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255 lines
6.1 KiB
C
255 lines
6.1 KiB
C
/* $OpenBSD: sshpty.c,v 1.31 2016/11/29 03:54:50 dtucker Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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* Allocating a pseudo-terminal, and making it the controlling tty.
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*
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* As far as I am concerned, the code I have written for this software
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* can be used freely for any purpose. Any derived versions of this
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* software must be clearly marked as such, and if the derived work is
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* incompatible with the protocol description in the RFC file, it must be
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* called by a name other than "ssh" or "Secure Shell".
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <sys/ioctl.h>
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#include <sys/stat.h>
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#include <signal.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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#ifdef HAVE_PATHS_H
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# include <paths.h>
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#endif
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#include <pwd.h>
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#include <stdarg.h>
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#include <string.h>
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#include <termios.h>
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#ifdef HAVE_UTIL_H
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# include <util.h>
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#endif
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#include <unistd.h>
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#include "sshpty.h"
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#include "log.h"
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#include "misc.h"
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#ifdef HAVE_PTY_H
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# include <pty.h>
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#endif
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#ifndef O_NOCTTY
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#define O_NOCTTY 0
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#endif
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#ifdef __APPLE__
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# include <AvailabilityMacros.h>
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# if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_5)
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# define __APPLE_PRIVPTY__
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# endif
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#endif
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/*
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* Allocates and opens a pty. Returns 0 if no pty could be allocated, or
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* nonzero if a pty was successfully allocated. On success, open file
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* descriptors for the pty and tty sides and the name of the tty side are
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* returned (the buffer must be able to hold at least 64 characters).
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*/
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int
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pty_allocate(int *ptyfd, int *ttyfd, char *namebuf, size_t namebuflen)
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{
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/* openpty(3) exists in OSF/1 and some other os'es */
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char *name;
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int i;
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i = openpty(ptyfd, ttyfd, NULL, NULL, NULL);
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if (i < 0) {
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error("openpty: %.100s", strerror(errno));
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return 0;
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}
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name = ttyname(*ttyfd);
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if (!name)
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fatal("openpty returns device for which ttyname fails.");
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strlcpy(namebuf, name, namebuflen); /* possible truncation */
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return 1;
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}
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/* Releases the tty. Its ownership is returned to root, and permissions to 0666. */
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void
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pty_release(const char *tty)
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{
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#if !defined(__APPLE_PRIVPTY__) && !defined(HAVE_OPENPTY)
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if (chown(tty, (uid_t) 0, (gid_t) 0) < 0)
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error("chown %.100s 0 0 failed: %.100s", tty, strerror(errno));
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if (chmod(tty, (mode_t) 0666) < 0)
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error("chmod %.100s 0666 failed: %.100s", tty, strerror(errno));
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#endif /* !__APPLE_PRIVPTY__ && !HAVE_OPENPTY */
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}
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/* Makes the tty the process's controlling tty and sets it to sane modes. */
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void
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pty_make_controlling_tty(int *ttyfd, const char *tty)
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{
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int fd;
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#ifdef _UNICOS
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if (setsid() < 0)
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error("setsid: %.100s", strerror(errno));
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fd = open(tty, O_RDWR|O_NOCTTY);
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if (fd != -1) {
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signal(SIGHUP, SIG_IGN);
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ioctl(fd, TCVHUP, (char *)NULL);
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signal(SIGHUP, SIG_DFL);
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setpgid(0, 0);
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close(fd);
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} else {
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error("Failed to disconnect from controlling tty.");
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}
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debug("Setting controlling tty using TCSETCTTY.");
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ioctl(*ttyfd, TCSETCTTY, NULL);
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fd = open("/dev/tty", O_RDWR);
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if (fd < 0)
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error("%.100s: %.100s", tty, strerror(errno));
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close(*ttyfd);
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*ttyfd = fd;
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#else /* _UNICOS */
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/* First disconnect from the old controlling tty. */
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#ifdef TIOCNOTTY
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fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
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if (fd >= 0) {
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(void) ioctl(fd, TIOCNOTTY, NULL);
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close(fd);
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}
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#endif /* TIOCNOTTY */
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if (setsid() < 0)
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error("setsid: %.100s", strerror(errno));
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/*
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* Verify that we are successfully disconnected from the controlling
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* tty.
