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 int
  49 openpty(int *amaster, int *aslave, char *name, struct termios *termp,
  50         struct winsize *winp)
  51 {
  52         char line[] = "/dev/ptyXX";
  53         const char *cp1, *cp2;
  54         int master, slave, ttygid;
  55         struct group *gr;
  56
  57         if ((gr = getgrnam("tty")) != NULL)
  58                 ttygid = gr->gr_gid;
  59         else
  60                 ttygid = -1;
  61
  62         for (cp1 = "pqrsPQRS"; *cp1; cp1++) {
  63                 line[8] = *cp1;
  64                 for (cp2 = "0123456789abcdefghijklmnopqrstuv"; *cp2; cp2++) {
  65                         line[5] = 'p';
  66                         line[9] = *cp2;
  67                         if ((master = open(line, O_RDWR, 0)) == -1) {
  68                                 if (errno == ENOENT)
  69                                         return (-1);    /* out of ptys */
  70                         } else {
  71                                 line[5] = 't';
  72                                 (void) chown(line, getuid(), ttygid);
  73                                 (void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
  74                                 (void) revoke(line);
  75                                 if ((slave = open(line, O_RDWR, 0)) != -1) {
  76                                         *amaster = master;
  77                                         *aslave = slave;
  78                                         if (name)
  79                                                 strcpy(name, line);
  80                                         if (termp)
  81                                                 (void) tcsetattr(slave,
  82                                                         TCSAFLUSH, termp);
  83                                         if (winp)
  84                                                 (void) ioctl(slave, TIOCSWINSZ,
  85                                                         (char *)winp);
  86                                         return (0);
  87                                 }
  88                                 (void) close(master);
  89                         }
  90                 }
  91         }
  92         errno = ENOENT; /* out of ptys */
  93         return (-1);
  94 }
  95
  96 int
  97 forkpty(int *amaster, char *name, struct termios *termp, struct winsize *winp)
  98 {
  99         int master, slave, pid;
 100
 101         if (openpty(&master, &slave, name, termp, winp) == -1)
 102                 return (-1);
 103         switch (pid = fork()) {
 104         case -1:
 105                 return (-1);
 106         case 0:
 107                 /*
 108                  * child
 109                  */
 110                 (void) close(master);
 111                 login_tty(slave);
 112                 return (0);
 113         }
 114         /*
 115          * parent
 116          */
 117         *amaster = master;
 118         (void) close(slave);
 119         return (pid);
 120 }