xref.cc

swf文件查看工具,能够看flash文件的格式

  if (obj.getDict()->lookup("XRefStm", &obj2)->isInt()) {
    pos2 = (Guint)obj2.getInt();
    readXRef(&pos2);
    if (!ok) {
      obj2.free();
      goto err1;
    }
  }
  obj2.free();

  obj.free();
  return more;

 err1:
  obj.free();
  ok = gFalse;
  return gFalse;
}

GBool XRef::readXRefStream(Stream *xrefStr, Guint *pos) {
  Dict *dict;
  int w[3];
  GBool more;
  Object obj, obj2, idx;
  int newSize, first, n, i;

  dict = xrefStr->getDict();

  if (!dict->lookupNF("Size", &obj)->isInt()) {
    goto err1;
  }
  newSize = obj.getInt();
  obj.free();
  if (newSize < 0) {
    goto err1;
  }
  if (newSize > size) {
    entries = (XRefEntry *)greallocn(entries, newSize, sizeof(XRefEntry));
    for (i = size; i < newSize; ++i) {
      entries[i].offset = 0xffffffff;
      entries[i].type = xrefEntryFree;
    }
    size = newSize;
  }

  if (!dict->lookupNF("W", &obj)->isArray() ||
      obj.arrayGetLength() < 3) {
    goto err1;
  }
  for (i = 0; i < 3; ++i) {
    if (!obj.arrayGet(i, &obj2)->isInt()) {
      obj2.free();
      goto err1;
    }
    w[i] = obj2.getInt();
    obj2.free();
    if (w[i] < 0 || w[i] > 4) {
      goto err1;
    }
  }
  obj.free();

  xrefStr->reset();
  dict->lookupNF("Index", &idx);
  if (idx.isArray()) {
    for (i = 0; i+1 < idx.arrayGetLength(); i += 2) {
      if (!idx.arrayGet(i, &obj)->isInt()) {
	idx.free();
	goto err1;
      }
      first = obj.getInt();
      obj.free();
      if (!idx.arrayGet(i+1, &obj)->isInt()) {
	idx.free();
	goto err1;
      }
      n = obj.getInt();
      obj.free();
      if (first < 0 || n < 0 ||
	  !readXRefStreamSection(xrefStr, w, first, n)) {
	idx.free();
	goto err0;
      }
    }
  } else {
    if (!readXRefStreamSection(xrefStr, w, 0, newSize)) {
      idx.free();
      goto err0;
    }
  }
  idx.free();

  dict->lookupNF("Prev", &obj);
  if (obj.isInt()) {
    *pos = (Guint)obj.getInt();
    more = gTrue;
  } else {
    more = gFalse;
  }
  obj.free();
  if (trailerDict.isNone()) {
    trailerDict.initDict(dict);
  }

  return more;

 err1:
  obj.free();
 err0:
  ok = gFalse;
  return gFalse;
}

GBool XRef::readXRefStreamSection(Stream *xrefStr, int *w, int first, int n) {
  Guint offset;
  int type, gen, c, newSize, i, j;

  if (first + n < 0) {
    return gFalse;
  }
  if (first + n > size) {
    for (newSize = size ? 2 * size : 1024;
	 first + n > newSize && newSize > 0;
	 newSize <<= 1) ;
    if (newSize < 0) {
      return gFalse;
    }
    entries = (XRefEntry *)greallocn(entries, newSize, sizeof(XRefEntry));
    for (i = size; i < newSize; ++i) {
      entries[i].offset = 0xffffffff;
      entries[i].type = xrefEntryFree;
    }
    size = newSize;
  }
  for (i = first; i < first + n; ++i) {
    if (w[0] == 0) {
      type = 1;
    } else {
      for (type = 0, j = 0; j < w[0]; ++j) {
	if ((c = xrefStr->getChar()) == EOF) {
	  return gFalse;
	}
	type = (type << 8) + c;
      }
    }
    for (offset = 0, j = 0; j < w[1]; ++j) {
      if ((c = xrefStr->getChar()) == EOF) {
	return gFalse;
      }
      offset = (offset << 8) + c;
    }
    for (gen = 0, j = 0; j < w[2]; ++j) {
      if ((c = xrefStr->getChar()) == EOF) {
	return gFalse;
      }
      gen = (gen << 8) + c;
    }
    if (entries[i].offset == 0xffffffff) {
      switch (type) {
      case 0:
	entries[i].offset = offset;
	entries[i].gen = gen;
	entries[i].type = xrefEntryFree;
	break;
      case 1:
	entries[i].offset = offset;
	entries[i].gen = gen;
	entries[i].type = xrefEntryUncompressed;
	break;
      case 2:
	entries[i].offset = offset;
	entries[i].gen = gen;
	entries[i].type = xrefEntryCompressed;
	break;
      default:
	return gFalse;
      }
    }
  }

