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• OO Design - polymorphism - how to design for handing streams of different file types

  - by Kache4

  I've little experience with advanced OO practices, and I want to design this properly as an exercise. I'm thinking of implementing the following, and I'm asking if I'm going about this the right way. I have a class PImage that holds the raw data and some information I need for an image file. Its header is currently something like this: #include <boost/filesytem.hpp> #include <vector> namespace fs = boost::filesystem; class PImage { public: PImage(const fs::path& path, const unsigned char* buffer, int bufferLen); const vector<char> data() const { return data_; } const char* rawData() const { return &data_[0]; } /*** other assorted accessors ***/ private: fs::path path_; int width_; int height_; int filesize_; vector<char> data_; } I want to fill the width_ and height_ by looking through the file's header. The trivial/inelegant solution would be to have a lot of messy control flow that identifies the type of image file (.gif, .jpg, .png, etc) and then parse the header accordingly. Instead of using vector<char> data_, I was thinking of having PImage use a class, RawImageStream data_ that inherits from vector<char>. Each type of file I plan to support would then inherit from RawImageStream, e.g. RawGifStream, RawPngStream. Each RawXYZStream would encapsulate the respective header-parsing functions, and PImage would only have to do something like height_ = data_.getHeight();. Am I thinking this through correctly? How would I create the proper RawImageStream subclass for data_ to be in the PImage ctor? Is this where I could use an object factory? Anything I'm forgetting?

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• How would i down-sample a .wav file then reconstruct it using nyquist? - in matlab [closed]

  - by martin

  Possible Duplicate: How would i down-sample a .wav file then reconstruct it using nyquist? - in matlab This is all done in MatLab 2010 My objective is to show the results of: undersampling, nyquist rate/ oversampling First i need to downsample the .wav file to get an incomplete/ or impartial data stream that i can then reconstuct. Heres the flow chart of what im going to be doing So the flow is analog signal - sampling analog filter - ADC - resample down - resample up - DAC - reconstruction analog filter what needs to be achieved: F= Frequency F(Hz=1/s) E.x. 100Hz = 1000 (Cyc/sec) F(s)= 1/(2f) Example problem: 1000 hz = Highest frequency 1/2(1000hz) = 1/2000 = 5x10(-3) sec/cyc or a sampling rate of 5ms This is my first signal processing project using matlab. what i have so far. % Fs = frequency sampled (44100hz or the sampling frequency of a cd) [test,fs]=wavread('test.wav'); % loads the .wav file left=test(:,1); % Plot of the .wav signal time vs. strength time=(1/44100)*length(left); t=linspace(0,time,length(left)); plot(t,left) xlabel('time (sec)'); ylabel('relative signal strength') **%this is were i would need to sample it at the different frequecys (both above and below and at) nyquist frequency.*I think.*** soundsc(left,fs) % shows the resaultant audio file , which is the same as original ( only at or above nyquist frequency however) Can anyone tell me how to make it better, and how to do the various sampling at different frequencies?

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• saving WPF InkCanvas to a JPG - image is getting cropped

  - by Jason

  I have a WPF InkCanvas control I'm using to capture a signature in my application. The control looks like this - it's 700x300 However, when I save it as a JPG, the resulting image looks like this, also 700x300 The code I'm using to save sigPath = System.IO.Path.GetTempFileName(); MemoryStream ms = new MemoryStream(); FileStream fs = new FileStream(sigPath, FileMode.Create); RenderTargetBitmap rtb = new RenderTargetBitmap((int)inkSig.Width, (int)inkSig.Height, 96d, 96d, PixelFormats.Default); rtb.Render(inkSig); JpegBitmapEncoder encoder = new JpegBitmapEncoder(); encoder.Frames.Add(BitmapFrame.Create(rtb)); encoder.Save(fs); fs.Close(); This is the XAML I'm using: <Window x:Class="Consent.Client.SigPanel" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Background="Transparent" Topmost="True" AllowsTransparency="True" Title="SigPanel" Left="0" Top="0" Height="1024" Width="768" WindowStyle ="None" ShowInTaskbar="False" ResizeMode="NoResize" WindowStartupLocation="CenterScreen" > <Border BorderThickness="1" BorderBrush="Black" Background='#FFFFFFFF' x:Name='DocumentRoot' Width='750' Height='400' CornerRadius='10'> <StackPanel HorizontalAlignment="Center" VerticalAlignment="Center"> <TextBlock Name="txtLabel" FontSize="24" HorizontalAlignment="Center" >Label</TextBlock> <InkCanvas Opacity="1" Background="Beige" Name="inkSig" Width="700" Height="300" /> <StackPanel HorizontalAlignment="Center" Orientation="Horizontal"> <Button FontSize="24" Margin="10" Width="150" Name="btnSave" Click="btnSave_Click">Save</Button> <Button FontSize="24" Margin="10" Width="150" Name="btnCancel" Click="btnCancel_Click">Cancel</Button> <Button FontSize="24" Margin="10" Width="150" Name="btnClear" Click="btnClear_Click">Clear</Button> </StackPanel> </StackPanel> </Border> In the past this worked perfectly. I can't figure out what changed that is causing the image to shift when it is saved.

