@ -345,7 +347,7 @@ main(int argc, char **argv)
     
     set_progname(argv[0]);
     
-    while ((c = getopt(argc, argv, "hg:fNl:m:o:p:Sst:v")) != EOF) {
+    while ((c = getopt(argc, argv, "hg:fNl:m:o:P:p:Sst:v")) != EOF) {
 	switch (c) {
 	case 'h':
 	    usage();
@@ -379,6 +381,10 @@ main(int argc, char **argv)
 	    set_crontab_options(optarg);
 	    break;
 
+	case 'P':
+	    pidfile = optarg;
+	    break;
+	    
 	case 'p':
 	    micron_log_dev = optarg;
 	    break;
@@ -460,6 +466,18 @@ main(int argc, char **argv)
     } else if (micron_options.syslog_facility)
 	micron_log_open(progname, LOG_CRON);
 
+    if (pidfile) {
+	FILE *fp = fopen(pidfile, "w");
+	if (fp) {
+	    fprintf(fp, "%lu\n", (unsigned long) getpid());
+	    fclose(fp);
+	} else {
+	    micron_log(LOG_ERR, "can't open pidfile %s for writing: %s",
+		       pidfile, strerror(errno));
+	    pidfile = NULL;
+	} 
+    }
+    
     saved_umask = umask(077);
     crongroups_parse_all(PARSE_ALWAYS);
 
@@ -507,6 +525,9 @@ main(int argc, char **argv)
 	    thread_info[i].stop(thread_info[i].tid);
     }
 
+    if (pidfile)
+	unlink(pidfile);
+    
     micron_log_close();
     
     return EXIT_OK;