From bc6e654149018090b7954e6667d3c7e7654625f6 Mon Sep 17 00:00:00 2001

From: =?UTF-8?q?Dan=20Hor=C3=A1k?= <dan@danny.cz>

Date: Fri, 28 Jan 2011 14:18:39 +0100

Subject: [PATCH 53/61] ttyrun: run a program if a terminal device is available

Summary:     ttyrun: run a program if a terminal device is available

Description: Depending on your setup, Linux on System z might or might not

             provide a particular terminal or console. ttyrun safely starts

             getty programs and prevents respawns through the init program

             if a terminal is not available.

---

 iucvterm/doc/Makefile |    2 +-

 iucvterm/doc/ttyrun.8 |  146 +++++++++++++++++++++++++++++++++++++++

 iucvterm/src/Makefile |   11 +++-

 iucvterm/src/ttyrun.c |  183 +++++++++++++++++++++++++++++++++++++++++++++++++

 4 files changed, 339 insertions(+), 3 deletions(-)

 create mode 100644 iucvterm/doc/ttyrun.8

 create mode 100644 iucvterm/src/ttyrun.c

diff --git a/iucvterm/doc/Makefile b/iucvterm/doc/Makefile

index 5815f21..a646765 100644

--- a/iucvterm/doc/Makefile

+++ b/iucvterm/doc/Makefile

@@ -2,7 +2,7 @@

 include ../../common.mak

-MANS = iucvconn.1 iucvtty.1 ts-shell.1 hvc_iucv.9 chiucvallow.8

+MANS = iucvconn.1 iucvtty.1 ts-shell.1 hvc_iucv.9 chiucvallow.8 ttyrun.8

 all:

diff --git a/iucvterm/doc/ttyrun.8 b/iucvterm/doc/ttyrun.8

new file mode 100644

index 0000000..fc7a16f

--- /dev/null

+++ b/iucvterm/doc/ttyrun.8

@@ -0,0 +1,146 @@

+.\" ttyrun.8

+.\"

+.\"

+.\" Copyright IBM Corp. 2010

+.\" Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>

+.\" -------------------------------------------------------------------------

+.TH "ttyrun" "8" "April 2010" "s390-tools" "System Management Commands"

+.LO 8

+.

+.ds s ttyrun

+.

+.

+.SH NAME

+ttyrun \- Start a program if a specified terminal device is available

+.

+.

+.

+.SH SYNOPSIS

+.B \*s

+.RB [ \-e | \-\-exitstatus

+.IR status ]

+.I term

+.I program

+.RI [ "program_options" ]

+.br

+.B \*s

+.RB [ \-h | \-\-help ]

+.br

+.B \*s

+.RB [ \-v | \-\-version ]

+.

+.

+.

+.SH DESCRIPTION

+\fB\*s\fP is typically started during system initialization and is used

+to prevent a respawn through the

+.BR init (8)

+program when a terminal is not available.

+

+\fIterm\fP is the name of the terminal device and is a path relative to

+the \f(CW/dev\fP directory, for example, specify \f(CWhvc0\fP for

+\f(CW/dev/hvc0\fP.

+.br

+If the specified terminal device can be opened, \fB\*s\fP starts the

+specified program.

+

+If the terminal device cannot be opened, the behavior of \fB\*s\fP

+depends on the \fB\-e\fP option:

+.

+.RS 2

+.IP "\(bu" 2

+If the \fB\-e\fP option has been specified, \fB\*s\fP exits with the

+specified return value, or

+.IP "\(bu" 2

+If the \fB\-e\fP option has not been specified,  \fB\*s\fP sleeps until

+it receives a signal that causes an exit.

+.RE

+.PP

+\fIprogram\fP is an absolute path to the program to be started by

+\fB\*s\fP and \fIprogram_options\fP specify additional arguments.

+Depending on the program, arguments might be required.  The variable

+\f(CW%t\fP in the \fIprogram_options\fP is resolved to the terminal

+device specified with \fIterm\fP.

+.

+.

+.

+.SH OPTIONS

+.TP

+.BR \-e ", " \-\-exitstatus\~\fIstatus\fP

+Specifies an exit status that is returned when the terminal device

+is not available.  \fIstatus\fP must be an integer in the range 1 to 255.

+

+You can use this status value in an upstart job file to prevent

+respawning.

+.

+.TP

+.BR \-h ", " \-\-help

+Displays a short help text, then exits.

+.

+.TP

+.BR \-v ", " \-\-version

+Displays the version number of \fB\*s\fP, then exits.

+.

+.

+.

+.SH "RETURN VALUES"

+\fB\*s\fP exits with one of the following return values to report an

+error condition:

+.TP

+.B 1

+\fB\*s\fP has been started with an argument that is not valid or

+required but missing.

