2007-06-01 Tatsuhiro Tsujikawa <tujikawa at rednoah dot com>

	* src/FileAllocationCommand.cc: Derived from RealtimeCommand.
	* src/CheckIntegrityCommand.cc: Derived from RealtimeCommand.
	
	* src/MetalinkEntry.h
	(checksum): Changed to ChecksumHandle
	* src/MetalinkRequestInfo.cc
	(checksum): Changed to ChecksumHandle

	* src/File.cc
	(mkdirs): OPEN_MODE -> DIR_OPEN_MODE
	* src/common.h
	(DIR_OPEN_MODE): New definition

	* src/RequestGroup.cc
	(prepareForNextAction): Added an argument.

	* src/message.h
	(MSG_GOOD_CHECKSUM): New definition
	(MSG_BAD_CHECKSUM): New definition

	* src/HttpResponseCommand.cc
	(handleDefaultEncoding): Continue download sequence in new
	non-segmented download.

	* src/FileAllocationEntry.h
	(_nextDownloadCommand): New variable.

	* src/DownloadCommand.cc
	(prepareForNextSegment): Create ChecksumCommand if checksum is
	available.	

	* src/RealtimeCommand.h, src/RealtimeCommand.cc: New class.

	* src/IteratableChecksumValidator.h,
	src/IteratableChecksumValidator.cc: New class.

	* src/ChecksumCommand.h, src/ChecksumCommand.cc: New class.

32 files changed, 637 insertions, 131 deletions

diff --git a/src/CheckIntegrityCommand.cc b/src/CheckIntegrityCommand.cc
index 7a4bf430..51df08d3 100644
--- a/src/CheckIntegrityCommand.cc
+++ b/src/CheckIntegrityCommand.cc
@@ -51,20 +51,23 @@ void CheckIntegrityCommand::initValidator()
   _validator->init();
 }
 
-bool CheckIntegrityCommand::execute()
+bool CheckIntegrityCommand::executeInternal()
 {
-  setStatusRealtime();
-  _e->noWait = true;
-
-  try {
-    _validator->validateChunk();
-    if(_validator->finished()) {
-      if(_requestGroup->downloadFinished()) {
-	logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED, cuid, _requestGroup->getFilePath().c_str());
-	return true;
-      }
-      if(_requestGroup->needsFileAllocation()) {
-	_e->_fileAllocationMan->pushFileAllocationEntry(new FileAllocationEntry(cuid, _req, _requestGroup)); 
+  _validator->validateChunk();
+  if(_validator->finished()) {
+    if(_requestGroup->downloadFinished()) {
+      logger->notice(MSG_DOWNLOAD_ALREADY_COMPLETED, cuid, _requestGroup->getFilePath().c_str());
+      return true;
+    }
+    if(_requestGroup->needsFileAllocation()) {
+      FileAllocationEntryHandle entry = new FileAllocationEntry(cuid, _req, _requestGroup);
+      entry->setNextDownloadCommand(_nextDownloadCommand);
+      _nextDownloadCommand = 0;
+      _e->_fileAllocationMan->pushFileAllocationEntry(entry); 
+    } else {
+      if(_nextDownloadCommand) {
+	_e->commands.push_back(_nextDownloadCommand);
+	_nextDownloadCommand = 0;
       } else {
 	int32_t numCommandsToGenerate = 15;
 	Commands commands = _requestGroup->getNextCommand(_e, numCommandsToGenerate);
@@ -72,19 +75,23 @@ bool CheckIntegrityCommand::execute()
 	commands.push_front(command);
 	_e->addCommand(commands);
       }
-      return true;
-    } else {
-      _e->commands.push_back(this);
-      return false;
     }
-  } catch(Exception* e) {
-    _requestGroup->getSegmentMan()->errors++;
-    logger->error("CUID#%d - Exception caught while validating file integrity.", e, cuid);
-    delete e;
-    logger->error(MSG_DOWNLOAD_NOT_COMPLETE, cuid, _requestGroup->getFilePath().c_str());
-    // TODO this is wrong. There may exist invalid chunk data before catching
-    // exception. Fix this.
-    _requestGroup->markPieceDone(_validator->getCurrentOffset());
     return true;
+  } else {
+    _e->commands.push_back(this);
+    return false;
   }
 }
+
+bool CheckIntegrityCommand::handleException(Exception* e)
+{
+  logger->error("CUID#%d - Exception caught while validating file integrity.", e, cuid);
+  delete e;
+  logger->error(MSG_DOWNLOAD_NOT_COMPLETE, cuid, _requestGroup->getFilePath().c_str());
+  // TODO this is wrong. There may exist invalid chunk data before catching
+  // exception. Fix this.
+  // The one of the solution is having a copy of bitfield before settting its
+  // all bit to 1. If exception is thrown, then assign the copy to the bitfield.
+  _requestGroup->markPieceDone(_validator->getCurrentOffset());
+  return true;
+}
diff --git a/src/CheckIntegrityCommand.h b/src/CheckIntegrityCommand.h
index 88f19eb6..414b70da 100644
--- a/src/CheckIntegrityCommand.h
+++ b/src/CheckIntegrityCommand.h
@@ -35,25 +35,22 @@
 #ifndef _D_CHECK_INTEGRITY_COMMAND_H_
 #define _D_CHECK_INTEGRITY_COMMAND_H_
 
-#include "Command.h"
+#include "RealtimeCommand.h"
 #include "Request.h"
-#include "RequestGroup.h"
-#include "DownloadEngine.h"
 #include "IteratableChunkChecksumValidator.h"
+#include "DownloadCommand.h"
 
