/*      $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;
}