utmpd - zygaena/hammerhead

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#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
# Copyright 2014 Shruti V Sampat <shrutisampat@gmail.com>
# Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#
# Copyright (c) 2018, Joyent, Inc.

PROG= utmpd
OBJS= $(PROG).o
DEFAULTFILES= utmpd.dfl
MANIFEST= utmp.xml
SVCMETHOD= svc-utmpd

include ../Makefile.cmd
include ../Makefile.cmd.64
include ../Makefile.ctf

ROOTMANIFESTDIR = $(ROOTSVCSYSTEM)

FILEMODE = 555

.KEEP_STATE:

all: $(PROG)

install: all $(DIRS) $(ROOTLIBPROG) $(ROOTETCDEFAULTFILES) $(ROOTMANIFEST) \
	$(ROOTSVCMETHOD)

$(PROG): $(OBJS)
	$(LINK.c) -o $(PROG) $(OBJS) $(LDLIBS)
	$(POST_PROCESS)

check:	$(CHKMANIFEST)

clean:
	$(RM) $(OBJS)

include ../Makefile.targ
#!/sbin/sh
#
# CDDL HEADER START
#
# The contents of this file are subject to the terms of the
# Common Development and Distribution License (the "License").
# You may not use this file except in compliance with the License.
#
# You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
# or http://www.opensolaris.org/os/licensing.
# See the License for the specific language governing permissions
# and limitations under the License.
#
# When distributing Covered Code, include this CDDL HEADER in each
# file and include the License file at usr/src/OPENSOLARIS.LICENSE.
# If applicable, add the following below this CDDL HEADER, with the
# fields enclosed by brackets "[]" replaced with your own identifying
# information: Portions Copyright [yyyy] [name of copyright owner]
#
# CDDL HEADER END
#
#
# Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#

. /lib/svc/share/smf_include.sh

[ ! -x /usr/lib/utmpd ] && exit $SMF_EXIT_ERR_CONFIG

# If a utmppipe exists, check for a utmpd process and exit
# if the daemon is already running.

if [ -p /var/run/utmppipe ]; then
	if /usr/bin/pgrep -x -u 0 -z `smf_zonename` utmpd >/dev/null 2>&1; then
		echo "$0: utmpd is already running"
		exit 1
	fi
fi

/bin/rm -f /var/run/utmppipe
/usr/lib/utmpd &
<?xml version="1.0"?>
<!DOCTYPE service_bundle SYSTEM "/usr/share/lib/xml/dtd/service_bundle.dtd.1">
<!--
 Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 Use is subject to license terms.

 CDDL HEADER START

 The contents of this file are subject to the terms of the
 Common Development and Distribution License, Version 1.0 only
 (the "License").  You may not use this file except in compliance
 with the License.

 You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 or http://www.opensolaris.org/os/licensing.
 See the License for the specific language governing permissions
 and limitations under the License.

 When distributing Covered Code, include this CDDL HEADER in each
 file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 If applicable, add the following below this CDDL HEADER, with the
 fields enclosed by brackets "[]" replaced with your own identifying
 information: Portions Copyright [yyyy] [name of copyright owner]

 CDDL HEADER END

	NOTE:  This service manifest is not editable; its contents will
	be overwritten by package or patch operations, including
	operating system upgrade.  Make customizations in a different
	file.
-->

<service_bundle type='manifest' name='SUNWcsr:utmpd'>

<service
	name='system/utmp'
	type='service'
	version='1'>

	<!--
		We need to mark this as enabled in the seed, due to
		svc.startd not waiting for manifest import before
		making decisions on whether to start sulogin (see
		6194195).
	-->
	<create_default_instance enabled='true' />

	<single_instance/>

	<dependency
		name='milestone'
		grouping='require_all'
		restart_on='none'
		type='service'>
		<service_fmri value='svc:/milestone/sysconfig' />
	</dependency>

	<dependent
		name='utmpd_multi-user'
		grouping='optional_all'
		restart_on='none'>
		<service_fmri value='svc:/milestone/multi-user' />
	</dependent>

	<exec_method
		type='method'
		name='start'
		exec='/lib/svc/method/svc-utmpd'
		timeout_seconds='60' />

	<exec_method
		type='method'
		name='stop'
		exec=':kill'
		timeout_seconds='60' />

	<stability value='Unstable' />

	<template>
		<common_name>
			<loctext xml:lang='C'> utmpx monitoring
			</loctext>
		</common_name>
		<documentation>
			<manpage title='utmpd' section='8'
				manpath='/usr/share/man' />
			<manpage title='utmpx' section='5'
				manpath='/usr/share/man' />
		</documentation>
	</template>
</service>

