/*      $NetBSD: pty.c,v 1.32 2018/06/24 09:30:26 kamil Exp $   */

/*-
* Copyright (c) 1990, 1993, 1994
*      The Regents of the University of California.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
static char sccsid[] = "@(#)pty.c       8.3 (Berkeley) 5/16/94";
#else
__RCSID("$NetBSD: pty.c,v 1.32 2018/06/24 09:30:26 kamil Exp $");
#endif
#endif /* LIBC_SCCS and not lint */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/stat.h>

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <stdio.h>
#include <string.h>
#include <termios.h>
#include <unistd.h>
#include <util.h>

/*
* XXX: `v' removed until no ports are using console devices which use ttyv0
*/
#define TTY_LETTERS     "pqrstuwxyzPQRST"
#define TTY_OLD_SUFFIX  "0123456789abcdef"
#define TTY_NEW_SUFFIX  "ghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

int
openpty(int *amaster, int *aslave, char *name, struct termios *term,
       struct winsize *winp)
{
       char line[] = "/dev/XtyXX";
       const char *cp1, *cp2, *cp, *linep;
       int master, slave;
       gid_t ttygid;
       mode_t mode;
       struct group grs, *grp;
       char grbuf[1024];
       struct ptmget pt;

       _DIAGASSERT(amaster != NULL);
       _DIAGASSERT(aslave != NULL);
       /* name may be NULL */
       /* term may be NULL */
       /* winp may be NULL */

       if ((master = open("/dev/ptm", O_RDWR)) != -1) {
               if (ioctl(master, TIOCPTMGET, &pt) != -1) {
                       (void)close(master);
                       master = pt.cfd;
                       slave = pt.sfd;
                       linep = pt.sn;
                       goto gotit;
               }
               (void)close(master);
       }

       (void)getgrnam_r("tty", &grs, grbuf, sizeof(grbuf), &grp);
       if (grp != NULL) {
               ttygid = grp->gr_gid;
               mode = S_IRUSR|S_IWUSR|S_IWGRP;
       } else {
               ttygid = getgid();
               mode = S_IRUSR|S_IWUSR;
       }

       for (cp1 = TTY_LETTERS; *cp1; cp1++) {
               line[8] = *cp1;
               for (cp = cp2 = TTY_OLD_SUFFIX TTY_NEW_SUFFIX; *cp2; cp2++) {
                       line[5] = 'p';
                       line[9] = *cp2;
                       if ((master = open(line, O_RDWR, 0)) == -1) {
                               if (errno != ENOENT)
                                       continue;       /* busy */
                               if ((size_t)(cp2 - cp + 1) < sizeof(TTY_OLD_SUFFIX))
                                       return -1; /* out of ptys */
                               else
                                       break;  /* out of ptys in this group */
                       }
                       line[5] = 't';
                       linep = line;
                       if (chown(line, getuid(), ttygid) == 0 &&
                           chmod(line, mode) == 0 &&
                           revoke(line) == 0 &&
                           (slave = open(line, O_RDWR, 0)) != -1) {
gotit:
                               *amaster = master;
                               *aslave = slave;
                               if (name)
                                       (void)strcpy(name, linep);
                               if (term)
                                       (void)tcsetattr(slave, TCSAFLUSH, term);
                               if (winp)
                                       (void)ioctl(slave, TIOCSWINSZ, winp);
                               return 0;
                       }
                       (void)close(master);
               }
       }
       errno = ENOENT; /* out of ptys */
       return -1;
}

pid_t
forkpty(int *amaster, char *name, struct termios *term, struct winsize *winp)
{
       int master, slave;
       pid_t pid;

       _DIAGASSERT(amaster != NULL);
       /* name may be NULL */
       /* term may be NULL */
       /* winp may be NULL */

       if (openpty(&master, &slave, name, term, winp) == -1)
               return -1;
       switch (pid = fork()) {
       case -1:
               return -1;
       case 0:
               /*
                * child
                */
               (void)close(master);
               login_tty(slave);
               return 0;
       }
       /*
        * parent
        */
       *amaster = master;
       (void)close(slave);
       return pid;
}