/*  This file is part of the KDE libraries

    SPDX-FileCopyrightText: 2001 Malte Starostik <malte@kde.org>

    Handling of EPS previews SPDX-FileCopyrightText: 2003 Philipp Hullmann <phull@gmx.de>

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

*/

/*  This function gets a path of a DVI, EPS, PS or PDF file and

    produces a PNG-Thumbnail which is stored as a QImage

    The program works as follows

    1. Test if file is a DVI file

    2. Create a child process (1), in which the

       file is to be changed into a PNG

    3. Child-process (1) :

    4. If file is DVI continue with 6

    5. If file is no DVI continue with 9

    6. Create another child process (2), in which the DVI is

       turned into PS using dvips

    7. Parent process (2) :

       Turn the recently created PS file into a PNG file using gs

    8. continue with 10

    9. Turn the PS,PDF or EPS file into a PNG file using gs

    10. Parent process (1)

        store data in a QImage

*/

#ifdef HAVE_CONFIG_H

#include <config.h>

#endif

#include <assert.h>

#include <ctype.h>

#include <stdlib.h>

#include <stdio.h>

#include <unistd.h>

#include <signal.h>

#ifdef HAVE_SYS_SELECT_H

#include <sys/select.h>

#endif

#include <sys/time.h>

#include <sys/wait.h>

#include <fcntl.h>

#include <errno.h>

#include <QColor>

#include <QFile>

#include <QImage>

#include <QVector>

#include "gscreator.h"

#include "dscparse.h"

#include <KPluginFactory>

K_PLUGIN_CLASS_WITH_JSON(GSCreator, "gsthumbnail.json")

Unexecuted instantiation: gsthumbnail_factory::tr(char const*, char const*, int)

Unexecuted instantiation: gsthumbnail_factory::~gsthumbnail_factory()

// This PS snippet will be prepended to the actual file so that only

// the first page is output.

static const char *psprolog =

    "%!PS-Adobe-3.0\n"

    "/.showpage.orig /showpage load def\n"

    "/.showpage.firstonly {\n"

    "    .showpage.orig\n"

    "    quit\n"

    "} def\n"

    "/showpage { .showpage.firstonly } def\n";

// This is the code recommended by Adobe tech note 5002 for including

// EPS files.

static const char *epsprolog =

    "%!PS-Adobe-3.0\n"

    "userdict begin /pagelevel save def /showpage { } def\n"

    "0 setgray 0 setlinecap 1 setlinewidth 0 setlinejoin 10 setmiterlimit\n"

    "[ ] 0 setdash newpath false setoverprint false setstrokeadjust\n";

static const char * gsargs_ps[] = {

    "gs",

    "-sDEVICE=png16m",

    "-sOutputFile=-",

    "-dSAFER",

    "-dPARANOIDSAFER",

    "-dNOPAUSE",

    "-dFirstPage=1",

    "-dLastPage=1",

    "-q",

    "-",

    nullptr, // file name

    "-c",

    "showpage",

    "-c",

    "quit",

    nullptr

};

static const char * gsargs_eps[] = {

    "gs",

    "-sDEVICE=png16m",

    "-sOutputFile=-",

    "-dSAFER",

    "-dPARANOIDSAFER",

    "-dNOPAUSE",

    nullptr, // page size

    nullptr, // resolution

    "-q",

    "-",

    nullptr, // file name

    "-c",

    "pagelevel",

    "-c",

    "restore",

    "-c",

    "end",

    "-c",

    "showpage",

    "-c",

    "quit",

    nullptr

};

static const char *dvipsargs[] = {

    "dvips",

    "-n",

    "1",

    "-q",

    "-o",

    "-",

    nullptr, // file name

    nullptr

};

static bool correctDVI(const QString& filename);

namespace {

  bool got_sig_term = false;

  void handle_sigterm( int ) {

    got_sig_term = true;

  }

}

GSCreator::GSCreator(QObject *parent, const QVariantList &args)

  : KIO::ThumbnailCreator(parent, args)

{

}

KIO::ThumbnailResult GSCreator::create(const KIO::ThumbnailRequest &request)

{

  const QString path = request.url().toLocalFile();

  const int width = request.targetSize().width();

  const int height = request.targetSize().height();

// The code in the loop (when testing whether got_sig_term got set)

// should read some variation of:

//    parentJob()->wasKilled()

//

// Unfortunatelly, that's currently impossible without breaking BIC.

// So we need to catch the signal ourselves.

// Otherwise, on certain funny PS files (for example

// http://www.tjhsst.edu/~Eedanaher/pslife/life.ps )

// gs would run forever after we were dead.