</service_bundle>
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2014, 2015 Shruti V Sampat <shrutisampat@gmail.com>
 * Copyright (c) 2016 by Delphix. All rights reserved.
 */

/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
/*	  All Rights Reserved  	*/

/*
 * Portions of such source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

/*
 * utmpd	- utmp daemon
 *
 *		This program receives requests from  pututxline(3)
 *		via a named pipe to watch the process to make sure it cleans up
 *		its utmpx entry on termination.
 *		The program keeps a list of procs
 *		and uses poll() on their /proc files to detect termination.
 *		Also the  program periodically scans the /etc/utmpx file for
 *		processes that aren't in the table so they can be watched.
 *
 *		If utmpd doesn't hear back over the pipe from pututline(3) that
 *		the process has removed its entry it cleans the entry when the
 *		the process terminates.
 *		The AT&T Copyright above is there since we borrowed the pipe
 *		mechanism from init(8).
 */


#include	<sys/types.h>
#include	<signal.h>
#include	<stdio.h>
#include	<stdio_ext.h>
#include	<unistd.h>
#include	<utmpx.h>
#include	<errno.h>
#include	<termio.h>
#include	<sys/termios.h>
#include	<sys/tty.h>
#include	<ctype.h>
#include	<sys/stat.h>
#include	<sys/statvfs.h>
#include	<fcntl.h>
#include	<time.h>
#include	<sys/stropts.h>
#include	<wait.h>
#include	<syslog.h>
#include	<stdlib.h>
#include	<string.h>
#include	<poll.h>
#include	<deflt.h>
#include	<procfs.h>
#include	<sys/resource.h>
#include	<limits.h>

#define	dprintf(x)	if (Debug) (void) printf x

/*
 * Memory allocation keyed off MAX_FDS
 */
#define	MAX_FDS		4064	/* Maximum # file descriptors */
#define	EXTRA_MARGIN	32	/* Allocate this many more FDS over Max_Fds */
/*
 * MAX_POLLNV & RESETS - paranoia to cover an error case that might not exist
 */
#define	MAX_POLL_ERRS	1024	/* Count of bad errors */
#define	MAX_RESETS	1024	/* Maximum times to reload tables */
#define	POLL_TIMEOUT	300	/* Default Timeout for poll() in seconds */
#define	CLEANIT		1	/* Used by rem_pid() */
#define	DONT_CLEAN	0	/* Used by rem_pid() */
#define	UTMP_DEFAULT	"/etc/default/utmpd"
#define	WARN_TIME	3600	/* seconds between utmp checks */
#define	WTMPX_UFREQ	60	/* seconds between updating WTMPX's atime */


/*
 * The pidrec structure describes the data shipped down the pipe to
 * us from the pututxline() library in
 * lib/libc/port/gen/getutx.c
 */

/*
 * pd_type's
 */
#define	ADDPID	1
#define	REMPID	2

struct	pidrec {
	int	pd_type;		/* Command type */
	pid_t	pd_pid;			/* pid to add or remove */
};


/*
 * Since this program uses poll(2) and poll takes an array of file descriptors
 * as an argument we maintain our data in tables.
 * One table is the file descriptor array for poll, another parallel
 * array is a table which contains the process ID of the corresponding
 * open fd.  These tables are kept sorted by process ID for quick lookups.
 */

struct	pidentry {
	pid_t	pl_pid;			/* pid to watch for */
	int	pl_status;		/* Exit status of proc */
};

static struct pidentry *pidtable = NULL;

static pollfd_t *fdtable = NULL;

static int	pidcnt = 0;		/* Number of procs being watched */
static char	*prog_name;		/* To save the invocation name away */
static char	*UTMPPIPE_DIR =	"/var/run";
static char	*UTMPPIPE = "/var/run/utmppipe";
static int	Pfd = -1;		/* File descriptor of named pipe */
static int	Poll_timeout = POLL_TIMEOUT;
static int	WTMPXfd = -1;		/* File descriptor of WTMPX_FILE */
static int	WTMPX_ufreq = WTMPX_UFREQ;
static int	Debug = 0;		/* Set by command line argument */
static int	Max_fds		= MAX_FDS;

