openpty.c

压缩包中包含LINUX下多个命令的源码

/* 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.
 * 4. 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.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#ifdef HAVE_SYS_CDEFS_H
# include <sys/cdefs.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#ifdef HAVE_TERMIOS_H
# include <termios.h>
#else
# ifdef HAVE_TERMIO_H
#  include <termio.h>
# endif
#endif
#include <errno.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include <stdio.h>
#ifdef HAVE_STRING_H
# include <string.h>
#endif
#include <grp.h>

#ifdef HAVE_PTSNAME
# include <stdlib.h>
# ifdef HAVE_STROPTS_H
#  include <stropts.h>
# endif
#endif

/* Slightly modified version of libutil. There's probably
   a better way to do this.
   Adapted to inetutils by Bernhard Rosenkraenzer <[e-mail]>
   This is taken from R. W. Stevens book.  The orignal did not have the
   necessary magic to work under SYSVR4 STREAM ttys.
   Alain Magloire.
*/

static int ptym_open __P ((char *pts_name));
static int ptys_open __P ((int fdm, char * pts_name));

int
openpty(int *amaster, int *aslave, char *name, struct termios *termp, struct winsize *winp)
{
	char line[20];
	*amaster = ptym_open(line);
	if (*amaster < 0)
		return -1;
	*aslave = ptys_open(*amaster, line);
	if (*aslave < 0) {
		close(*amaster);
		return -1;
	}
	if (name)
		strcpy(name, line);
#ifndef TCSAFLUSH
#define TCSAFLUSH TCSETAF
#endif
	if (termp)
		(void) tcsetattr(*aslave, TCSAFLUSH, termp);
#ifdef TIOCSWINSZ
	if (winp)
		(void) ioctl(*aslave, TIOCSWINSZ, (char *)winp);
#endif
	return 0;
}

static int
ptym_open(char * pts_name)
{
	int fdm;
#ifdef HAVE_PTSNAME
	char *ptr;

	strcpy(pts_name, "/dev/ptmx");
	fdm = open(pts_name, O_RDWR);
	if (fdm < 0)
		return -1;
	if (grantpt(fdm) < 0) { /* grant access to slave */
		close(fdm);
		return -2;
	}
	if (unlockpt(fdm) < 0) { /* clear slave's lock flag */
		close(fdm);
		return -3;
	}
	ptr = ptsname(fdm);
	if (ptr == NULL) { /* get slave's name */
		close (fdm);
		return -4;
	}
	strcpy(pts_name, ptr); /* return name of slave */
	return fdm;            /* return fd of master */
#else
	char *ptr1, *ptr2;

	strcpy(pts_name, "/dev/ptyXY");
	/* array index: 012345689 (for references in following code) */
	for (ptr1 = "pqrstuvwxyzPQRST"; *ptr1 != 0; ptr1++) {
		pts_name[8] = *ptr1;
		for (ptr2 = "0123456789abcdef"; *ptr2 != 0; ptr2++) {
			pts_name[9] = *ptr2;
			/* try to open master */
			fdm = open(pts_name, O_RDWR);
			if (fdm < 0) {
				if (errno == ENOENT) /* different from EIO */
					return -1;  /* out of pty devices */
				else
					continue;  /* try next pty device */
			}
			pts_name[5] = 't'; /* chage "pty" to "tty" */
			return fdm;   /* got it, return fd of master */
		}
	}
	return -1; /* out of pty devices */
#endif
}

static int
ptys_open(int fdm, char * pts_name)
{
	int fds;
#ifdef HAVE_PTSNAME
	/* following should allocate controlling terminal */
	fds = open(pts_name, O_RDWR);
	if (fds < 0) {
		close(fdm);
		return -5;
	}
	if (ioctl(fds, I_PUSH, "ptem") < 0) {
		close(fdm);
		close(fds);
		return -6;
	}
	if (ioctl(fds, I_PUSH, "ldterm") < 0) {
		close(fdm);
		close(fds);
		return -7;
	}
	if (ioctl(fds, I_PUSH, "ttcompat") < 0) {
		close(fdm);
		close(fds);
		return -8;
	}

	if (ioctl(fdm, I_PUSH, "pckt") < 0) {
		close(fdm);
		close(fds);
		return -8;
	}
	
	if (ioctl(fdm, I_SRDOPT, RMSGN|RPROTDAT) < 0) {
		close(fdm);
		close(fds);
		return -8;
	}

	return fds;
#else
	int gid;
	struct group *grptr;

	grptr = getgrnam("tty");
	if (grptr != NULL)
		gid = grptr->gr_gid;
	else
		gid = -1;  /* group tty is not in the group file */
	/* following two functions don't work unless we're root */
	chown(pts_name, getuid(), gid);
	chmod(pts_name, S_IRUSR | S_IWUSR | S_IWGRP);
	fds = open(pts_name, O_RDWR);
	if (fds < 0) {
		close(fdm);
		return -1;
	}
	return fds;
#endif
}