1 /* $OpenBSD: pty.c,v 1.13 2004/05/28 07:03:47 deraadt Exp $ */ 2 3 /*- 4 * Copyright (c) 1990, 1993 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 #if defined(LIBC_SCCS) && !defined(lint) 33 /* from: static char sccsid[] = "@(#)pty.c 8.1 (Berkeley) 6/4/93"; */ 34 static const char rcsid[] = "$Id: pty.c,v 1.13 2004/05/28 07:03:47 deraadt Exp $"; 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include <sys/cdefs.h> 38 #include <sys/types.h> 39 #include <sys/stat.h> 40 #include <sys/ioctl.h> 41 #include <fcntl.h> 42 #include <termios.h> 43 #include <errno.h> 44 #include <unistd.h> 45 #include <stdio.h> 46 #include <string.h> 47 #include <grp.h> 48 #include <sys/tty.h> 49 50 #include "util.h" 51 52 #define TTY_LETTERS "pqrstuvwxyzPQRST" 53 #define TTY_SUFFIX "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" 54 55 int 56 openpty(int *amaster, int *aslave, char *name, struct termios *termp, 57 struct winsize *winp) 58 { 59 char line[] = "/dev/ptyXX"; 60 const char *cp1, *cp2; 61 int master, slave, fd; 62 struct ptmget ptm; 63 struct group *gr; 64 gid_t ttygid; 65 66 /* 67 * Try to use /dev/ptm and the PTMGET ioctl to get a properly set up 68 * and owned pty/tty pair. If this fails, (because we might not have 69 * the ptm device, etc.) fall back to using the traditional method 70 * of walking through the pty entries in /dev for the moment, until 71 * there is less chance of people being seriously boned by running 72 * kernels without /dev/ptm in them. 73 */ 74 fd = open(PATH_PTMDEV, O_RDWR, 0); 75 if (fd == -1) 76 goto walkit; 77 if ((ioctl(fd, PTMGET, &ptm) == -1)) { 78 close(fd); 79 goto walkit; 80 } 81 close(fd); 82 master = ptm.cfd; 83 slave = ptm.sfd; 84 if (name) { 85 /* 86 * Manual page says "at least 16 characters". 87 */ 88 strlcpy(name, ptm.sn, 16); 89 } 90 *amaster = master; 91 *aslave = slave; 92 if (termp) 93 (void) tcsetattr(slave, TCSAFLUSH, termp); 94 if (winp) 95 (void) ioctl(slave, TIOCSWINSZ, (char *)winp); 96 return (0); 97 walkit: 98 if ((gr = getgrnam("tty")) != NULL) 99 ttygid = gr->gr_gid; 100 else 101 ttygid = -1; 102 103 for (cp1 = TTY_LETTERS; *cp1; cp1++) { 104 line[8] = *cp1; 105 for (cp2 = TTY_SUFFIX; *cp2; cp2++) { 106 line[9] = *cp2; 107 line[5] = 'p'; 108 if ((master = open(line, O_RDWR, 0)) == -1) { 109 if (errno == ENOENT) 110 return (-1); /* out of ptys */ 111 } else { 112 line[5] = 't'; 113 (void) chown(line, getuid(), ttygid); 114 (void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP); 115 (void) revoke(line); 116 if ((slave = open(line, O_RDWR, 0)) != -1) { 117 *amaster = master; 118 *aslave = slave; 119 if (name) { 120 /* 121 * Manual page says "at least 122 * 16 characters". 123 */ 124 strlcpy(name, line, 16); 125 } 126 if (termp) 127 (void) tcsetattr(slave, 128 TCSAFLUSH, termp); 129 if (winp) 130 (void) ioctl(slave, TIOCSWINSZ, 131 (char *)winp); 132 return (0); 133 } 134 (void) close(master); 135 } 136 } 137 } 138 errno = ENOENT; /* out of ptys */ 139 return (-1); 140 } 141 142 pid_t 143 forkpty(amaster, name, termp, winp) 144 int *amaster; 145 char *name; 146 struct termios *termp; 147 struct winsize *winp; 148 { 149 int master, slave; 150 pid_t pid; 151 152 if (openpty(&master, &slave, name, termp, winp) == -1) 153 return (-1); 154 switch (pid = fork()) { 155 case -1: 156 return (-1); 157 case 0: 158 /* 159 * child 160 */ 161 (void) close(master); 162 login_tty(slave); 163 return (0); 164 } 165 /* 166 * parent 167 */ 168 *amaster = master; 169 (void) close(slave); 170 return (pid); 171 } 172