xref.cc

来自「source code: Covert TXT to PDF」· CC 代码 · 共 668 行 · 第 1/2 页

  return more;

 err1:
  obj.free();
 err2:
  ok = gFalse;
  return gFalse;
}

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

  error(0, "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;

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

    // look for object
    } else if (isdigit(*p)) {
      num = atoi(p);
      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;
		entries = (XRefEntry *)
		            grealloc(entries, newSize * sizeof(XRefEntry));
		for (i = size; i < newSize; ++i) {
		  entries[i].offset = 0xffffffff;
		  entries[i].used = gFalse;
		}
		size = newSize;
	      }
	      if (!entries[num].used || gen >= entries[num].gen) {
		entries[num].offset = pos - start;
		entries[num].gen = gen;
		entries[num].used = gTrue;
	      }
	    }
	  }
	}
      }

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

  if (gotRoot)
    return gTrue;

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

#ifndef NO_DECRYPTION
GBool XRef::checkEncrypted(GString *ownerPassword, GString *userPassword) {
  Object encrypt, filterObj, versionObj, revisionObj, lengthObj;
  Object ownerKey, userKey, permissions, fileID, fileID1;
  GBool encrypted1;
  GBool ret;

  ret = gFalse;

  permFlags = defPermFlags;
  ownerPasswordOk = gFalse;
  trailerDict.dictLookup("Encrypt", &encrypt);
  if ((encrypted1 = encrypt.isDict())) {
    ret = gTrue;
    encrypt.dictLookup("Filter", &filterObj);
    if (filterObj.isName("Standard")) {
      encrypt.dictLookup("V", &versionObj);
      encrypt.dictLookup("R", &revisionObj);
      encrypt.dictLookup("Length", &lengthObj);
      encrypt.dictLookup("O", &ownerKey);
      encrypt.dictLookup("U", &userKey);
      encrypt.dictLookup("P", &permissions);
      trailerDict.dictLookup("ID", &fileID);
      if (versionObj.isInt() &&
	  revisionObj.isInt() &&
	  ownerKey.isString() && ownerKey.getString()->getLength() == 32 &&
	  userKey.isString() && userKey.getString()->getLength() == 32 &&
	  permissions.isInt() &&
	  fileID.isArray()) {
	encVersion = versionObj.getInt();
	encRevision = revisionObj.getInt();
	if (lengthObj.isInt()) {
	  keyLength = lengthObj.getInt() / 8;
	} else {
	  keyLength = 5;
	}
	permFlags = permissions.getInt();
	if (encVersion >= 1 && encVersion <= 2 &&
	    encRevision >= 2 && encRevision <= 3) {
	  fileID.arrayGet(0, &fileID1);
	  if (fileID1.isString()) {
	    if (Decrypt::makeFileKey(encVersion, encRevision, keyLength,
				     ownerKey.getString(), userKey.getString(),
				     permFlags, fileID1.getString(),
				     ownerPassword, userPassword, fileKey,
				     &ownerPasswordOk)) {
	      if (ownerPassword && !ownerPasswordOk) {
		error(-1, "Incorrect owner password");
	      }
	      ret = gFalse;
	    } else {
	      error(-1, "Incorrect password");
	    }
	  } else {
	    error(-1, "Weird encryption info");
	  }
	  fileID1.free();
	} else {
	  error(-1, "Unsupported version/revision (%d/%d) of Standard security handler",
		encVersion, encRevision);
	}
      } else {
	error(-1, "Weird encryption info");
      }
      fileID.free();
      permissions.free();
      userKey.free();
      ownerKey.free();
      lengthObj.free();
      revisionObj.free();
      versionObj.free();
    } else {
      error(-1, "Unknown security handler '%s'",
	    filterObj.isName() ? filterObj.getName() : "???");
    }
    filterObj.free();
  }
  encrypt.free();

  // this flag has to be set *after* we read the O/U/P strings
  encrypted = encrypted1;

  return ret;
}
#else
GBool XRef::checkEncrypted(GString *ownerPassword, GString *userPassword) {
  Object obj;
  GBool encrypted;

  trailerDict.dictLookup("Encrypt", &obj);
  if ((encrypted = !obj.isNull())) {
    error(-1, "PDF file is encrypted and this version of the Xpdf tools");
    error(-1, "was built without decryption support.");
  }
  obj.free();
  return encrypted;
}
#endif

GBool XRef::okToPrint(GBool ignoreOwnerPW) {
#ifndef NO_DECRYPTION
  if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permPrint)) {
    return gFalse;
  }
#endif
  return gTrue;
}

GBool XRef::okToChange(GBool ignoreOwnerPW) {
#ifndef NO_DECRYPTION
  if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permChange)) {
    return gFalse;
  }
#endif
  return gTrue;
}

GBool XRef::okToCopy(GBool ignoreOwnerPW) {
#ifndef NO_DECRYPTION
  if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permCopy)) {
    return gFalse;
  }
#endif
  return gTrue;
}

GBool XRef::okToAddNotes(GBool ignoreOwnerPW) {
#ifndef NO_DECRYPTION
  if ((ignoreOwnerPW || !ownerPasswordOk) && !(permFlags & permNotes)) {
    return gFalse;
  }
#endif
  return gTrue;
}

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) {
    obj->initNull();
    return obj;
  }

  e = &entries[num];
  if (e->gen == gen && e->offset != 0xffffffff) {
    obj1.initNull();
    parser = new Parser(this,
	       new Lexer(this,
		 str->makeSubStream(start + e->offset, gFalse, 0, &obj1)));
    parser->getObj(&obj1);
    parser->getObj(&obj2);
    parser->getObj(&obj3);
    if (obj1.isInt() && obj1.getInt() == num &&
	obj2.isInt() && obj2.getInt() == gen &&
	obj3.isCmd("obj")) {
#ifndef NO_DECRYPTION
      parser->getObj(obj, encrypted ? fileKey : (Guchar *)NULL, keyLength,
		     num, gen);
#else
      parser->getObj(obj);
#endif
    } else {
      obj->initNull();
    }
    obj1.free();
    obj2.free();
    obj3.free();
    delete parser;
  } else {
    obj->initNull();
  }
  return obj;
}

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;
}