-class CheckIntegrityCommand : public Command {
+class CheckIntegrityCommand : public RealtimeCommand {
 private:
   RequestHandle _req;
-  RequestGroup* _requestGroup;
-  DownloadEngine* _e;
   IteratableChunkChecksumValidatorHandle _validator;
+  DownloadCommand* _nextDownloadCommand;
 public:
   CheckIntegrityCommand(int cuid, const RequestHandle& req, RequestGroup* requestGroup, DownloadEngine* e):
-    Command(cuid),
+    RealtimeCommand(cuid, requestGroup, e),
     _req(req),
-    _requestGroup(requestGroup),
-    _e(e),
-    _validator(0)
+    _validator(0),
+    _nextDownloadCommand(0)
   {
     ++_requestGroup->numConnection;
   }
@@ -61,11 +58,19 @@ public:
   virtual ~CheckIntegrityCommand()
   {
     --_requestGroup->numConnection;
+    delete _nextDownloadCommand;
   }
 
   void initValidator();
 
-  virtual bool execute();
+  virtual bool executeInternal();
+
+  virtual bool handleException(Exception* e);
+
+  void setNextDownloadCommand(DownloadCommand* command)
+  {
+    _nextDownloadCommand = command;
+  }
 };
 
 #endif // _D_CHECK_INTEGRITY_COMMAND_H_
diff --git a/src/Checksum.h b/src/Checksum.h
index d4134510..eb1d5c34 100644
--- a/src/Checksum.h
+++ b/src/Checksum.h
@@ -74,4 +74,6 @@ class Checksum {
 };
 #endif // ENABLE_MESSAGE_DIGEST
 
+typedef SharedHandle<Checksum> ChecksumHandle;
+
 #endif // _D_CHECKSUM_H_
diff --git a/src/ChecksumCommand.cc b/src/ChecksumCommand.cc
new file mode 100644
index 00000000..dcfdc0bb
--- /dev/null
+++ b/src/ChecksumCommand.cc
@@ -0,0 +1,79 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#include "ChecksumCommand.h"
+#include "DlAbortEx.h"
+#include "message.h"
+
+void ChecksumCommand::initValidator()
+{
+  _validator = new IteratableChecksumValidator();
+  _validator->setChecksum(_requestGroup->getChecksum());
+  _validator->setDiskWriter(_requestGroup->getSegmentMan()->diskWriter);
+  _validator->setBitfield(_requestGroup->getSegmentMan()->getBitfield());
+  if(!_validator->canValidate()) {
+    // insufficient checksums.
+    throw new DlAbortEx("Insufficient checksums.");
+  }
+  _validator->init();
+}
+
+bool ChecksumCommand::executeInternal()
+{
+  _validator->validateChunk();
+  if(_validator->finished()) {
+    if(_requestGroup->downloadFinished()) {
+      logger->notice(MSG_GOOD_CHECKSUM, cuid, _requestGroup->getFilePath().c_str());
+      return true;
+    } else {
+      logger->error(MSG_BAD_CHECKSUM, cuid, _requestGroup->getFilePath().c_str());
+      return true;
+    }
+  } else {
+    _e->commands.push_back(this);
+    return false;
+  }
+
+}
+
+bool ChecksumCommand::handleException(Exception* e)
+{
+  logger->error("CUID#%d - Exception caught while validating file integrity.", e, cuid);
+  delete e;
+  logger->error(MSG_DOWNLOAD_NOT_COMPLETE, cuid, _requestGroup->getFilePath().c_str());
+  // TODO We need to set bitfield back to the state when validation begun.
+  // The one of the solution is having a copy of bitfield before settting its
+  // all bit to 1. If exception is thrown, then assign the copy to the bitfield.
+  return true;
+}
diff --git a/src/ChecksumCommand.h b/src/ChecksumCommand.h
new file mode 100644
index 00000000..06260380
--- /dev/null
+++ b/src/ChecksumCommand.h
@@ -0,0 +1,66 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef _D_CHECKSUM_COMMAND_H_
+#define _D_CHECKSUM_COMMAND_H_
+
+#include "RealtimeCommand.h"
+#include "IteratableChecksumValidator.h"
+
+class ChecksumCommand : public RealtimeCommand
+{
+private:
+  IteratableChecksumValidatorHandle _validator;
+public:
+  ChecksumCommand(int cuid, RequestGroup* requestGroup, DownloadEngine* e):
+    RealtimeCommand(cuid, requestGroup, e),
+    _validator(0)
+  {
+    ++_requestGroup->numConnection;
+  }
+
+  virtual ~ChecksumCommand()
+  {
+    --_requestGroup->numConnection;
+  }
+
+  void initValidator();
+
+  virtual bool executeInternal();
+
+  virtual bool handleException(Exception* e);
+};
+
+
+#endif // _D_CHECKSUM_COMMAND_H_
diff --git a/src/ChunkChecksumValidator.cc b/src/ChunkChecksumValidator.cc
index cb9590fb..ee0d537f 100644
--- a/src/ChunkChecksumValidator.cc
+++ b/src/ChunkChecksumValidator.cc
@@ -49,7 +49,7 @@ void ChunkChecksumValidator::validateSameLengthChecksum(BitfieldMan* bitfieldMan
   string actualChecksum = diskWriter->messageDigest(offset, dataLength, algo);
   if(actualChecksum != expectedChecksum) {
     logger->info(EX_INVALID_CHUNK_CHECKSUM,
-		 index, offset, dataLength,
+		 index, offset,
 		 expectedChecksum.c_str(), actualChecksum.c_str());
     bitfieldMan->unsetBit(index);
   }
@@ -71,7 +71,7 @@ void ChunkChecksumValidator::validateDifferentLengthChecksum(BitfieldMan* bitfie
     if(expectedChecksum != actualChecksum) {
       // wrong checksum
       logger->info(EX_INVALID_CHUNK_CHECKSUM,
-		   index, offset, dataLength,
+		   index, offset,
 		   expectedChecksum.c_str(), actualChecksum.c_str());
       bitfieldMan->unsetBitRange(startIndex, endIndex);
     }
diff --git a/src/Command.cc b/src/Command.cc
index e9b7f25f..7f701883 100644
--- a/src/Command.cc
+++ b/src/Command.cc
@@ -35,18 +35,3 @@
 #include "Command.h"
 
 int Command::uuidGen = 0;
-
-bool Command::statusMatch(Command::STATUS statusFilter) const
-{
-  return statusFilter <= status;
-}
-
-void Command::transitStatus()
-{
-  switch(status) {
-  case STATUS_REALTIME:
-    break;
-  default:
-    status = STATUS_INACTIVE;
-  }
-}
diff --git a/src/Command.h b/src/Command.h
index 87cdd825..49f4b3d4 100644
--- a/src/Command.h
+++ b/src/Command.h
@@ -71,9 +71,20 @@ public:
 
   void setStatusRealtime() { this->status = STATUS_REALTIME; }
 
-  void transitStatus();
+  bool statusMatch(Command::STATUS statusFilter) const
+  {
+    return statusFilter <= status;
+  }
 