// #### Reconsider for KDE 4 ###

// (24/12/03 - luis_pedro)

//

  typedef void ( *sighandler_t )( int );

  // according to linux's "man signal" the above typedef is a gnu extension

  sighandler_t oldhandler = signal( SIGTERM, handle_sigterm );

  int input[2];

  int output[2];

  int dvipipe[2];

  QByteArray data(1024, '\0');

  bool ok = false;

  // Test if file is DVI

  bool no_dvi =!correctDVI(request.url().toLocalFile());

  if (pipe(input) == -1) {

    return KIO::ThumbnailResult::fail();

  }

  if (pipe(output) == -1) {

    close(input[0]);

    close(input[1]);

    return KIO::ThumbnailResult::fail();

  }

  KDSC dsc;

  endComments = false;

  dsc.setCommentHandler(this);

  if (no_dvi)

  {

    FILE* fp = fopen(QFile::encodeName(path), "r");

    if (fp == nullptr) return KIO::ThumbnailResult::fail();

    char buf[4096];

    int count;

    while ((count = fread(buf, sizeof(char), 4096, fp)) != 0

           && !endComments) {

      dsc.scanData(buf, count);

    }

    fclose(fp);

    if (dsc.pjl() || dsc.ctrld()) {

      // this file is a mess.

      return KIO::ThumbnailResult::fail();

    }

  }

  std::unique_ptr<KDSCBBOX> bbox = dsc.bbox();

  const bool is_encapsulated = no_dvi

    && (path.endsWith(QLatin1String(".eps"), Qt::CaseInsensitive)

        || path.endsWith(QLatin1String(".epsi"), Qt::CaseInsensitive))

    && bbox.get() != nullptr

    && (bbox->width() > 0)

    && (bbox->height() > 0)

    && (dsc.page_count() <= 1);

  char translation[64] = "";

  char pagesize[32] = "";

  char resopt[32] = "";

  if (is_encapsulated) {

    // GhostScript's rendering at the extremely low resolutions

    // required for thumbnails leaves something to be desired. To

    // get nicer images, we render to four times the required

    // resolution and let QImage scale the result.

    const int hres = (width * 72) / bbox->width();

    const int vres = (height * 72) / bbox->height();

    const int resolution = (hres > vres ? vres : hres) * 4;

    const int gswidth = ((bbox->urx() - bbox->llx()) * resolution) / 72;

    const int gsheight = ((bbox->ury() - bbox->lly()) * resolution) / 72;

    snprintf(pagesize, 31, "-g%ix%i", gswidth, gsheight);

    snprintf(resopt, 31, "-r%i", resolution);

    snprintf(translation, 63,

       " 0 %i sub 0 %i sub translate\n", bbox->llx(),

       bbox->lly());

  }

  const CDSC_PREVIEW_TYPE previewType =

    static_cast<CDSC_PREVIEW_TYPE>(dsc.preview());

  switch (previewType) {

  case CDSC_TIFF:

  case CDSC_WMF:

  case CDSC_PICT:

    // FIXME: these should take precedence, since they can hold

    // color previews, which EPSI can't (or can it?).

     break;

  case CDSC_EPSI:

    {

      if (!bbox) {

        break;

      }

      const int xscale = bbox->width() / width;

      const int yscale = bbox->height() / height;

      const int scale = xscale < yscale ? xscale : yscale;

      if (scale == 0) break;

      if (auto result = getEPSIPreview(path,

                         dsc.beginpreview(),

                         dsc.endpreview(),

                         bbox->width() / scale,

                         bbox->height() / scale); result.isValid())

        return result;

      // If the preview extraction routine fails, gs is used to

      // create a thumbnail.

    }

    break;

  case CDSC_NOPREVIEW:

  default:

    // need to run ghostscript in these cases

    break;

  }

  pid_t pid = fork();

  if (pid == 0) {

    // Child process (1)

    //    close(STDERR_FILENO);

    // find first zero entry in gsargs and put the filename

    // or - (stdin) there, if DVI

    const char **gsargs = gsargs_ps;

    const char **arg = gsargs;

    if (no_dvi && is_encapsulated) {

      gsargs = gsargs_eps;

      arg = gsargs;

      // find first zero entry and put page size there

      while (*arg) ++arg;

      *arg = pagesize;

      // find second zero entry and put resolution there

      while (*arg) ++arg;

      *arg = resopt;

    }

    // find next zero entry and put the filename there

    QByteArray fname = QFile::encodeName( path );

    while (*arg)

      ++arg;

    if( no_dvi )

      *arg = fname.data();

    else

      *arg = "-";

    // find first zero entry in dvipsargs and put the filename there

    arg = dvipsargs;

    while (*arg)

      ++arg;

