1 /* $OpenBSD: pty.c,v 1.22 2022/04/20 14:00:19 millert 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 #include <sys/types.h> 33 #include <sys/stat.h> 34 #include <sys/ioctl.h> 35 #include <fcntl.h> 36 #include <termios.h> 37 #include <errno.h> 38 #include <unistd.h> 39 #include <stdio.h> 40 #include <string.h> 41 #include <grp.h> 42 #include <sys/tty.h> 43 44 #include "util.h" 45 46 int 47 getptmfd(void) 48 { 49 return (open(PATH_PTMDEV, O_RDWR|O_CLOEXEC)); 50 } 51 52 int 53 openpty(int *amaster, int *aslave, char *name, const struct termios *termp, 54 const struct winsize *winp) 55 { 56 int ptmfd; 57 58 if ((ptmfd = getptmfd()) == -1) 59 return (-1); 60 if (fdopenpty(ptmfd, amaster, aslave, name, termp, winp) == -1) { 61 close(ptmfd); 62 return (-1); 63 } 64 close(ptmfd); 65 return (0); 66 } 67 68 int 69 fdopenpty(int ptmfd, int *amaster, int *aslave, char *name, 70 const struct termios *termp, const struct winsize *winp) 71 { 72 int master, slave; 73 struct ptmget ptm; 74 75 /* 76 * Use /dev/ptm and the PTMGET ioctl to get a properly set up and 77 * owned pty/tty pair. 78 */ 79 if (ioctl(ptmfd, PTMGET, &ptm) == -1) 80 return (-1); 81 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, winp); 96 return (0); 97 } 98 99 pid_t 100 forkpty(int *amaster, char *name, const struct termios *termp, 101 const struct winsize *winp) 102 { 103 int ptmfd; 104 pid_t pid; 105 106 if ((ptmfd = getptmfd()) == -1) 107 return (-1); 108 if ((pid = fdforkpty(ptmfd, amaster, name, termp, winp)) == -1) { 109 close(ptmfd); 110 return (-1); 111 } 112 close(ptmfd); 113 return (pid); 114 } 115 116 pid_t 117 fdforkpty(int ptmfd, int *amaster, char *name, const struct termios *termp, 118 const struct winsize *winp) 119 { 120 int master, slave; 121 pid_t pid; 122 123 if (fdopenpty(ptmfd, &master, &slave, name, termp, winp) == -1) 124 return (-1); 125 switch (pid = fork()) { 126 case -1: 127 (void) close(master); 128 (void) close(slave); 129 return (-1); 130 case 0: 131 /* 132 * child 133 */ 134 (void) close(master); 135 login_tty(slave); 136 return (0); 137 } 138 /* 139 * parent 140 */ 141 *amaster = master; 142 (void) close(slave); 143 return (pid); 144 } 145