lib/libutil/pty.c

   1 /*      $NetBSD: pty.c,v 1.30 2009/01/18 12:13:04 lukem 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 1.30 2009/01/18 12:13:04 lukem 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         if ((master = open("/dev/ptm", O_RDWR)) != -1) {
  81                 struct ptmget pt;
  82                 if (ioctl(master, TIOCPTMGET, &pt) != -1) {
  83                         (void)close(master);
  84                         master = pt.cfd;
  85                         slave = pt.sfd;
  86                         linep = pt.sn;
  87                         goto gotit;
  88                 }
  89                 (void)close(master);
  90         }
  91
  92         (void)getgrnam_r("tty", &grs, grbuf, sizeof(grbuf), &grp);
  93         if (grp != NULL) {
  94                 ttygid = grp->gr_gid;
  95                 mode = S_IRUSR|S_IWUSR|S_IWGRP;
  96         } else {
  97                 ttygid = getgid();
  98                 mode = S_IRUSR|S_IWUSR;
  99         }
 100
 101         for (cp1 = TTY_LETTERS; *cp1; cp1++) {
 102                 line[8] = *cp1;
 103                 for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
 104                         line[5] = 'p';
 105                         line[9] = *cp2;
 106                         if ((master = open(line, O_RDWR, 0)) == -1) {
 107                                 if (errno != ENOENT)
 108                                         continue;       /* busy */
 109                                 if ((size_t)(cp2 - cp + 1) < sizeof(TTY_OLD_SUFFIX))
 110                                         return -1; /* out of ptys */
 111                                 else
 112                                         break;  /* out of ptys in this group */
 113                         }
 114                         line[5] = 't';
 115                         linep = line;
 116                         if (chown(line, getuid(), ttygid) == 0 &&
 117                             chmod(line, mode) == 0 &&
 118                             revoke(line) == 0 &&
 119                             (slave = open(line, O_RDWR, 0)) != -1) {
 120 gotit:
 121                                 *amaster = master;
 122                                 *aslave = slave;
 123                                 if (name)
 124                                         (void)strcpy(name, linep);
 125                                 if (term)
 126                                         (void)tcsetattr(slave, TCSAFLUSH, term);
 127                                 if (winp)
 128                                         (void)ioctl(slave, TIOCSWINSZ, winp);
 129                                 return 0;
 130                         }
 131                         (void)close(master);
 132                 }
 133         }
 134         errno = ENOENT; /* out of ptys */
 135         return -1;
 136 }
 137
 138 pid_t
 139 forkpty(int *amaster, char *name, struct termios *term, struct winsize *winp)
 140 {
 141         int master, slave;
 142         pid_t pid;
 143
 144         _DIAGASSERT(amaster != NULL);
 145         /* name may be NULL */
 146         /* term may be NULL */
 147         /* winp may be NULL */
 148
 149         if (openpty(&master, &slave, name, term, winp) == -1)
 150                 return -1;
 151         switch (pid = fork()) {
 152         case -1:
 153                 return -1;
 154         case 0:
 155                 /*
 156                  * child
 157                  */
 158                 (void)close(master);
 159                 login_tty(slave);
 160                 return 0;
 161         }
 162         /*
 163          * parent
 164          */
 165         *amaster = master;
 166         (void)close(slave);
 167         return pid;
 168 }