don't allow user to add same file twice to createchanmsg instance

git-svn-id: http://svn.code.sf.net/p/retroshare/code/trunk@3700 b45a01b8-16f6-495d-af2f-9b41ad6348cc

retroshare-gui/src/gui/channels/CreateChannelMsg.cpp

@@ -301,11 +301,30 @@ void CreateChannelMsg::addAttachment(const std::string &path)
 	/* add widget in for new destination */
 	uint32_t flags =  SFI_TYPE_CHANNEL | SFI_STATE_EXTRA;
 
+
+	// check attachment if hash exists already
+	std::list<SubFileItem* >::iterator  it;
+
+	for(it= mAttachments.begin(); it != mAttachments.end(); it++){
+
+		if((*it)->FilePath() == path){
+			QMessageBox::warning(this, tr("RetroShare"),
+	                   tr("File already Added and Hashed"),
+	                   QMessageBox::Ok, QMessageBox::Ok);
+
+			return;
+		}
+
+	}
+
 	// channels creates copy of file into channels directory and shares this
 
 	FileInfo fInfo;
 	rsChannels->channelExtraFileHash(path, mChannelId, fInfo);
 
+
+
+
 	// file is not innitial
 	SubFileItem *file = new SubFileItem(fInfo.hash, fInfo.fname, fInfo.path, fInfo.size,
 			flags, mChannelId); // destroyed when fileFrame (this subfileitem) is destroyed