GfxTilingPattern *GfxTilingPattern::parse(Object *patObj) {
  GfxTilingPattern *pat;
  Dict *dict;
  int paintTypeA, tilingTypeA;
  double bboxA[4], matrixA[6];
  double xStepA, yStepA;
  Object resDictA;
  Object obj1, obj2;
  int i;

  if (!patObj->isStream()) {
    return NULL;
  }
  dict = patObj->streamGetDict();

  if (dict->lookup("PaintType", &obj1)->isInt()) {
    paintTypeA = obj1.getInt();
  } else {
    paintTypeA = 1;
    error(-1, "Invalid or missing PaintType in pattern");
  }
  obj1.free();
  if (dict->lookup("TilingType", &obj1)->isInt()) {
    tilingTypeA = obj1.getInt();
  } else {
    tilingTypeA = 1;
    error(-1, "Invalid or missing TilingType in pattern");
  }
  obj1.free();
  bboxA[0] = bboxA[1] = 0;
  bboxA[2] = bboxA[3] = 1;
  if (dict->lookup("BBox", &obj1)->isArray() &&
      obj1.arrayGetLength() == 4) {
    for (i = 0; i < 4; ++i) {
      if (obj1.arrayGet(i, &obj2)->isNum()) {
	bboxA[i] = obj2.getNum();
      }
      obj2.free();
    }
  } else {
    error(-1, "Invalid or missing BBox in pattern");
  }
  obj1.free();
  if (dict->lookup("XStep", &obj1)->isNum()) {
    xStepA = obj1.getNum();
  } else {
    xStepA = 1;
    error(-1, "Invalid or missing XStep in pattern");
  }
  obj1.free();
  if (dict->lookup("YStep", &obj1)->isNum()) {
    yStepA = obj1.getNum();
  } else {
    yStepA = 1;
    error(-1, "Invalid or missing YStep in pattern");
  }
  obj1.free();
  if (!dict->lookup("Resources", &resDictA)->isDict()) {
    resDictA.free();
    resDictA.initNull();
    error(-1, "Invalid or missing Resources in pattern");
  }
  matrixA[0] = 1; matrixA[1] = 0;
  matrixA[2] = 0; matrixA[3] = 1;
  matrixA[4] = 0; matrixA[5] = 0;
  if (dict->lookup("Matrix", &obj1)->isArray() &&
      obj1.arrayGetLength() == 6) {
    for (i = 0; i < 6; ++i) {
      if (obj1.arrayGet(i, &obj2)->isNum()) {
	matrixA[i] = obj2.getNum();
      }
      obj2.free();
    }
  }
  obj1.free();

  pat = new GfxTilingPattern(paintTypeA, tilingTypeA, bboxA, xStepA, yStepA,
			     &resDictA, matrixA, patObj);
  resDictA.free();
  return pat;
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.