    *arg = fname.data();

    if( !no_dvi ){

      pipe(dvipipe);

      pid_t pid_two = fork();

      if( pid_two == 0 ){

  // Child process (2), reopen stdout on the pipe "dvipipe" and exec dvips

  close(input[0]);

  close(input[1]);

  close(output[0]);

  close(output[1]);

  close(dvipipe[0]);

  dup2( dvipipe[1], STDOUT_FILENO);

  execvp(dvipsargs[0], const_cast<char *const *>(dvipsargs));

  _exit(1);

      }

      else if(pid_two != -1){

  close(input[1]);

  close(output[0]);

  close(dvipipe[1]);

  dup2( dvipipe[0], STDIN_FILENO);

  dup2( output[1], STDOUT_FILENO);

  execvp(gsargs[0], const_cast<char *const *>(gsargs));

  _exit(1);

      }

      else{

  // fork() (2) failed, close these

  close(dvipipe[0]);

  close(dvipipe[1]);

      }

    }

    else if( no_dvi ){

      // Reopen stdin/stdout on the pipes and exec gs

      close(input[1]);

      close(output[0]);

      dup2(input[0], STDIN_FILENO);

      dup2(output[1], STDOUT_FILENO);

      execvp(gsargs[0], const_cast<char *const *>(gsargs));

      _exit(1);

    }

  }

  else if (pid != -1) {

    // Parent process, write first-page-only-hack (the hack is not

    // used if DVI) and read the png output

    close(input[0]);

    close(output[1]);

    const char *prolog;

    if (is_encapsulated)

      prolog = epsprolog;

    else

      prolog = psprolog;

    int count = write(input[1], prolog, strlen(prolog));

    if (is_encapsulated)

      write(input[1], translation, strlen(translation));

    close(input[1]);

    if (count == static_cast<int>(strlen(prolog))) {

      int offset = 0;

  while (!ok) {

    fd_set fds;

    FD_ZERO(&fds);

    FD_SET(output[0], &fds);

    struct timeval tv;

    tv.tv_sec = 20;

    tv.tv_usec = 0;

    got_sig_term = false;

    if (select(output[0] + 1, &fds, nullptr, nullptr, &tv) <= 0) {

            if ( ( errno == EINTR || errno == EAGAIN ) && !got_sig_term ) continue;

      break; // error, timeout or master wants us to quit (SIGTERM)

          }

    if (FD_ISSET(output[0], &fds)) {

      count = read(output[0], data.data() + offset, 1024);

      if (count == -1)

        break;

      else

        if (count) // prepare for next block

    {

      offset += count;

      data.resize(offset + 1024);

    }

        else // got all data

    {

      data.resize(offset);

      ok = true;

    }

    }

  }

    }

    if (!ok) // error or timeout, gs probably didn't exit yet

    {

      kill(pid, SIGTERM);

    }

    int status = 0;

    int ret;

    do {

      ret = waitpid(pid, &status, 0);

    } while (ret == -1 && errno == EINTR);

    if (ret != pid || (status != 0  && status != 256) )

      ok = false;

  }

  else {

    // fork() (1) failed, close these

    close(input[0]);

    close(input[1]);

    close(output[1]);

  }

  close(output[0]);

  QImage img;

  bool loaded = img.loadFromData( data );

  if (!loaded) {

    // Sometimes gs spits some warning messages before the actual image

    // try to skip them

    const QByteArray pngHeader = "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A";

    const int pngMarkerIndex = data.indexOf(pngHeader);

    if (pngMarkerIndex > 0) {

      data = data.mid(pngMarkerIndex);

      loaded = img.loadFromData( data );

    }

  }

  if ( got_sig_term &&

  oldhandler != SIG_ERR &&

  oldhandler != SIG_DFL &&

  oldhandler != SIG_IGN ) {

    oldhandler( SIGTERM ); // propagate the signal. Other things might rely on it

  }

  if ( oldhandler != SIG_ERR ) signal( SIGTERM, oldhandler );

  if (loaded) {

    return KIO::ThumbnailResult::pass(img);

  }

  return KIO::ThumbnailResult::fail();

}

void GSCreator::comment(Name name)

{

    switch (name) {

    case EndPreview:

    case BeginProlog:

    case Page:

      endComments = true;

      break;

    default:

      break;

    }

}

// Quick function to check if the filename corresponds to a valid DVI

// file. Returns true if <filename> is a DVI file, false otherwise.

static bool correctDVI(const QString& filename)

{

  QFile f(filename);

  if (!f.open(QIODevice::ReadOnly))

    return false;

  unsigned char test[4];

  if ( f.read( (char *)test,2)<2 || test[0] != 247 || test[1] != 2  )

    return false;

  int n = f.size();

  if ( n < 134 ) // Too short for a dvi file

    return false;

  f.seek( n-4 );

  unsigned char trailer[4] = { 0xdf,0xdf,0xdf,0xdf };

  if ( f.read( (char *)test, 4 )<4 || strncmp( (char *)test, (char*) trailer, 4 ) )

    return false;

