kpty.cpp

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/*

   This file is part of the KDE libraries
   Copyright (C) 2002 Waldo Bastian <bastian@kde.org>
   Copyright (C) 2002-2003,2007-2008 Oswald Buddenhagen <ossi@kde.org>
   Copyright (C) 2010 KDE e.V. <kde-ev-board@kde.org>
     Author Adriaan de Groot <groot@kde.org>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
   Boston, MA 02110-1301, USA.
*/

#include "kpty_p.h"

#include <config.h>

#ifdef __sgi
#define __svr4__
#endif

#ifdef __osf__
#define _OSF_SOURCE
#include <float.h>
#endif

#ifdef _AIX
#define _ALL_SOURCE
#endif

// __USE_XOPEN isn't defined by default in ICC
// (needed for ptsname(), grantpt() and unlockpt())
#ifdef __INTEL_COMPILER
#  ifndef __USE_XOPEN
#    define __USE_XOPEN
#  endif
#endif

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/param.h>

#include <errno.h>
#include <fcntl.h>
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <grp.h>

#if defined(HAVE_PTY_H)
# include <pty.h>
#endif

#ifdef HAVE_LIBUTIL_H
# include <libutil.h>
#elif defined(HAVE_UTIL_H)
# include <util.h>
#endif

#ifdef HAVE_UTEMPTER
extern "C" {
# include <utempter.h>
}
#else
# include <utmp.h>
# ifdef HAVE_UTMPX
#  include <utmpx.h>
# endif
# if !defined(_PATH_UTMPX) && defined(_UTMPX_FILE)
#  define _PATH_UTMPX _UTMPX_FILE
# endif
# if !defined(_PATH_WTMPX) && defined(_WTMPX_FILE)
#  define _PATH_WTMPX _WTMPX_FILE
# endif
#endif

/* for HP-UX (some versions) the extern C is needed, and for other
   platforms it doesn't hurt */
extern "C" {
#include <termios.h>
#if defined(HAVE_TERMIO_H)
# include <termio.h> // struct winsize on some systems
#endif
}

#if defined (_HPUX_SOURCE)
# define _TERMIOS_INCLUDED
# include <bsdtty.h>
#endif

#ifdef HAVE_SYS_STROPTS_H
# include <sys/stropts.h>   // Defines I_PUSH
# define _NEW_TTY_CTRL
#endif

#if defined (__FreeBSD__) || defined (__NetBSD__) || defined (__OpenBSD__) || defined (__bsdi__) || defined(__APPLE__) || defined (__DragonFly__)
# define _tcgetattr(fd, ttmode) ioctl(fd, TIOCGETA, (char *)ttmode)
#else
# if defined(_HPUX_SOURCE) || defined(__Lynx__) || defined (__CYGWIN__) || defined(__sun)
#  define _tcgetattr(fd, ttmode) tcgetattr(fd, ttmode)
# else
#  define _tcgetattr(fd, ttmode) ioctl(fd, TCGETS, (char *)ttmode)
# endif
#endif

#if defined (__FreeBSD__) || defined (__NetBSD__) || defined (__OpenBSD__) || defined (__bsdi__) || defined(__APPLE__) || defined (__DragonFly__)
# define _tcsetattr(fd, ttmode) ioctl(fd, TIOCSETA, (char *)ttmode)
#else
# if defined(_HPUX_SOURCE) || defined(__CYGWIN__) || defined(__sun)
#  define _tcsetattr(fd, ttmode) tcsetattr(fd, TCSANOW, ttmode)
# else
#  define _tcsetattr(fd, ttmode) ioctl(fd, TCSETS, (char *)ttmode)
# endif
#endif

#include <kdebug.h>
#include <kstandarddirs.h>  // findExe
#include <kde_file.h>

#include <QtCore/Q_PID>

#define TTY_GROUP "tty"

#ifndef PATH_MAX
# ifdef MAXPATHLEN
#  define PATH_MAX MAXPATHLEN
# else
#  define PATH_MAX 1024
# endif
#endif

// private functions //

// private data //

KPtyPrivate::KPtyPrivate(KPty* parent) :
    masterFd(-1), slaveFd(-1), ownMaster(true), q_ptr(parent)
{
}

