usr/src/cmd/rmt/rmt.c - illumos-gate - Gitiles

 /*
  * 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 2005 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
  */

 #pragma ident	"%Z%%M%	%I%	%E% SMI"

 /*
  *  Multi-process streaming 4.3bsd /etc/rmt server.
  *  Has three locks (for stdin, stdout, and the tape)
  *  that are passed by signals and received by sigpause().
  */

 #include <stdio.h>
 #include <locale.h>
 #include <sys/types.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <string.h>
 #include <signal.h>
 #include <setjmp.h>
 #include <sys/ioctl.h>
 #include <sys/mtio.h>
 #include <sys/wait.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/param.h>

 static sigset_t	cmdmask, maskall, newmask;
 static sigset_t	sendmask, tapemask;

 static struct mtop mtop;
 static struct mtget mtget;
 static jmp_buf sjbuf;

 #define	RECV	SIGIO
 #define	TAPE	SIGURG
 #define	SEND	SIGALRM
 #define	ERROR	SIGTERM
 #define	OPEN	SIGUSR1
 #define	CLOSE	SIGUSR2

 /*
  * Support for Version 1 of the extended RMT protocol:
  * Placing RMTIVERSION (-1) into the mt_op field of the ioctl ('I')
  * request will return the current version of the RMT protocol that
  * the server supports.  For servers that don't support Version 1,
  * an error is returned and the client knows to only use Version 0
  * (stock BSD) calls, which include mt_op values in the range of [0-7].
  *
  * Note: The RMTIVERSION request must be made in order for the extended
  * protocol commands to be recognized.
  */
 #define	RMTIVERSION	-1
 #define	RMT_VERSION	1

 /*
  * These requests are made to the extended RMT protocol by specifying the
  * new 'i' command of RMT Protocol Version 1.  They are intended to allow
  * an intelligent client to communicate with both BSD and Solaris RMT
  * servers heterogeneously.  The 'i' command taks an mtop structure as
  * argument, exactly like the 'I' command does.
  */
 #define	RMTICACHE	0
 #define	RMTINOCACHE	1
 #define	RMTIRETEN	2
 #define	RMTIERASE	3
 #define	RMTIEOM		4
 #define	RMTINBSF	5

 /*
  * These requests are made to the extended RMT protocol by specifying the
  * new 's' command of RMT Protocol Version 1.  They are intended to allow
  * an intelligent client to obtain "mt status" information with both BSD
  * and Solaris RMT servers heterogeneously.  They return the requested
  * piece of the mtget structure as an ascii integer.  The request is made
  * by sending the required character immediately after the 's' character
  * without any trailing newline.  A single ascii integer is returned, else
  * an error is returned.
  */
 #define	MTS_TYPE	'T'		/* mtget.mt_type */
 #define	MTS_DSREG	'D'		/* mtget.mt_dsreg */
 #define	MTS_ERREG	'E'		/* mtget.mt_erreg */
 #define	MTS_RESID	'R'		/* mtget.mt_resid */
 #define	MTS_FILENO	'F'		/* mtget.mt_fileno */
 #define	MTS_BLKNO	'B'		/* mtget.mt_blkno */
 #define	MTS_FLAGS	'f'		/* mtget.mt_flags */
 #define	MTS_BF		'b'		/* mtget.mt_bf */

 #define	MAXCHILD 1
 static pid_t	childpid[MAXCHILD];
 static int	children;

 static int	tape = -1;
 static size_t	maxrecsize = 0;
 static char	*record;

 #define	SSIZE	64
 static char	pos[SSIZE], op[SSIZE], mode[SSIZE], count[SSIZE];
 static char	device[MAXPATHLEN];

 static FILE	*debug;
 #define	DEBUG(f)		if (debug) (void) fprintf(debug, (f))
 #define	DEBUG1(f, a)		if (debug) (void) fprintf(debug, (f), (a))
 #define	DEBUG2(f, a, b)		if (debug) (void) fprintf(debug, (f), (a), (b))
 #define	DEBUG3(f, a, b, c)	if (debug) \
 				    (void) fprintf(debug, (f), (a), (b), (c))

 static char key;