+.TP

+.B 2

+\fB\*s\fP could open the file specified for \fIterm\fP but the

+file is not a terminal device.

+.TP

+.B 3

+\fB\*s\fP could not start the specified program.

+.PP

+The return values 1 to 3 might also be returned when the \fB\-e\fP

+option is used and the terminal device is not available.

+.TP

+.B 4 \- 255

+The terminal device is not available and the \fB\-e\fP option

+specifies an exit status in this range.

+.

+.

+.

+.SH "EXAMPLES"

+.SS inittab

+To start \fB/sbin/agetty\fP on terminal device "hvc1", specify:

+.PP

+.ft CW

+.in +0.25in

+.nf

+h1:2345:respawn:/sbin/\*s hvc1 /sbin/agetty -L 9600 %t linux

+.fi

+.in -0.25in

+.ft

+.

+.SS upstart job/event files

+To start \fB/sbin/agetty\fP on terminal device "hvc1", add the following

+settings to the job file:

+.PP

+.ft CW

+.in +0.25in

+.nf

+respawn

+normal exit 42

+exec /sbin/\*s -e 42 hvc1 /sbin/agetty -L 9600 %t linux

+.fi

+.in -0.25in

+.ft

+.PP

+With the normal exit statement, you specify an exit status that will

+prevent upstart from respawning the program.  To prevent respawning with

+\fB\*s\fP, you must specify the same value for the \fB\-e\fP option.

+.

+.

+.

+.SH "SEE ALSO"

+.BR agetty (8),

+.BR mingetty (8),

+.BR inittab (5),

+.BR events (5)

diff --git a/iucvterm/src/Makefile b/iucvterm/src/Makefile

index f1f8f7c..369c887 100644

--- a/iucvterm/src/Makefile

+++ b/iucvterm/src/Makefile

@@ -11,20 +11,27 @@ CPPFLAGS += -DUSE_NLS -DGETTEXT_TEXTDOMAIN=\"$(GETTEXT_TEXTDOMAIN)\"

 #CPPFLAGS += -D__DEBUG__

 PROGRAMS = iucvconn iucvtty

+SYSTOOLS = ttyrun

-all: $(PROGRAMS)

+all: $(PROGRAMS) $(SYSTOOLS)

 check:

 install:

 	for prg in $(PROGRAMS); do \

 	  $(INSTALL) -g $(GROUP) -o $(OWNER) -m 755 $$prg $(USRBINDIR) ; \

 	done

+	for prg in $(SYSTOOLS); do \

+	  $(INSTALL) -g $(GROUP) -o $(OWNER) -m 755 $$prg $(BINDIR) ; \

+	done

 clean:

-	-rm -f *.o $(PROGRAMS)

+	-rm -f *.o $(PROGRAMS) $(SYSTOOLS)

 iucvconn: iucvconn.o getopt.o auditlog.o functions.o

 iucvtty: LDLIBS = -lutil

 iucvtty: iucvtty.o getopt.o auditlog.o functions.o

+ttyrun: GETTEXT_TEXTDOMAIN = ttyrun

+ttyrun: ttyrun.o

+

 .PHONY: install clean

diff --git a/iucvterm/src/ttyrun.c b/iucvterm/src/ttyrun.c

new file mode 100644

index 0000000..55c2bc2

--- /dev/null

+++ b/iucvterm/src/ttyrun.c

@@ -0,0 +1,183 @@

+/*

+ * ttyrun - Start a program if a specified terminal device is available

+ *

+ *

+ * ttyrun is typically used to prevent a respawn through the init(8)

+ * program when a terminal is not available.

+ * ttyrun runs the specific program if the specified terminal device

+ * can be opened successfully.  Otherwise the program enters a sleep or

+ * exits with a specified return value.

+ *

+ * Example: To start /sbin/agetty on terminal device hvc1, use:

+ *

+ *	 h1:2345:respawn:/sbin/ttyrun hvc1 /sbin/agetty -L 9600 %t linux

+ *

+ * Note: %t is resolved to the terminal device "hvc1" before /sbin/agetty

+ *	 is started.

+ *

+ * Return values:

+ *	   1 - invalid argument or parameter is missing

+ *	   2 - terminal does not resolve to a terminal device

+ *	   3 - starting the specified program failed

+ *    1..255 - terminal is not available and the return code is

+ *	       specified with the -e option

+ *

+ * Copyright IBM Corp. 2010

+ * Author(s): Hendrik Brueckner <brueckner@linux.vnet.ibm.com>

+ */

+#include <errno.h>

+#include <getopt.h>

+#include <limits.h>

+#include <signal.h>

+#include <stdlib.h>

+#include <stdio.h>

+#include <string.h>

+#include <sys/types.h>

+#include <syslog.h>

+#include <fcntl.h>

+#include <unistd.h>

+

+#include "zt_common.h"

