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pty.c revision 1.16 
      1 /*	$NetBSD: pty.c,v 1.16 2000/07/10 11:16:38 ad Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1990, 1993, 1994
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *	This product includes software developed by the University of
     18  *	California, Berkeley and its contributors.
     19  * 4. Neither the name of the University nor the names of its contributors
     20  *    may be used to endorse or promote products derived from this software
     21  *    without specific prior written permission.
     22  *
     23  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     33  * SUCH DAMAGE.
     34  */
     35 
     36 #include <sys/cdefs.h>
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
     40 #else
     41 __RCSID("$NetBSD: pty.c,v 1.16 2000/07/10 11:16:38 ad Exp $");
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #include <sys/types.h>
     46 #include <sys/ioctl.h>
     47 #include <sys/stat.h>
     48 
     49 #include <assert.h>
     50 #include <errno.h>
     51 #include <fcntl.h>
     52 #include <grp.h>
     53 #include <stdio.h>
     54 #include <string.h>
     55 #include <termios.h>
     56 #include <unistd.h>
     57 #include <util.h>
     58 
     59 #define TTY_LETTERS	"pqrstuvwxyzPQRST"
     60 
     61 int
     62 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
     63 	struct winsize *winp)
     64 {
     65 	static char line[] = "/dev/XtyXX";
     66 	const char *cp1, *cp2;
     67 	int master, slave;
     68 	gid_t ttygid;
     69 	struct group *gr;
     70 
     71 	_DIAGASSERT(amaster != NULL);
     72 	_DIAGASSERT(aslave != NULL);
     73 	/* name may be NULL */
     74 	/* termp may be NULL */
     75 	/* winp may be NULL */
     76 
     77 	if ((gr = getgrnam("tty")) != NULL)
     78 		ttygid = gr->gr_gid;
     79 	else
     80 		ttygid = (gid_t) -1;
     81 
     82 	for (cp1 = TTY_LETTERS; *cp1; cp1++) {
     83 		line[8] = *cp1;
     84 		for (cp2 = "0123456789abcdef"; *cp2; cp2++) {
     85 			line[5] = 'p';
     86 			line[9] = *cp2;
     87 			if ((master = open(line, O_RDWR, 0)) == -1) {
     88 				if (errno == ENOENT)
     89 					return (-1);	/* out of ptys */
     90 			} else {
     91 				line[5] = 't';
     92 				(void) chown(line, getuid(), ttygid);
     93 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
     94 				(void) revoke(line);
     95 				if ((slave = open(line, O_RDWR, 0)) != -1) {
     96 					*amaster = master;
     97 					*aslave = slave;
     98 					if (name)
     99 						strcpy(name, line);
    100 					if (termp)
    101 						(void) tcsetattr(slave,
    102 							TCSAFLUSH, termp);
    103 					if (winp)
    104 						(void) ioctl(slave, TIOCSWINSZ,
    105 						    winp);
    106 					return (0);
    107 				}
    108 				(void) close(master);
    109 			}
    110 		}
    111 	}
    112 	errno = ENOENT;	/* out of ptys */
    113 	return (-1);
    114 }
    115 
    116 pid_t
    117 forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
    118 {
    119 	int master, slave;
    120 	pid_t pid;
    121 
    122 	_DIAGASSERT(amaster != NULL);
    123 	/* name may be NULL */
    124 	/* termp may be NULL */
    125 	/* winp may be NULL */
    126 
    127 	if (openpty(&master, &slave, name, termp, winp) == -1)
    128 		return (-1);
    129 	switch (pid = fork()) {
    130 	case -1:
    131 		return (-1);
    132 	case 0:
    133 		/*
    134 		 * child
    135 		 */
    136 		(void) close(master);
    137 		login_tty(slave);
    138 		return (0);
    139 	}
    140 	/*
    141 	 * parent
    142 	 */
    143 	*amaster = master;
    144 	(void) close(slave);
    145 	return (pid);
    146 }
    147