 #ifdef __STDC__
 static void respond(offset_t, int);
 static void getstring(char *, size_t);
 static void checkbuf(size_t);
 #else
 static void respond();
 static void getstring();
 static void checkbuf();
 #endif

 static void
 catch(int sig)
 {
 	switch (sig) {
 	default:    return;
 	case OPEN:  key = 'O';	break;
 	case CLOSE: key = 'C';	break;
 	case ERROR: key = 'E';	break;
 	}
 	(void) sigprocmask(SIG_SETMASK, &maskall, (sigset_t *)0);
 	longjmp(sjbuf, 1);
 }

 int
 main(int argc, char *argv[])
 {
 	struct sigaction sa;
 	pid_t parent = getpid(), next = parent;
 	int saverr;
 	offset_t rval;
 	ssize_t cc;
 	size_t n, i;

 	(void) setlocale(LC_ALL, "");
 #if !defined(TEXT_DOMAIN)	/* Should be defined by cc -D */
 #define	TEXT_DOMAIN "SYS_TEST"
 #endif
 	(void) textdomain(TEXT_DOMAIN);

 	if (argc > 1) {
 		if ((debug = fopen(argv[1], "w")) == NULL)
 			exit(1);
 		setbuf(debug, NULL);
 	}
 	(void) sigemptyset(&maskall);
 	(void) sigaddset(&maskall, RECV);
 	(void) sigaddset(&maskall, OPEN);
 	(void) sigaddset(&maskall, CLOSE);
 	(void) sigaddset(&maskall, ERROR);
 	(void) sigaddset(&maskall, TAPE);
 	(void) sigaddset(&maskall, SEND);

 	tapemask = maskall;
 	(void) sigdelset(&tapemask, TAPE);

 	sendmask = maskall;
 	(void) sigdelset(&sendmask, SEND);

 	(void) sigemptyset(&cmdmask);
 	(void) sigaddset(&cmdmask, TAPE);
 	(void) sigaddset(&cmdmask, SEND);

 	(void) sigemptyset(&sa.sa_mask);

 	sa.sa_handler = catch;
 	sa.sa_flags = SA_RESTART;
 	(void) sigaction(RECV, &sa, (struct sigaction *)0);
 	(void) sigaction(SEND, &sa, (struct sigaction *)0);
 	(void) sigaction(TAPE, &sa, (struct sigaction *)0);
 	(void) sigaction(OPEN, &sa, (struct sigaction *)0);
 	(void) sigaction(CLOSE, &sa, (struct sigaction *)0);
 	(void) sigaction(ERROR, &sa, (struct sigaction *)0);

 	(void) sigprocmask(SIG_SETMASK, &maskall, (sigset_t *)0);

 	(void) kill(parent, TAPE);
 	(void) kill(parent, SEND);

 	while (read(0, &key, 1) == 1) {
 		switch (key) {
 		case 'L':		/* lseek */
 			getstring(count, sizeof (count));
 			getstring(pos, sizeof (pos));
 			DEBUG2("rmtd: L %s %s\n", count, pos);
 			(void) kill(next, RECV);
 			(void) sigsuspend(&tapemask);
 			rval = llseek(tape, atoll(count), atoi(pos));
 			saverr = errno;
 			(void) kill(next, TAPE);
 			(void) sigsuspend(&sendmask);
 			respond(rval, saverr);
 			break;

 		case 'I':		/* ioctl */
 		case 'i': {		/* extended version ioctl */
 			int bad = 0;

