lib/libutil/pty.c

   1 /*      $NetBSD: pty.c,v 1.31 2009/02/20 16:44:06 christos Exp $        */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993, 1994
   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/cdefs.h>
  33 #if defined(LIBC_SCCS) && !defined(lint)
  34 #if 0
  35 static char sccsid[] = "@(#)pty.c       8.3 (Berkeley) 5/16/94";
  36 #else
  37 __RCSID("$NetBSD: pty.c,v 1.31 2009/02/20 16:44:06 christos Exp $");
  38 #endif
  39 #endif /* LIBC_SCCS and not lint */
  40
  41 #include <sys/types.h>
  42 #include <sys/ioctl.h>
  43 #include <sys/stat.h>
  44
  45 #include <assert.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <grp.h>
  49 #include <stdio.h>
  50 #include <string.h>
  51 #include <termios.h>
  52 #include <unistd.h>
  53 #include <util.h>
  54
  55 /*
  56  * XXX: `v' removed until no ports are using console devices which use ttyv0
  57  */
  58 #define TTY_LETTERS     "pqrstuwxyzPQRST"
  59 #define TTY_OLD_SUFFIX  "0123456789abcdef"
  60 #define TTY_NEW_SUFFIX  "ghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
  61
  62 int
  63 openpty(int *amaster, int *aslave, char *name, struct termios *term,
  64         struct winsize *winp)
  65 {
  66         char line[] = "/dev/XtyXX";
  67         const char *cp1, *cp2, *cp, *linep;
  68         int master, slave;
  69         gid_t ttygid;
  70         mode_t mode;
  71         struct group grs, *grp;
  72         char grbuf[1024];
  73
  74         _DIAGASSERT(amaster != NULL);
  75         _DIAGASSERT(aslave != NULL);
  76         /* name may be NULL */
  77         /* term may be NULL */
  78         /* winp may be NULL */
  79
  80 #ifndef __minix
  81         if ((master = open("/dev/ptm", O_RDWR)) != -1) {
  82                 struct ptmget pt;
  83                 if (ioctl(master, TIOCPTMGET, &pt) != -1) {
  84                         (void)close(master);
  85                         master = pt.cfd;
  86                         slave = pt.sfd;
  87                         linep = pt.sn;
  88                         goto gotit;
  89                 }
  90                 (void)close(master);
  91         }
  92 #endif
  93
  94         (void)getgrnam_r("tty", &grs, grbuf, sizeof(grbuf), &grp);
  95         if (grp != NULL) {
  96                 ttygid = grp->gr_gid;
  97                 mode = S_IRUSR|S_IWUSR|S_IWGRP;
  98         } else {
  99                 ttygid = getgid();
 100                 mode = S_IRUSR|S_IWUSR;
 101         }
 102
 103         for (cp1 = TTY_LETTERS; *cp1; cp1++) {
 104                 line[8] = *cp1;
 105                 for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
 106                         line[5] = 'p';
 107                         line[9] = *cp2;
 108                         if ((master = open(line, O_RDWR | O_NOCTTY, 0)) == -1) {
 109                                 if (errno != ENOENT)
 110                                         continue;       /* busy */
 111                                 if ((size_t)(cp2 - cp + 1) < sizeof(TTY_OLD_SUFFIX))
 112                                         return -1; /* out of ptys */
 113                                 else
 114                                         break;  /* out of ptys in this group */
 115                         }
 116                         line[5] = 't';
 117                         linep = line;
 118                         if (chown(line, getuid(), ttygid) == 0 &&
 119                             chmod(line, mode) == 0 &&
 120 #ifndef __minix
 121                             revoke(line) == 0 &&
 122 #endif
 123                             (slave = open(line, O_RDWR | O_NOCTTY, 0)) != -1) {
 124 #ifndef __minix
 125 gotit:
 126 #endif
 127                                 *amaster = master;
 128                                 *aslave = slave;
 129                                 if (name)
 130                                         (void)strcpy(name, linep);
 131                                 if (term)
 132                                         (void)tcsetattr(slave, TCSAFLUSH, term);
 133                                 if (winp)
 134                                         (void)ioctl(slave, TIOCSWINSZ, winp);
 135                                 return 0;
 136                         }
 137                         (void)close(master);
 138                 }
 139         }
 140         errno = ENOENT; /* out of ptys */
 141         return -1;
 142 }
 143
 144 pid_t
 145 forkpty(int *amaster, char *name, struct termios *term, struct winsize *winp)
 146 {
 147         int master, slave;
 148         pid_t pid;
 149
 150         _DIAGASSERT(amaster != NULL);
 151         /* name may be NULL */
 152         /* term may be NULL */
 153         /* winp may be NULL */
 154
 155         if (openpty(&master, &slave, name, term, winp) == -1)
 156                 return -1;
 157         switch (pid = fork()) {
 158         case -1:
 159                 return -1;
 160         case 0:
 161                 /*
 162                  * child
 163                  */
 164                 (void)close(master);
 165                 login_tty(slave);
 166                 return 0;
 167         }
 168         /*
 169          * parent
 170          */
 171         *amaster = master;
 172         (void)close(slave);
 173         return pid;
 174 }