303 lines
7.2 KiB
C
303 lines
7.2 KiB
C
/*
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* Copyright (c) 2002 The FreeBSD Project, Inc.
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* All rights reserved.
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*
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* This software includes code contributed to the FreeBSD Project
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* by Ryan Younce of North Carolina State University.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the FreeBSD Project nor the names of its
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* contributors may be used to endorse or promote products derived from
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* this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT AND CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__FBSDID("$FreeBSD$");
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#endif /* not lint */
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#include "namespace.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/time.h>
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#include <sys/resource.h>
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#include <sys/sysctl.h>
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#include <sys/ioctl.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <grp.h>
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#include <paths.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include <unistd.h>
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#include "un-namespace.h"
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#define PTM_PREFIX "pty" /* pseudo tty master naming convention */
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#define PTS_PREFIX "tty" /* pseudo tty slave naming convention */
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#define NEWPTS_PREFIX "pts/"
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#define PTMX "ptmx"
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/*
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* The following are range values for pseudo TTY devices. Pseudo TTYs have a
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* name of /dev/[pt]ty[p-sP-S][0-9a-v], yielding 256 combinations per major.
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*/
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#define PT_MAX 256
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#define PT_DEV1 "pqrsPQRS"
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#define PT_DEV2 "0123456789abcdefghijklmnopqrstuv"
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/*
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* grantpt(3) support utility.
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*/
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#define _PATH_PTCHOWN "/usr/libexec/pt_chown"
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/*
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* ISPTM(x) returns 0 for struct stat x if x is not a pty master.
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* The bounds checking may be unnecessary but it does eliminate doubt.
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*/
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#define ISPTM(x) (S_ISCHR((x).st_mode) && \
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minor((x).st_rdev) >= 0 && \
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minor((x).st_rdev) < PT_MAX)
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static int
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is_pts(int fd)
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{
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int nb;
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return (_ioctl(fd, TIOCGPTN, &nb) == 0);
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}
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int
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__use_pts(void)
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{
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int use_pts;
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size_t len;
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int error;
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len = sizeof(use_pts);
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error = sysctlbyname("kern.pts.enable", &use_pts, &len, NULL, 0);
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if (error) {
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struct stat sb;
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if (stat("/dev/ptmx", &sb) != 0)
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return (0);
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use_pts = 1;
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}
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return (use_pts);
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}
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/*
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* grantpt(): grant ownership of a slave pseudo-terminal device to the
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* current user.
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*/
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int
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grantpt(int fildes)
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{
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int retval, serrno, status;
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pid_t pid, spid;
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gid_t gid;
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char *slave;
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sigset_t oblock, nblock;
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struct group *grp;
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retval = -1;
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serrno = errno;
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if ((slave = ptsname(fildes)) != NULL) {
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/*
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* Block SIGCHLD.
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*/
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(void)sigemptyset(&nblock);
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(void)sigaddset(&nblock, SIGCHLD);
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(void)_sigprocmask(SIG_BLOCK, &nblock, &oblock);
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switch (pid = fork()) {
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case -1:
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break;
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case 0: /* child */
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/*
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* pt_chown expects the master pseudo TTY to be its
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* standard input.
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*/
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(void)_dup2(fildes, STDIN_FILENO);
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(void)_sigprocmask(SIG_SETMASK, &oblock, NULL);
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execl(_PATH_PTCHOWN, _PATH_PTCHOWN, (char *)NULL);
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_exit(EX_UNAVAILABLE);
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/* NOTREACHED */
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default: /* parent */
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/*
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* Just wait for the process. Error checking is
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* done below.
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*/
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while ((spid = _waitpid(pid, &status, 0)) == -1 &&
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(errno == EINTR))
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;
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if (spid != -1 && WIFEXITED(status) &&
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WEXITSTATUS(status) == EX_OK)
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retval = 0;
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else
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errno = EACCES;
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break;
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}
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/*
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* Restore process's signal mask.
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*/
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(void)_sigprocmask(SIG_SETMASK, &oblock, NULL);
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if (retval) {
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/*
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* pt_chown failed. Try to manually change the
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* permissions for the slave.
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*/
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gid = (grp = getgrnam("tty")) ? grp->gr_gid : -1;
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if (chown(slave, getuid(), gid) == -1 ||
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chmod(slave, S_IRUSR | S_IWUSR | S_IWGRP) == -1)
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errno = EACCES;
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else
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retval = 0;
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}
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}
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if (!retval)
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errno = serrno;
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return (retval);
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}
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/*
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* posix_openpt(): open the first available master pseudo-terminal device
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* and return descriptor.
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*/
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int
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posix_openpt(int oflag)
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{
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char *mc1, *mc2, master[] = _PATH_DEV PTM_PREFIX "XY";
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const char *pc1, *pc2;
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int fildes, bflag, serrno;
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fildes = -1;
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bflag = 0;
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serrno = errno;
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/*
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* Check flag validity. POSIX doesn't require it,
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* but we still do so.
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*/
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if (oflag & ~(O_RDWR | O_NOCTTY))
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errno = EINVAL;
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else {
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if (__use_pts()) {
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fildes = _open(_PATH_DEV PTMX, oflag);
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return (fildes);
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}
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mc1 = master + strlen(_PATH_DEV PTM_PREFIX);
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mc2 = mc1 + 1;
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/* Cycle through all possible master PTY devices. */
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for (pc1 = PT_DEV1; !bflag && (*mc1 = *pc1); ++pc1)
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for (pc2 = PT_DEV2; (*mc2 = *pc2) != '\0'; ++pc2) {
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/*
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* Break out if we successfully open a PTY,
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* or if open() fails due to limits.
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*/
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if ((fildes = _open(master, oflag)) != -1 ||
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(errno == EMFILE || errno == ENFILE)) {
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++bflag;
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break;
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}
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}
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if (fildes != -1)
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errno = serrno;
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else if (!bflag)
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errno = EAGAIN;
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}
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return (fildes);
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}
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/*
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* ptsname(): return the pathname of the slave pseudo-terminal device
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* associated with the specified master.
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*/
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char *
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ptsname(int fildes)
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{
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static char slave[] = _PATH_DEV PTS_PREFIX "XY";
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static char new_slave[] = _PATH_DEV NEWPTS_PREFIX "4294967295";
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char *retval;
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struct stat sbuf;
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retval = NULL;
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if (_fstat(fildes, &sbuf) == 0) {
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if (!ISPTM(sbuf))
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errno = EINVAL;
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else {
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if (!is_pts(fildes)) {
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(void)snprintf(slave, sizeof(slave),
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_PATH_DEV PTS_PREFIX "%s",
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devname(sbuf.st_rdev, S_IFCHR) +
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strlen(PTM_PREFIX));
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retval = slave;
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} else {
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(void)snprintf(new_slave, sizeof(new_slave),
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_PATH_DEV NEWPTS_PREFIX "%s",
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devname(sbuf.st_rdev, S_IFCHR) +
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strlen(PTM_PREFIX));
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retval = new_slave;
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}
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}
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}
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return (retval);
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}
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/*
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* unlockpt(): unlock a pseudo-terminal device pair.
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*/
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int
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unlockpt(int fildes)
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{
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int retval;
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struct stat sbuf;
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/*
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* Unlocking a master/slave pseudo-terminal pair has no meaning in a
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* non-streams PTY environment. However, we do ensure fildes is a
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* valid master pseudo-terminal device.
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*/
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if ((retval = _fstat(fildes, &sbuf)) == 0 && !ISPTM(sbuf)) {
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errno = EINVAL;
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retval = -1;
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}
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return (retval);
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}
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