2010-07-16 Tatsuhiro Tsujikawa <t-tujikawa@users.sourceforge.net>

	Added --conditional-get option.  Download file only when the local
	file is older than remote file.  This function only works with
	HTTP(S) downloads only. It does not work if file size is specified
	in Metalink. It also ignores Content-Disposition header. If a
	control file exists, this option will be ignored. This function
	uses If-Modified-Since header to get only newer file
	conditionally. When getting modification time of local file, it
	uses user supplied filename(see --out option) or filename part in
	URI if --out is not specified.
	* doc/aria2c.1.txt
	* src/HttpHeader.cc
	* src/HttpHeader.h
	* src/HttpRequest.cc
	* src/HttpRequest.h
	* src/HttpRequestCommand.cc
	* src/HttpResponse.cc
	* src/HttpResponseCommand.cc
	* src/OptionHandlerFactory.cc
	* src/TimeA2.cc
	* src/TimeA2.h
	* src/prefs.cc
	* src/prefs.h
	* src/usage_text.h
	* test/HttpResponseTest.cc
	* test/TimeTest.cc

1 files changed, 20 insertions, 1 deletions

diff --git a/src/HttpResponseCommand.cc b/src/HttpResponseCommand.cc
index b523699a..3a24a97d 100644
--- a/src/HttpResponseCommand.cc
+++ b/src/HttpResponseCommand.cc
@@ -119,7 +119,26 @@ bool HttpResponseCommand::executeInternal()
       (getOption()->getAsInt(PREF_MAX_HTTP_PIPELINING));
   }
 
-  if(httpResponse->getResponseStatus() >= HttpHeader::S300) {
+  if(!httpResponse->getHttpRequest()->getIfModifiedSinceHeader().empty()) {
+    if(httpResponse->getResponseStatus() == HttpHeader::S304) {
+      uint64_t totalLength = httpResponse->getEntityLength();
+      getFileEntry()->setLength(totalLength);
+      getRequestGroup()->initPieceStorage();
+      getPieceStorage()->markAllPiecesDone();
+      getLogger()->notice(MSG_DOWNLOAD_ALREADY_COMPLETED,
+                          util::itos(getRequestGroup()->getGID()).c_str(),
+                          getRequestGroup()->getFirstFilePath().c_str());
+      poolConnection();
+      getFileEntry()->poolRequest(getRequest());
+      return true;
+    } else if(httpResponse->getResponseStatus() == HttpHeader::S200 ||
+              httpResponse->getResponseStatus() == HttpHeader::S206) {
+      // Remote file is newer than local file. We allow overwrite.
+      getOption()->put(PREF_ALLOW_OVERWRITE, V_TRUE);
+    }
+  }
+  if(httpResponse->getResponseStatus() >= HttpHeader::S300 &&
+     httpResponse->getResponseStatus() != HttpHeader::S304) {
     if(httpResponse->getResponseStatus() == HttpHeader::S404) {
       getRequestGroup()->increaseAndValidateFileNotFoundCount();
     }