413 lines
10 KiB
C
Executable File
413 lines
10 KiB
C
Executable File
/*
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* Dropbear - a SSH2 server
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*
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* Copied from OpenSSH-3.5p1 source, modified by Matt Johnston 2003
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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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/*RCSID("OpenBSD: sshpty.c,v 1.7 2002/06/24 17:57:20 deraadt Exp ");*/
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#include "includes.h"
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#include "dbutil.h"
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#include "errno.h"
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#include "sshpty.h"
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/* Pty allocated with _getpty gets broken if we do I_PUSH:es to it. */
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#if defined(HAVE__GETPTY) || defined(HAVE_OPENPTY)
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#undef HAVE_DEV_PTMX
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#endif
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#ifdef HAVE_PTY_H
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# include <pty.h>
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#endif
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#if defined(USE_DEV_PTMX) && defined(HAVE_STROPTS_H)
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# include <stropts.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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/*
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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, int namebuflen)
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{
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#if defined(HAVE_OPENPTY)
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/* exists in recent (4.4) BSDs and OSF/1 */
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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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dropbear_log(LOG_WARNING,
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"pty_allocate: 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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dropbear_exit("ttyname fails for openpty device");
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}
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strlcpy(namebuf, name, namebuflen); /* possible truncation */
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return 1;
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#else /* HAVE_OPENPTY */
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#ifdef HAVE__GETPTY
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/*
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* _getpty(3) exists in SGI Irix 4.x, 5.x & 6.x -- it generates more
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* pty's automagically when needed
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*/
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char *slave;
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slave = _getpty(ptyfd, O_RDWR, 0622, 0);
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if (slave == NULL) {
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dropbear_log(LOG_WARNING,
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"pty_allocate: _getpty: %.100s", strerror(errno));
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return 0;
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}
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strlcpy(namebuf, slave, namebuflen);
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/* Open the slave side. */
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*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
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if (*ttyfd < 0) {
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dropbear_log(LOG_WARNING,
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"pty_allocate error: ttyftd open error");
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close(*ptyfd);
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return 0;
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}
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return 1;
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#else /* HAVE__GETPTY */
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#if defined(USE_DEV_PTMX)
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/*
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* This code is used e.g. on Solaris 2.x. (Note that Solaris 2.3
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* also has bsd-style ptys, but they simply do not work.)
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*
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* Linux systems may have the /dev/ptmx device, but this code won't work.
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*/
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int ptm;
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char *pts;
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ptm = open("/dev/ptmx", O_RDWR | O_NOCTTY);
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if (ptm < 0) {
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dropbear_log(LOG_WARNING,
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"pty_allocate: /dev/ptmx: %.100s", strerror(errno));
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return 0;
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}
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if (grantpt(ptm) < 0) {
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dropbear_log(LOG_WARNING,
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"grantpt: %.100s", strerror(errno));
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return 0;
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}
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if (unlockpt(ptm) < 0) {
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dropbear_log(LOG_WARNING,
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"unlockpt: %.100s", strerror(errno));
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return 0;
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}
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pts = ptsname(ptm);
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if (pts == NULL) {
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dropbear_log(LOG_WARNING,
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"Slave pty side name could not be obtained.");
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}
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strlcpy(namebuf, pts, namebuflen);
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*ptyfd = ptm;
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/* Open the slave side. */
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*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
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if (*ttyfd < 0) {
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dropbear_log(LOG_ERR,
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"error opening pts %.100s: %.100s", namebuf, strerror(errno));
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close(*ptyfd);
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return 0;
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}
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#ifndef HAVE_CYGWIN
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/*
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* Push the appropriate streams modules, as described in Solaris pts(7).
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* HP-UX pts(7) doesn't have ttcompat module.
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*/
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if (ioctl(*ttyfd, I_PUSH, "ptem") < 0) {
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dropbear_log(LOG_WARNING,
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"ioctl I_PUSH ptem: %.100s", strerror(errno));
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}
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if (ioctl(*ttyfd, I_PUSH, "ldterm") < 0) {
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dropbear_log(LOG_WARNING,
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"ioctl I_PUSH ldterm: %.100s", strerror(errno));
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}
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#ifndef __hpux
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if (ioctl(*ttyfd, I_PUSH, "ttcompat") < 0) {
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dropbear_log(LOG_WARNING,
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"ioctl I_PUSH ttcompat: %.100s", strerror(errno));
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}
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#endif
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#endif
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return 1;
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#else /* USE_DEV_PTMX */
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#ifdef HAVE_DEV_PTS_AND_PTC
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/* AIX-style pty code. */
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const char *name;
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*ptyfd = open("/dev/ptc", O_RDWR | O_NOCTTY);
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if (*ptyfd < 0) {
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dropbear_log(LOG_ERR,
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"Could not open /dev/ptc: %.100s", strerror(errno));
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return 0;
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}
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name = ttyname(*ptyfd);
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if (!name) {
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dropbear_exit("ttyname fails for /dev/ptc device");
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}
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strlcpy(namebuf, name, namebuflen);
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*ttyfd = open(name, O_RDWR | O_NOCTTY);
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if (*ttyfd < 0) {
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dropbear_log(LOG_ERR,
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"Could not open pty slave side %.100s: %.100s",
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name, strerror(errno));
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close(*ptyfd);
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return 0;
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}
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return 1;
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#else /* HAVE_DEV_PTS_AND_PTC */
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/* BSD-style pty code. */
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char buf[64];
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int i;
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const char *ptymajors = "pqrstuvwxyzabcdefghijklmnoABCDEFGHIJKLMNOPQRSTUVWXYZ";
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const char *ptyminors = "0123456789abcdef";
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int num_minors = strlen(ptyminors);
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int num_ptys = strlen(ptymajors) * num_minors;
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struct termios tio;
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for (i = 0; i < num_ptys; i++) {
