Add crontab entry option -n for "No mail when run successful"

OK jmc@ millert@

4 files changed, 95 insertions, 60 deletions

diff --git a/usr.sbin/cron/crontab.5 b/usr.sbin/cron/crontab.5
index 9c2e651980a..cdda7bb40dd 100644
--- a/usr.sbin/cron/crontab.5
+++ b/usr.sbin/cron/crontab.5
@@ -17,9 +17,9 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 .\" OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.\" $OpenBSD: crontab.5,v 1.34 2016/10/12 17:27:08 schwarze Exp $
+.\" $OpenBSD: crontab.5,v 1.35 2018/06/13 11:27:30 job Exp $
 .\"
-.Dd $Mdocdate: October 12 2016 $
+.Dd $Mdocdate: June 13 2018 $
 .Dt CRONTAB 5
 .Os
 .Sh NAME
@@ -193,14 +193,20 @@ will be changed into newline characters, and all data
 after the first
 .Ql %
 will be sent to the command as standard input.
-If the
-.Ar command
-field begins with
-.Ql -q ,
-execution will not be logged.
-Use whitespace to separate
-.Ql -q
-from the command.
+.Pp
+Commands may be modified as follows:
+.Bl -tag -width Ds
+.It Fl n Ar command
+No mail is sent after a successful run.
+The execution output will only be mailed if the command exits with a non-zero
+exit code.
+The
+.Fl -n
+option is an attempt to cure potentially copious volumes of mail coming from
+.Xr cron 8 .
+.It Fl q Ar command
+Execution will not be logged.
+.El
 .Pp
 Commands are executed by
 .Xr cron 8
@@ -329,6 +335,9 @@ Ranges may include
 .It
 Months or days of the week can be specified by name.
 .It
+Mailing after a successful run can be suppressed with
+.Fl n .
+.It
 Logging can be suppressed with
 .Ql -q .
 .It
diff --git a/usr.sbin/cron/do_command.c b/usr.sbin/cron/do_command.c
index 6a4022fcc9a..0e711b636bb 100644
--- a/usr.sbin/cron/do_command.c
+++ b/usr.sbin/cron/do_command.c
@@ -1,8 +1,9 @@
-/*	$OpenBSD: do_command.c,v 1.57 2017/10/23 08:39:26 friehm Exp $	*/
+/*	$OpenBSD: do_command.c,v 1.58 2018/06/13 11:27:30 job Exp $	*/
 
 /* Copyright 1988,1990,1993,1994 by Paul Vixie
  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
  * Copyright (c) 1997,2000 by Internet Software Consortium, Inc.
+ * Copyright (c) 2018 Job Snijders <job@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -80,7 +81,6 @@ child_process(entry *e, user *u)
 	char **p, *input_data, *usernm;
 	auth_session_t *as;
 	login_cap_t *lc;
-	int children = 0;
 	extern char **environ;
 
 	/* mark ourselves as different to PS command watchers */
@@ -146,7 +146,9 @@ child_process(entry *e, user *u)
 
 	/* fork again, this time so we can exec the user's command.
 	 */
-	switch (fork()) {
+
+	pid_t	jobpid;
+	switch (jobpid = fork()) {
 	case -1:
 		syslog(LOG_ERR, "(CRON) CAN'T FORK (%m)");
 		_exit(EXIT_FAILURE);
@@ -260,8 +262,6 @@ child_process(entry *e, user *u)
 		break;
 	}
 
-	children++;
-
 	/* middle process, child of original cron, parent of process running
 	 * the user's command.
 	 */
@@ -283,7 +283,8 @@ child_process(entry *e, user *u)
 	 * we would block here.  thus we must fork again.
 	 */
 
-	if (*input_data && fork() == 0) {
+	pid_t	stdinjob;
+	if (*input_data && (stdinjob = fork()) == 0) {
 		FILE *out = fdopen(stdin_pipe[WRITE_PIPE], "w");
 		int need_newline = FALSE;
 		int escaped = FALSE;
@@ -331,8 +332,6 @@ child_process(entry *e, user *u)
 	 */
 	close(stdin_pipe[WRITE_PIPE]);
 
-	children++;
-
 	/*
 	 * read output from the grandchild.  it's stderr has been redirected to
 	 * it's stdout, which has been redirected to our pipe.  if there is any
@@ -342,15 +341,17 @@ child_process(entry *e, user *u)
 
 	(void) signal(SIGPIPE, SIG_IGN);
 	in = fdopen(stdout_pipe[READ_PIPE], "r");
+
+	char	*mailto;
+	FILE	*mail = NULL;
+	int	status = 0;
+	pid_t	mailpid;
+	size_t	bytes = 1;
+
 	if (in != NULL) {
 		int	ch = getc(in);
 
 		if (ch != EOF) {
-			FILE	*mail = NULL;
-			char	*mailto;
-			size_t	bytes = 1;
-			int	status = 0;
-			pid_t	mailpid;
 
 			/* get name of recipient.  this is MAILTO if set to a
 			 * valid local username; USER otherwise.
@@ -415,30 +416,6 @@ child_process(entry *e, user *u)
 					fputc(ch, mail);
 			}
 
