diff --git a/ChangeLog b/ChangeLog
index 934e8d8b..72c56334 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+2009-05-03  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
+
+	Fixed the bug that read-only file with wrong file size will cause
+	error because it cannot be truncated to the correct size.  Now if
+	file size is different than the expected one, re-open file in
+	writable mode.
+	* src/AbstractSingleDiskAdaptor.cc
+	* src/AbstractSingleDiskAdaptor.h
+	* src/BtCheckIntegrityEntry.cc
+	* src/DiskAdaptor.h
+	* src/MultiDiskAdaptor.h
+	* src/RequestGroup.cc
+
 2009-05-03  Tatsuhiro Tsujikawa  <t-tujikawa@users.sourceforge.net>
 
 	Fixed the bug that with --check-integrity option aria2 reports
diff --git a/src/AbstractSingleDiskAdaptor.cc b/src/AbstractSingleDiskAdaptor.cc
index f1c71493..695eab7c 100644
--- a/src/AbstractSingleDiskAdaptor.cc
+++ b/src/AbstractSingleDiskAdaptor.cc
@@ -42,7 +42,8 @@
 
 namespace aria2 {
 
-AbstractSingleDiskAdaptor::AbstractSingleDiskAdaptor():totalLength(0) {}
+AbstractSingleDiskAdaptor::AbstractSingleDiskAdaptor():
+  totalLength(0), _readOnly(false) {}
 
 AbstractSingleDiskAdaptor::~AbstractSingleDiskAdaptor() {}
 
@@ -126,11 +127,13 @@ bool AbstractSingleDiskAdaptor::directIOAllowed() const
 void AbstractSingleDiskAdaptor::enableReadOnly()
 {
   diskWriter->enableReadOnly();
+  _readOnly = true;
 }
 
 void AbstractSingleDiskAdaptor::disableReadOnly()
 {
   diskWriter->disableReadOnly();
+  _readOnly = false;
 }
 
 void AbstractSingleDiskAdaptor::cutTrailingGarbage()
diff --git a/src/AbstractSingleDiskAdaptor.h b/src/AbstractSingleDiskAdaptor.h
index b01f29a2..f8c9e3a1 100644
--- a/src/AbstractSingleDiskAdaptor.h
+++ b/src/AbstractSingleDiskAdaptor.h
@@ -46,6 +46,7 @@ class AbstractSingleDiskAdaptor : public DiskAdaptor {
 protected:
   SharedHandle<DiskWriter> diskWriter;
   uint64_t totalLength;
+  bool _readOnly;
 public:
   AbstractSingleDiskAdaptor();
 
@@ -84,6 +85,8 @@ public:
   // Make sure that DiskWriter is set before calling this function.
   virtual void disableReadOnly();
     
+  virtual bool isReadOnlyEnabled() const { return _readOnly; }
+  
   virtual void cutTrailingGarbage();
 
   virtual std::string getFilePath() = 0;
diff --git a/src/BtCheckIntegrityEntry.cc b/src/BtCheckIntegrityEntry.cc
index 1be5e251..211467c2 100644
--- a/src/BtCheckIntegrityEntry.cc
+++ b/src/BtCheckIntegrityEntry.cc
@@ -51,11 +51,14 @@ BtCheckIntegrityEntry::~BtCheckIntegrityEntry() {}
 void BtCheckIntegrityEntry::onDownloadIncomplete(std::deque<Command*>& commands,
 						 DownloadEngine* e)
 {
-  // Now reopen DiskAdaptor with read only disabled.
-  _requestGroup->getPieceStorage()->getDiskAdaptor()->closeFile();
-  _requestGroup->getPieceStorage()->getDiskAdaptor()->disableReadOnly();
-  _requestGroup->getPieceStorage()->getDiskAdaptor()->openFile();
-
+  const SharedHandle<DiskAdaptor>& diskAdaptor =
+    _requestGroup->getPieceStorage()->getDiskAdaptor();
+  if(diskAdaptor->isReadOnlyEnabled()) {
+    // Now reopen DiskAdaptor with read only disabled.
+    diskAdaptor->closeFile();
+    diskAdaptor->disableReadOnly();
+    diskAdaptor->openFile();
+  }
   SharedHandle<BtFileAllocationEntry> entry
     (new BtFileAllocationEntry(_requestGroup));
   proceedFileAllocation(commands, entry, e);
diff --git a/src/DiskAdaptor.h b/src/DiskAdaptor.h
index a07d42e0..959f430b 100644
--- a/src/DiskAdaptor.h
+++ b/src/DiskAdaptor.h
@@ -100,6 +100,8 @@ public:
 
   virtual void disableReadOnly() {}
 
+  virtual bool isReadOnlyEnabled() const { return false; }
+
   // Assumed each file length is stored in fileEntries or DiskAdaptor knows it.
   // If each actual file's length is larger than that, truncate file to that
   // length.
diff --git a/src/MultiDiskAdaptor.h b/src/MultiDiskAdaptor.h
index ae9695e7..21fa60a6 100644
--- a/src/MultiDiskAdaptor.h
+++ b/src/MultiDiskAdaptor.h
@@ -155,6 +155,8 @@ public:
 
   virtual void disableReadOnly();
 
+  virtual bool isReadOnlyEnabled() const { return _readOnly; }
+
   void setPieceLength(size_t pieceLength) {
     this->pieceLength = pieceLength;
   }
diff --git a/src/RequestGroup.cc b/src/RequestGroup.cc
index a33d179c..d65a687d 100644
--- a/src/RequestGroup.cc
+++ b/src/RequestGroup.cc
@@ -311,7 +311,20 @@ void RequestGroup::createInitialCommand(std::deque<Command*>& commands,
 	}
       }
       _progressInfoFile = progressInfoFile;
-
+      {
+	uint64_t actualFileSize = _pieceStorage->getDiskAdaptor()->size();
+	if(actualFileSize != btContext->getTotalLength()) {
+	  // Re-open file in writable mode to allow the program
+	  // truncate the file to the specified length
+	  _logger->debug("File size not match. Re-open file in writable mode."
+			 " Expected:%s Actual:%s",
+			 Util::uitos(btContext->getTotalLength()).c_str(),
+			 Util::uitos(actualFileSize).c_str());
+	  _pieceStorage->getDiskAdaptor()->closeFile();
+	  _pieceStorage->getDiskAdaptor()->disableReadOnly();
+	  _pieceStorage->getDiskAdaptor()->openFile();
+	}
+      }
       if(!btContext->isPrivate() && _option->getAsBool(PREF_ENABLE_DHT)) {
 	std::deque<Command*> commands;
 	DHTSetup().setup(commands, e, _option);
@@ -371,7 +384,7 @@ void RequestGroup::processCheckIntegrityEntry(std::deque<Command*>& commands,
   if(e->option->getAsBool(PREF_CHECK_INTEGRITY) &&
      entry->isValidationReady()) {
     entry->initValidator();
-    entry->cutTrailingGarbage();    
+    entry->cutTrailingGarbage();
     e->_checkIntegrityMan->pushEntry(entry);
   } else
 #endif // ENABLE_MESSAGE_DIGEST