KPtyPrivate::~KPtyPrivate()
{
}

#ifndef HAVE_OPENPTY
bool KPtyPrivate::chownpty(bool grant)
{
    return !QProcess::execute(KStandardDirs::findExe("kgrantpty"),
        QStringList() << (grant?"--grant":"--revoke") << QString::number(masterFd));
}
#endif

// public member functions //

KPty::KPty() :
    d_ptr(new KPtyPrivate(this))
{
}

KPty::KPty(KPtyPrivate *d) :
    d_ptr(d)
{
    d_ptr->q_ptr = this;
}

KPty::~KPty()
{
    close();
    delete d_ptr;
}

bool KPty::open()
{
  Q_D(KPty);

  if (d->masterFd >= 0)
    return true;

  d->ownMaster = true;

  QByteArray ptyName;

  // Find a master pty that we can open ////////////////////////////////

  // Because not all the pty animals are created equal, they want to
  // be opened by several different methods.

  // We try, as we know them, one by one.

#ifdef HAVE_OPENPTY

  char ptsn[PATH_MAX];
  if (::openpty( &d->masterFd, &d->slaveFd, ptsn, 0, 0))
  {
    d->masterFd = -1;
    d->slaveFd = -1;
    kWarning(175) << "Can't open a pseudo teletype";
    return false;
  }
  d->ttyName = ptsn;

#else

#ifdef HAVE__GETPTY // irix

  char *ptsn = _getpty(&d->masterFd, O_RDWR|O_NOCTTY, S_IRUSR|S_IWUSR, 0);
  if (ptsn) {
    d->ttyName = ptsn;
    goto grantedpt;
  }

#elif defined(HAVE_PTSNAME) || defined(TIOCGPTN)

#ifdef HAVE_POSIX_OPENPT
  d->masterFd = ::posix_openpt(O_RDWR|O_NOCTTY);
#elif defined(HAVE_GETPT)
  d->masterFd = ::getpt();
#elif defined(PTM_DEVICE)
  d->masterFd = KDE_open(PTM_DEVICE, O_RDWR|O_NOCTTY);
#else
# error No method to open a PTY master detected.
#endif
  if (d->masterFd >= 0)
  {
#ifdef HAVE_PTSNAME
    char *ptsn = ptsname(d->masterFd);
    if (ptsn) {
        d->ttyName = ptsn;
#else
    int ptyno;
    if (!ioctl(d->masterFd, TIOCGPTN, &ptyno)) {
        char buf[32];
        sprintf(buf, "/dev/pts/%d", ptyno);
        d->ttyName = buf;
#endif
#ifdef HAVE_GRANTPT
        if (!grantpt(d->masterFd))
           goto grantedpt;
#else
        goto gotpty;
#endif
    }
    ::close(d->masterFd);
    d->masterFd = -1;
  }
#endif // HAVE_PTSNAME || TIOCGPTN

  // Linux device names, FIXME: Trouble on other systems?
  for (const char* s3 = "pqrstuvwxyzabcde"; *s3; s3++)
  {
    for (const char* s4 = "0123456789abcdef"; *s4; s4++)
    {
      ptyName = QString().sprintf("/dev/pty%c%c", *s3, *s4).toAscii();
      d->ttyName = QString().sprintf("/dev/tty%c%c", *s3, *s4).toAscii();

      d->masterFd = KDE_open(ptyName.data(), O_RDWR);
      if (d->masterFd >= 0)
      {
#ifdef Q_OS_SOLARIS
        /* Need to check the process group of the pty.
         * If it exists, then the slave pty is in use,
         * and we need to get another one.
         */
        int pgrp_rtn;
        if (ioctl(d->masterFd, TIOCGPGRP, &pgrp_rtn) == 0 || errno != EIO) {
          ::close(d->masterFd);
          d->masterFd = -1;
          continue;
        }
#endif /* Q_OS_SOLARIS */
        if (!access(d->ttyName.data(),R_OK|W_OK)) // checks availability based on permission bits
        {
          if (!geteuid())
          {
            struct group* p = getgrnam(TTY_GROUP);
            if (!p)
              p = getgrnam("wheel");
            gid_t gid = p ? p->gr_gid : getgid ();