-			/* only close pipe if we opened it -- i.e., we're
-			 * mailing...
-			 */
-
-			if (mail) {
-				/* Note: the pclose will probably see
-				 * the termination of the grandchild
-				 * in addition to the mail process, since
-				 * it (the grandchild) is likely to exit
-				 * after closing its stdout.
-				 */
-				status = cron_pclose(mail, mailpid);
-			}
-
-			/* if there was output and we could not mail it,
-			 * log the facts so the poor user can figure out
-			 * what's going on.
-			 */
-			if (mail && status) {
-				syslog(LOG_NOTICE, "(%s) MAIL (mailed %zu byte"
-				"%s of output but got status 0x%04x)", usernm,
-				bytes, (bytes == 1) ? "" : "s", status);
-			}
-
 		} /*if data from grandchild*/
 
 		fclose(in);	/* also closes stdout_pipe[READ_PIPE] */
@@ -446,20 +423,50 @@ child_process(entry *e, user *u)
 
 	/* wait for children to die.
 	 */
-	for (; children > 0; children--) {
-		int waiter;
-		pid_t pid;
-
-		while ((pid = wait(&waiter)) < 0 && errno == EINTR)
+	int waiter;
+	if (jobpid > 0) {
+				;
+		while (waitpid(jobpid, &waiter, 0) < 0 && errno == EINTR)
 			;
-		if (pid < 0) {
-			break;
+
+		/* If everything went well, and -n was set, _and_ we have mail,
+		 * we won't be mailing... so shoot the messenger!
+		 */
+		if (WIFEXITED(waiter) && WEXITSTATUS(waiter) == 0
+		    && (e->flags & MAIL_WHEN_ERR) == MAIL_WHEN_ERR
+		    && mail) {
+			kill(mailpid, SIGKILL);
+			(void)fclose(mail);
+			mail = NULL;
 		}
-		/*
-		if (WIFSIGNALED(waiter) && WCOREDUMP(waiter))
-			Debug(DPROC, (", dumped core"))
+
+		/* only close pipe if we opened it -- i.e., we're
+		* mailing...
 		*/
+		if (mail) {
+			/*
+			 * Note: the pclose will probably see the termination
+			 * of the grandchild in addition to the mail process,
+			 * since it (the grandchild) is likely to exit after
+			 * closing its stdout.
+			 */
+			status = cron_pclose(mail, mailpid);
+		}
+
+		/* if there was output and we could not mail it,
+		 * log the facts so the poor user can figure out
+		 * what's going on.
+		 */
+		if (mail && status) {
+			syslog(LOG_NOTICE, "(%s) MAIL (mailed %zu byte"
+			    "%s of output but got status 0x%04x)", usernm,
+			    bytes, (bytes == 1) ? "" : "s", status);
+		}
 	}
+
+	if (stdinjob > 0)
+		while (waitpid(stdinjob, &waiter, 0) < 0 && errno == EINTR)
+			;
 }
 
 int
diff --git a/usr.sbin/cron/entry.c b/usr.sbin/cron/entry.c
index 761f01d3d6f..bb0221bffb6 100644
--- a/usr.sbin/cron/entry.c
+++ b/usr.sbin/cron/entry.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: entry.c,v 1.48 2015/11/14 13:09:14 millert Exp $	*/
+/*	$OpenBSD: entry.c,v 1.49 2018/06/13 11:27:30 job Exp $	*/
 
 /*
  * Copyright 1988,1990,1993,1994 by Paul Vixie
@@ -338,14 +338,32 @@ load_entry(FILE *file, void (*error_func)(const char *), struct passwd *pw,
 	ch = get_char(file);
 	while (ch == '-') {
 		switch (ch = get_char(file)) {
+		case 'n':
+			/* only allow the user to set the option once */
+			if ((e->flags & MAIL_WHEN_ERR) == MAIL_WHEN_ERR) {
+				ecode = e_option;
+				goto eof;
+			}
+			e->flags |= MAIL_WHEN_ERR;
+			break;
 		case 'q':
+			/* only allow the user to set the option once */
+			if ((e->flags & DONT_LOG) == DONT_LOG) {
+				ecode = e_option;
+				goto eof;
+			}
 			e->flags |= DONT_LOG;
-			Skip_Nonblanks(ch, file)
 			break;
 		default:
 			ecode = e_option;
 			goto eof;
 		}
+		ch = get_char(file);
+		if (ch!='\t' && ch!=' ') {
+			ecode = e_option;
+			goto eof;
+		}
+
 		Skip_Blanks(ch, file)
 		if (ch == EOF || ch == '\n') {
 			ecode = e_cmd;
diff --git a/usr.sbin/cron/structs.h b/usr.sbin/cron/structs.h
index af0d75c3b55..c380b14f90d 100644
--- a/usr.sbin/cron/structs.h
+++ b/usr.sbin/cron/structs.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: structs.h,v 1.8 2016/01/11 14:23:50 millert Exp $	*/
+/*	$OpenBSD: structs.h,v 1.9 2018/06/13 11:27:30 job Exp $	*/
 
 /*
  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
@@ -38,6 +38,7 @@ typedef	struct _entry {
 #define	DOW_STAR	0x08
 #define	WHEN_REBOOT	0x10
 #define	DONT_LOG	0x20
+#define	MAIL_WHEN_ERR	0x40
 } entry;
 
 			/* the crontab database will be a list of the