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snprintf(buf, sizeof buf, "/dev/pty%c%c", ptymajors[i / num_minors],
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ptyminors[i % num_minors]);
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snprintf(namebuf, namebuflen, "/dev/tty%c%c",
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ptymajors[i / num_minors], ptyminors[i % num_minors]);
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*ptyfd = open(buf, O_RDWR | O_NOCTTY);
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if (*ptyfd < 0) {
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/* Try SCO style naming */
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snprintf(buf, sizeof buf, "/dev/ptyp%d", i);
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snprintf(namebuf, namebuflen, "/dev/ttyp%d", i);
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*ptyfd = open(buf, O_RDWR | O_NOCTTY);
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if (*ptyfd < 0) {
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continue;
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}
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}
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/* Open the slave side. */
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*ttyfd = open(namebuf, O_RDWR | O_NOCTTY);
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if (*ttyfd < 0) {
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dropbear_log(LOG_ERR,
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"pty_allocate: %.100s: %.100s", namebuf, strerror(errno));
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close(*ptyfd);
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return 0;
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}
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/* set tty modes to a sane state for broken clients */
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if (tcgetattr(*ptyfd, &tio) < 0) {
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dropbear_log(LOG_WARNING,
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"ptyallocate: tty modes failed: %.100s", strerror(errno));
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} else {
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tio.c_lflag |= (ECHO | ISIG | ICANON);
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tio.c_oflag |= (OPOST | ONLCR);
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tio.c_iflag |= ICRNL;
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/* Set the new modes for the terminal. */
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if (tcsetattr(*ptyfd, TCSANOW, &tio) < 0) {
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dropbear_log(LOG_WARNING,
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"Setting tty modes for pty failed: %.100s",
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strerror(errno));
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}
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}
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return 1;
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}
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dropbear_log(LOG_WARNING, "failed to open any /dev/pty?? devices");
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return 0;
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#endif /* HAVE_DEV_PTS_AND_PTC */
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#endif /* USE_DEV_PTMX */
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#endif /* HAVE__GETPTY */
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#endif /* HAVE_OPENPTY */
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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_name)
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{
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if (chown(tty_name, (uid_t) 0, (gid_t) 0) < 0
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&& (errno != ENOENT)) {
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dropbear_log(LOG_ERR,
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"chown %.100s 0 0 failed: %.100s", tty_name, strerror(errno));
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}
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if (chmod(tty_name, (mode_t) 0666) < 0
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&& (errno != ENOENT)) {
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dropbear_log(LOG_ERR,
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"chmod %.100s 0666 failed: %.100s", tty_name, strerror(errno));
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}
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}
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/* Makes the tty the processes 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_name)
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{
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int fd;
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#ifdef USE_VHANGUP
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void *old;
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#endif /* USE_VHANGUP */
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/* Solaris has a problem with TIOCNOTTY for a bg process, so
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* we disable the signal which would STOP the process - matt */
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signal(SIGTTOU, SIG_IGN);
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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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dropbear_log(LOG_ERR,
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"setsid: %.100s", strerror(errno));
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}
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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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dropbear_log(LOG_ERR,
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"Failed to disconnect from controlling tty.\n");
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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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if (ioctl(*ttyfd, TIOCSCTTY, NULL) < 0) {
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dropbear_log(LOG_ERR,
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"ioctl(TIOCSCTTY): %.100s", strerror(errno));
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}
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#endif /* TIOCSCTTY */
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#ifdef HAVE_NEWS4
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if (setpgrp(0,0) < 0) {
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dropbear_log(LOG_ERR,
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error("SETPGRP %s",strerror(errno)));
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}
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#endif /* HAVE_NEWS4 */
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#ifdef USE_VHANGUP
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old = mysignal(SIGHUP, SIG_IGN);
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vhangup();
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mysignal(SIGHUP, old);
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#endif /* USE_VHANGUP */
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fd = open(tty_name, O_RDWR);
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if (fd < 0) {
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dropbear_log(LOG_ERR,
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"%.100s: %.100s", tty_name, strerror(errno));
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} else {
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#ifdef USE_VHANGUP
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close(*ttyfd);
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*ttyfd = fd;
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#else /* USE_VHANGUP */
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close(fd);
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#endif /* USE_VHANGUP */
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}
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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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dropbear_log(LOG_ERR,
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"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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}
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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, int row, int col,
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int xpixel, int ypixel)
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{
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struct winsize w;
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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_name)
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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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if (grp) {
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gid = grp->gr_gid;
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mode = S_IRUSR | S_IWUSR | S_IWGRP;
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} else {
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gid = pw->pw_gid;
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mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;
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}
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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_name, &st)) {
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dropbear_exit("pty_setowner: stat(%.101s) failed: %.100s",
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tty_name, strerror(errno));
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}
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if (st.st_uid != pw->pw_uid || st.st_gid != gid) {
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if (chown(tty_name, 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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dropbear_log(LOG_ERR,
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"chown(%.100s, %u, %u) failed: %.100s",
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tty_name, (unsigned int)pw->pw_uid, (unsigned int)gid,
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strerror(errno));
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} else {
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dropbear_exit("chown(%.100s, %u, %u) failed: %.100s",
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tty_name, (unsigned int)pw->pw_uid, (unsigned int)gid,
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strerror(errno));
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}
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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_name, 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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dropbear_log(LOG_ERR,
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"chmod(%.100s, 0%o) failed: %.100s",
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tty_name, mode, strerror(errno));
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} else {
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dropbear_exit("chmod(%.100s, 0%o) failed: %.100s",
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tty_name, mode, strerror(errno));
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}
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}
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}
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}
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