diff --git a/src/ByteArrayDiskWriter.cc b/src/ByteArrayDiskWriter.cc
new file mode 100644
index 00000000..dfc94ede
--- /dev/null
+++ b/src/ByteArrayDiskWriter.cc
@@ -0,0 +1,80 @@
+/* <!-- copyright */
+/*
+ * aria2 - a simple utility for downloading files faster
+ *
+ * Copyright (C) 2006 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+/* copyright --> */
+#include "ByteArrayDiskWriter.h"
+
+ByteArrayDiskWriter::ByteArrayDiskWriter():buf(NULL) {
+}
+
+ByteArrayDiskWriter::~ByteArrayDiskWriter() {
+  closeFile();
+}
+
+void ByteArrayDiskWriter::clear() {
+  if(buf != NULL) {
+    delete [] buf;
+    buf = NULL;
+  }
+}
+
+void ByteArrayDiskWriter::init() {
+  maxBufLength = 256;
+  buf = new char[maxBufLength];
+  bufLength = 0;
+}
+
+void ByteArrayDiskWriter::reset() {
+  clear();
+  init();
+}
+
+void ByteArrayDiskWriter::initAndOpenFile(string filename) {
+  openFile(filename);
+}
+
+void ByteArrayDiskWriter::openFile(const string& filename) {
+  clear();
+  init();
+}
+
+void ByteArrayDiskWriter::closeFile() {
+  clear();
+}
+
+void ByteArrayDiskWriter::openExistingFile(string filename) {
+  openFile(filename);
+}
+
+void ByteArrayDiskWriter::writeData(const char* data, int dataLength, long long int position) {
+  if(bufLength+dataLength >= maxBufLength) {
+    expandBuffer(bufLength+dataLength);
+  }
+  memcpy(buf+bufLength, data, dataLength);
+  bufLength += dataLength;
+}
+
+void ByteArrayDiskWriter::expandBuffer(int newSize) {
+  char* newbuf = new char[newSize];
+  memcpy(newbuf, buf, bufLength);
+  delete [] buf;
+  buf = newbuf;
+  maxBufLength = newSize;
+}
diff --git a/src/ByteArrayDiskWriter.h b/src/ByteArrayDiskWriter.h
new file mode 100644
index 00000000..c5abe81c
--- /dev/null
+++ b/src/ByteArrayDiskWriter.h
@@ -0,0 +1,65 @@
+/* <!-- copyright */
+/*
+ * aria2 - a simple utility for downloading files faster
+ *
+ * Copyright (C) 2006 Tatsuhiro Tsujikawa
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+/* copyright --> */
+#ifndef _D_BYTE_ARRAY_DISK_WRITER_H_
+#define _D_BYTE_ARRAY_DISK_WRITER_H_
+
+#include "DiskWriter.h"
+
+class ByteArrayDiskWriter : public DiskWriter {
+private:
+  char* buf;
+  int maxBufLength;
+  int bufLength;
+
+  void init();
+  void clear();
+  void expandBuffer(int newSize);
+public:
+  ByteArrayDiskWriter();
+  virtual ~ByteArrayDiskWriter();
+
+
+  virtual void initAndOpenFile(string filename);
+
+  virtual void openFile(const string& filename);
+
+  virtual void closeFile();
+
+  virtual void openExistingFile(string filename);
+
+  // position is ignored
+  virtual void writeData(const char* data, int len, long long int position = 0);
+  // not implemented yet
+  virtual int readData(char* data, int len, long long int position) { return 0; }
+  // not implemented yet
+  virtual string sha1Sum(long long int offset, long long int length) { return ""; }
+
+  const char* getByteArray() const {
+    return buf;
+  }
+  int getByteArrayLength() const {
+    return bufLength;
+  }
+  void reset();
+};
+
+#endif // _D_BYTE_ARRAY_DISK_WRITER_H_