            chown(d->ttyName.data(), getuid(), gid);
            chmod(d->ttyName.data(), S_IRUSR|S_IWUSR|S_IWGRP);
          }
          goto gotpty;
        }
        ::close(d->masterFd);
        d->masterFd = -1;
      }
    }
  }

  kWarning(175) << "Can't open a pseudo teletype";
  return false;

 gotpty:
  KDE_struct_stat st;
  if (KDE_stat(d->ttyName.data(), &st))
    return false; // this just cannot happen ... *cough*  Yeah right, I just
                  // had it happen when pty #349 was allocated.  I guess
                  // there was some sort of leak?  I only had a few open.
  if (((st.st_uid != getuid()) ||
       (st.st_mode & (S_IRGRP|S_IXGRP|S_IROTH|S_IWOTH|S_IXOTH))) &&
      !d->chownpty(true))
  {
    kWarning(175)
      << "chownpty failed for device " << ptyName << "::" << d->ttyName
      << "\nThis means the communication can be eavesdropped." << endl;
  }

 grantedpt:

#ifdef HAVE_REVOKE
  revoke(d->ttyName.data());
#endif

#ifdef HAVE_UNLOCKPT
  unlockpt(d->masterFd);
#elif defined(TIOCSPTLCK)
  int flag = 0;
  ioctl(d->masterFd, TIOCSPTLCK, &flag);
#endif

  d->slaveFd = KDE_open(d->ttyName.data(), O_RDWR | O_NOCTTY);
  if (d->slaveFd < 0)
  {
    kWarning(175) << "Can't open slave pseudo teletype";
    ::close(d->masterFd);
    d->masterFd = -1;
    return false;
  }

#if (defined(__svr4__) || defined(__sgi__) || defined(Q_OS_SOLARIS))
  // Solaris uses STREAMS for terminal handling. It is possible
  // for the pty handling modules to be left off the stream; in that
  // case push them on. ioctl(fd, I_FIND, ...) is documented to return
  // 1 if the module is on the stream already.
  {
    static const char *pt = "ptem";
    static const char *ld = "ldterm";
    if (ioctl(d->slaveFd, I_FIND, pt) == 0)
      ioctl(d->slaveFd, I_PUSH, pt);
    if (ioctl(d->slaveFd, I_FIND, ld) == 0)
      ioctl(d->slaveFd, I_PUSH, ld);
  }
#endif

#endif /* HAVE_OPENPTY */

  fcntl(d->masterFd, F_SETFD, FD_CLOEXEC);
  fcntl(d->slaveFd, F_SETFD, FD_CLOEXEC);

  return true;
}

bool KPty::open(int fd)
{
#if !defined(HAVE_PTSNAME) && !defined(TIOCGPTN)
    kWarning(175) << "Unsupported attempt to open pty with fd" << fd;
    return false;
#else
    Q_D(KPty);

    if (d->masterFd >= 0) {
        kWarning(175) << "Attempting to open an already open pty";
        return false;
    }

    d->ownMaster = false;

# ifdef HAVE_PTSNAME
    char *ptsn = ptsname(fd);
    if (ptsn) {
        d->ttyName = ptsn;
# else
    int ptyno;
    if (!ioctl(fd, TIOCGPTN, &ptyno)) {
        char buf[32];
        sprintf(buf, "/dev/pts/%d", ptyno);
        d->ttyName = buf;
# endif
    } else {
        kWarning(175) << "Failed to determine pty slave device for fd" << fd;
        return false;
    }

    d->masterFd = fd;
    if (!openSlave()) {
        d->masterFd = -1;
        return false;
    }

    return true;
#endif
}

void KPty::closeSlave()
{
    Q_D(KPty);

    if (d->slaveFd < 0)
        return;
    ::close(d->slaveFd);
    d->slaveFd = -1;
}

bool KPty::openSlave()
{
    Q_D(KPty);