 			getstring(op, sizeof (op));
 			getstring(count, sizeof (count));
 			DEBUG3("rmtd: %c %s %s\n", key, op, count);
 			mtop.mt_op = atoi(op);
 			mtop.mt_count = atoi(count);
 			if (key == 'i') {
 				/*
 				 * Map the supported compatibility defines
 				 * into real ioctl values.
 				 */
 				switch (mtop.mt_op) {
 				case RMTICACHE:
 				case RMTINOCACHE:	/* not support on Sun */
 					bad = 1;
 					break;
 				case RMTIRETEN:
 					mtop.mt_op = MTRETEN;
 					break;
 				case RMTIERASE:
 					mtop.mt_op = MTERASE;
 					break;
 				case RMTIEOM:
 					mtop.mt_op = MTEOM;
 					break;
 				case RMTINBSF:
 					mtop.mt_op = MTNBSF;
 					break;
 				default:
 					bad = 1;
 					break;
 				}
 			}
 			if (bad) {
 				respond(-1LL, EINVAL);
 			} else {
 				(void) kill(next, RECV);
 				(void) sigsuspend(&tapemask);
 				if (mtop.mt_op == RMTIVERSION) {
 					mtop.mt_count = RMT_VERSION;
 					rval = (offset_t)mtop.mt_count;
 				} else {
 					rval = (offset_t)ioctl(tape, MTIOCTOP,
 					    (char *)&mtop);
 				}
 				saverr = errno;
 				(void) kill(next, TAPE);
 				(void) sigsuspend(&sendmask);
 				respond(rval < 0 ?
 				    rval : (offset_t)mtop.mt_count,
 				    saverr);
 			}
 			break;
 		}

 		case 'S':		/* status */
 		case 's': {		/* extended status */
 			char skey;

 			DEBUG1("rmtd: %c\n", key);
 			if (key == 's') {
 				if (read(0, &skey, 1) != 1)
 					continue;
 			}
 			(void) kill(next, RECV);
 			(void) sigsuspend(&tapemask);
 			errno = 0;
 			rval = (offset_t)ioctl(tape, MTIOCGET, (char *)&mtget);
 			saverr = errno;
 			(void) kill(next, TAPE);
 			(void) sigsuspend(&sendmask);
 			if (rval < 0)
 				respond(rval, saverr);
 			else {
 				if (key == 's') {	/* extended status */
 					DEBUG1("rmtd: s%c\n", key);
 					switch (skey) {
 					case MTS_TYPE:
 						respond(
 						    (offset_t)mtget.mt_type,
 						    saverr);
 						break;
 					case MTS_DSREG:
 						respond(
 						    (offset_t)mtget.mt_dsreg,
 						    saverr);
 						break;
 					case MTS_ERREG:
 						respond(
 						    (offset_t)mtget.mt_erreg,
 						    saverr);
 						break;
 					case MTS_RESID:
 						respond(
 						    (offset_t)mtget.mt_resid,
 						    saverr);
 						break;
 					case MTS_FILENO:
 						respond(
 						    (offset_t)mtget.mt_fileno,
 						    saverr);
 						break;
 					case MTS_BLKNO:
 						respond(
 						    (offset_t)mtget.mt_blkno,
 						    saverr);
 						break;
 					case MTS_FLAGS:
 						respond(
 						    (offset_t)mtget.mt_flags,
 						    saverr);
 						break;
 					case MTS_BF:
 						respond((offset_t)mtget.mt_bf,
 						    saverr);
 						break;
 					default:
 						respond(-1LL, EINVAL);
 						break;
 					}
 				} else {
 					respond((offset_t)sizeof (mtget),
 					    saverr);
 					(void) write(1, (char *)&mtget,
 					    sizeof (mtget));
 				}
 			}
 			break;
 		}

 		case 'W':
 			getstring(count, sizeof (count));
 			n = (size_t)atol(count);
 			checkbuf(n);
 			DEBUG1("rmtd: W %s\n", count);
 #ifdef lint
 			cc = 0;
 #endif
 			for (i = 0; i < n; i += (size_t)cc) {
 				cc = read(0, &record[i], n - i);
 				if (cc <= 0) {
 					DEBUG1(gettext("%s: premature eof\n"),
 						"rmtd");
 					exit(2);
 				}
 			}
 			(void) kill(next, RECV);
 			(void) sigsuspend(&tapemask);
 			rval = (offset_t)write(tape, record, n);
 			saverr = errno;
 			(void) kill(next, TAPE);
 			(void) sigsuspend(&sendmask);
 			respond(rval, saverr);
 			break;