-  bool statusMatch(Command::STATUS statusFilter) const;
+  void transitStatus()
+  {
+    switch(status) {
+    case STATUS_REALTIME:
+      break;
+    default:
+      status = STATUS_INACTIVE;
+    }
+  }
 };
 
 typedef deque<Command*> Commands;
diff --git a/src/DownloadCommand.cc b/src/DownloadCommand.cc
index f28cc4c6..2e488ee9 100644
--- a/src/DownloadCommand.cc
+++ b/src/DownloadCommand.cc
@@ -40,6 +40,7 @@
 #include "InitiateConnectionCommandFactory.h"
 #include "message.h"
 #include "prefs.h"
+#include "ChecksumCommand.h"
 #include <sys/time.h>
 
 DownloadCommand::DownloadCommand(int cuid,
@@ -125,6 +126,11 @@ bool DownloadCommand::executeInternal() {
 
 bool DownloadCommand::prepareForNextSegment() {
   if(_requestGroup->getSegmentMan()->finished()) {
+    if(!_requestGroup->getChecksum().isNull() &&
+       !_requestGroup->getChecksum()->isEmpty()) {
+      ChecksumCommand* command = new ChecksumCommand(cuid, _requestGroup, e);
+      e->commands.push_back(command);
+    }
     return true;
   } else {
     // Merge segment with next segment, if segment.index+1 == nextSegment.index
diff --git a/src/File.cc b/src/File.cc
index 4100348c..7ddc71a2 100644
--- a/src/File.cc
+++ b/src/File.cc
@@ -94,6 +94,7 @@ bool File::mkdirs() {
   if(!dirs.size()) {
     return true;
   }
+
   string accDir;
   if(Util::startsWith(name, "/")) {
     accDir = "/";
@@ -104,7 +105,7 @@ bool File::mkdirs() {
     if(File(accDir).isDir()) {
       continue;
     }
-    if(mkdir(accDir.c_str(), OPEN_MODE) == -1) {
+    if(mkdir(accDir.c_str(), DIR_OPEN_MODE) == -1) {
       return false;
     }
   }
diff --git a/src/FileAllocationCommand.cc b/src/FileAllocationCommand.cc
index 92f26b6f..ae9750cf 100644
--- a/src/FileAllocationCommand.cc
+++ b/src/FileAllocationCommand.cc
@@ -35,39 +35,43 @@
 #include "FileAllocationCommand.h"
 #include "InitiateConnectionCommandFactory.h"
 #include "message.h"
+#include "DownloadCommand.h"
 
-bool FileAllocationCommand::execute()
+bool FileAllocationCommand::executeInternal()
 {
-  setStatusRealtime();
-  _e->noWait = true;
-  try {
-    _fileAllocationEntry->allocateChunk();
-
-    if(_fileAllocationEntry->allocationFinished()) {
-      int64_t totalLength = _requestGroup->getSegmentMan()->totalSize;
-      logger->debug("%d seconds to allocate %lld byte(s)",
-		    _timer.difference(), totalLength);
+  _fileAllocationEntry->allocateChunk();
+  
+  if(_fileAllocationEntry->allocationFinished()) {
+    int64_t totalLength = _requestGroup->getSegmentMan()->totalSize;
+    logger->debug("%d seconds to allocate %lld byte(s)",
+		  _timer.difference(), totalLength);
     
-      _e->_fileAllocationMan->markCurrentFileAllocationEntryDone();
-
+    _e->_fileAllocationMan->markCurrentFileAllocationEntryDone();
+    
+    if(_fileAllocationEntry->getNextDownloadCommand()) {
+      _e->commands.push_back(_fileAllocationEntry->getNextDownloadCommand());
+      _fileAllocationEntry->setNextDownloadCommand(0);
+    } else {
       int32_t numCommandsToGenerate = 15;
       Commands commands = _requestGroup->getNextCommand(_e, numCommandsToGenerate);
-
+      
       Command* command = InitiateConnectionCommandFactory::createInitiateConnectionCommand(cuid, _req, _requestGroup, _e);
-
+      
       commands.push_front(command);
-
+    
       _e->addCommand(commands);
-      return true;
-    } else {
-      _e->commands.push_back(this);
-      return false;
     }
-  } catch(Exception* e) {
-    _requestGroup->getSegmentMan()->errors++;
-    logger->error("CUID#%d - Exception caught while allocating file space.", e, cuid);
-    delete e;
-    logger->notice(MSG_DOWNLOAD_NOT_COMPLETE, cuid, _requestGroup->getFilePath().c_str());
     return true;
+  } else {
+    _e->commands.push_back(this);
+    return false;
   }
 }
+
+bool FileAllocationCommand::handleException(Exception* e)
+{
+  logger->error("CUID#%d - Exception caught while allocating file space.", e, cuid);
+  delete e;
+  logger->error(MSG_DOWNLOAD_NOT_COMPLETE, cuid, _requestGroup->getFilePath().c_str());
+  return true;
+}
diff --git a/src/FileAllocationCommand.h b/src/FileAllocationCommand.h
index 0ca78937..22d77a07 100644
--- a/src/FileAllocationCommand.h
+++ b/src/FileAllocationCommand.h
@@ -35,29 +35,25 @@
 #ifndef _D_FILE_ALLOCATION_COMMAND_H_
 #define _D_FILE_ALLOCATION_COMMAND_H_
 