    if (d->slaveFd >= 0)
        return true;
    if (d->masterFd < 0) {
        kWarning(175) << "Attempting to open pty slave while master is closed";
        return false;
    }
    d->slaveFd = KDE_open(d->ttyName.data(), O_RDWR | O_NOCTTY);
    if (d->slaveFd < 0) {
        kWarning(175) << "Can't open slave pseudo teletype";
        return false;
    }
    fcntl(d->slaveFd, F_SETFD, FD_CLOEXEC);
    return true;
}

void KPty::close()
{
    Q_D(KPty);

    if (d->masterFd < 0)
        return;
    closeSlave();
    if (d->ownMaster) {
#ifndef HAVE_OPENPTY
        // don't bother resetting unix98 pty, it will go away after closing master anyway.
        if (memcmp(d->ttyName.data(), "/dev/pts/", 9)) {
            if (!geteuid()) {
                struct stat st;
                if (!stat(d->ttyName.data(), &st)) {
                    chown(d->ttyName.data(), 0, st.st_gid == getgid() ? 0 : -1);
                    chmod(d->ttyName.data(), S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH);
                }
            } else {
                fcntl(d->masterFd, F_SETFD, 0);
                d->chownpty(false);
            }
        }
#endif
        ::close(d->masterFd);
    }
    d->masterFd = -1;
}

void KPty::setCTty()
{
    Q_D(KPty);

    // Setup job control //////////////////////////////////

    // Become session leader, process group leader,
    // and get rid of the old controlling terminal.
    setsid();

    // make our slave pty the new controlling terminal.
#ifdef TIOCSCTTY
    ioctl(d->slaveFd, TIOCSCTTY, 0);
#else
    // __svr4__ hack: the first tty opened after setsid() becomes controlling tty
    ::close(KDE_open(d->ttyName, O_WRONLY, 0));
#endif

    // make our new process group the foreground group on the pty
    int pgrp = getpid();
#if defined(_POSIX_VERSION) || defined(__svr4__)
    tcsetpgrp(d->slaveFd, pgrp);
#elif defined(TIOCSPGRP)
    ioctl(d->slaveFd, TIOCSPGRP, (char *)&pgrp);
#endif
}

void KPty::login(const char *user, const char *remotehost)
{
#ifdef HAVE_UTEMPTER
    Q_D(KPty);

    addToUtmp(d->ttyName, remotehost, d->masterFd);
    Q_UNUSED(user);
#else
# ifdef HAVE_UTMPX
    struct utmpx l_struct;
# else
    struct utmp l_struct;
# endif
    memset(&l_struct, 0, sizeof(l_struct));
    // note: strncpy without terminators _is_ correct here. man 4 utmp

    if (user)
      strncpy(l_struct.ut_name, user, sizeof(l_struct.ut_name));

    if (remotehost) {
      strncpy(l_struct.ut_host, remotehost, sizeof(l_struct.ut_host));
# ifdef HAVE_STRUCT_UTMP_UT_SYSLEN
      l_struct.ut_syslen = qMin(strlen(remotehost), sizeof(l_struct.ut_host));
# endif
    }

# ifndef __GLIBC__
    Q_D(KPty);
    const char *str_ptr = d->ttyName.data();
    if (!memcmp(str_ptr, "/dev/", 5))
        str_ptr += 5;
    strncpy(l_struct.ut_line, str_ptr, sizeof(l_struct.ut_line));
#  ifdef HAVE_STRUCT_UTMP_UT_ID
    strncpy(l_struct.ut_id,
            str_ptr + strlen(str_ptr) - sizeof(l_struct.ut_id),
            sizeof(l_struct.ut_id));
#  endif
# endif

# ifdef HAVE_UTMPX
    gettimeofday(&l_struct.ut_tv, 0);
# else
    l_struct.ut_time = time(0);
# endif

# ifdef HAVE_LOGIN
#  ifdef HAVE_LOGINX
    ::loginx(&l_struct);
#  else
    ::login(&l_struct);
#  endif
# else
#  ifdef HAVE_STRUCT_UTMP_UT_TYPE
    l_struct.ut_type = USER_PROCESS;
#  endif
#  ifdef HAVE_STRUCT_UTMP_UT_PID
    l_struct.ut_pid = getpid();
#   ifdef HAVE_STRUCT_UTMP_UT_SESSION
    l_struct.ut_session = getsid(0);
#   endif
#  endif
#  ifdef HAVE_UTMPX
    utmpxname(_PATH_UTMPX);
    setutxent();
    pututxline(&l_struct);
    endutxent();
    updwtmpx(_PATH_WTMPX, &l_struct);
#  else
    utmpname(_PATH_UTMP);
    setutent();
    pututline(&l_struct);
    endutent();
    updwtmp(_PATH_WTMP, &l_struct);
#  endif
# endif
#endif
}