 		case 'R':
 			getstring(count, sizeof (count));
 			n = (size_t)atol(count);
 			checkbuf(n);
 			DEBUG1("rmtd: R %s\n", count);
 			(void) kill(next, RECV);
 			(void) sigsuspend(&tapemask);
 			rval = (offset_t)read(tape, record, n);
 			saverr = errno;
 			(void) kill(next, TAPE);
 			(void) sigsuspend(&sendmask);
 			respond(rval, saverr);
 			(void) write(1, record, (size_t)rval);
 			break;

 		default:
 			DEBUG2(gettext("%s: garbage command '%c'\n"),
 				"rmtd", key);
 			/*FALLTHROUGH*/

 		case 'C':
 		case 'O':
 			/* rendezvous back into a single process */
 			if (setjmp(sjbuf) == 0 || getpid() != parent) {
 				(void) sigsuspend(&tapemask);
 				(void) sigsuspend(&sendmask);
 				(void) kill(parent, key == 'O' ? OPEN :
 					key == 'C' ? CLOSE : ERROR);
 				(void) sigemptyset(&newmask);
 				(void) sigsuspend(&newmask);
 			}
 			while (children > 0) {
 				(void) kill(childpid[--children], SIGKILL);
 				while (wait(NULL) != childpid[children])
 					;
 			}
 			next = parent;
 			if (key == 'C') {
 				getstring(device, sizeof (device));
 				DEBUG1("rmtd: C %s\n", device);
 				rval = (offset_t)close(tape);
 				respond(rval, errno);
 				(void) kill(parent, TAPE);
 				(void) kill(parent, SEND);
 				continue;
 			}
 			if (key != 'O') 		/* garbage command */
 				exit(3);
 			(void) close(tape);
 			getstring(device, sizeof (device));
 			getstring(mode, sizeof (mode));
 			DEBUG2("rmtd: O %s %s\n", device, mode);
 			/*
 			 * Due to incompatibilities in the
 			 * assignment of mode bits between
 			 * BSD and System V, we strip all
 			 * but the read/write bits.  However,
 			 * we also want to handle things larger
 			 * than 2GB, so we also force O_LARGEFILE.
 			 */
 			tape = open(device, O_LARGEFILE |
 			    (atoi(mode) & (O_RDONLY|O_WRONLY|O_RDWR)));
 			respond((offset_t)tape, errno);
 			if (tape >= 0)			/* fork off */
 				while (children < MAXCHILD &&
 					(childpid[children] = fork()) > 0)
 						next = childpid[children++];
 			if (next == parent) {
 				(void) kill(parent, RECV);
 				(void) kill(parent, TAPE);
 				(void) kill(parent, SEND);
 			}
 			(void) sigsuspend(&cmdmask);
 			continue;
 		}
 		(void) kill(next, SEND);
 		(void) sigsuspend(&cmdmask);
 	}
 	(void) kill(next, RECV);
 	return (0);
 }

 static void
 respond(offset_t rval, int Errno)
 {
 	char resp[SSIZE];
 	char *errstr = strerror(Errno);

 	if (rval < 0) {
 		(void) snprintf(resp, SSIZE, "E%d\n%s\n", Errno, errstr);
 		DEBUG2("rmtd: E %d (%s)\n", Errno, errstr);
 	} else {
 		(void) snprintf(resp, SSIZE, "A%lld\n", rval);
 		DEBUG1("rmtd: A %lld\n", rval);
 	}
 	resp[SSIZE - 1] = '\0';
 	(void) write(1, resp, (int)strlen(resp));
 }

 static void
 getstring(char *cp, size_t size)
 {
 	char *limit = cp + size - 1;

 	cp--;			/* nullify first increment */
 	do {
 		cp++;
 		if (read(0, cp, 1) != 1)
 			exit(0);
 	} while ((*cp != '\n') && (cp < limit));
 	*cp = '\0';
 }

