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 #if defined(__minix)
  46 #include <stdlib.h>
  47 #endif /* defined(__minix) */
  48 #include <assert.h>
  49 #include <errno.h>
  50 #include <fcntl.h>
  51 #include <grp.h>
  52 #include <stdio.h>
  53 #include <string.h>
  54 #include <termios.h>
  55 #include <unistd.h>
  56 #include <util.h>
  57
  58 /*
  59  * XXX: `v' removed until no ports are using console devices which use ttyv0
  60  */
  61 #define TTY_LETTERS     "pqrstuwxyzPQRST"
  62 #define TTY_OLD_SUFFIX  "0123456789abcdef"
  63 #define TTY_NEW_SUFFIX  "ghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
  64
  65 int
  66 openpty(int *amaster, int *aslave, char *name, struct termios *term,
  67         struct winsize *winp)
  68 {
  69         char line[] = "/dev/XtyXX";
  70         const char *cp1, *cp2, *cp, *linep;
  71         int master, slave;
  72         gid_t ttygid;
  73         mode_t mode;
  74         struct group grs, *grp;
  75         char grbuf[1024];
  76
  77         _DIAGASSERT(amaster != NULL);
  78         _DIAGASSERT(aslave != NULL);
  79         /* name may be NULL */
  80         /* term may be NULL */
  81         /* winp may be NULL */
  82
  83 #if !defined(__minix)
  84         if ((master = open("/dev/ptm", O_RDWR)) != -1) {
  85                 struct ptmget pt;
  86                 if (ioctl(master, TIOCPTMGET, &pt) != -1) {
  87                         (void)close(master);
  88                         master = pt.cfd;
  89                         slave = pt.sfd;
  90                         linep = pt.sn;
  91                         goto gotit;
  92                 }
  93                 (void)close(master);
  94         }
  95 #else
  96         /*
  97          * On MINIX3, we implement non-root openpty(3) using Unix98 PTYs.
  98          * If this fails, the fallback code below works for root only.
  99          */
 100         if ((master = posix_openpt(O_RDWR | O_NOCTTY)) != -1) {
 101                 if (grantpt(master) != -1 && unlockpt(master) != -1 &&
 102                     (linep = ptsname(master)) != NULL &&
 103                     (slave = open(linep, O_RDWR | O_NOCTTY)) != -1)
 104                         goto gotit;
 105                 (void)close(master);
 106         }
 107 #endif /* !defined(__minix) */
 108
 109         (void)getgrnam_r("tty", &grs, grbuf, sizeof(grbuf), &grp);
 110         if (grp != NULL) {
 111                 ttygid = grp->gr_gid;
 112                 mode = S_IRUSR|S_IWUSR|S_IWGRP;
 113         } else {
 114                 ttygid = getgid();
 115                 mode = S_IRUSR|S_IWUSR;
 116         }
 117
 118         for (cp1 = TTY_LETTERS; *cp1; cp1++) {
 119                 line[8] = *cp1;
 120                 for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
 121                         line[5] = 'p';
 122                         line[9] = *cp2;
 123 #if defined(__minix)
 124                         if ((master = open(line, O_RDWR | O_NOCTTY, 0)) == -1) {
 125 #else
 126                         if ((master = open(line, O_RDWR, 0)) == -1) {
 127 #endif /* defined(__minix) */
 128                                 if (errno != ENOENT)
 129                                         continue;       /* busy */
 130                                 if ((size_t)(cp2 - cp + 1) < sizeof(TTY_OLD_SUFFIX))
 131                                         return -1; /* out of ptys */
 132                                 else
 133                                         break;  /* out of ptys in this group */
 134                         }
 135                         line[5] = 't';
 136                         linep = line;
 137                         if (chown(line, getuid(), ttygid) == 0 &&
 138                             chmod(line, mode) == 0 &&
 139 #if !defined(__minix)
 140                             revoke(line) == 0 &&
 141 #endif /* !defined(__minix) */
 142 #if defined(__minix)
 143                         (slave = open(line, O_RDWR | O_NOCTTY, 0)) != -1) {
 144 #else
 145                             (slave = open(line, O_RDWR, 0)) != -1) {
 146 #endif /* defined(__minix) */
 147 gotit:
 148                                 *amaster = master;
 149                                 *aslave = slave;
 150                                 if (name)
 151                                         (void)strcpy(name, linep);
 152                                 if (term)
 153                                         (void)tcsetattr(slave, TCSAFLUSH, term);
 154                                 if (winp)
 155                                         (void)ioctl(slave, TIOCSWINSZ, winp);
 156                                 return 0;
 157                         }
 158                         (void)close(master);
 159                 }
 160         }
 161         errno = ENOENT; /* out of ptys */
 162         return -1;
 163 }
 164
 165 pid_t
 166 forkpty(int *amaster, char *name, struct termios *term, struct winsize *winp)
 167 {
 168         int master, slave;
 169         pid_t pid;
 170
 171         _DIAGASSERT(amaster != NULL);
 172         /* name may be NULL */
 173         /* term may be NULL */
 174         /* winp may be NULL */
 175
 176         if (openpty(&master, &slave, name, term, winp) == -1)
 177                 return -1;
 178         switch (pid = fork()) {
 179         case -1:
 180                 return -1;
 181         case 0:
 182                 /*
 183                  * child
 184                  */
 185                 (void)close(master);
 186                 login_tty(slave);
 187                 return 0;
 188         }
 189         /*
 190          * parent
 191          */
 192         *amaster = master;
 193         (void)close(slave);
 194         return pid;
 195 }