-#include "Command.h"
+#include "RealtimeCommand.h"
 #include "Request.h"
-#include "RequestGroup.h"
-#include "DownloadEngine.h"
 #include "TimeA2.h"
 #include "FileAllocationEntry.h"
 
-class FileAllocationCommand : public Command {
+class FileAllocationCommand : public RealtimeCommand {
 private:
   RequestHandle _req;
-  RequestGroup* _requestGroup;
-  DownloadEngine* _e;
   FileAllocationEntryHandle _fileAllocationEntry;
   Time _timer;
 public:
   FileAllocationCommand(int cuid, const RequestHandle& req, RequestGroup* requestGroup, DownloadEngine* e, const FileAllocationEntryHandle& fileAllocationEntry):
-    Command(cuid),
+    RealtimeCommand(cuid, requestGroup, e),
     _req(req),
-    _requestGroup(requestGroup),
-    _e(e),
     _fileAllocationEntry(fileAllocationEntry) {}
 
-  virtual bool execute();
+  virtual bool executeInternal();
+
+  virtual bool handleException(Exception* e);
 };
 
 #endif // _D_FILE_ALLOCATION_COMMAND_H_
diff --git a/src/FileAllocationEntry.cc b/src/FileAllocationEntry.cc
index 77690475..80809030 100644
--- a/src/FileAllocationEntry.cc
+++ b/src/FileAllocationEntry.cc
@@ -33,9 +33,16 @@
  */
 /* copyright --> */
 #include "FileAllocationEntry.h"
+#include "DownloadCommand.h"
 
 #define BUFSIZE 16*1024
 
+FileAllocationEntry::~FileAllocationEntry()
+{
+  --_requestGroup->numConnection;
+  delete _nextDownloadCommand;
+}
+
 void FileAllocationEntry::allocateChunk()
 {
   int32_t bufSize = BUFSIZE;
diff --git a/src/FileAllocationEntry.h b/src/FileAllocationEntry.h
index f3f9446c..d8cea83a 100644
--- a/src/FileAllocationEntry.h
+++ b/src/FileAllocationEntry.h
@@ -39,12 +39,15 @@
 #include "Request.h"
 #include "RequestGroup.h"
 
+class DownloadCommand;
+
 class FileAllocationEntry {
 private:
   int _cuid;
   RequestHandle _currentRequest;
   RequestGroup* _requestGroup;
   int64_t _offset;
+  DownloadCommand* _nextDownloadCommand;
 public:
   FileAllocationEntry(int cuid,
 		      const RequestHandle& currentRequest,
@@ -53,15 +56,13 @@ public:
     _cuid(cuid),
     _currentRequest(currentRequest),
     _requestGroup(requestGroup),
-    _offset(offset)
+    _offset(offset),
+    _nextDownloadCommand(0)
   {
     ++_requestGroup->numConnection;
   }
 
-  ~FileAllocationEntry()
-  {
-    --_requestGroup->numConnection;
-  }
+  ~FileAllocationEntry();
 
   int getCUID() const
   {
@@ -94,6 +95,16 @@ public:
   {
     return _requestGroup->getSegmentMan()->totalSize <= _offset;
   }
+
+  void setNextDownloadCommand(DownloadCommand* command)
+  {
+    _nextDownloadCommand = command;
+  }
+
+  DownloadCommand* getNextDownloadCommand() const
+  {
+    return _nextDownloadCommand;
+  }
 };
 
 typedef SharedHandle<FileAllocationEntry> FileAllocationEntryHandle;
diff --git a/src/HttpDownloadCommand.cc b/src/HttpDownloadCommand.cc
index c23142ee..de4d6f27 100644
--- a/src/HttpDownloadCommand.cc
+++ b/src/HttpDownloadCommand.cc
@@ -47,9 +47,7 @@ HttpDownloadCommand::HttpDownloadCommand(int cuid,
 HttpDownloadCommand::~HttpDownloadCommand() {}
 
 bool HttpDownloadCommand::prepareForNextSegment() {
-  if(_requestGroup->getSegmentMan()->finished()) {
-    return true;
-  } else {
+  if(!_requestGroup->getSegmentMan()->finished()) {
     if(req->isKeepAlive()) {
       Command* command = new HttpRequestCommand(cuid, req, _requestGroup, e, socket);
       e->commands.push_back(command);
@@ -57,5 +55,7 @@ bool HttpDownloadCommand::prepareForNextSegment() {
     } else {
       return DownloadCommand::prepareForNextSegment();
     }
+  } else {
+    return DownloadCommand::prepareForNextSegment();
   }
 }
diff --git a/src/HttpResponseCommand.cc b/src/HttpResponseCommand.cc
index 1ba9b680..f3dcfe09 100644
--- a/src/HttpResponseCommand.cc
+++ b/src/HttpResponseCommand.cc
@@ -91,7 +91,7 @@ bool HttpResponseCommand::executeInternal()
     _requestGroup->validateFilename(httpResponse->determinFilename());
     _requestGroup->validateTotalLength(httpResponse->getEntityLength());
 
-    createHttpDownloadCommand(httpResponse);
+    e->commands.push_back(createHttpDownloadCommand(httpResponse));
     return true;
   } else {
     // TODO validate totalsize against hintTotalSize if it is provided.
@@ -136,8 +136,13 @@ bool HttpResponseCommand::handleDefaultEncoding(const HttpResponseHandle& httpRe
     }
   }
 
+  DownloadCommand* command = 0;
+  File file(_requestGroup->getFilePath());
+  if(_requestGroup->getRemainingUris().empty() && !file.exists()) {
+    command = createHttpDownloadCommand(httpResponse);
+  }
   _requestGroup->loadAndOpenFile();
-  _requestGroup->prepareForNextAction(cuid, req, e);
+  _requestGroup->prepareForNextAction(cuid, req, e, command);
   e->noWait = true;
   return true;
 }
@@ -157,11 +162,11 @@ bool HttpResponseCommand::handleOtherEncoding(const HttpResponseHandle& httpResp
   req->setKeepAlive(false);
   segment = _requestGroup->getSegmentMan()->getSegment(cuid);	
   _requestGroup->getSegmentMan()->diskWriter->initAndOpenFile(_requestGroup->getSegmentMan()->getFilePath());
-  createHttpDownloadCommand(httpResponse);
+  e->commands.push_back(createHttpDownloadCommand(httpResponse));
   return true;
 }
 
