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pty.c revision 1.7 
      1 /*-
      2  * Copyright (c) 1990, 1993
      3  *	The Regents of the University of California.  All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #if defined(LIBC_SCCS) && !defined(lint)
     35 #if 0
     36 static char sccsid[] = "@(#)pty.c	8.1 (Berkeley) 6/4/93";
     37 #else
     38 static char rcsid[] = "$NetBSD: pty.c,v 1.7 1996/11/12 16:39:38 mycroft Exp $";
     39 #endif
     40 #endif /* LIBC_SCCS and not lint */
     41 
     42 #include <sys/cdefs.h>
     43 #include <sys/types.h>
     44 #include <sys/stat.h>
     45 #include <sys/ioctl.h>
     46 #include <fcntl.h>
     47 #include <termios.h>
     48 #include <errno.h>
     49 #include <unistd.h>
     50 #include <stdio.h>
     51 #include <string.h>
     52 #include <grp.h>
     53 #include <util.h>
     54 
     55 #ifdef i386
     56 /* PCVT conflicts with ttyv*. */
     57 #define TTY_LETTERS "pqrstuwxyzPQRST"
     58 #else
     59 #define TTY_LETTERS "pqrstuvwxyzPQRST"
     60 #endif
     61 
     62 int
     63 openpty(amaster, aslave, name, termp, winp)
     64 	int *amaster, *aslave;
     65 	char *name;
     66 	struct termios *termp;
     67 	struct winsize *winp;
     68 {
     69 	static char line[] = "/dev/XtyXX";
     70 	register const char *cp1, *cp2;
     71 	register int master, slave, ttygid;
     72 	struct group *gr;
     73 
     74 	if ((gr = getgrnam("tty")) != NULL)
     75 		ttygid = gr->gr_gid;
     76 	else
     77 		ttygid = -1;
     78 
     79 	line[5] = 'p';
     80 	for (cp1 = TTY_LETTERS; *cp1; cp1++) {
     81 		line[8] = *cp1;
     82 		for (cp2 = "0123456789abcdef"; *cp2; cp2++) {
     83 			line[9] = *cp2;
     84 			if ((master = open(line, O_RDWR, 0)) == -1) {
     85 				if (errno == ENOENT)
     86 					return (-1);	/* out of ptys */
     87 			} else {
     88 				line[5] = 't';
     89 				(void) chown(line, getuid(), ttygid);
     90 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
     91 				(void) revoke(line);
     92 				if ((slave = open(line, O_RDWR, 0)) != -1) {
     93 					*amaster = master;
     94 					*aslave = slave;
     95 					if (name)
     96 						strcpy(name, line);
     97 					if (termp)
     98 						(void) tcsetattr(slave,
     99 							TCSAFLUSH, termp);
    100 					if (winp)
    101 						(void) ioctl(slave, TIOCSWINSZ,
    102 							(char *)winp);
    103 					return (0);
    104 				}
    105 				(void) close(master);
    106 				line[5] = 'p';
    107 			}
    108 		}
    109 	}
    110 	errno = ENOENT;	/* out of ptys */
    111 	return (-1);
    112 }
    113 
    114 pid_t
    115 forkpty(amaster, name, termp, winp)
    116 	int *amaster;
    117 	char *name;
    118 	struct termios *termp;
    119 	struct winsize *winp;
    120 {
    121 	int master, slave;
    122 	pid_t pid;
    123 
    124 	if (openpty(&master, &slave, name, termp, winp) == -1)
    125 		return (-1);
    126 	switch (pid = fork()) {
    127 	case -1:
    128 		return (-1);
    129 	case 0:
    130 		/*
    131 		 * child
    132 		 */
    133 		(void) close(master);
    134 		login_tty(slave);
    135 		return (0);
    136 	}
    137 	/*
    138 	 * parent
    139 	 */
    140 	*amaster = master;
    141 	(void) close(slave);
    142 	return (pid);
    143 }
    144