 static void
 checkbuf(size_t size)
 {
 	if (size <= maxrecsize)
 		return;
 	if (record != 0)
 		free(record);
 	if ((record = malloc(size)) == NULL) {
 		DEBUG2(gettext("%s: cannot allocate %ld-byte buffer\n"),
 		    size, "rmtd");
 		exit(4);
 	}
 	maxrecsize = size;
 }
	/*
	* 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 2005 Sun Microsystems, Inc. All rights reserved.
	* Use is subject to license terms.
	*/

	#pragma ident "%Z%%M% %I% %E% SMI"

	/*
	* Multi-process streaming 4.3bsd /etc/rmt server.
	* Has three locks (for stdin, stdout, and the tape)
	* that are passed by signals and received by sigpause().
	*/

	#include <stdio.h>
	#include <locale.h>
	#include <sys/types.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <string.h>
	#include <signal.h>
	#include <setjmp.h>
	#include <sys/ioctl.h>
	#include <sys/mtio.h>
	#include <sys/wait.h>
	#include <stdlib.h>
	#include <unistd.h>
	#include <sys/param.h>

	static sigset_t cmdmask, maskall, newmask;
	static sigset_t sendmask, tapemask;

	static struct mtop mtop;
	static struct mtget mtget;
	static jmp_buf sjbuf;

	#define RECV SIGIO
	#define TAPE SIGURG
	#define SEND SIGALRM
	#define ERROR SIGTERM
	#define OPEN SIGUSR1
	#define CLOSE SIGUSR2

	/*
	* Support for Version 1 of the extended RMT protocol:
	* Placing RMTIVERSION (-1) into the mt_op field of the ioctl ('I')
	* request will return the current version of the RMT protocol that
	* the server supports. For servers that don't support Version 1,
	* an error is returned and the client knows to only use Version 0
	* (stock BSD) calls, which include mt_op values in the range of [0-7].
	*
	* Note: The RMTIVERSION request must be made in order for the extended
	* protocol commands to be recognized.
	*/
	#define RMTIVERSION -1
	#define RMT_VERSION 1

	/*
	* These requests are made to the extended RMT protocol by specifying the
	* new 'i' command of RMT Protocol Version 1. They are intended to allow
	* an intelligent client to communicate with both BSD and Solaris RMT
	* servers heterogeneously. The 'i' command taks an mtop structure as
	* argument, exactly like the 'I' command does.
	*/
	#define RMTICACHE 0
	#define RMTINOCACHE 1
	#define RMTIRETEN 2
	#define RMTIERASE 3
	#define RMTIEOM 4
	#define RMTINBSF 5

	/*
	* These requests are made to the extended RMT protocol by specifying the
	* new 's' command of RMT Protocol Version 1. They are intended to allow
	* an intelligent client to obtain "mt status" information with both BSD
	* and Solaris RMT servers heterogeneously. They return the requested
	* piece of the mtget structure as an ascii integer. The request is made
	* by sending the required character immediately after the 's' character
	* without any trailing newline. A single ascii integer is returned, else
	* an error is returned.
	*/
	#define MTS_TYPE 'T' /* mtget.mt_type */
	#define MTS_DSREG 'D' /* mtget.mt_dsreg */
	#define MTS_ERREG 'E' /* mtget.mt_erreg */
	#define MTS_RESID 'R' /* mtget.mt_resid */
	#define MTS_FILENO 'F' /* mtget.mt_fileno */
	#define MTS_BLKNO 'B' /* mtget.mt_blkno */
	#define MTS_FLAGS 'f' /* mtget.mt_flags */
	#define MTS_BF 'b' /* mtget.mt_bf */

	#define MAXCHILD 1
	static pid_t childpid[MAXCHILD];
	static int children;

	static int tape = -1;
	static size_t maxrecsize = 0;
	static char *record;