-void HttpResponseCommand::createHttpDownloadCommand(const HttpResponseHandle& httpResponse)
+HttpDownloadCommand* HttpResponseCommand::createHttpDownloadCommand(const HttpResponseHandle& httpResponse)
 {
   TransferEncodingHandle enc = 0;
   if(httpResponse->isTransferEncodingSpecified()) {
@@ -179,7 +184,7 @@ void HttpResponseCommand::createHttpDownloadCommand(const HttpResponseHandle& ht
   command->setLowestDownloadSpeedLimit(e->option->getAsInt(PREF_LOWEST_SPEED_LIMIT));
   command->setTransferDecoder(enc);
 
-  e->commands.push_back(command);
+  return command;
 }
 
 bool HttpResponseCommand::doTorrentStuff(const HttpResponseHandle& httpResponse)
@@ -195,6 +200,6 @@ bool HttpResponseCommand::doTorrentStuff(const HttpResponseHandle& httpResponse)
   _requestGroup->getSegmentMan()->isSplittable = false;
   _requestGroup->getSegmentMan()->downloadStarted = true;
   _requestGroup->getSegmentMan()->diskWriter->initAndOpenFile("/tmp/aria2"+Util::itos((int32_t)getpid()));
-  createHttpDownloadCommand(httpResponse);
+  e->commands.push_back(createHttpDownloadCommand(httpResponse));
   return true;
 }
diff --git a/src/HttpResponseCommand.h b/src/HttpResponseCommand.h
index 8c1c6576..f2c77061 100644
--- a/src/HttpResponseCommand.h
+++ b/src/HttpResponseCommand.h
@@ -37,6 +37,7 @@
 
 #include "AbstractCommand.h"
 #include "HttpConnection.h"
+#include "HttpDownloadCommand.h"
 
 class HttpResponseCommand : public AbstractCommand {
 private:
@@ -44,7 +45,7 @@ private:
 
   bool handleDefaultEncoding(const HttpResponseHandle& httpResponse);
   bool handleOtherEncoding(const HttpResponseHandle& httpResponse);
-  void createHttpDownloadCommand(const HttpResponseHandle& httpResponse);
+  HttpDownloadCommand* createHttpDownloadCommand(const HttpResponseHandle& httpResponse);
   bool doTorrentStuff(const HttpResponseHandle& httpResponse);
 protected:
   bool executeInternal();
diff --git a/src/IteratableChecksumValidator.cc b/src/IteratableChecksumValidator.cc
new file mode 100644
index 00000000..e094a632
--- /dev/null
+++ b/src/IteratableChecksumValidator.cc
@@ -0,0 +1,81 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#include "IteratableChecksumValidator.h"
+#include "Util.h"
+#include "message.h"
+
+#define BUFSIZE 16*1024
+
+void IteratableChecksumValidator::validateChunk()
+{
+  if(!finished()) {
+    
+    char data[BUFSIZE];
+
+    int32_t size = _diskWriter->readData(data, sizeof(data), _currentOffset);
+
+    _ctx->digestUpdate(data, size);
+    _currentOffset += sizeof(data);    
+
+    if(finished()) {
+      unsigned char* digest = new unsigned char[_ctx->digestLength()];
+      try {
+	_ctx->digestFinal(digest);
+	if(_checksum->getMessageDigest() != Util::toHex(digest, _ctx->digestLength())) {
+	  _bitfield->clearAllBit();
+	}
+	delete [] digest;
+      } catch(...) {
+	delete [] digest;
+	throw;
+      }
+    }
+  }
+}
+
+bool IteratableChecksumValidator::canValidate() const
+{
+  // We assume file is already opened using DiskWriter::open or openExistingFile.
+  return !_checksum.isNull() && !_checksum->isEmpty();
+}
+
+void IteratableChecksumValidator::init()
+{
+  _bitfield->setAllBit();
+  _currentOffset = 0;
+
+  _ctx = new MessageDigestContext(_checksum->getDigestAlgo());
+  _ctx->digestInit();
+}
diff --git a/src/IteratableChecksumValidator.h b/src/IteratableChecksumValidator.h
new file mode 100644
index 00000000..fd941072
--- /dev/null
+++ b/src/IteratableChecksumValidator.h
@@ -0,0 +1,93 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef _D_ITERATABLE_CHECKSUM_VALIDATOR_H_
+#define _D_ITERATABLE_CHECKSUM_VALIDATOR_H_
+
+#include "common.h"
+#include "BitfieldMan.h"
+#include "Checksum.h"
+#include "DiskWriter.h"
+#include "LogFactory.h"
+#include "messageDigest.h"
+
+class IteratableChecksumValidator
+{
+private:
+  DiskWriterHandle _diskWriter;
+  BitfieldMan* _bitfield;
+  int64_t _currentOffset;
+  ChecksumHandle _checksum;
+  const Logger* logger;
+  MessageDigestContextHandle _ctx;
+
+  string calculateActualChecksum();
+public:
+  IteratableChecksumValidator():_diskWriter(0), _bitfield(0), _currentOffset(0), _checksum(0), logger(LogFactory::getInstance()), _ctx(0) {}
+
+  bool canValidate() const;
+
+  void init();
+
+  void validateChunk();
+
+  bool finished() const
+  {
+    return _currentOffset >= _bitfield->getTotalLength();
+  }
+
+  void setDiskWriter(const DiskWriterHandle& diskWriter)
+  {
+    _diskWriter = diskWriter;
+  }
+
+  void setBitfield(BitfieldMan* bitfield)
+  {
+    _bitfield = bitfield;
+  }
+
+  void setChecksum(const ChecksumHandle& checksum)
+  {
+    _checksum = checksum;
+  }
+
+  int64_t getCurrentOffset() const
+  {
+    return _currentOffset;
+  }
+};
+
+typedef SharedHandle<IteratableChecksumValidator> IteratableChecksumValidatorHandle;
+
+#endif // _D_ITERATABLE_CHECKSUM_VALIDATOR_H_
diff --git a/src/Makefile.am b/src/Makefile.am
index 2da5d272..069533b0 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -95,7 +95,10 @@ SRCS =  Socket.h\
 	UriFileListParser.cc UriFileListParser.h\
 	SegmentManFactory.h\
 	AbstractSegmentManFactory.h\
-	DefaultSegmentManFactory.cc DefaultSegmentManFactory.h
+	DefaultSegmentManFactory.cc DefaultSegmentManFactory.h\
+	RealtimeCommand.cc RealtimeCommand.h\
+	IteratableChecksumValidator.cc IteratableChecksumValidator.h\
+	ChecksumCommand.cc ChecksumCommand.h
 #	debug_new.cpp
 