/*
 * This program has three main components plus utilities and debug routines
 *	Receiver - receives the process ID or process for us to watch.
 *		   (Uses a named pipe to get messages)
 *	Watcher	 - Use poll(2) to watch for processes to die so they
 *		   can be cleaned up (get marked as DEAD_PROCESS)
 *	Scanner	 - periodically scans the utmpx file for stale entries
 *		   or live entries that we don't know about.
 */

static int wait_for_pids();	/* Watcher - uses poll */
static void scan_utmps();	/* Scanner, reads utmpx file */
static void drain_pipe();	/* Receiver - reads mesgs over UTMPPIPE */
static void setup_pipe();	/* For setting up receiver */

static void add_pid();		/* Adds a process to the table */
static void rem_pid();		/* Removes a process from the table */
static int find_pid();		/* Finds a process in the table */
static int proc_to_fd();	/* Takes a pid and returns an fd for its proc */
static void load_tables();	/* Loads up the tables the first time around */
static int pidcmp();		/* For sorting pids */

static void clean_entry();	/* Removes entry from our table and calls ... */
static void clean_utmpx_ent();	/* Cleans a utmpx entry */

static void fatal() __NORETURN;	/* Prints error message and calls exit */
static void nonfatal();		/* Prints error message */
static void print_tables();	/* Prints out internal tables for Debug */
static int proc_is_alive(pid_t pid);	/* Check if a process is alive */
static void warn_utmp(void);

/* Validate defaults from file and assign */
static int validate_default(char *defp, int *flag);

/*
 * main()  - Main does basic setup and calls wait_for_pids() to do the work
 */

int
main(int argc, char *argv[])
{
	char *defp;
	struct rlimit rlim;
	int i;
	time_t curtime, now;
	char msg[256];

	prog_name = argv[0];			/* Save invocation name */

	if (getuid() != 0)  {
		(void) fprintf(stderr,
		    "You must be root to run this program\n");
		fatal("You must be root to run this program");
	}

	if (argc > 1) {
		if ((argc == 2 && (int)strlen(argv[1]) >= 2) &&
		    (argv[1][0] == '-' && argv[1][1] == 'd')) {
			Debug = 1;
		} else {
			(void) fprintf(stderr,
			    "%s: Wrong number of arguments\n", prog_name);
			(void) fprintf(stderr,
			    "Usage: %s [-debug]\n", prog_name);
			exit(2);
		}
	}

	/*
	 * Read defaults file for poll timeout, WTMPX update frequency
	 * and maximum number of processes to monitor.
	 */
	if (defopen(UTMP_DEFAULT) == 0) {
		if ((defp = defread("SCAN_PERIOD=")) != NULL)
			if (validate_default(defp, &Poll_timeout) == -1) {
				(void) snprintf(msg, sizeof (msg), "SCAN_PERIOD"
				    " should be a positive integer, found %s",
				    defp);
				nonfatal(msg);
			}
		dprintf(("Poll timeout set to %d\n", Poll_timeout));

		if ((defp = defread("WTMPX_UPDATE_FREQ=")) != NULL)
			if (validate_default(defp, &WTMPX_ufreq) == -1) {
				(void) snprintf(msg, sizeof (msg),
				    "WTMPX_UPDATE_FREQ should be a positive "
				    "integer, found %s", defp);
				nonfatal(msg);
			}
		dprintf(("WTMPX update frequency set to %d\n", WTMPX_ufreq));

		/*
		 * Paranoia - if polling on large number of FDs is expensive /
		 * buggy the number can be set lower in the field.
		 */
		if ((defp = defread("MAX_FDS=")) != NULL)
			if (validate_default(defp, &Max_fds) == -1) {
				(void) snprintf(msg, sizeof (msg), "MAX_FDS "
				    "should be a positive integer, found %s",
				    defp);
				nonfatal(msg);
			}
		dprintf(("Max fds set to %d\n", Max_fds));
		(void) defopen((char *)NULL);
	}

	if (Debug == 0) {
		/*
		 * Daemonize ourselves
		 */
		if (fork()) {
			exit(0);
		}
		(void) close(0);
		(void) close(1);
		(void) close(2);
		/*
		 * We open these to avoid accidentally writing to a proc file
		 */
		(void) open("/dev/null", O_RDONLY);
		(void) open("/dev/null", O_WRONLY);
		(void) open("/dev/null", O_WRONLY);
		(void) setsid();		/* release process from tty */
	}

	openlog(prog_name, LOG_PID, LOG_DAEMON);	/* For error messages */
	warn_utmp();	/* check to see if utmp came back by accident */

	/*
	 * Allocate the pidtable and fdtable.  An earlier version did
	 * this as we go, but this is simpler.
	 */
	if ((pidtable = malloc(Max_fds * sizeof (struct pidentry))) == NULL)
		fatal("Malloc failed");
	if ((fdtable = malloc(Max_fds * sizeof (pollfd_t))) == NULL)
		fatal("Malloc failed");