	#define SSIZE 64
	static char pos[SSIZE], op[SSIZE], mode[SSIZE], count[SSIZE];
	static char device[MAXPATHLEN];

	static FILE *debug;
	#define DEBUG(f) if (debug) (void) fprintf(debug, (f))
	#define DEBUG1(f, a) if (debug) (void) fprintf(debug, (f), (a))
	#define DEBUG2(f, a, b) if (debug) (void) fprintf(debug, (f), (a), (b))
	#define DEBUG3(f, a, b, c) if (debug) \
	(void) fprintf(debug, (f), (a), (b), (c))

	static char key;

	#ifdef __STDC__
	static void respond(offset_t, int);
	static void getstring(char *, size_t);
	static void checkbuf(size_t);
	#else
	static void respond();
	static void getstring();
	static void checkbuf();
	#endif

	static void
	catch(int sig)
	{
	switch (sig) {
	default: return;
	case OPEN: key = 'O'; break;
	case CLOSE: key = 'C'; break;
	case ERROR: key = 'E'; break;
	}
	(void) sigprocmask(SIG_SETMASK, &maskall, (sigset_t *)0);
	longjmp(sjbuf, 1);
	}

	int
	main(int argc, char *argv[])
	{
	struct sigaction sa;
	pid_t parent = getpid(), next = parent;
	int saverr;
	offset_t rval;
	ssize_t cc;
	size_t n, i;

	(void) setlocale(LC_ALL, "");
	#if !defined(TEXT_DOMAIN) /* Should be defined by cc -D */
	#define TEXT_DOMAIN "SYS_TEST"
	#endif
	(void) textdomain(TEXT_DOMAIN);

	if (argc > 1) {
	if ((debug = fopen(argv[1], "w")) == NULL)
	exit(1);
	setbuf(debug, NULL);
	}
	(void) sigemptyset(&maskall);
	(void) sigaddset(&maskall, RECV);
	(void) sigaddset(&maskall, OPEN);
	(void) sigaddset(&maskall, CLOSE);
	(void) sigaddset(&maskall, ERROR);
	(void) sigaddset(&maskall, TAPE);
	(void) sigaddset(&maskall, SEND);

	tapemask = maskall;
	(void) sigdelset(&tapemask, TAPE);

	sendmask = maskall;
	(void) sigdelset(&sendmask, SEND);

	(void) sigemptyset(&cmdmask);
	(void) sigaddset(&cmdmask, TAPE);
	(void) sigaddset(&cmdmask, SEND);

	(void) sigemptyset(&sa.sa_mask);

	sa.sa_handler = catch;
	sa.sa_flags = SA_RESTART;
	(void) sigaction(RECV, &sa, (struct sigaction *)0);
	(void) sigaction(SEND, &sa, (struct sigaction *)0);
	(void) sigaction(TAPE, &sa, (struct sigaction *)0);
	(void) sigaction(OPEN, &sa, (struct sigaction *)0);
	(void) sigaction(CLOSE, &sa, (struct sigaction *)0);
	(void) sigaction(ERROR, &sa, (struct sigaction *)0);

	(void) sigprocmask(SIG_SETMASK, &maskall, (sigset_t *)0);

	(void) kill(parent, TAPE);
	(void) kill(parent, SEND);

	while (read(0, &key, 1) == 1) {
	switch (key) {
	case 'L': /* lseek */
	getstring(count, sizeof (count));
	getstring(pos, sizeof (pos));
	DEBUG2("rmtd: L %s %s\n", count, pos);
	(void) kill(next, RECV);
	(void) sigsuspend(&tapemask);
	rval = llseek(tape, atoll(count), atoi(pos));
	saverr = errno;
	(void) kill(next, TAPE);
	(void) sigsuspend(&sendmask);
	respond(rval, saverr);
	break;

	case 'I': /* ioctl */
	case 'i': { /* extended version ioctl */
	int bad = 0;