 if ENABLE_BITTORRENT
@@ -220,9 +223,9 @@ libaria2c_a_SOURCES = $(SRCS)
 aria2c_LDADD = libaria2c.a @LIBINTL@ @ALLOCA@ @LIBGNUTLS_LIBS@\
 	@LIBGCRYPT_LIBS@ @OPENSSL_LIBS@ @XML_LIBS@ @LIBARES_LIBS@\
 	@LIBCARES_LIBS@
-#aria2c_LDFLAGS = -pg
+aria2c_LDFLAGS = -pg
 AM_CPPFLAGS =  -Wall\
 	-I../lib -I../intl -I$(top_srcdir)/intl\
 	@LIBGNUTLS_CFLAGS@ @LIBGCRYPT_CFLAGS@ @OPENSSL_CFLAGS@ @XML_CPPFLAGS@\
 	@LIBARES_CPPFLAGS@ @LIBCARES_CPPFLAGS@\
-	-D_FILE_OFFSET_BITS=64 -DLOCALEDIR=\"$(localedir)\" @DEFS@#  -pg
\ No newline at end of file
+	-D_FILE_OFFSET_BITS=64 -DLOCALEDIR=\"$(localedir)\" @DEFS@  -pg
\ No newline at end of file
diff --git a/src/Makefile.in b/src/Makefile.in
index 98e61e0a..61b0b801 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -237,8 +237,11 @@ am__libaria2c_a_SOURCES_DIST = Socket.h SocketCore.cc SocketCore.h \
 	MultiUrlRequestInfo.h UriFileListParser.cc UriFileListParser.h \
 	SegmentManFactory.h AbstractSegmentManFactory.h \
 	DefaultSegmentManFactory.cc DefaultSegmentManFactory.h \
-	MetaEntry.h Data.cc Data.h Dictionary.cc Dictionary.h List.cc \
-	List.h MetaFileUtil.cc MetaFileUtil.h MetaEntryVisitor.h \
+	RealtimeCommand.cc RealtimeCommand.h \
+	IteratableChecksumValidator.cc IteratableChecksumValidator.h \
+	ChecksumCommand.cc ChecksumCommand.h MetaEntry.h Data.cc \
+	Data.h Dictionary.cc Dictionary.h List.cc List.h \
+	MetaFileUtil.cc MetaFileUtil.h MetaEntryVisitor.h \
 	ShaVisitor.cc ShaVisitor.h PeerConnection.cc PeerConnection.h \
 	PeerMessageUtil.cc PeerMessageUtil.h PeerAbstractCommand.cc \
 	PeerAbstractCommand.h PeerInitiateConnectionCommand.cc \
@@ -419,8 +422,9 @@ am__objects_3 = SocketCore.$(OBJEXT) Command.$(OBJEXT) \
 	IteratableChunkChecksumValidator.$(OBJEXT) \
 	CheckIntegrityCommand.$(OBJEXT) SingleUrlRequestInfo.$(OBJEXT) \
 	MultiUrlRequestInfo.$(OBJEXT) UriFileListParser.$(OBJEXT) \
-	DefaultSegmentManFactory.$(OBJEXT) $(am__objects_1) \
-	$(am__objects_2)
+	DefaultSegmentManFactory.$(OBJEXT) RealtimeCommand.$(OBJEXT) \
+	IteratableChecksumValidator.$(OBJEXT) \
+	ChecksumCommand.$(OBJEXT) $(am__objects_1) $(am__objects_2)
 am_libaria2c_a_OBJECTS = $(am__objects_3)
 libaria2c_a_OBJECTS = $(am_libaria2c_a_OBJECTS)
 am__installdirs = "$(DESTDIR)$(bindir)"
@@ -649,19 +653,22 @@ SRCS = Socket.h SocketCore.cc SocketCore.h Command.cc Command.h \
 	MultiUrlRequestInfo.h UriFileListParser.cc UriFileListParser.h \
 	SegmentManFactory.h AbstractSegmentManFactory.h \
 	DefaultSegmentManFactory.cc DefaultSegmentManFactory.h \
-	$(am__append_1) $(am__append_2)
+	RealtimeCommand.cc RealtimeCommand.h \
+	IteratableChecksumValidator.cc IteratableChecksumValidator.h \
+	ChecksumCommand.cc ChecksumCommand.h $(am__append_1) \
+	$(am__append_2)
 noinst_LIBRARIES = libaria2c.a
 libaria2c_a_SOURCES = $(SRCS)
 aria2c_LDADD = libaria2c.a @LIBINTL@ @ALLOCA@ @LIBGNUTLS_LIBS@\
 	@LIBGCRYPT_LIBS@ @OPENSSL_LIBS@ @XML_LIBS@ @LIBARES_LIBS@\
 	@LIBCARES_LIBS@
 