	/*
	 * Up the limit on FDs
	 */
	if (getrlimit(RLIMIT_NOFILE, &rlim) == 0) {
		rlim.rlim_cur = Max_fds + EXTRA_MARGIN + 1;
		rlim.rlim_max = Max_fds + EXTRA_MARGIN + 1;
		if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) {
			fatal("Out of File Descriptors");
		}
	} else
		fatal("getrlimit returned failure");

	(void) enable_extended_FILE_stdio(-1, -1);

	if ((WTMPXfd = open(WTMPX_FILE, O_RDONLY)) < 0)
		nonfatal("WARNING: unable to open " WTMPX_FILE " for update.");

	/*
	 * Loop here scanning the utmpx file and waiting for processes
	 * to terminate.  Most of the activity is directed out of wait_for_pids.
	 * If wait_for_pids fails we reload the table and try again.
	 */

	curtime = time(NULL);
	dprintf(("utmp warning timer set to %d seconds\n", WARN_TIME));

	for (i = 0; i < MAX_RESETS; i++) {
		load_tables();
		while (wait_for_pids() == 1) {
			now = time(NULL);
			if ((now - curtime) >= WARN_TIME) {
				dprintf(("utmp warning timer expired\n"));
				warn_utmp();
				curtime = now;
			}
		}
	}

	(void) close(WTMPXfd);

	/*
	 * We only get here if we had a bunch of resets - so give up
	 */
	fatal("Too many resets, giving up");
	return (1);
}

/*
 * load_tables()	- Designed to be called repeatedly if we need to
 *			  restart things.  Zeros the pidcount, and loads
 *			  the tables by scanning utmpx
 */

static void
load_tables()
{
	int i;

	dprintf(("Load tables\n"));

	/*
	 * Close any open files.
	 */
	for (i = 0; i < pidcnt; i++)
		(void) close(fdtable[i].fd);

	pidcnt = 0;
	Pfd = -1;
	setup_pipe();		/* Setup the pipe to receive messages */
	scan_utmps();		/* Read in USER procs entries to watch */
}


/*
 *			*** The Watcher ***
 *
 * Wait_for_pids	- wait for the termination of a process in the table.
 *			  Returns 1 on normal exist, 0 on failure.
 */

static int
wait_for_pids()
{
	register struct pollfd *pfd;
	register int i;
	pid_t pid;
	int ret_val = 0;
	int timeout;
	static time_t last_timeout  = 0;
	static int bad_error  = 0;	/* Count of POLL errors */

	/*
	 * First time through we initialize last_timeout to now.
	 */
	if (last_timeout == 0)
		last_timeout = time(NULL);

	/*
	 * Recalculate timeout - checking to see if time expired.
	 */

	if ((timeout = Poll_timeout - (time(NULL) - last_timeout)) <= 0) {
		timeout = Poll_timeout;
		last_timeout = time(NULL);
		scan_utmps();
	}

	fdtable[0].events = POLLRDNORM;

	for (i = 0; i < (timeout / WTMPX_ufreq); i++) {

		/*
		 * Loop here while getting EAGAIN
		 */

		while ((ret_val = poll(fdtable, pidcnt, WTMPX_ufreq*1000)) < 0)
			if (errno == EAGAIN)
				(void) sleep(2);
			else
				fatal("poll");
		/*
		 * The results of pread(2) are discarded; we only want
		 * to update the access time of WTMPX_FILE.
		 * Periodically touching WTMPX helps determine when the
		 * OS became unavailable when the OS boots again .
		 * See PSARC 2004/462 for more information.
		 */

		(void) pread(WTMPXfd, (void *)&pid, sizeof (pid), 0);

		if (ret_val)		/* file descriptor(s) need attention */
			break;
	}

	/*
	 * If ret_val == 0 the poll timed out - reset last_time and
	 * call scan_utmps
	 */
	if (ret_val == 0) {
		last_timeout = time(NULL);
		scan_utmps();
		return (1);
	}

	/*
	 * Check the pipe file descriptor
	 */
	if (fdtable[0].revents & POLLRDNORM) {
		drain_pipe();
		fdtable[0].revents = 0;
		ret_val--;
	}

