#ifndef lintstatic char *sccsid = "@(#)write.c	4.1      ULTRIX  7/17/90";#endif lint/************************************************************************ *									* *			Copyright (c) 1985,86,87,88,89 by		* *		Digital Equipment Corporation, Maynard, MA		* *			All rights reserved.				* *									* *   This software is furnished under a license and may be used and	* *   copied  only  in accordance with the terms of such license and	* *   with the  inclusion  of  the  above  copyright  notice.   This	* *   software  or  any  other copies thereof may not be provided or	* *   otherwise made available to any other person.  No title to and	* *   ownership of the software is hereby transferred.			* *									* *   This software is  derived  from  software  received  from  the	* *   University    of   California,   Berkeley,   and   from   Bell	* *   Laboratories.  Use, duplication, or disclosure is  subject  to	* *   restrictions  under  license  agreements  with  University  of	* *   California and with AT&T.						* *									* *   The information in this software is subject to change  without	* *   notice  and should not be construed as a commitment by Digital	* *   Equipment Corporation.						* *									* *   Digital assumes no responsibility for the use  or  reliability	* *   of its software on equipment which is not supplied by Digital.	* *									* ************************************************************************//* * *   Modification history: * * 06 May 89 -- dal *	Took 4.3BSD version, with void signal handler changes. *//*	static char *sccsid = "@(#)write.c	4.13 3/13/86";*//* * write to another user */#include <stdio.h>#include <ctype.h>#include <sys/types.h>#include <sys/stat.h>#include <signal.h>#include <utmp.h>#include <sys/time.h>#define	NMAX	sizeof(ubuf.ut_name)#define	LMAX	sizeof(ubuf.ut_line)char	*strcat();char	*strcpy();struct	utmp ubuf;int	signum[] = {SIGHUP, SIGINT, SIGQUIT, 0};char	me[NMAX + 1]	= "???";char	*him;char	*mytty;char	histty[32];char	ttybuf[32];char	*histtya;char	*ttyname();char	*rindex();int	logcnt;void	eof();void	timout();FILE	*tf;char	*getenv();main(argc, argv)	int argc;	char *argv[];{	struct stat stbuf;	register i;	register FILE *uf;	int c1, c2;	long clock = time(0);	int suser = getuid() == 0;	int nomesg = 0;	struct tm *localtime();	struct tm *localclock = localtime( &clock );	if (argc < 2) {		fprintf(stderr, "Usage: write user [ttyname]\n");		exit(1);	}	him = argv[1];	if (argc > 2)		histtya = argv[2];	if ((uf = fopen("/etc/utmp", "r")) == NULL) {		perror("write: Can't open /etc/utmp");		if (histtya == 0)			exit(10);		goto cont;	}	mytty = ttyname(2);	if (mytty == NULL) {		fprintf(stderr, "write: Can't find your tty\n");		exit(1);	}	if (stat(mytty, &stbuf) < 0) {		perror("write: Can't stat your tty");		exit(1);	}	if ((stbuf.st_mode&020) == 0) {		fprintf(stderr,			"write: You have write permission turned off\n");		if (!suser)			exit(1);	}	mytty = rindex(mytty, '/') + 1;	if (histtya) {		strcpy(histty, "/dev/");		strcat(histty, histtya);	}	while (fread((char *)&ubuf, sizeof(ubuf), 1, uf) == 1) {		if (ubuf.ut_name[0] == '\0')			continue;		if (strcmp(ubuf.ut_line, mytty)==0) {			for (i=0; i<NMAX; i++) {				c1 = ubuf.ut_name[i];				if (c1 == ' ')					c1 = 0;				me[i] = c1;				if (c1 == 0)					break;			}		}		if (him[0] == '-' && him[1] == 0)			goto nomat;		for (i=0; i<NMAX; i++) {			c1 = him[i];			c2 = ubuf.ut_name[i];			if (c1 == 0)				if (c2 == 0 || c2 == ' ')					break;			if (c1 != c2)				goto nomat;		}		if (histtya && strncmp(histtya, ubuf.ut_line,		    sizeof(ubuf.ut_line)))			continue;		logcnt++;		if (histty[0]==0 || nomesg && histtya == 0) {			strcpy(ttybuf, "/dev/");			strcat(ttybuf, ubuf.ut_line);			if (histty[0]==0)				strcpy(histty, ttybuf);			if (access(ttybuf, 0) < 0 || stat(ttybuf, &stbuf) < 0 ||			    (stbuf.st_mode&020) == 0)				nomesg++;			else {				strcpy(histty, ttybuf);				nomesg = 0;			}		}	nomat:		;	}	fclose(uf);	if (logcnt==0) {		fprintf(stderr, "write: %s not logged in%s\n", him,			histtya ? " on that tty" : "");		exit(1);	}	if (histtya==0 && logcnt > 1) {		fprintf(stderr,		"write: %s logged in more than once ... writing to %s\n",			him, histty+5);	}cont:	if (access(histty, 0) < 0) {		fprintf(stderr, "write: No such tty\n");		exit(1);	}	signal(SIGALRM, timout);	alarm(5);	if ((tf = fopen(histty, "w")) == NULL) {		fprintf(stderr, "write: Permission denied\n");		exit(1);	}	alarm(0);	sigs(eof);	{ char hostname[32];	  gethostname(hostname, sizeof (hostname));	  fprintf(tf,	      "\r\nMessage from %s@%s on %s at %d:%02d ...\r\n\007\007\007",	      me, hostname, mytty, localclock->tm_hour, localclock->tm_min);	fflush(tf);	}	for (;;) {		char buf[BUFSIZ];		register char *bp;		i = read(0, buf, sizeof buf);		if (i <= 0)			eof();		if (buf[0] == '!') {			buf[i] = 0;			ex(buf);			continue;		}		for (bp = buf; --i >= 0; bp++) {			if (*bp == '\n')				putc('\r', tf);			if (!isascii(*bp)) {				putc('M', tf);				putc('-', tf);				*bp = toascii(*bp);			}			if (isprint(*bp) ||			    *bp == ' ' || *bp == '\t' || *bp == '\n') {				putc(*bp, tf);			} else {				putc('^', tf);				putc(*bp ^ 0100, tf);			}			if (*bp == '\n')				fflush(tf);			if (ferror(tf) || feof(tf)) {				printf("\n\007Write failed (%s logged out?)\n",					him);				exit(1);			}		}	}}voidtimout(){	fprintf(stderr, "write: Timeout opening their tty\n");	exit(1);}voideof(){	fprintf(tf, "EOF\r\n");	exit(0);}ex(bp)	char *bp;{	register i;	sigs(SIG_IGN);	i = fork();	if (i < 0) {		printf("Try again\n");		goto out;	}	if (i == 0) {		fclose(tf);		/* Close his terminal */		setgid(getgid());	/* Give up effective group privs */		sigs((void (*)())0);		execl(getenv("SHELL") ?		    getenv("SHELL") : "/bin/sh", "sh", "-c", bp+1, 0);		exit(0);	}	while (wait((int *)NULL) != i)		;	printf("!\n");out:	sigs(eof);}sigs(sig)	void (*sig)();{	register i;	for (i=0; signum[i]; i++)		signal(signum[i], sig);}