From: gak@gakbox.Sun.COM (Richard Stueven)
Subject: Re: /bin/write on the 3b1
Date: 16 Apr 90 15:15:03 GMT
Reply-To: gak@gakbox.EBay.Sun.COM (Richard Stueven)
Organization: Sun Microsystems, Inc.  Mt. View, Ca.
Lines: 461

In article <285@iczer-1.UUCP> emm@iczer-1.UUCP (Edward M. Markowski) writes:
>
>Does anybody have a version of write that does not use /dev/error
>for writing to the console?
>
>It is a pain to keep using that little icon to carry on a
>conversation(sp?).

Offerred as-is...with thanks to Kent Landfield somewhere in Omaha
for the original hack several years ago...

have fun

gak
=======================================================================
/*
 * write to another user
 * (modified for char by char transmission)
 */

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <utmp.h>
#include <time.h>
#include <sys/termio.h>

#define NMAX sizeof(ubuf.ut_name)
#define LMAX sizeof(ubuf.ut_line)
#define EOFC '\004'
#define BEL '\007'
#define IOBUFSIZ 256
#define myfildes 1

int	errno;
char	*strcat();
char	*strcpy();
struct utmp ubuf;
int	signum[] = {
	SIGHUP, SIGINT, SIGQUIT, 0};


int	onstop();
char	me[10]  = "???";
char	*him;
char	*mytty;
char	histty[32];
char	*histtya;
int	hisfildes;
int	modeset;
char	*ttyname();
void    exit();
void    perror();
unsigned	alarm();
char	*rindex();
int	logcnt;
int	find;
int	die();
int	timout();
FILE    *tf;
char	*getenv();
struct termio new_term, old_term;

#ifdef BSD4.1
struct ltchars o_ltchars;
struct ltchars ltchars;
#endif

char	erase, werase, lkill;
char	erase, werase, lkill;
char	iobuf[IOBUFSIZ];
char	*ptr = iobuf;

main(argc, argv)
char	*argv[];
{
	struct stat stbuf;
	register i;
	int	c1, c2;
	char	c;
	register FILE *uf;
	long	time();
	long	clock;
	struct tm *localtime();
	struct tm *localclock;

	clock = time( 0 );
	localclock = localtime( &clock );
	if (argc < 2) {
		printf("usage: %s user [ttyname]\n", argv[0]);
		exit(1);
	}
	him = argv[1];
	if (argc > 2)
		histtya = argv[2];
	if ((uf = fopen("/etc/utmp", "r")) == NULL) {
		printf("cannot open /etc/utmp\n");
		goto cont;
	}
	mytty = ttyname(2);
	if (mytty == NULL) {
		printf("Can't find your tty\n");
		exit(1);
	}
	mytty = rindex(mytty, '/') + 1;

	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 || !histtya[0])
			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;
			}
		logcnt++;
		if (histtya)
			if (strcmp(histtya, ubuf.ut_line))
				goto nomat;

		find++;
		if (histty[0] == 0) {
			strcpy(histty, "/dev/");
			strcat(histty, ubuf.ut_line);
		}
nomat:
		;
	}
cont:
	if (logcnt == 0) {
		printf("%s not logged in.\n", him);
		exit(1);
	}
	fclose(uf);
	if (histtya == 0 && logcnt > 1) {
		printf("%s logged more than once\nwriting to %s\n", him, histty + 5);
	}
	if (!find) {
		printf("%s not on that tty\n", him);
		exit(1);
	}
	if (access(histty, 0) < 0) {
		printf("No such tty\n");
		exit(1);
	}
	signal(SIGALRM, timout);
	alarm(5);
	if ((tf = fopen(histty, "w")) == NULL)
		goto perm;
	alarm(0);

	hisfildes = fileno(tf);
	if (fstat(hisfildes, &stbuf) < 0)
		goto perm;
	if ((stbuf.st_mode & 02) == 0)
		goto perm;

	sigs(die);
#ifdef BSD4.1
	sigset(SIGTSTP, onstop);
#endif
	setmode(myfildes);

	fprintf(tf, "\r\nMessage from ");
#ifdef interdata
	fprintf(tf, "(Interdata) " );
#endif
	fprintf(tf, "%s on %s at %d:%02d ...\r\n"
	    , me, mytty , localclock ->tm_hour , localclock ->tm_min );
	fflush(tf);
	printf("Writing, type control/d to exit.\n");

	while (0 <= read(0, &c, 1) && c != EOFC) {
		if (c == erase)
			erase_char();
		else if (c == lkill)
			kill_line();
		else if (c == werase)
			erase_word();
		else if (c == '\n') {
			putch('\n', hisfildes);
			putch('\n', myfildes);
			if (iobuf[0] == '!') {
				*ptr++ = 0;
				ex(iobuf);
				iobuf[0] = 0;
			}
			ptr = iobuf;
		} else if (ptr != iobuf + IOBUFSIZ) {
			putch(c, hisfildes);
			putch(c, myfildes);
			*ptr++ = c;
		} else {
			putch(BEL, myfildes);
			putch(BEL, hisfildes);
		}
	}
	die();