void KPty::logout()
{
#ifdef HAVE_UTEMPTER
    Q_D(KPty);

    removeLineFromUtmp(d->ttyName, d->masterFd);
#else
    Q_D(KPty);

    const char *str_ptr = d->ttyName.data();
    if (!memcmp(str_ptr, "/dev/", 5))
        str_ptr += 5;
# ifdef __GLIBC__
    else {
        const char *sl_ptr = strrchr(str_ptr, '/');
        if (sl_ptr)
            str_ptr = sl_ptr + 1;
    }
# endif
# ifdef HAVE_LOGIN
#  ifdef HAVE_LOGINX
    ::logoutx(str_ptr, 0, DEAD_PROCESS);
#  else
    ::logout(str_ptr);
#  endif
# else
#  ifdef HAVE_UTMPX
    struct utmpx l_struct, *ut;
#  else
    struct utmp l_struct, *ut;
#  endif
    memset(&l_struct, 0, sizeof(l_struct));

    strncpy(l_struct.ut_line, str_ptr, sizeof(l_struct.ut_line));

#  ifdef HAVE_UTMPX
    utmpxname(_PATH_UTMPX);
    setutxent();
    if ((ut = getutxline(&l_struct))) {
#  else
    utmpname(_PATH_UTMP);
    setutent();
    if ((ut = getutline(&l_struct))) {
#  endif
        memset(ut->ut_name, 0, sizeof(*ut->ut_name));
        memset(ut->ut_host, 0, sizeof(*ut->ut_host));
#  ifdef HAVE_STRUCT_UTMP_UT_SYSLEN
        ut->ut_syslen = 0;
#  endif
#  ifdef HAVE_STRUCT_UTMP_UT_TYPE
        ut->ut_type = DEAD_PROCESS;
#  endif
#  ifdef HAVE_UTMPX
        gettimeofday(&(ut->ut_tv), 0);
        pututxline(ut);
    }
    endutxent();
#  else
        ut->ut_time = time(0);
        pututline(ut);
    }
    endutent();
#  endif
# endif
#endif
}

bool KPty::tcGetAttr(struct ::termios *ttmode) const
{
    Q_D(const KPty);

#ifdef Q_OS_SOLARIS
    if (_tcgetattr(d->slaveFd, ttmode) == 0) return true;
#endif
    return _tcgetattr(d->masterFd, ttmode) == 0;
}

bool KPty::tcSetAttr(struct ::termios *ttmode)
{
    Q_D(KPty);

#ifdef Q_OS_SOLARIS
    if (_tcsetattr(d->slaveFd, ttmode) == 0) return true;
#endif
    return _tcsetattr(d->masterFd, ttmode) == 0;
}

bool KPty::setWinSize(int lines, int columns)
{
    Q_D(KPty);

    struct winsize winSize;
    memset(&winSize, 0, sizeof(winSize));
    winSize.ws_row = (unsigned short)lines;
    winSize.ws_col = (unsigned short)columns;
    return ioctl(d->masterFd, TIOCSWINSZ, (char *)&winSize) == 0;
}

bool KPty::setEcho(bool echo)
{
    struct ::termios ttmode;
    if (!tcGetAttr(&ttmode))
        return false;
    if (!echo)
        ttmode.c_lflag &= ~ECHO;
    else
        ttmode.c_lflag |= ECHO;
    return tcSetAttr(&ttmode);
}

const char *KPty::ttyName() const
{
    Q_D(const KPty);

    return d->ttyName.data();
}

int KPty::masterFd() const
{
    Q_D(const KPty);

    return d->masterFd;
}

int KPty::slaveFd() const
{
    Q_D(const KPty);

    return d->slaveFd;
}