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pty.c revision 1.28 
      1 /*	$NetBSD: pty.c,v 1.28 2005/01/19 01:54:09 mycroft 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 1.28 2005/01/19 01:54:09 mycroft 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 *term,
     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 	mode_t mode;
     71 	struct group *gr;
     72 
     73 	_DIAGASSERT(amaster != NULL);
     74 	_DIAGASSERT(aslave != NULL);
     75 	/* name may be NULL */
     76 	/* term may be NULL */
     77 	/* winp may be NULL */
     78 
     79 	if ((master = open("/dev/ptm", O_RDWR)) != -1) {
     80 		struct ptmget pt;
     81 		if (ioctl(master, TIOCPTMGET, &pt) != -1) {
     82 			(void)close(master);
     83 			master = pt.cfd;
     84 			slave = pt.sfd;
     85 			linep = pt.sn;
     86 			goto gotit;
     87 		}
     88 		(void)close(master);
     89 	}
     90 
     91 	if ((gr = getgrnam("tty")) != NULL) {
     92 		ttygid = gr->gr_gid;
     93 		mode = S_IRUSR|S_IWUSR|S_IWGRP;
     94 	} else {
     95 		ttygid = getgid();
     96 		mode = S_IRUSR|S_IWUSR;
     97 	}
     98 
     99 	for (cp1 = TTY_LETTERS; *cp1; cp1++) {
    100 		line[8] = *cp1;
    101 		for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
    102 			line[5] = 'p';
    103 			line[9] = *cp2;
    104 			if ((master = open(line, O_RDWR, 0)) == -1) {
    105 				if (errno != ENOENT)
    106 					continue;	/* busy */
    107 				if (cp2 - cp + 1 < sizeof(TTY_OLD_SUFFIX))
    108 					return -1; /* out of ptys */
    109 				else
    110 					break;	/* out of ptys in this group */
    111 			}
    112 			line[5] = 't';
    113 			linep = line;
    114 			if (chown(line, getuid(), ttygid) == 0 &&
    115 			    chmod(line, mode) == 0 &&
    116 			    revoke(line) == 0 &&
    117 			    (slave = open(line, O_RDWR, 0)) != -1) {
    118 gotit:
    119 				*amaster = master;
    120 				*aslave = slave;
    121 				if (name)
    122 					(void)strcpy(name, linep);
    123 				if (term)
    124 					(void)tcsetattr(slave, TCSAFLUSH, term);
    125 				if (winp)
    126 					(void)ioctl(slave, TIOCSWINSZ, winp);
    127 				return 0;
    128 			}
    129 			(void)close(master);
    130 		}
    131 	}
    132 	errno = ENOENT;	/* out of ptys */
    133 	return -1;
    134 }
    135 
    136 pid_t
    137 forkpty(int *amaster, char *name, struct termios *term, struct winsize *winp)
    138 {
    139 	int master, slave;
    140 	pid_t pid;
    141 
    142 	_DIAGASSERT(amaster != NULL);
    143 	/* name may be NULL */
    144 	/* term may be NULL */
    145 	/* winp may be NULL */
    146 
    147 	if (openpty(&master, &slave, name, term, winp) == -1)
    148 		return -1;
    149 	switch (pid = fork()) {
    150 	case -1:
    151 		return -1;
    152 	case 0:
    153 		/*
    154 		 * child
    155 		 */
    156 		(void)close(master);
    157 		login_tty(slave);
    158 		return 0;
    159 	}
    160 	/*
    161 	 * parent
    162 	 */
    163 	*amaster = master;
    164 	(void)close(slave);
    165 	return pid;
    166 }
    167