	getstring(op, sizeof (op));
	getstring(count, sizeof (count));
	DEBUG3("rmtd: %c %s %s\n", key, op, count);
	mtop.mt_op = atoi(op);
	mtop.mt_count = atoi(count);
	if (key == 'i') {
	/*
	* Map the supported compatibility defines
	* into real ioctl values.
	*/
	switch (mtop.mt_op) {
	case RMTICACHE:
	case RMTINOCACHE: /* not support on Sun */
	bad = 1;
	break;
	case RMTIRETEN:
	mtop.mt_op = MTRETEN;
	break;
	case RMTIERASE:
	mtop.mt_op = MTERASE;
	break;
	case RMTIEOM:
	mtop.mt_op = MTEOM;
	break;
	case RMTINBSF:
	mtop.mt_op = MTNBSF;
	break;
	default:
	bad = 1;
	break;
	}
	}
	if (bad) {
	respond(-1LL, EINVAL);
	} else {
	(void) kill(next, RECV);
	(void) sigsuspend(&tapemask);
	if (mtop.mt_op == RMTIVERSION) {
	mtop.mt_count = RMT_VERSION;
	rval = (offset_t)mtop.mt_count;
	} else {
	rval = (offset_t)ioctl(tape, MTIOCTOP,
	(char *)&mtop);
	}
	saverr = errno;
	(void) kill(next, TAPE);
	(void) sigsuspend(&sendmask);
	respond(rval < 0 ?
	rval : (offset_t)mtop.mt_count,
	saverr);
	}
	break;
	}

	case 'S': /* status */
	case 's': { /* extended status */
	char skey;

	DEBUG1("rmtd: %c\n", key);
	if (key == 's') {
	if (read(0, &skey, 1) != 1)
	continue;
	}
	(void) kill(next, RECV);
	(void) sigsuspend(&tapemask);
	errno = 0;
	rval = (offset_t)ioctl(tape, MTIOCGET, (char *)&mtget);
	saverr = errno;
	(void) kill(next, TAPE);
	(void) sigsuspend(&sendmask);
	if (rval < 0)
	respond(rval, saverr);
	else {
	if (key == 's') { /* extended status */
	DEBUG1("rmtd: s%c\n", key);
	switch (skey) {
	case MTS_TYPE:
	respond(
	(offset_t)mtget.mt_type,
	saverr);
	break;
	case MTS_DSREG:
	respond(
	(offset_t)mtget.mt_dsreg,
	saverr);
	break;
	case MTS_ERREG:
	respond(
	(offset_t)mtget.mt_erreg,
	saverr);
	break;
	case MTS_RESID:
	respond(
	(offset_t)mtget.mt_resid,
	saverr);
	break;
	case MTS_FILENO:
	respond(
	(offset_t)mtget.mt_fileno,
	saverr);
	break;
	case MTS_BLKNO:
	respond(
	(offset_t)mtget.mt_blkno,
	saverr);
	break;
	case MTS_FLAGS:
	respond(
	(offset_t)mtget.mt_flags,
	saverr);
	break;
	case MTS_BF:
	respond((offset_t)mtget.mt_bf,
	saverr);
	break;
	default:
	respond(-1LL, EINVAL);
	break;
	}
	} else {
	respond((offset_t)sizeof (mtget),
	saverr);
	(void) write(1, (char *)&mtget,
	sizeof (mtget));
	}
	}
	break;
	}

	case 'W':
	getstring(count, sizeof (count));
	n = (size_t)atol(count);
	checkbuf(n);
	DEBUG1("rmtd: W %s\n", count);
	#ifdef lint
	cc = 0;
	#endif
	for (i = 0; i < n; i += (size_t)cc) {
	cc = read(0, &record[i], n - i);
	if (cc <= 0) {
	DEBUG1(gettext("%s: premature eof\n"),
	"rmtd");
	exit(2);
	}
	}
	(void) kill(next, RECV);
	(void) sigsuspend(&tapemask);
	rval = (offset_t)write(tape, record, n);
	saverr = errno;
	(void) kill(next, TAPE);
	(void) sigsuspend(&sendmask);
	respond(rval, saverr);
	break;