	(void) sleep(5);	/* Give parents time to cleanup children */

	/*
	 * We got here because the status of one of the pids that
	 * we are polling on has changed, so search the table looking
	 * for the entry.
	 *
	 * The table is scanned backwards so that entries can be removed
	 * while we go since the table is compacted from high down to low
	 */
	for (i = pidcnt - 1; i > 0; i--) {
		/*
		 * Break out of the loop if we've processed all the entries.
		 */
		if (ret_val == 0)
			break;

		pfd = &fdtable[i];

		if (pfd->fd < 0) {
			rem_pid((pid_t)0, i, DONT_CLEAN);
			continue;
		}
		/*
		 * POLLHUP	- Process terminated
		 */
		if (pfd->revents & POLLHUP) {
			psinfo_t psinfo;

			if (pread(pfd->fd, &psinfo, sizeof (psinfo), (off_t)0)
			    != sizeof (psinfo)) {
				dprintf(("! %d: terminated, status 0x%.4x\n", \
				    (int)pidtable[i].pl_pid, psinfo.pr_wstat));
				pidtable[i].pl_status = psinfo.pr_wstat;

			} else {
				dprintf(("! %d: terminated\n", \
				    (int)pidtable[i].pl_pid));
				pidtable[i].pl_status = 0;
			}
			/*
			 * PID gets removed when terminated only
			 */
			rem_pid((pid_t)0, i, CLEANIT);
			ret_val--;
			continue;
		}
		/*
		 * POLLNVAL and POLLERR
		 *	These error's shouldn't occurr but until their fixed
		 *	we perform some simple error recovery.
		 */
		if (pfd->revents & (POLLNVAL|POLLERR)) {
			dprintf(("Poll Err = %d pid = %d i = %d\n", \
			    pfd->revents, (int)pidtable[i].pl_pid, i));

			pid = pidtable[i].pl_pid; /* Save pid for below */
			/*
			 * If its POLLNVAL we just remove the process for
			 * now, it will get picked up in the next scan.
			 * POLLERR pids get re-added after being deleted.
			 */
			if (pfd->revents & POLLNVAL) {
				rem_pid((pid_t)0, i, DONT_CLEAN);
			} else {			/* Else... POLLERR */
				rem_pid((pid_t)0, i, DONT_CLEAN);
				add_pid(pid);
			}

			if (bad_error++ > MAX_POLL_ERRS) {
				bad_error = 0;
				return (0);	/* 0 Indicates severe error */
			}
			ret_val--;
			continue;
		}

		/*
		 * No more bits should be set in revents but check anyway
		 */
		if (pfd->revents != 0) {
			dprintf(("%d: unknown err %d\n", \
			    (int)pidtable[i].pl_pid, pfd->revents));

			rem_pid((pid_t)0, i, DONT_CLEAN);
			ret_val--;

			if (bad_error++ > MAX_POLL_ERRS) {
				bad_error = 0;
				return (0);	/* 0 Indicates severe error */
			}
			return (1);
		}
	}
	return (1);			/* 1 Indicates Everything okay */
}

/*
 *		*** The Scanner ***
 *
 * scan_utmps()		- Scan the utmpx file.
 *			  For each USER_PROCESS check
 *			  if its alive or dead.  If alive and its not in
 *			  our table to be watched, put it there.  If its
 *			  dead, remove it from our table and clean it up.
 */

static void
scan_utmps()
{
	struct	utmpx	*utmpx;
	int	i;

	dprintf(("Scan utmps\n"));
	/*
	 * Scan utmpx.
	 */
	setutxent();
	while ((utmpx = getutxent()) != NULL) {
		if (utmpx->ut_type == USER_PROCESS) {
			/*
			 * Is the process alive?
			 */
			if (proc_is_alive(utmpx->ut_pid)) {
				/*
				 * Yes, the process is alive, so add it if we
				 * don't have it in our table.
				 */
				if (find_pid(utmpx->ut_pid, &i) == 0)
					add_pid(utmpx->ut_pid);	/* No, add it */
			} else {
				/*
				 * No, the process is dead, so remove it if its
				 * in our table, otherwise just clean it.
				 */
				if (find_pid(utmpx->ut_pid, &i) == 1)
					rem_pid(utmpx->ut_pid, i, CLEANIT);
				else
					clean_utmpx_ent(utmpx);
			}
		}
	}
	/*
	 * Close it to flush the buffer.
	 */
	endutxent();
}


