Create a pid file if running in daemon mode - casantos

Author: ptc

crond.8

@@ -4,7 +4,7 @@
 crond - dillon's lightweight cron daemon
 .SH SYNOPSIS
 .PP
-\f[B]crond [-s dir] [-c dir] [-t dir] [-m user\@host] [-M mailhandler] [-S|-L file] [-l loglevel] [-b|-f|-d]\f[]
+\f[B]crond [-s dir] [-c dir] [-t dir] [-m user\@host] [-M mailhandler] [-S|-L file] [-P|-p file] [-l loglevel] [-b|-f|-d]\f[]
 .SH OPTIONS
 .PP
 \f[B]crond\f[] is a background daemon that parses individual
@@ -69,6 +69,16 @@ log to specified file instead of syslog.
 .RS
 .RE
 .TP
+.B -P
+do not create a process-id file.
+.RS
+.RE
+.TP
+.B -L file
+Write process-id to specified file instead of /var/run/crond.pi
+.RS
+.RE
+.TP
 .B -l loglevel
 log events at the specified, or more important, loglevels.
 The default is `notice'.

defs.h

@@ -54,6 +54,9 @@
 #ifndef CRONTABS
 #define CRONTABS	"/var/spool/cron/crontabs"
 #endif
+#ifndef PIDFILE
+#define PIDFILE     "/var/run/crond.pid"
+#endif
 #ifndef CRONSTAMPS
 #define CRONSTAMPS	"/var/spool/cron/cronstamps"
 #endif

main.c

@@ -32,11 +32,13 @@ short DebugOpt = 0;
 short LogLevel = LOG_LEVEL;
 short ForegroundOpt = 0;
 short SyslogOpt = 1;
+short PidFileOpt = 1;
 const char  *CDir = CRONTABS;
 const char  *SCDir = SCRONTABS;
 const char *TSDir = CRONSTAMPS;
 const char *LogFile = NULL; 	/* opened with mode 0600 */
 const char *LogHeader = LOGHEADER;
+const char *PidFile = PIDFILE;
 const char *SendMail = NULL;
 const char *Mailto = NULL;
 char *TempDir;
@@ -72,7 +74,7 @@ main(int ac, char **av)
 
 	opterr = 0;
 
-	while ((i = getopt(ac,av,"dl:L:fbSc:s:m:M:t:")) != -1) {
+	while ((i = getopt(ac,av,"dl:L:fbSc:s:m:M:t:Pp:")) != -1) {
 		switch (i) {
 			case 'l':
 				{
@@ -161,19 +163,28 @@ main(int ac, char **av)
 			case 'm':
 				if (*optarg != 0) Mailto = optarg;
 				break;
+            case 'P':
+                PidFileOpt = 0;
+                break;
+            case 'p':
+                PidFileOpt = 1;
+                PidFile = optarg;
+                break;
 			default:
 				/*
 				 * check for parse error
 				 */
 				printf("dillon's cron daemon " VERSION "\n");
-				printf("crond [-s dir] [-c dir] [-t dir] [-m user@host] [-M mailer] [-S|-L [file]] [-l level] [-b|-f|-d]\n");
+				printf("crond [-s dir] [-c dir] [-t dir] [-m user@host] [-M mailer] [-S|-L [file]] [-P|-p [file]] [-l level] [-b|-f|-d]\n");
 				printf("-s            directory of system crontabs (defaults to %s)\n", SCRONTABS);
 				printf("-c            directory of per-user crontabs (defaults to %s)\n", CRONTABS);
 				printf("-t            directory of timestamps (defaults to %s)\n", CRONSTAMPS);
 				printf("-m user@host  where should cron output be directed? (defaults to local user)\n");
 				printf("-M mailer     (defaults to %s)\n", SENDMAIL);
 				printf("-S            log to syslog using identity '%s' (default)\n", LOG_IDENT);
 				printf("-L file       log to specified file instead of syslog\n");
+                printf("-P            do not create process-id file\n");
+                printf("-p file       write pid to specified file instead of %s\n", PIDFILE);
 				printf("-l loglevel   log events <= this level (defaults to %s (level %d))\n", LevelAry[LOG_LEVEL], LOG_LEVEL);
 				printf("-b            run in background (default)\n");
 				printf("-f            run in foreground\n");
@@ -219,16 +230,48 @@ main(int ac, char **av)
 
 		int fd;
 		int pid;
+        int pipe_fd[2];
+        int status;
+
+        if (pipe(pipe_fd) < 0) {
+            //pipe failed
+            perror("pipe");
+            exit(1);
+        }
 
 		if ((pid = fork()) < 0) {
 			/* fork failed */
 			perror("fork");
 			exit(1);
 		} else if (pid > 0) {
-			/* parent */
-			exit(0);
-		}
+			/* parent, reads from pipe */
+            close(pipe_fd[1]);
+            if (read(pipe_fd[0], &status, sizeof(status)) > 0) {
+                exit(status);
+            }
+            /* error: got zero bytes, so child just closed the write end */
+            exit(1);
+        }
+
 		/* child continues */
+        close(pipe_fd[0]);
+        status = 0;
+
+        /* write pid file or exit */
+
+        if (PidFileOpt) {
+            if ((fd = open(PidFile, O_WRONLY|O_CREAT|O_TRUNC, 0644)) < 0) {
+                status = errno;
+                fprintf(stderr, "failed to open PID file '%s', reason: %s\n", PidFile, strerror(status));
+                goto daemon_error;
+            }
+            if (fdprintf(fd, "%d\n", getpid()) < 0) {
+                status = errno;
+                fprintf(stderr, "failed to write PID file '%s', reason: %s\n", PidFile, strerror(status));
+                goto daemon_error;
+            }
+            close(fd);
+        }
 
 		/* become session leader, detach from terminal */
 
@@ -260,11 +303,16 @@ main(int ac, char **av)
 				fclose(stderr);
 				dup2(fd, 2);
 			} else {
-				int n = errno;
-				fdprintf(2, "failed to open logfile '%s', reason: %s\n", LogFile, strerror(n));
-				exit(n);
+				status = errno;
+				fdprintf(2, "failed to open logfile '%s', reason: %s\n", LogFile, strerror(errno));
+				goto daemon_error;
 			}
 		}
+        daemon_error:
+        write(pipe_fd[1], &status, sizeof(status));
+        if (status != 0) {
+            exit(status);
+        }
 	} else {
 		/* daemon in foreground */
 

subs.c

@@ -11,7 +11,7 @@
 
 Prototype void printlogf(int level, const char *ctl, ...);
 Prototype void fdprintlogf(int level, int fd, const char *ctl, ...);
-Prototype void fdprintf(int fd, const char *ctl, ...);
+Prototype int fdprintf(int fd, const char *ctl, ...);
 Prototype void initsignals(void);
 Prototype char Hostname[SMALL_BUFFER];
 
@@ -40,16 +40,19 @@ fdprintlogf(int level, int fd, const char *ctl, ...)
 	va_end(va);
 }
 
-void
+int
 fdprintf(int fd, const char *ctl, ...)
 {
 	va_list va;
 	char buf[LOG_BUFFER];
+    int n;
 
 	va_start(va, ctl);
 	vsnprintf(buf, sizeof(buf), ctl, va);
-	write(fd, buf, strlen(buf));
+	n = write(fd, buf, strlen(buf));
 	va_end(va);
+
+    return n;
 }
 
 void