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pty.c revision 1.5 
      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 /* from: static char sccsid[] = "@(#)pty.c	8.1 (Berkeley) 6/4/93"; */
     36 static char *rcsid = "$Id: pty.c,v 1.5 1995/06/05 19:44:01 pk Exp $";
     37 #endif /* LIBC_SCCS and not lint */
     38 
     39 #include <sys/cdefs.h>
     40 #include <sys/types.h>
     41 #include <sys/stat.h>
     42 #include <sys/ioctl.h>
     43 #include <fcntl.h>
     44 #include <termios.h>
     45 #include <errno.h>
     46 #include <unistd.h>
     47 #include <stdio.h>
     48 #include <string.h>
     49 #include <grp.h>
     50 
     51 int login_tty __P((int));
     52 int openpty __P((int *, int *, char *, struct termios *, struct winsize *));
     53 pid_t forkpty __P((int *, char *, struct termios *, struct winsize *));
     54 
     55 int
     56 openpty(amaster, aslave, name, termp, winp)
     57 	int *amaster, *aslave;
     58 	char *name;
     59 	struct termios *termp;
     60 	struct winsize *winp;
     61 {
     62 	static char line[] = "/dev/ptyXX";
     63 	register const char *cp1, *cp2;
     64 	register int master, slave, ttygid;
     65 	struct group *gr;
     66 
     67 	if ((gr = getgrnam("tty")) != NULL)
     68 		ttygid = gr->gr_gid;
     69 	else
     70 		ttygid = -1;
     71 
     72 	for (cp1 = "pqrstuvwxyzPQRST"; *cp1; cp1++) {
     73 		line[8] = *cp1;
     74 		for (cp2 = "0123456789abcdef"; *cp2; cp2++) {
     75 			line[9] = *cp2;
     76 			if ((master = open(line, O_RDWR, 0)) == -1) {
     77 				if (errno == ENOENT)
     78 					return (-1);	/* out of ptys */
     79 			} else {
     80 				line[5] = 't';
     81 				(void) chown(line, getuid(), ttygid);
     82 				(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
     83 				(void) revoke(line);
     84 				if ((slave = open(line, O_RDWR, 0)) != -1) {
     85 					*amaster = master;
     86 					*aslave = slave;
     87 					if (name)
     88 						strcpy(name, line);
     89 					if (termp)
     90 						(void) tcsetattr(slave,
     91 							TCSAFLUSH, termp);
     92 					if (winp)
     93 						(void) ioctl(slave, TIOCSWINSZ,
     94 							(char *)winp);
     95 					return (0);
     96 				}
     97 				(void) close(master);
     98 				line[5] = 'p';
     99 			}
    100 		}
    101 	}
    102 	errno = ENOENT;	/* out of ptys */
    103 	return (-1);
    104 }
    105 
    106 pid_t
    107 forkpty(amaster, name, termp, winp)
    108 	int *amaster;
    109 	char *name;
    110 	struct termios *termp;
    111 	struct winsize *winp;
    112 {
    113 	int master, slave;
    114 	pid_t pid;
    115 
    116 	if (openpty(&master, &slave, name, termp, winp) == -1)
    117 		return (-1);
    118 	switch (pid = fork()) {
    119 	case -1:
    120 		return (-1);
    121 	case 0:
    122 		/*
    123 		 * child
    124 		 */
    125 		(void) close(master);
    126 		login_tty(slave);
    127 		return (0);
    128 	}
    129 	/*
    130 	 * parent
    131 	 */
    132 	*amaster = master;
    133 	(void) close(slave);
    134 	return (pid);
    135 }
    136