/*
 *			*** Receiver Routines ***
 */

/*
 * setup_pipe	- Set up the pipe to read pids over
 */

static void
setup_pipe()
{

	struct statvfs statvfs_buf;
	/*
	 * This code & comments swiped from init and left stock since it works
	 */

	if (Pfd < 0) {
		if ((statvfs(UTMPPIPE_DIR, &statvfs_buf) == 0) &&
		    ((statvfs_buf.f_flag & ST_RDONLY) == 0)) {
			(void) unlink(UTMPPIPE);
			(void) mknod(UTMPPIPE, S_IFIFO | 0600, 0);
		}
		Pfd = open(UTMPPIPE, O_RDWR | O_NDELAY);
	}
	if (Pfd < 0)
		nonfatal(UTMPPIPE);
	/*
	 * This code from init modified to be poll based instead of SIGPOLL,
	 * signal based.
	 */

	if (Pfd >= 0) {
		/*
		 * Read pipe in message discard mode.  When read reads a
		 * pidrec size record, the remainder of the message will
		 * be discarded.  Though there shouldn't be any it will
		 * help resynch if someone else wrote some garbage.
		 */
		(void) ioctl(Pfd, I_SRDOPT, RMSGD);
	}

	/*
	 * My code.  We use slot 0 in the table to hold the fd of the pipe
	 */
	add_pid(0);			/* Proc 0 guaranteed to get slot 0 */
	fdtable[0].fd = Pfd;		/* Pfd could be -1, should be okay */
	fdtable[0].events = POLLRDNORM;
}

/*
 * drain_pipe()		- The receiver routine that reads the pipe
 */

static void
drain_pipe()
{
	struct pidrec prec;
	register struct pidrec *p = &prec;
	int bytes_read;
	int i;

	for (;;) {
		/*
		 * Important Note: Either read will really fail (in which case
		 * return is all we can do) or will get EAGAIN (Pfd was opened
		 * O_NDELAY), in which case we also want to return.
		 */

		if ((bytes_read = read(Pfd, p, sizeof (struct pidrec))) !=
		    sizeof (struct pidrec))  {
			/*
			 * Something went wrong reading, so read until pipe
			 * is empty
			 */
			if (bytes_read > 0)
				while (read(Pfd, p, sizeof (struct pidrec)) > 0)
					;
			return;
		}

		dprintf(("drain_pipe: Recd command %d, pid %d\n",
		    p->pd_type, (int)p->pd_pid));
		switch (p->pd_type) {
		case ADDPID:
			/*
			 * Check if we already have the process, adding it
			 * if we don't.
			 */
			if (find_pid(p->pd_pid, &i) == 0)
				add_pid(p->pd_pid);
			break;

		case REMPID:
			rem_pid(p->pd_pid, -1, DONT_CLEAN);
			break;
		default:
			nonfatal("Bad message on utmppipe\n");
				break;
		}
	}
}


/*
 *		*** Utilities for add and removing entries in the tables ***
 */

/*
 * add_pid	- add a pid to the fd table and the pidtable.
 *		  these tables are sorted tables for quick lookups.
 *
 */
static void
add_pid(pid_t pid)
{
	int fd = 0;
	int i = 0, move_amt;
	int j;
	static int first_time = 1;

	/*
	 * Check to see if the pid is already in our table, or being passed
	 * pid zero.
	 */
	if (pidcnt != 0 && (find_pid(pid, &j) == 1 || pid == 0))
		return;

	if (pidcnt >= Max_fds) {
		if (first_time == 1) {
			/*
			 * Print this error only once
			 */
			nonfatal("File Descriptor limit exceeded");
			first_time = 0;
		}
		return;
	}
	/*
	 * Open the /proc file checking if there's still a valid proc file.
	 */
	if (pid != 0 && (fd = proc_to_fd(pid)) == -1) {
		/*
		 * No, so the process died before we got to watch for it.
		 */
		return;
	}

	/*
	 * We only do this code if we're not putting in the first element
	 * Which we know will be for proc zero which is used by setup_pipe
	 * for its pipe fd.
	 */
	if (pidcnt != 0) {
		for (i = 0; i < pidcnt; i++) {
			if (pid <= pidtable[i].pl_pid)
				break;
		}

		/*
		 * Handle the case where we're not sticking our entry on the
		 * the end, or overwriting an existing entry.
		 */
		if (i != pidcnt && pid != pidtable[i].pl_pid) {

			move_amt = pidcnt - i;
			/*
			 * Move table down
			 */
			if (move_amt != 0) {
				(void) memmove(&pidtable[i+1], &pidtable[i],
				    move_amt * sizeof (struct pidentry));
				(void) memmove(&fdtable[i+1], &fdtable[i],
				    move_amt * sizeof (pollfd_t));
			}
		}
	}

