lib/libutil/pty.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   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  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)pty.c    8.3 (Berkeley) 5/16/94
  30  * $FreeBSD: src/lib/libutil/pty.c,v 1.10 1999/08/28 00:05:51 peter Exp $
  31  * $DragonFly: src/lib/libutil/pty.c,v 1.6 2007/12/30 13:44:33 matthias Exp $
  32  */
  33
  34 #include <sys/types.h>
  35 #include <sys/ioctl.h>
  36 #include <sys/stat.h>
  37
  38 #include <errno.h>
  39 #include <fcntl.h>
  40 #include <grp.h>
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <termios.h>
  44 #include <unistd.h>
  45
  46 #include "libutil.h"
  47
  48 #define UNIX98_PTYS     1
  49
  50 int
  51 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
  52         struct winsize *winp)
  53 {
  54         char line[] = "/dev/ptyXX";
  55         const char *cp1, *cp2;
  56         int master, slave, ttygid;
  57         struct group *gr;
  58         const char *slave_name;
  59
  60         if ((gr = getgrnam("tty")) != NULL)
  61                 ttygid = gr->gr_gid;
  62         else
  63                 ttygid = -1;
  64
  65 #ifdef UNIX98_PTYS
  66         master = posix_openpt(O_RDWR|O_NOCTTY);
  67         if (master == -1)
  68                 goto fallback;
  69
  70         if (grantpt(master) != 0) {
  71                 close(master);
  72                 goto fallback;
  73         }
  74
  75         if (unlockpt(master) != 0) {
  76                 close(master);
  77                 goto fallback;
  78         }
  79
  80         slave_name = ptsname(master);
  81         if (slave_name == NULL) {
  82                 close(master);
  83                 goto fallback;
  84         }
  85
  86         slave = open(slave_name, O_RDWR);
  87         if (slave == -1) {
  88                 close(master);
  89                 goto fallback;
  90         }
  91
  92         *amaster = master;
  93         *aslave = slave;
  94
  95         if (name)
  96                 strcpy(name, slave_name);
  97         if (termp)
  98                 tcsetattr(slave, TCSAFLUSH, termp);
  99         if (winp)
 100                 ioctl(slave, TIOCSWINSZ, (char *)winp);
 101
 102         return (0);
 103
 104 fallback:
 105 #endif
 106
 107         for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
 108                 line[8] = *cp1;
 109                 for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
 110                         line[5] = 'p';
 111                         line[9] = *cp2;
 112                         if ((master = open(line, O_RDWR, 0)) == -1) {
 113                                 if (errno == ENOENT)
 114                                         return (-1);    /* out of ptys */
 115                         } else {
 116                                 line[5] = 't';
 117                                 (void) chown(line, getuid(), ttygid);
 118                                 (void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
 119                                 (void) revoke(line);
 120                                 if ((slave = open(line, O_RDWR, 0)) != -1) {
 121                                         *amaster = master;
 122                                         *aslave = slave;
 123                                         if (name)
 124                                                 strcpy(name, line);
 125                                         if (termp)
 126                                                 (void) tcsetattr(slave,
 127                                                         TCSAFLUSH, termp);
 128                                         if (winp)
 129                                                 (void) ioctl(slave, TIOCSWINSZ,
 130                                                         (char *)winp);
 131                                         return (0);
 132                                 }
 133                                 (void) close(master);
 134                         }
 135                 }
 136         }
 137         errno = ENOENT; /* out of ptys */
 138         return (-1);
 139 }
 140
 141 int
 142 forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
 143 {
 144         int master, slave, pid;
 145
 146         if (openpty(&master, &slave, name, termp, winp) == -1)
 147                 return (-1);
 148         switch (pid = fork()) {
 149         case -1:
 150                 return (-1);
 151         case 0:
 152                 /*
 153                  * child
 154                  */
 155                 (void) close(master);
 156                 login_tty(slave);
 157                 return (0);
 158         }
 159         /*
 160          * parent
 161          */
 162         *amaster = master;
 163         (void) close(slave);
 164         return (pid);
 165 }