perm:
	printf("Permission denied\n");
	perror("write");
	exit(1);
}


timout()
{

	printf("Timeout opening their tty\n");
	exit(1);
}


die()
{

	fprintf(tf, "EOF\r\n");
	if (modeset) 
		resetmode(myfildes);
	exit(0);
}


#ifdef BSD4.1
onstop()
{
	register char	*p;

	if (modeset) 
		resetmode(myfildes);
	sigset(SIGTSTP, SIG_DFL);
	kill(getpid(), SIGTSTP);
	sigrelse(SIGTSTP);

	/* resume here */
	sighold(SIGTSTP);
	sigset(SIGTSTP, onstop);
	setmode(myfildes);
	/* put the line out again */
	putch('\n', myfildes);
	for ( p = iobuf; p < ptr; )
		putch(*p++, myfildes);
}


#endif

ex(bp)
char	*bp;
{
	register i;

	holdsigs();
	resetmode(myfildes);

	i = fork();
	if (i < 0) {
		printf("Try again\n");
		goto out;
	}
	if (i == 0) {
		sigs(SIG_DFL);
#ifdef BSD
		sigset(SIGTSTP, SIG_DFL);
#endif
		execl(getenv("SHELL") ? getenv("SHELL") : "/bin/sh", "sh", "-c", bp + 1, 0);
		exit(0);
	}

	while (wait((int *)NULL) != i)
		;
	printf("!\n");
out:
	relsigs();
	setmode(myfildes);
}


sigs(sig)
int	(*sig)();
{
	register i;

	for (i = 0; signum[i]; i++)
#ifdef BSD
		sigset(signum[i], sig);
#else
	signal(signum[i], sig);
#endif
}


holdsigs()
{
#ifdef BSD4.1
	register i;

	for (i = 0; signum[i]; i++)
		sighold(signum[i]);
	sighold(SIGTSTP);
#endif
}


relsigs()
{
#ifdef BSD4.1
	register i;

	for (i = 0; signum[i]; i++)
		sigrelse(signum[i]);
	sigrelse(SIGTSTP);
#endif
}





#define seterror printf("write: unable to alter terminal state\n"), \
                 exit(1)
int	setmode (filedes)
int	filedes;
{
	if (modeset)    
		return;                 /* if modes already set */


#ifdef BSD4.1
	holdsigs(SIGTSTP);
#endif

	if (ioctl (filedes, TCGETA, &old_term)) /* get current terminal state */
		seterror;

	new_term = old_term;                    /* copy current terminal state */

	new_term.c_lflag &= ~(ICANON | ECHO | ECHOE);
	new_term.c_cc[VMIN] = 1;
	new_term.c_cc[VTIME] = 0;
	erase = new_term.c_cc[VERASE];
	lkill = new_term.c_cc[VKILL];

#ifdef BSD4.1
	if (ioctl (filede, TIOCGLTC, &o_ltchars))
		seterror;
	ltchars = o_ltchars;
	werase = ltchars.t_werasc;
#else
	werase = '\027';
#endif

	if (ioctl(filedes, TCSETA, &new_term))
		seterror;

	modeset++;
	relsigs ();
}


resetmode (filedes)
int	filedes;
{
	if (!modeset)
		return;

	holdsigs ();

	if (ioctl(filedes, TCSETA, &old_term)) {
		printf("write : error resetting tty\n");
		exit (1);
	}

	modeset = 0;
	relsigs ();
}


erase_char()
{
	if (ptr > iobuf) {
		putch('\b', myfildes);
		putch(' ', myfildes);
		putch('\b', myfildes);

		putch('\b', hisfildes);
		putch(' ' , hisfildes);
		putch('\b', hisfildes);

		ptr--;
	}
}


erase_word()
{
	while (ptr > iobuf && ptr[-1] == ' ')
		erase_char();
	while (ptr > iobuf && ptr[-1] != ' ')
		erase_char();
}


kill_line()
{
	while (ptr > iobuf)
		erase_char();
}


putch(c, f)
char	c;
register int	f;
{
	if (0 >= write(f, &c, 1)) {
		perror("write");
		die();
	}
}


/*
 * Return the ptr in sp at which the character c last
 * appears; NULL if not found
 *
 * Identical to v7 rindex, included for portability.
 */

char	*
rindex(sp, c)
register char	*sp, c;
{
	register char	*r;

	r = NULL;
	do {
		if (*sp == c)
			r = sp;
	} while (*sp++);
	return(r);
}
Richard Stueven        ...!att!attmail!gak          gak@sun.com

I like to know what I'm doing when I'm doing what I do when I'm
doing it because I don't know what to do when I'm not doing it.  - S.Ridgeway