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      1 /*	$NetBSD: pty.c,v 1.32 2018/06/24 09:30:26 kamil 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 1.32 2018/06/24 09:30:26 kamil 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 	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 grs, *grp;
     72 	char grbuf[1024];
     73 	struct ptmget pt;
     74 
     75 	_DIAGASSERT(amaster != NULL);
     76 	_DIAGASSERT(aslave != NULL);
     77 	/* name may be NULL */
     78 	/* term may be NULL */
     79 	/* winp may be NULL */
     80 
     81 	if ((master = open("/dev/ptm", O_RDWR)) != -1) {
     82 		if (ioctl(master, TIOCPTMGET, &pt) != -1) {
     83 			(void)close(master);
     84 			master = pt.cfd;
     85 			slave = pt.sfd;
     86 			linep = pt.sn;
     87 			goto gotit;
     88 		}
     89 		(void)close(master);
     90 	}
     91 
     92 	(void)getgrnam_r("tty", &grs, grbuf, sizeof(grbuf), &grp);
     93 	if (grp != NULL) {
     94 		ttygid = grp->gr_gid;
     95 		mode = S_IRUSR|S_IWUSR|S_IWGRP;
     96 	} else {
     97 		ttygid = getgid();
     98 		mode = S_IRUSR|S_IWUSR;
     99 	}
    100 
    101 	for (cp1 = TTY_LETTERS; *cp1; cp1++) {
    102 		line[8] = *cp1;
    103 		for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
    104 			line[5] = 'p';
    105 			line[9] = *cp2;
    106 			if ((master = open(line, O_RDWR, 0)) == -1) {
    107 				if (errno != ENOENT)
    108 					continue;	/* busy */
    109 				if ((size_t)(cp2 - cp + 1) < sizeof(TTY_OLD_SUFFIX))
    110 					return -1; /* out of ptys */
    111 				else
    112 					break;	/* out of ptys in this group */
    113 			}
    114 			line[5] = 't';
    115 			linep = line;
    116 			if (chown(line, getuid(), ttygid) == 0 &&
    117 			    chmod(line, mode) == 0 &&
    118 			    revoke(line) == 0 &&
    119 			    (slave = open(line, O_RDWR, 0)) != -1) {
    120 gotit:
    121 				*amaster = master;
    122 				*aslave = slave;
    123 				if (name)
    124 					(void)strcpy(name, linep);
    125 				if (term)
    126 					(void)tcsetattr(slave, TCSAFLUSH, term);
    127 				if (winp)
    128 					(void)ioctl(slave, TIOCSWINSZ, winp);
    129 				return 0;
    130 			}
    131 			(void)close(master);
    132 		}
    133 	}
    134 	errno = ENOENT;	/* out of ptys */
    135 	return -1;
    136 }
    137 
    138 pid_t
    139 forkpty(int *amaster, char *name, struct termios *term, struct winsize *winp)
    140 {
    141 	int master, slave;
    142 	pid_t pid;
    143 
    144 	_DIAGASSERT(amaster != NULL);
    145 	/* name may be NULL */
    146 	/* term may be NULL */
    147 	/* winp may be NULL */
    148 
    149 	if (openpty(&master, &slave, name, term, winp) == -1)
    150 		return -1;
    151 	switch (pid = fork()) {
    152 	case -1:
    153 		return -1;
    154 	case 0:
    155 		/*
    156 		 * child
    157 		 */
    158 		(void)close(master);
    159 		login_tty(slave);
    160 		return 0;
    161 	}
    162 	/*
    163 	 * parent
    164 	 */
    165 	*amaster = master;
    166 	(void)close(slave);
    167 	return pid;
    168 }
    169