sysdeps/generic/pty.c

   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 static char sccsid[] = "@(#)pty.c       8.1 (Berkeley) 6/4/93";
  36 #endif /* LIBC_SCCS and not lint */
  37
  38 #include <sys/cdefs.h>
  39 #include <sys/types.h>
  40 #include <sys/stat.h>
  41 #include <sys/ioctl.h>
  42 #include <fcntl.h>
  43 #include <termios.h>
  44 #include <errno.h>
  45 #include <unistd.h>
  46 #include <stdio.h>
  47 #include <string.h>
  48 #include <grp.h>
  49 #include <pty.h>
  50 #include <utmp.h>
  51
  52 int
  53 openpty(amaster, aslave, name, termp, winp)
  54         int *amaster, *aslave;
  55         char *name;
  56         struct termios *termp;
  57         struct winsize *winp;
  58 {
  59         static char line[] = "/dev/ptyXX";
  60         register const char *cp1, *cp2;
  61         register int master, slave, ttygid;
  62         size_t buflen = sysconf (_SC_GETGR_R_SIZE_MAX);
  63         char buffer[buflen];
  64         struct group grbuffer;
  65         struct group *gr;
  66
  67         if (getgrnam_r("tty", &grbuffer, buffer, buflen, &gr) >= 0)
  68                 ttygid = gr->gr_gid;
  69         else
  70                 ttygid = -1;
  71
  72         for (cp1 = "pqrs"; *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         __set_errno (ENOENT);   /* out of ptys */
 103         return (-1);
 104 }
 105
 106 int
 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, pid;
 114
 115         if (openpty(&master, &slave, name, termp, winp) == -1)
 116                 return (-1);
 117         switch (pid = fork()) {
 118         case -1:
 119                 return (-1);
 120         case 0:
 121                 /*
 122                  * child
 123                  */
 124                 (void) close(master);
 125                 login_tty(slave);
 126                 return (0);
 127         }
 128         /*
 129          * parent
 130          */
 131         *amaster = master;
 132         (void) close(slave);
 133         return (pid);
 134 }