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pty.c revision 1.22 
      1 /*	$NetBSD: pty.c,v 1.22 2004/05/27 03:12:48 christos 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. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 #if 0
     35 static char sccsid[] = "@(#)pty.c	8.3 (Berkeley) 5/16/94";
     36 #else
     37 __RCSID("$NetBSD: pty.c,v 1.22 2004/05/27 03:12:48 christos Exp $");
     38 #endif
     39 #endif /* LIBC_SCCS and not lint */
     40 
     41 #include <sys/types.h>
     42 #include <sys/ioctl.h>
     43 #include <sys/stat.h>
     44 
     45 #include <assert.h>
     46 #include <errno.h>
     47 #include <fcntl.h>
     48 #include <grp.h>
     49 #include <stdio.h>
     50 #include <string.h>
     51 #include <termios.h>
     52 #include <unistd.h>
     53 #include <util.h>
     54 
     55 /*
     56  * XXX: `v' removed until no ports are using console devices which use ttyv0
     57  */
     58 #define TTY_LETTERS	"pqrstuwxyzPQRST"
     59 #define TTY_OLD_SUFFIX	"0123456789abcdef"
     60 #define TTY_NEW_SUFFIX	"ghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
     61 
     62 int
     63 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
     64 	struct winsize *winp)
     65 {
     66 	static char line[] = "/dev/XtyXX";
     67 	const char *cp1, *cp2, *cp, *linep;
     68 	int master, slave;
     69 	gid_t ttygid;
     70 	struct group *gr;
     71 
     72 	_DIAGASSERT(amaster != NULL);
     73 	_DIAGASSERT(aslave != NULL);
     74 	/* name may be NULL */
     75 	/* termp may be NULL */
     76 	/* winp may be NULL */
     77 
     78 	if ((master = open("/dev/ptm", O_RDWR)) != -1) {
     79 		struct ptmget pt;
     80 		if (ioctl(master, TIOCPTMGET, &pt) != -1) {
     81 			(void)close(master);
     82 			master = pt.cfd;
     83 			slave = pt.sfd;
     84 			linep = pt.sn;
     85 			goto gotit;
     86 		}
     87 	}
     88 
     89 	if ((gr = getgrnam("tty")) != NULL)
     90 		ttygid = gr->gr_gid;
     91 	else
     92 		ttygid = (gid_t) -1;
     93 
     94 	for (cp1 = TTY_LETTERS; *cp1; cp1++) {
     95 		line[8] = *cp1;
     96 		for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
     97 			line[5] = 'p';
     98 			line[9] = *cp2;
     99 			if ((master = open(line, O_RDWR, 0)) == -1) {
    100 				if (errno == ENOENT) {
    101 					if (cp2 - cp + 1 < sizeof(TTY_OLD_SUFFIX))
    102 						return (-1); /* out of ptys */
    103 					else
    104 						break;
    105 				}
    106 			} else {
    107 				line[5] = 't';
    108 				(void) chown(line, getuid(), ttygid);
    109 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
    110 				(void) revoke(line);
    111 				linep = line;
    112 				if ((slave = open(line, O_RDWR, 0)) != -1) {
    113 gotit:
    114 					*amaster = master;
    115 					*aslave = slave;
    116 					if (name)
    117 						strcpy(name, linep);
    118 					if (termp)
    119 						(void) tcsetattr(slave,
    120 							TCSAFLUSH, termp);
    121 					if (winp)
    122 						(void) ioctl(slave, TIOCSWINSZ,
    123 						    winp);
    124 					return (0);
    125 				}
    126 				(void) close(master);
    127 			}
    128 		}
    129 	}
    130 	errno = ENOENT;	/* out of ptys */
    131 	return (-1);
    132 }
    133 
    134 pid_t
    135 forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
    136 {
    137 	int master, slave;
    138 	pid_t pid;
    139 
    140 	_DIAGASSERT(amaster != NULL);
    141 	/* name may be NULL */
    142 	/* termp may be NULL */
    143 	/* winp may be NULL */
    144 
    145 	if (openpty(&master, &slave, name, termp, winp) == -1)
    146 		return (-1);
    147 	switch (pid = fork()) {
    148 	case -1:
    149 		return (-1);
    150 	case 0:
    151 		/*
    152 		 * child
    153 		 */
    154 		(void) close(master);
    155 		login_tty(slave);
    156 		return (0);
    157 	}
    158 	/*
    159 	 * parent
    160 	 */
    161 	*amaster = master;
    162 	(void) close(slave);
    163 	return (pid);
    164 }
    165