-#aria2c_LDFLAGS = -pg
+aria2c_LDFLAGS = -pg
 AM_CPPFLAGS = -Wall\
 	-I../lib -I../intl -I$(top_srcdir)/intl\
 	@LIBGNUTLS_CFLAGS@ @LIBGCRYPT_CFLAGS@ @OPENSSL_CFLAGS@ @XML_CPPFLAGS@\
 	@LIBARES_CPPFLAGS@ @LIBCARES_CPPFLAGS@\
-	-D_FILE_OFFSET_BITS=64 -DLOCALEDIR=\"$(localedir)\" @DEFS@#  -pg
+	-D_FILE_OFFSET_BITS=64 -DLOCALEDIR=\"$(localedir)\" @DEFS@  -pg
 
 all: all-am
 
@@ -769,6 +776,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/BtUnchokeMessage.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ByteArrayDiskWriter.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/CheckIntegrityCommand.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ChecksumCommand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ChunkChecksumValidator.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/ChunkedEncoding.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/Command.Po@am__quote@
@@ -828,6 +836,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/HttpResponse.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/HttpResponseCommand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/InitiateConnectionCommandFactory.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/IteratableChecksumValidator.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/IteratableChunkChecksumValidator.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/List.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/LogFactory.Po@am__quote@
@@ -853,6 +862,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/PeerListenCommand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/PeerMessageUtil.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/Piece.Po@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/RealtimeCommand.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/Request.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/RequestFactory.Po@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/RequestGroup.Po@am__quote@
diff --git a/src/MetalinkEntry.cc b/src/MetalinkEntry.cc
index 55d44407..6c77f848 100644
--- a/src/MetalinkEntry.cc
+++ b/src/MetalinkEntry.cc
@@ -40,6 +40,7 @@ MetalinkEntry::MetalinkEntry():
   size(0)
 #ifdef ENABLE_MESSAGE_DIGEST
   ,
+  checksum(0),
   chunkChecksum(0)
 #endif // ENABLE_MESSAGE_DIGEST
 {}
diff --git a/src/MetalinkEntry.h b/src/MetalinkEntry.h
index 71c9df31..bc9aa4e2 100644
--- a/src/MetalinkEntry.h
+++ b/src/MetalinkEntry.h
@@ -48,7 +48,7 @@ public:
   string language;
   string os;
   int64_t size;
-  Checksum checksum;
+  ChecksumHandle checksum;
 public:
   MetalinkResources resources;
 #ifdef ENABLE_MESSAGE_DIGEST
diff --git a/src/MetalinkRequestInfo.cc b/src/MetalinkRequestInfo.cc
index 495a5c3e..69e28c2a 100644
--- a/src/MetalinkRequestInfo.cc
+++ b/src/MetalinkRequestInfo.cc
@@ -106,7 +106,7 @@ RequestInfos MetalinkRequestInfo::execute() {
 		FindBitTorrentUrl());
       Strings urls;
       int maxConnection = 0;
-      Checksum checksum;
+      ChecksumHandle checksum = 0;
       if(itr == entry->resources.end()) {
 	entry->reorderResourcesByPreference();
 	
diff --git a/src/RealtimeCommand.cc b/src/RealtimeCommand.cc
new file mode 100644
index 00000000..a613fc59
--- /dev/null
+++ b/src/RealtimeCommand.cc
@@ -0,0 +1,49 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#include "RealtimeCommand.h"
+
+bool RealtimeCommand::execute()
+{
+  setStatusRealtime();
+  _e->noWait = true;
+  try {
+    return executeInternal();
+  } catch(Exception* e) {
+    _requestGroup->getSegmentMan()->errors++;
+    bool r =  handleException(e);
+    delete e;
+    return r;
+  }
+}
diff --git a/src/RealtimeCommand.h b/src/RealtimeCommand.h
new file mode 100644
index 00000000..915aa56b
--- /dev/null
+++ b/src/RealtimeCommand.h
@@ -0,0 +1,62 @@
+/* <!-- copyright */
+/*
+ * aria2 - The high speed download utility
+ *
+ * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * In addition, as a special exception, the copyright holders give
+ * permission to link the code of portions of this program with the
+ * OpenSSL library under certain conditions as described in each
+ * individual source file, and distribute linked combinations
+ * including the two.
+ * You must obey the GNU General Public License in all respects
+ * for all of the code used other than OpenSSL.  If you modify
+ * file(s) with this exception, you may extend this exception to your
+ * version of the file(s), but you are not obligated to do so.  If you
+ * do not wish to do so, delete this exception statement from your
+ * version.  If you delete this exception statement from all source
+ * files in the program, then also delete it here.
+ */
+/* copyright --> */
+#ifndef _D_REALTIME_COMMAND_H_
+#define _D_REALTIME_COMMAND_H_
+
+#include "common.h"
+#include "RequestGroup.h"
+#include "DownloadEngine.h"
+#include "Exception.h"
+
+class RealtimeCommand : public Command {
+protected:
+  RequestGroup* _requestGroup;
+  DownloadEngine* _e;
+public:
+  RealtimeCommand(int cuid, RequestGroup* requestGroup, DownloadEngine* e):
+    Command(cuid),
+    _requestGroup(requestGroup),
+    _e(e) {}
+
+  virtual ~RealtimeCommand() {}
+
+  virtual bool execute();
+
+  virtual bool executeInternal() = 0;
+
+  virtual bool handleException(Exception* e) = 0;
+};
+
+#endif // _D_REALTIME_COMMAND_H_
diff --git a/src/RequestGroup.cc b/src/RequestGroup.cc
index 7ebb011b..63e8ac7b 100644
--- a/src/RequestGroup.cc
+++ b/src/RequestGroup.cc
@@ -191,21 +191,28 @@ bool RequestGroup::downloadFinishedByFileLength()
   }
 }
 
