/*
    This file is part of the KDE libraries
    SPDX-FileCopyrightText: 2002 Waldo Bastian <bastian@kde.org>
    SPDX-FileCopyrightText: 2002-2003, 2007-2008 Oswald Buddenhagen <ossi@kde.org>
    SPDX-FileCopyrightText: 2010 KDE e.V. <kde-ev-board@kde.org>
    SPDX-FileContributor: 2010 Adriaan de Groot <groot@kde.org>

    SPDX-License-Identifier: LGPL-2.0-or-later
*/

#include "kpty_p.h"

#include <kpty_debug.h>
#include <QProcess>

#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 HAVE_PTY_H
# include <pty.h>
#endif

#if HAVE_LIBUTIL_H
# include <libutil.h>
#elif HAVE_UTIL_H
# include <util.h>
#endif

#ifdef UTEMPTER_PATH
// utempter uses 'add' and 'del' whereas ulog-helper uses 'login' and 'logout'
#  ifndef UTEMPTER_ULOG
#    define UTEMPTER_ADD "add"
#    define UTEMPTER_DEL "del"
#  else
#    define UTEMPTER_ADD "login"
#    define UTEMPTER_DEL "logout"
#  endif
class UtemptProcess : public QProcess
{
public:
    void setupChildProcess() override
    {
        // These are the file descriptors the utempter helper wants
        dup2(cmdFd, 0);
        dup2(cmdFd, 1);
        dup2(cmdFd, 3);
    }
    int cmdFd;
};
#else
# include <utmp.h>
# if 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 HAVE_TERMIO_H
# include <termio.h> // struct winsize on some systems
#endif
}

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

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

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

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

#include <qplatformdefs.h>

#include <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)
{
#ifdef UTEMPTER_PATH
    utempterPath = QStringLiteral(UTEMPTER_PATH);
#endif
}

KPtyPrivate::~KPtyPrivate()
{
}

#if ! HAVE_OPENPTY
bool KPtyPrivate::chownpty(bool grant)
{
    return !QProcess::execute(QFile::decodeName(CMAKE_INSTALL_PREFIX "/" KF5_LIBEXEC_INSTALL_DIR "/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.

#if HAVE_OPENPTY

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

#else

#if 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 HAVE_PTSNAME || defined(TIOCGPTN)

#if HAVE_POSIX_OPENPT
    d->masterFd = ::posix_openpt(O_RDWR | O_NOCTTY);
#elif HAVE_GETPT
    d->masterFd = ::getpt();
#elif defined(PTM_DEVICE)
    d->masterFd = QT_OPEN(PTM_DEVICE, QT_OPEN_RDWR | O_NOCTTY);
#else
# error No method to open a PTY master detected.
#endif
    if (d->masterFd >= 0) {
#if 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
#if 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).toLatin1();
            d->ttyName = QString().sprintf("/dev/tty%c%c", *s3, *s4).toLatin1();

            d->masterFd = QT_OPEN(ptyName.data(), QT_OPEN_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;
            }
        }
    }

    qCWarning(KPTY_LOG) << "Can't open a pseudo teletype";
    return false;

gotpty:
    QFileInfo info(d->ttyName.data());
    if (!info.exists()) {
        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 (((info.ownerId() != getuid()) ||
            (info.permissions() & (QFile::ReadGroup | QFile::ExeGroup | QFile::ReadOther | QFile::WriteOther | QFile::ExeOther))) &&
            !d->chownpty(true)) {
        qCWarning(KPTY_LOG)
                << "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 = QT_OPEN(d->ttyName.data(), QT_OPEN_RDWR | O_NOCTTY);
    if (d->slaveFd < 0) {
        qCWarning(KPTY_LOG) << "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 !HAVE_PTSNAME && !defined(TIOCGPTN)
    qCWarning(KPTY_LOG) << "Unsupported attempt to open pty with fd" << fd;
    return false;
#else
    Q_D(KPty);

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

    d->ownMaster = false;

# if 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 {
        qCWarning(KPTY_LOG) << "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) {
        qCWarning(KPTY_LOG) << "Attempting to open pty slave while master is closed";
        return false;
    }
    d->slaveFd = QT_OPEN(d->ttyName.data(), QT_OPEN_RDWR | O_NOCTTY);
    if (d->slaveFd < 0) {
        qCWarning(KPTY_LOG) << "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) {
#if ! 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 UTEMPTER_PATH
    Q_D(KPty);

    Q_UNUSED(user);

    // Emulating libutempter version 1.1.6
    if (!d->utempterPath.isEmpty()) {
        UtemptProcess utemptProcess;
        utemptProcess.cmdFd = d->masterFd;
        utemptProcess.setProgram(d->utempterPath);
        utemptProcess.setArguments(QStringList() << QStringLiteral(UTEMPTER_ADD) << QString::fromLocal8Bit(remotehost));
        utemptProcess.setProcessChannelMode(QProcess::ForwardedChannels);
        utemptProcess.start();
        utemptProcess.waitForFinished();
    }

#else
# if 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));
# if 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));
#  if 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

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

# if HAVE_LOGIN
#  if HAVE_LOGINX
    ::loginx(&l_struct);
#  else
    ::login(&l_struct);
#  endif
# else
#  if HAVE_STRUCT_UTMP_UT_TYPE
    l_struct.ut_type = USER_PROCESS;
#  endif
#  if HAVE_STRUCT_UTMP_UT_PID
    l_struct.ut_pid = getpid();
#   if HAVE_STRUCT_UTMP_UT_SESSION
    l_struct.ut_session = getsid(0);
#   endif
#  endif
#  if 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 UTEMPTER_PATH
    Q_D(KPty);

    // Emulating libutempter version 1.1.6
    if (!d->utempterPath.isEmpty()) {
        UtemptProcess utemptProcess;
        utemptProcess.cmdFd = d->masterFd;
        utemptProcess.setProgram(d->utempterPath);
        utemptProcess.setArguments(QStringList(QStringLiteral(UTEMPTER_DEL)));
        utemptProcess.setProcessChannelMode(QProcess::ForwardedChannels);
        utemptProcess.start();
        utemptProcess.waitForFinished();
    }

#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
# if HAVE_LOGIN
#  if HAVE_LOGINX
    ::logoutx(str_ptr, 0, DEAD_PROCESS);
#  else
    ::logout(str_ptr);
#  endif
# else
#  if 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));

#  if 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));
#  if HAVE_STRUCT_UTMP_UT_SYSLEN
        ut->ut_syslen = 0;
#  endif
#  if HAVE_STRUCT_UTMP_UT_TYPE
        ut->ut_type = DEAD_PROCESS;
#  endif
#  if 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;
}