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*/
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fd = open(_PATH_TTY, O_RDWR | O_NOCTTY);
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if (fd >= 0) {
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error("Failed to disconnect from controlling tty.");
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close(fd);
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}
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/* Make it our controlling tty. */
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#ifdef TIOCSCTTY
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debug("Setting controlling tty using TIOCSCTTY.");
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if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0)
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error("ioctl(TIOCSCTTY): %.100s", strerror(errno));
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#endif /* TIOCSCTTY */
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#ifdef NEED_SETPGRP
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if (setpgrp(0,0) < 0)
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error("SETPGRP %s",strerror(errno));
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#endif /* NEED_SETPGRP */
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fd = open(tty, O_RDWR);
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if (fd < 0)
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error("%.100s: %.100s", tty, strerror(errno));
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else
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close(fd);
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/* Verify that we now have a controlling tty. */
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fd = open(_PATH_TTY, O_WRONLY);
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if (fd < 0)
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error("open /dev/tty failed - could not set controlling tty: %.100s",
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strerror(errno));
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else
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close(fd);
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#endif /* _UNICOS */
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}
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/* Changes the window size associated with the pty. */
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void
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pty_change_window_size(int ptyfd, u_int row, u_int col,
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u_int xpixel, u_int ypixel)
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{
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struct winsize w;
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/* may truncate u_int -> u_short */
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w.ws_row = row;
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w.ws_col = col;
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w.ws_xpixel = xpixel;
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w.ws_ypixel = ypixel;
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(void) ioctl(ptyfd, TIOCSWINSZ, &w);
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}
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void
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pty_setowner(struct passwd *pw, const char *tty)
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{
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struct group *grp;
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gid_t gid;
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mode_t mode;
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struct stat st;
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/* Determine the group to make the owner of the tty. */
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grp = getgrnam("tty");
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gid = (grp != NULL) ? grp->gr_gid : pw->pw_gid;
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mode = (grp != NULL) ? 0620 : 0600;
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/*
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* Change owner and mode of the tty as required.
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* Warn but continue if filesystem is read-only and the uids match/
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* tty is owned by root.
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*/
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if (stat(tty, &st))
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fatal("stat(%.100s) failed: %.100s", tty,
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strerror(errno));
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#ifdef WITH_SELINUX
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ssh_selinux_setup_pty(pw->pw_name, tty);
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#endif
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if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
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if (chown(tty, pw->pw_uid, gid) < 0) {
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if (errno == EROFS &&
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(st.st_uid == pw->pw_uid || st.st_uid == 0))
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debug("chown(%.100s, %u, %u) failed: %.100s",
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tty, (u_int)pw->pw_uid, (u_int)gid,
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strerror(errno));
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else
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fatal("chown(%.100s, %u, %u) failed: %.100s",
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tty, (u_int)pw->pw_uid, (u_int)gid,
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strerror(errno));
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}
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}
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if ((st.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) != mode) {
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if (chmod(tty, mode) < 0) {
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if (errno == EROFS &&
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(st.st_mode & (S_IRGRP | S_IROTH)) == 0)
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debug("chmod(%.100s, 0%o) failed: %.100s",
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tty, (u_int)mode, strerror(errno));
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else
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fatal("chmod(%.100s, 0%o) failed: %.100s",
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tty, (u_int)mode, strerror(errno));
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}
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}
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}
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/* Disconnect from the controlling tty. */
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void
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disconnect_controlling_tty(void)
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{
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#ifdef TIOCNOTTY
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int fd;
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if ((fd = open(_PATH_TTY, O_RDWR | O_NOCTTY)) >= 0) {
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(void) ioctl(fd, TIOCNOTTY, NULL);
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close(fd);
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}
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#endif /* TIOCNOTTY */
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}
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