	/*
	 * Fill in the events field for poll and copy the entry into the array
	 */
	fdtable[i].events = 0;
	fdtable[i].revents = 0;
	fdtable[i].fd = fd;

	/*
	 * Likewise, setup pid field and pointer (index) to the fdtable entry
	 */
	pidtable[i].pl_pid = pid;

	pidcnt++;			/* Bump the pid count */
	dprintf(("  add_pid: pid = %d fd = %d index = %d pidcnt = %d\n",
	    (int)pid, fd, i, pidcnt));
}


/*
 * rem_pid	- Remove an entry from the table and check to see if its
 *		  not in the utmpx file.
 *		  If i != -1 don't look up the pid, use i as index
 *
 * pid          - Pid of process to clean or 0 if we don't know it
 *
 * i            - Index into table or -1 if we need to look it up
 *
 * clean_it     - Clean the entry, or just remove from table?
 */

static void
rem_pid(pid_t pid, int i, int clean_it)
{
	int move_amt;

	dprintf(("  rem_pid: pid = %d i = %d", (int)pid, i));

	/*
	 * Don't allow slot 0 in the table to be removed - utmppipe fd
	 */
	if ((i == -1 && pid == 0) || (i == 0))	{
		dprintf((" - attempted to remove proc 0\n"));
		return;
	}

	if (i != -1 || find_pid(pid, &i) == 1) {	/* Found the entry */
		(void) close(fdtable[i].fd);	/* We're done with the fd */

		dprintf((" fd = %d\n", fdtable[i].fd));

		if (clean_it == CLEANIT)
			clean_entry(i);

		move_amt = (pidcnt - i) - 1;
		/*
		 * Remove entries from the tables.
		 */
		(void) memmove(&pidtable[i], &pidtable[i+1],
		    move_amt * sizeof (struct pidentry));

		(void) memmove(&fdtable[i], &fdtable[i+1],
		    move_amt * sizeof (pollfd_t));

		/*
		 * decrement the pid count - one less pid to worry about
		 */
		pidcnt--;
	}
	if (i == -1)
		dprintf((" - entry not found \n"));
}


/*
 * find_pid	- Returns an index into the pidtable of the specifed pid,
 *		  else -1 if not found
 */

static int
find_pid(pid_t pid, int *i)
{
	struct pidentry pe;
	struct pidentry *p;

	pe.pl_pid = pid;
	p = bsearch(&pe, pidtable, pidcnt, sizeof (struct pidentry), pidcmp);

	if (p == NULL)
		return (0);
	else {
		*i = p - (struct pidentry *)pidtable;
		return (1);
	}
}


/*
 * Pidcmp - Used by besearch for sorting and finding  process IDs.
 */

static int
pidcmp(struct pidentry *a, struct pidentry *b)
{
	if (b == NULL || a == NULL)
		return (0);
	return (a->pl_pid - b->pl_pid);
}


/*
 * proc_to_fd	- Take a process ID and return an open file descriptor to the
 *		  /proc file for the specified process.
 */
static int
proc_to_fd(pid_t pid)
{
	char procname[64];
	int fd, dfd;

	(void) sprintf(procname, "/proc/%d/psinfo", (int)pid);

	if ((fd = open(procname, O_RDONLY)) >= 0) {
		/*
		 * dup the fd above the low order values to assure
		 * stdio works for other fds - paranoia.
		 */
		if (fd < EXTRA_MARGIN) {
			dfd = fcntl(fd, F_DUPFD, EXTRA_MARGIN);
			if (dfd > 0) {
				(void) close(fd);
				fd = dfd;
			}
		}
		/*
		 * More paranoia - set the close on exec flag
		 */
		(void) fcntl(fd, F_SETFD, 1);
		return (fd);
	}
	if (errno == ENOENT)
		return (-1);

	if (errno == EMFILE) {
		/*
		 * This is fatal, since libc won't be able to allocate
		 * any fds for the pututxline() routines
		 */
		fatal("Out of file descriptors");
	}
	fatal(procname);		/* Only get here on error */
	return (-1);
}


/*
 *		*** Utmpx Cleaning Utilities ***
 */

/*
 * Clean_entry	- Cleans the specified entry - where i is an index
 *		  into the pid_table.
 */
static void
clean_entry(int i)
{
	struct utmpx *u;

	if (pidcnt == 0)
		return;

	dprintf(("    Cleaning %d\n", (int)pidtable[i].pl_pid));

	/*
	 * Double check if the process is dead.
	 */
	if (proc_is_alive(pidtable[i].pl_pid)) {
		dprintf(("      Bad attempt to clean %d\n",
		    (int)pidtable[i].pl_pid));
		return;
	}