	case 'R':
	getstring(count, sizeof (count));
	n = (size_t)atol(count);
	checkbuf(n);
	DEBUG1("rmtd: R %s\n", count);
	(void) kill(next, RECV);
	(void) sigsuspend(&tapemask);
	rval = (offset_t)read(tape, record, n);
	saverr = errno;
	(void) kill(next, TAPE);
	(void) sigsuspend(&sendmask);
	respond(rval, saverr);
	(void) write(1, record, (size_t)rval);
	break;

	default:
	DEBUG2(gettext("%s: garbage command '%c'\n"),
	"rmtd", key);
	/FALLTHROUGH/

	case 'C':
	case 'O':
	/* rendezvous back into a single process */
	if (setjmp(sjbuf) == 0 \|\| getpid() != parent) {
	(void) sigsuspend(&tapemask);
	(void) sigsuspend(&sendmask);
	(void) kill(parent, key == 'O' ? OPEN :
	key == 'C' ? CLOSE : ERROR);
	(void) sigemptyset(&newmask);
	(void) sigsuspend(&newmask);
	}
	while (children > 0) {
	(void) kill(childpid[--children], SIGKILL);
	while (wait(NULL) != childpid[children])
	;
	}
	next = parent;
	if (key == 'C') {
	getstring(device, sizeof (device));
	DEBUG1("rmtd: C %s\n", device);
	rval = (offset_t)close(tape);
	respond(rval, errno);
	(void) kill(parent, TAPE);
	(void) kill(parent, SEND);
	continue;
	}
	if (key != 'O') /* garbage command */
	exit(3);
	(void) close(tape);
	getstring(device, sizeof (device));
	getstring(mode, sizeof (mode));
	DEBUG2("rmtd: O %s %s\n", device, mode);
	/*
	* Due to incompatibilities in the
	* assignment of mode bits between
	* BSD and System V, we strip all
	* but the read/write bits. However,
	* we also want to handle things larger
	* than 2GB, so we also force O_LARGEFILE.
	*/
	tape = open(device, O_LARGEFILE \|
	(atoi(mode) & (O_RDONLY\|O_WRONLY\|O_RDWR)));
	respond((offset_t)tape, errno);
	if (tape >= 0) /* fork off */
	while (children < MAXCHILD &&
	(childpid[children] = fork()) > 0)
	next = childpid[children++];
	if (next == parent) {
	(void) kill(parent, RECV);
	(void) kill(parent, TAPE);
	(void) kill(parent, SEND);
	}
	(void) sigsuspend(&cmdmask);
	continue;
	}
	(void) kill(next, SEND);
	(void) sigsuspend(&cmdmask);
	}
	(void) kill(next, RECV);
	return (0);
	}

	static void
	respond(offset_t rval, int Errno)
	{
	char resp[SSIZE];
	char *errstr = strerror(Errno);

	if (rval < 0) {
	(void) snprintf(resp, SSIZE, "E%d\n%s\n", Errno, errstr);
	DEBUG2("rmtd: E %d (%s)\n", Errno, errstr);
	} else {
	(void) snprintf(resp, SSIZE, "A%lld\n", rval);
	DEBUG1("rmtd: A %lld\n", rval);
	}
	resp[SSIZE - 1] = '\0';
	(void) write(1, resp, (int)strlen(resp));
	}

	static void
	getstring(char *cp, size_t size)
	{
	char *limit = cp + size - 1;

	cp--; /* nullify first increment */
	do {
	cp++;
	if (read(0, cp, 1) != 1)
	exit(0);
	} while ((*cp != '\n') && (cp < limit));
	*cp = '\0';
	}

	static void
	checkbuf(size_t size)
	{
	if (size <= maxrecsize)
	return;
	if (record != 0)
	free(record);
	if ((record = malloc(size)) == NULL) {
	DEBUG2(gettext("%s: cannot allocate %ld-byte buffer\n"),
	size, "rmtd");
	exit(4);
	}
	maxrecsize = size;
	}