+

+

+#define TTY_ESCAPE_STR		"%t"

+

+#define EXIT_INVALID_ARG	1

+#define EXIT_NO_TERMINAL	2

+#define EXIT_EXEC_FAILED	3

+

+

+static const char usage[] =

+"Usage: %s [-e status] <term> <program> [<program_options>]\n"

+"       %s [-h|--help] [-v|--version]\n"

+"\n"

+"Start the program if the specified terminal device is available.\n"

+"If the terminal device cannot be opened, sleep until a signal is received\n"

+"that causes an exit or exit with the return value specified with status.\n"

+"\n"

+"-e, --exitstatus     Specifies an exit status in the range 1 to 255.\n"

+"-h, --help           Displays this help, then exits.\n"

+"-v, --version        Displays version information, then exits.\n";

+

+static void help_exit(const char *prg)

+{

+	printf(usage, prg, prg);

+	exit(EXIT_SUCCESS);

+}

+

+static void version_exit(const char *prg)

+{

+	printf("%s: Start a program if a terminal device is available, "

+	       "version %s\n", prg, RELEASE_STRING);

+	printf("Copyright IBM Corp. 2010\n");

+	exit(EXIT_SUCCESS);

+}

+

+static void err_exit(const char *prg, const char *msg)

+{

+	fprintf(stderr, "%s: %s\n", prg, msg);

+	exit(EXIT_INVALID_ARG);

+}

+

+static void wait_and_exit(void)

+{

+	/* sleep until a signal is received, then exit */

+	pause();

+	exit(EXIT_SUCCESS);

+}

+

+static const struct option prog_opts[] = {

+	{ "help",	no_argument, NULL, 'h'},

+	{ "version",	no_argument, NULL, 'v'},

+	{ "exitstatus",	required_argument, NULL, 'e'},

+	{ NULL,		no_argument, NULL,  0 },

+};

+

+int main(int argc, char *argv[])

+{

+	int rc, tty, i, c, index, done, term_index;

+	char terminal[PATH_MAX] = "";

+	unsigned long exitstatus;

+

+

+	/* parse command options */

+	if (argc == 1)

+		err_exit(argv[0], "One or more options are required but missing");

+

+	exitstatus = done = term_index = 0;

+	while (!done) {

+		c = getopt_long(argc, argv, "-hve:", prog_opts, NULL);

+		switch (c) {

+		case -1:

+			done = 1;

+			break;

+		case 1:

+			/* the first non-optional argument must be the

+			 * terminal device */

+			if (!strncmp(optarg, "/", 1))

+				strncpy(terminal, optarg, PATH_MAX - 1);

+			else

+				snprintf(terminal, PATH_MAX, "/dev/%s", optarg);

+			terminal[PATH_MAX - 1] = 0;

+			term_index = optind - 1;

+			done = 1;

+			break;

+		case 'e':

+			errno = 0;

+			exitstatus = strtoul(optarg, (char **) NULL, 10);

+			if (errno == ERANGE)

+				err_exit(argv[0], "The exit status must be "

+					"an integer in the range 1 to 255");

+

+			if (!exitstatus || exitstatus > 255)

+				err_exit(argv[0], "The exit status must be "

+					 "in the range 1 to 255");

+			break;

+		case 'h':

+			help_exit(argv[0]);

+		case 'v':

+			version_exit(argv[0]);

+		case '?':

+			fprintf(stderr, "Try %s --help for more information\n",

+				argv[0]);

+			exit(EXIT_INVALID_ARG);

+		}

+	}

+	index = optind;

+

+	/* check terminal */

+	if (!strlen(terminal))

+		err_exit(argv[0], "You must specify the name of "

+				  "a terminal device");

+

+	/* any program to start? */

+	if (index == argc)

+		err_exit(argv[0], "You must specify a program to start");

+

+	/* open and check terminal device */

+	tty = open(terminal, O_NOCTTY | O_RDONLY | O_NONBLOCK);

+	if (tty == -1) {

+		openlog(argv[0], LOG_PID, LOG_DAEMON);

+		syslog(LOG_INFO, "Could not open tty %s (%s)", terminal,

+		       strerror(errno));

+		closelog();

+

+		/* enter wait or exit */

+		if (exitstatus)

+			exit(exitstatus);

+		wait_and_exit();

+	}

+	rc = !isatty(tty);

+	close(tty);

+	if (rc)

+		exit(EXIT_NO_TERMINAL);

+

+	/* start getty program */

+	for (i = index; i < argc; i++)

+		if (!strcmp(argv[i], TTY_ESCAPE_STR) && term_index)

+			argv[i] = argv[term_index];

+	if (execv(argv[index], argv + index))

+		exit(EXIT_EXEC_FAILED);

+

+	exit(EXIT_SUCCESS);

+}

-- 

1.7.3.5