  // We suppose now that the dvi file is complete and OK

  return true;

}

KIO::ThumbnailResult GSCreator::getEPSIPreview(const QString &path, long start, long

             end, int imgwidth, int imgheight)

{

  FILE *fp;

  fp = fopen(QFile::encodeName(path), "r");

  if (fp == nullptr) return KIO::ThumbnailResult::fail();

  const long previewsize = end - start + 1;

  char *buf = (char *) malloc(previewsize);

  fseek(fp, start, SEEK_SET);

  int count = fread(buf, sizeof(char), previewsize - 1, fp);

  fclose(fp);

  buf[previewsize - 1] = 0;

  if (count != previewsize - 1)

  {

    free(buf);

    return KIO::ThumbnailResult::fail();

  }

  QString previewstr = QString::fromLatin1(buf);

  free(buf);

  int offset = 0;

  while ((offset < previewsize) && !(previewstr[offset].isDigit())) offset++;

  int digits = 0;

  while ((offset + digits < previewsize) && previewstr[offset + digits].isDigit()) digits++;

  int width = previewstr.mid(offset, digits).toInt();

  offset += digits + 1;

  while ((offset < previewsize) && !(previewstr[offset].isDigit())) offset++;

  digits = 0;

  while ((offset + digits < previewsize) && previewstr[offset + digits].isDigit()) digits++;

  int height = previewstr.mid(offset, digits).toInt();

  offset += digits + 1;

  while ((offset < previewsize) && !(previewstr[offset].isDigit())) offset++;

  digits = 0;

  while ((offset + digits < previewsize) && previewstr[offset + digits].isDigit()) digits++;

  int depth = previewstr.mid(offset, digits).toInt();

  // skip over the rest of the BeginPreview comment

  while ((offset < previewsize) &&

         previewstr[offset] != QLatin1Char('\n') &&

     previewstr[offset] != QLatin1Char('\r')) offset++;

  while ((offset < previewsize) && previewstr[offset] != QLatin1Char('%')) offset++;

  unsigned int imagedepth;

  switch (depth) {

  case 1:

  case 2:

  case 4:

  case 8:

    imagedepth = 8;

    break;

  case 12: // valid, but not (yet) supported

  default: // illegal value

    return KIO::ThumbnailResult::fail();

  }

  unsigned int colors = (1U << depth);

  QImage img(width, height, QImage::Format_Indexed8);

  img.setColorCount(colors);

  if (imagedepth <= 8) {

    for (unsigned int gray = 0; gray < colors; gray++) {

      unsigned int grayvalue = (255U * (colors - 1 - gray)) /

  (colors - 1);

      img.setColor(gray, qRgb(grayvalue, grayvalue, grayvalue));

    }

  }

  const unsigned int bits_per_scan_line = width * depth;

  unsigned int bytes_per_scan_line = bits_per_scan_line / 8;

  if (bits_per_scan_line % 8) bytes_per_scan_line++;

  const unsigned int bindatabytes = height * bytes_per_scan_line;

  QVector<unsigned char> bindata(bindatabytes);

  for (unsigned int i = 0; i < bindatabytes; i++) {

    if (offset >= previewsize)

      return KIO::ThumbnailResult::fail();

    while (!isxdigit(previewstr[offset].toLatin1()) &&

     offset < previewsize)

      offset++;

    bool ok = false;

    bindata[i] = static_cast<unsigned char>(previewstr.mid(offset, 2).toUInt(&ok, 16));

    if (!ok)

      return KIO::ThumbnailResult::fail();

    offset += 2;

  }

  for (int scanline = 0; scanline < height; scanline++) {

    unsigned char *scanlineptr = img.scanLine(scanline);

    for (int pixelindex = 0; pixelindex < width; pixelindex++) {

      unsigned char pixelvalue = 0;

      const unsigned int bitoffset =

        scanline * bytes_per_scan_line * 8U + pixelindex * depth;

      for (int depthindex = 0; depthindex < depth;

           depthindex++) {

        const unsigned int byteindex = (bitoffset + depthindex) / 8U;

        const unsigned int bitindex =

          7 - ((bitoffset + depthindex) % 8U);

        const unsigned char bitvalue =

          (bindata[byteindex] & static_cast<unsigned char>(1U << bitindex)) >> bitindex;

        pixelvalue |= (bitvalue << depthindex);

      }

      scanlineptr[pixelindex] = pixelvalue;

    }

  }

  QImage outimg = img.convertToFormat(QImage::Format_RGB32).scaled(imgwidth, imgheight, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);

  return !outimg.isNull() ? KIO::ThumbnailResult::pass(outimg) : KIO::ThumbnailResult::fail();

}

#include "gscreator.moc"