  return gTrue;
}

// Attempt to construct an xref table for a damaged file.
GBool XRef::constructXRef() {
  Parser *parser;
  Object newTrailerDict, obj;
  char buf[256];
  Guint pos;
  int num, gen;
  int newSize;
  int streamEndsSize;
  char *p;
  int i;
  GBool gotRoot;

  gfree(entries);
  size = 0;
  entries = NULL;

  error(-1, "PDF file is damaged - attempting to reconstruct xref table...");
  gotRoot = gFalse;
  streamEndsLen = streamEndsSize = 0;

  str->reset();
  while (1) {
    pos = str->getPos();
    if (!str->getLine(buf, 256)) {
      break;
    }
    p = buf;

    // skip whitespace
    while (*p && Lexer::isSpace(*p & 0xff)) ++p;

    // got trailer dictionary
    if (!strncmp(p, "trailer", 7)) {
      obj.initNull();
      parser = new Parser(NULL,
		 new Lexer(NULL,
		   str->makeSubStream(pos + 7, gFalse, 0, &obj)),
		 gFalse);
      parser->getObj(&newTrailerDict);
      if (newTrailerDict.isDict()) {
	newTrailerDict.dictLookupNF("Root", &obj);
	if (obj.isRef()) {
	  rootNum = obj.getRefNum();
	  rootGen = obj.getRefGen();
	  if (!trailerDict.isNone()) {
	    trailerDict.free();
	  }
	  newTrailerDict.copy(&trailerDict);
	  gotRoot = gTrue;
	}
	obj.free();
      }
      newTrailerDict.free();
      delete parser;

    // look for object
    } else if (isdigit(*p)) {
      num = atoi(p);
      if (num > 0) {
	do {
	  ++p;
	} while (*p && isdigit(*p));
	if (isspace(*p)) {
	  do {
	    ++p;
	  } while (*p && isspace(*p));
	  if (isdigit(*p)) {
	    gen = atoi(p);
	    do {
	      ++p;
	    } while (*p && isdigit(*p));
	    if (isspace(*p)) {
	      do {
		++p;
	      } while (*p && isspace(*p));
	      if (!strncmp(p, "obj", 3)) {
		if (num >= size) {
		  newSize = (num + 1 + 255) & ~255;
		  if (newSize < 0) {
		    error(-1, "Bad object number");
		    return gFalse;
		  }
		  entries = (XRefEntry *)
		      greallocn(entries, newSize, sizeof(XRefEntry));
		  for (i = size; i < newSize; ++i) {
		    entries[i].offset = 0xffffffff;
		    entries[i].type = xrefEntryFree;
		  }
		  size = newSize;
		}
		if (entries[num].type == xrefEntryFree ||
		    gen >= entries[num].gen) {
		  entries[num].offset = pos - start;
		  entries[num].gen = gen;
		  entries[num].type = xrefEntryUncompressed;
		}
	      }
	    }
	  }
	}
      }

