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/* $OpenBSD: pty.c,v 1.14 2005/08/02 21:46:23 espie Exp $ */
/*-
* Copyright (c) 1990, 1993
* 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>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <grp.h>
#include <sys/tty.h>
#include "util.h"
#define TTY_LETTERS "pqrstuvwxyzPQRST"
#define TTY_SUFFIX "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
int
openpty(int *amaster, int *aslave, char *name, struct termios *termp,
struct winsize *winp)
{
char line[] = "/dev/ptyXX";
const char *cp1, *cp2;
int master, slave, fd;
struct ptmget ptm;
struct group *gr;
gid_t ttygid;
/*
* Try to use /dev/ptm and the PTMGET ioctl to get a properly set up
* and owned pty/tty pair. If this fails, (because we might not have
* the ptm device, etc.) fall back to using the traditional method
* of walking through the pty entries in /dev for the moment, until
* there is less chance of people being seriously boned by running
* kernels without /dev/ptm in them.
*/
fd = open(PATH_PTMDEV, O_RDWR, 0);
if (fd == -1)
goto walkit;
if ((ioctl(fd, PTMGET, &ptm) == -1)) {
close(fd);
goto walkit;
}
close(fd);
master = ptm.cfd;
slave = ptm.sfd;
if (name) {
/*
* Manual page says "at least 16 characters".
*/
strlcpy(name, ptm.sn, 16);
}
*amaster = master;
*aslave = slave;
if (termp)
(void) tcsetattr(slave, TCSAFLUSH, termp);
if (winp)
(void) ioctl(slave, TIOCSWINSZ, (char *)winp);
return (0);
walkit:
if ((gr = getgrnam("tty")) != NULL)
ttygid = gr->gr_gid;
else
ttygid = -1;
for (cp1 = TTY_LETTERS; *cp1; cp1++) {
line[8] = *cp1;
for (cp2 = TTY_SUFFIX; *cp2; cp2++) {
line[9] = *cp2;
line[5] = 'p';
if ((master = open(line, O_RDWR, 0)) == -1) {
if (errno == ENOENT)
return (-1); /* out of ptys */
} else {
line[5] = 't';
(void) chown(line, getuid(), ttygid);
(void) chmod(line, S_IRUSR|S_IWUSR|S_IWGRP);
(void) revoke(line);
if ((slave = open(line, O_RDWR, 0)) != -1) {
*amaster = master;
*aslave = slave;
if (name) {
/*
* Manual page says "at least
* 16 characters".
*/
strlcpy(name, line, 16);
}
if (termp)
(void) tcsetattr(slave,
TCSAFLUSH, termp);
if (winp)
(void) ioctl(slave, TIOCSWINSZ,
(char *)winp);
return (0);
}
(void) close(master);
}
}
}
errno = ENOENT; /* out of ptys */
return (-1);
}
pid_t
forkpty(amaster, name, termp, winp)
int *amaster;
char *name;
struct termios *termp;
struct winsize *winp;
{
int master, slave;
pid_t pid;
if (openpty(&master, &slave, name, termp, 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);
}
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