-void RequestGroup::prepareForNextAction(int cuid, const RequestHandle& req, DownloadEngine* e)
+void RequestGroup::prepareForNextAction(int cuid, const RequestHandle& req, DownloadEngine* e, DownloadCommand* downloadCommand)
 {
   File existingFile(getFilePath());
   if(existingFile.size() > 0 && _option->get(PREF_CHECK_INTEGRITY) == V_TRUE) {
     CheckIntegrityCommand* command = new CheckIntegrityCommand(cuid, req, this, e);
+    command->setNextDownloadCommand(downloadCommand);
     command->initValidator();
     e->commands.push_back(command);
   } else if(needsFileAllocation()) {
-    e->_fileAllocationMan->pushFileAllocationEntry(new FileAllocationEntry(cuid, req, this));
+    FileAllocationEntryHandle entry = new FileAllocationEntry(cuid, req, this);
+    entry->setNextDownloadCommand(downloadCommand);
+    e->_fileAllocationMan->pushFileAllocationEntry(entry);
   } else {
-    int32_t numCommandsToGenerate = 15;
-    Commands commands = getNextCommand(e, numCommandsToGenerate);
-    Command* command = InitiateConnectionCommandFactory::createInitiateConnectionCommand(cuid, req, this, e);
-    commands.push_front(command);
-    e->addCommand(commands);
+    if(downloadCommand) {
+      e->commands.push_back(downloadCommand);
+    } else {
+      int32_t numCommandsToGenerate = 15;
+      Commands commands = getNextCommand(e, numCommandsToGenerate);
+      Command* command = InitiateConnectionCommandFactory::createInitiateConnectionCommand(cuid, req, this, e);
+      commands.push_front(command);
+      e->addCommand(commands);
+    }
   }
 }
 
diff --git a/src/RequestGroup.h b/src/RequestGroup.h
index fc15f8ca..d1e496b7 100644
--- a/src/RequestGroup.h
+++ b/src/RequestGroup.h
@@ -44,6 +44,8 @@
 #include "SegmentManFactory.h"
 #include "DefaultSegmentManFactory.h"
 
+class DownloadCommand;
+
 class DownloadEngine;
 
 class RequestGroup {
@@ -57,7 +59,7 @@ private:
   const Option* _option;
   const Logger* logger;
   ChunkChecksumHandle _chunkChecksum;
-  Checksum _checksum;
+  ChecksumHandle _checksum;
 
   void validateFilename(const string& expectedFilename,
 			const string& actualFilename) const;
@@ -79,6 +81,7 @@ public:
     _option(option),
     logger(LogFactory::getInstance()),
     _chunkChecksum(0),
+    _checksum(0),
     numConnection(0),
     isTorrent(false) {}
 
@@ -186,15 +189,20 @@ public:
 
   void loadAndOpenFile();
 
-  void prepareForNextAction(int cuid, const RequestHandle& req, DownloadEngine* e);
+  void prepareForNextAction(int cuid, const RequestHandle& req, DownloadEngine* e, DownloadCommand* downloadCommand = 0);
 
   bool downloadFinishedByFileLength();
 
-  void setChecksum(const Checksum& checksum)
+  void setChecksum(const ChecksumHandle& checksum)
   {
     _checksum = checksum;
   }
 
+  ChecksumHandle getChecksum() const
+  {
+    return _checksum;
+  }
+
   const string& getHintFilename() const
   {
     return _hintFilename;
diff --git a/src/Xml2MetalinkProcessor.cc b/src/Xml2MetalinkProcessor.cc
index 67925ddc..8289e551 100644
--- a/src/Xml2MetalinkProcessor.cc
+++ b/src/Xml2MetalinkProcessor.cc
@@ -112,13 +112,15 @@ MetalinkEntryHandle Xml2MetalinkProcessor::getEntry(const string& xpath) {
   string md;
   md = Util::toLower(Util::trim(xpathContent(xpath+"/m:verification/m:hash[@type=\"sha1\"]")));
   if(md.size() > 0) {
-    entry->checksum.setMessageDigest(md);
-    entry->checksum.setDigestAlgo(DIGEST_ALGO_SHA1);
+    entry->checksum = new Checksum();
+    entry->checksum->setMessageDigest(md);
+    entry->checksum->setDigestAlgo(DIGEST_ALGO_SHA1);
   } else {
     md = Util::toLower(Util::trim(xpathContent(xpath+"/m:verification/m:hash[@type=\"md5\"]")));
     if(md.size() > 0) {
-      entry->checksum.setMessageDigest(md);
-      entry->checksum.setDigestAlgo(DIGEST_ALGO_MD5);
+      entry->checksum = new Checksum();
+      entry->checksum->setMessageDigest(md);
+      entry->checksum->setDigestAlgo(DIGEST_ALGO_MD5);
     }
   }
   string piecesPath = xpath+"/m:verification/m:pieces";
diff --git a/src/common.h b/src/common.h
index ce6a63ab..2c61b472 100644
--- a/src/common.h
+++ b/src/common.h
@@ -79,5 +79,6 @@ typedef deque<string> Strings;
 typedef deque<int32_t> Integers;
 
 #define OPEN_MODE S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH
+#define DIR_OPEN_MODE S_IRWXU|S_IRWXG|S_IRWXO
 
 #endif // _D_COMMON_H_
diff --git a/src/message.h b/src/message.h
index 17a3f1ee..e45de293 100644
--- a/src/message.h
+++ b/src/message.h
@@ -57,6 +57,8 @@
 #define MSG_GOT_WRONG_PIECE _("CUID#%d - we got wrong piece. index=%d")
 #define MSG_DOWNLOAD_NOT_COMPLETE _("CUID#%d - Download not complete: %s")
 #define MSG_DOWNLOAD_ALREADY_COMPLETED _("CUID#%d - Download already completed: %s")
+#define MSG_GOOD_CHECKSUM _("CUID#%d - Good checksum: %s")
+#define MSG_BAD_CHECKSUM _("CUID#%d - Bad checksum: %s")
 
 #define MSG_TRACKER_WARNING_MESSAGE _("Tracker returned warning message: %s")
 #define MSG_SEGMENT_FILE_EXISTS _("The segment file %s exists.")
diff --git a/src/messageDigest.h b/src/messageDigest.h
index 8da9a25a..d7743586 100644
--- a/src/messageDigest.h
+++ b/src/messageDigest.h
@@ -146,5 +146,6 @@ public:
   }
 #endif // HAVE_LIBGCRYPT
 };
+typedef SharedHandle<MessageDigestContext> MessageDigestContextHandle;
 #endif // ENABLE_SSL
 #endif // _D_MESSAGE_DIGEST_H_