    } else if (!strncmp(p, "endstream", 9)) {
      if (streamEndsLen == streamEndsSize) {
	streamEndsSize += 64;
	streamEnds = (Guint *)greallocn(streamEnds,
					streamEndsSize, sizeof(int));
      }
      streamEnds[streamEndsLen++] = pos;
    }
  }

  if (gotRoot)
    return gTrue;

  error(-1, "Couldn't find trailer dictionary");
  return gFalse;
}

void XRef::setEncryption(int permFlagsA, GBool ownerPasswordOkA,
			 Guchar *fileKeyA, int keyLengthA, int encVersionA,
			 CryptAlgorithm encAlgorithmA) {
  int i;

  encrypted = gTrue;
  permFlags = permFlagsA;
  ownerPasswordOk = ownerPasswordOkA;
  if (keyLengthA <= 16) {
    keyLength = keyLengthA;
  } else {
    keyLength = 16;
  }
  for (i = 0; i < keyLength; ++i) {
    fileKey[i] = fileKeyA[i];
  }
  encVersion = encVersionA;
  encAlgorithm = encAlgorithmA;
}

GBool XRef::okToPrint(GBool ignoreOwnerPW) {
  return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permPrint);
}

GBool XRef::okToChange(GBool ignoreOwnerPW) {
  return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permChange);
}

GBool XRef::okToCopy(GBool ignoreOwnerPW) {
  return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permCopy);
}

GBool XRef::okToAddNotes(GBool ignoreOwnerPW) {
  return (!ignoreOwnerPW && ownerPasswordOk) || (permFlags & permNotes);
}

Object *XRef::fetch(int num, int gen, Object *obj) {
  XRefEntry *e;
  Parser *parser;
  Object obj1, obj2, obj3;

  // check for bogus ref - this can happen in corrupted PDF files
  if (num < 0 || num >= size) {
    goto err;
  }

  e = &entries[num];
  switch (e->type) {

  case xrefEntryUncompressed:
    if (e->gen != gen) {
      goto err;
    }
    obj1.initNull();
    parser = new Parser(this,
	       new Lexer(this,
		 str->makeSubStream(start + e->offset, gFalse, 0, &obj1)),
	       gTrue);
    parser->getObj(&obj1);
    parser->getObj(&obj2);
    parser->getObj(&obj3);
    if (!obj1.isInt() || obj1.getInt() != num ||
	!obj2.isInt() || obj2.getInt() != gen ||
	!obj3.isCmd("obj")) {
      obj1.free();
      obj2.free();
      obj3.free();
      delete parser;
      goto err;
    }
    parser->getObj(obj, encrypted ? fileKey : (Guchar *)NULL,
		   encAlgorithm, keyLength, num, gen);
    obj1.free();
    obj2.free();
    obj3.free();
    delete parser;
    break;

  case xrefEntryCompressed:
    if (gen != 0) {
      goto err;
    }
    if (!objStr || objStr->getObjStrNum() != (int)e->offset) {
      if (objStr) {
	delete objStr;
      }
      objStr = new ObjectStream(this, e->offset);
    }
    objStr->getObject(e->gen, num, obj);
    break;

  default:
    goto err;
  }

  return obj;

 err:
  return obj->initNull();
}

Object *XRef::getDocInfo(Object *obj) {
  return trailerDict.dictLookup("Info", obj);
}

// Added for the pdftex project.
Object *XRef::getDocInfoNF(Object *obj) {
  return trailerDict.dictLookupNF("Info", obj);
}

GBool XRef::getStreamEnd(Guint streamStart, Guint *streamEnd) {
  int a, b, m;

  if (streamEndsLen == 0 ||
      streamStart > streamEnds[streamEndsLen - 1]) {
    return gFalse;
  }

  a = -1;
  b = streamEndsLen - 1;
  // invariant: streamEnds[a] < streamStart <= streamEnds[b]
  while (b - a > 1) {
    m = (a + b) / 2;
    if (streamStart <= streamEnds[m]) {
      b = m;
    } else {
      a = m;
    }
  }
  *streamEnd = streamEnds[b];
  return gTrue;
}

Guint XRef::strToUnsigned(char *s) {
  Guint x;
  char *p;
  int i;

  x = 0;
  for (p = s, i = 0; *p && isdigit(*p) && i < 10; ++p, ++i) {
    x = 10 * x + (*p - '0');
  }
  return x;
}