	/*
	 * Find the entry that corresponds to this pid.
	 * Do nothing if entry not found in utmpx file.
	 */
	setutxent();
	while ((u = getutxent()) != NULL) {
		if (u->ut_pid == pidtable[i].pl_pid) {
			if (u->ut_type == USER_PROCESS) {
				clean_utmpx_ent(u);
			}
		}
	}
	endutxent();
}


/*
 * clean_utmpx_ent	- Clean a utmpx entry
 */

static void
clean_utmpx_ent(struct utmpx *u)
{
	dprintf(("      clean_utmpx_ent: %d\n", (int)u->ut_pid));
	u->ut_type = DEAD_PROCESS;
	(void) time(&u->ut_xtime);
	(void) pututxline(u);
	updwtmpx(WTMPX_FILE, u);
	/*
	 * XXX update wtmp for ! nonuserx entries?
	 */
}

/*
 *		*** Error Handling and Debugging Routines ***
 */

/*
 * fatal - Catastrophic failure
 */

static void
fatal(char *str)
{
	int oerrno = errno;

	syslog(LOG_ALERT, "%s", str);
	if (Debug == 1) {
		if ((errno = oerrno) != 0)
			perror(prog_name);
		dprintf(("%s\n", str));
	}
	exit(1);
}

/*
 * nonfatal - Non-Catastrophic failure - print message and errno
 */

static void
nonfatal(char *str)
{
	syslog(LOG_WARNING, "%s", str);

	if (Debug == 1) {
		if (errno != 0)
			perror(prog_name);
		dprintf(("%c%s\n", 7, str));
		print_tables();
		(void) sleep(5);	/* Time to read debug messages */
	}
}

/*
 * print_tables	- Print internal tables - for debugging
 */

static void
print_tables()
{
	int i;

	if (Debug == 0)
		return;

	dprintf(("pidtable: "));
	for (i = 0; i < pidcnt; i++)
		dprintf(("%d: %d  ", i, (int)pidtable[i].pl_pid));
	dprintf(("\n"));
	dprintf(("fdtable:  "));
	for (i = 0; i < pidcnt; i++)
		dprintf(("%d: %d  ", i, fdtable[i].fd));
	dprintf(("\n"));
}

/*
 * proc_is_alive	- Check to see if a process is alive AND its
 *			  not a zombie.  Returns 1 if process is alive
 *			  and zero if it is dead or a zombie.
 */

static int
proc_is_alive(pid_t pid)
{
	char psinfoname[64];
	int fd;
	psinfo_t psinfo;

	if (kill(pid, 0) != 0)
		return (0);		/* Kill failed - no process */

	/*
	 * The process exists, so check if it's a zombie.
	 */
	(void) sprintf(psinfoname, "/proc/%d/psinfo", (int)pid);

	if ((fd = open(psinfoname, O_RDONLY)) < 0 ||
	    read(fd, &psinfo, sizeof (psinfo)) != sizeof (psinfo)) {
		/*
		 * We either couldn't open the proc, or we did but the
		 * read of the psinfo file failed, so pid is nonexistent.
		 */
		psinfo.pr_nlwp = 0;
	}
	if (fd >= 0)
		(void) close(fd);

	/* if pr_nlwp == 0, process is a zombie */
	return (psinfo.pr_nlwp != 0);
}

/*
 * warn_utmp -	/var/adm/utmp has been deprecated. It should no longer
 *		be used.  Applications that try to directly manipulate
 *		it may cause problems. Since the file is no longer
 *		shipped, if it appears on a system it's because an
 *		old application created it.  We'll have utmpd
 *		complain about it periodically.
 */

static void
warn_utmp()
{
	struct stat s;

	if (lstat(UTMP_FILE, &s) == 0 &&
	    s.st_size % sizeof (struct utmp) == 0) {
		nonfatal("WARNING: /var/adm/utmp exists!\nSee "
		    "utmp(5) for more information");
	}
}

/*
 * validate_default - validate and assign defaults.
 */

static int
validate_default(char *defp, int *flag)
{
	long lval;
	char *endptr;

	errno = 0;
	lval = strtol(defp, &endptr, 10);

	if (errno != 0 || lval > INT_MAX || lval <= 0)
		return (-1);

	while (isspace(*endptr) != 0)
		endptr++;

	if (*endptr != '\0')
		return (-1);

	*flag = lval;
	return (0);
}
#
# Copyright 1994 Sun Microsystems, Inc.  All rights reserved.
# Use is subject to license terms.
#

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