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• Dealing with SerializationExceptions in C#

  - by Tony

  I get a SerializationException: (...) is not marked as serializable. error in the following code: [Serializable] public class Wind { public MyText text; public Size MSize; public Point MLocation; public int MNumber; /.../ } [Serializable] public class MyText { public string MString; public Font MFont; public StringFormat StrFormat; public float MySize; public Color FColor, SColor, TColor; public bool IsRequest; public decimal MWide; /.../ } and the List to be serialized: List<Wind> MyList = new List<Wind>(); Code Snippet: FileStream FS = new FileStream(AppDomain.CurrentDomain.BaseDirectory + "Sticks.dat", FileMode.Create); BinaryFormatter BF = new BinaryFormatter(); BF.Serialize(FS, MyList); FS.Close(); throws an Exception: System.Runtime.Serialization.SerializationException was unhandled Message="Type 'System.Drawing.StringFormat' in Assembly 'System.Drawing, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' is not marked as serializable." How do I solve this problem?

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• Excel 2007 file writer in C# results in a corrupt file

  - by Martin

  Hi, I am using a BinaryReader to read an Excel 2007 file from an Exchange mailbox using a OWA, the file is then written to disk using a BinaryWriter. My problem is that the two files don't match when the writer finishes. Worse still Excel 2007 won't open the writen file. Previously Excel 2003 has had no problem with the solution below. And Excel 2007 doesn't have an issue if the file is an Excel 2003 format file, only if the file format is Excel 2007 (*.xlsx). BinaryReader: using(System.IO.Stream stream = resource.GetInputStream(attachedFiles[k].Address)) { using(System.IO.BinaryReader br = new System.IO.BinaryReader(stream)) { attachment.Data = new byte[attachedFiles[k].Size]; int bufPosn=0, len=0; while ((len = br.Read( attachment.Data, bufPosn, attachment.Data.Length-bufPosn )) > 0) { bufPosn += len; } br.Close(); } } BinaryWriter: FileStream fs = new FileStream(fileName, FileMode.Create); BinaryWriter binWriter = new BinaryWriter(fs); binWriter.Write( content, 0, content.Length ); binWriter.Close(); fs.Close(); Suggestions gratfully received.

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• Are Subversion 1.6 & Xcode 3.2 compatible?

  - by Meltemi

  Trying to get Xcode to work with Subversion server. Server: Subversion upgraded to 1.6.9 (Mac OS X Leopard 10.5.8) Client: Xcode 3.2.1 (Snow Leopard 10.6.2 with Subversion 1.6.5 though not sure that matters) Repository on server is setup and working fine via command line. However, I get an error when trying to create the Repository connection in Xcode: Error: 160043 (Unsupported FS format) Description: Expected FS format '2'; found format '4' a Google search seems to say that the server needs to be updated...but it's running 1.6.9 which is the most current version I'm aware of. Anyone know how to make this work? Is it even possible? I'm well aware of the command line usage but I would like to get Xcode & SVN talking... Revisiting this after some time: Using command line: username$ svn+ssh://hostname/Library/Subversion/Repository/test yields the same result: Description: Expected FS format '2'; found format Can anyone verify that I need to upgrade Subversion on the client machine to match version on server (1.6.9)?!? was hoping i wouldn't have to unless it was a "major" revision (ie. 1.5.x - 1.6.x)

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• Cast to delegate type fails in JScript.NET

  - by dnewcome

  I am trying to do async IO using BeginRead() in JScript.NET, but I can't get the callback function to work correctly. Here is the code: function readFileAsync() { var fs : FileStream = new FileStream( 'test.txt', FileMode.Open, FileAccess.Read ); var result : IAsyncResult = fs.BeginRead( new byte[8], 0, 8, readFileCallback ), fs ); Thread.Sleep( Timeout.Infinite ); } var readFileCallback = function( result : IAsyncResult ) : void { print( 'ListenerCallback():' ); } The exception is a cast failure: Unhandled Exception: System.InvalidCastException: Unable to cast object of type 'Microsoft.JScript.Closure' to type 'System.AsyncCallback'. at JScript 0.readFileAsync(Object this, VsaEngine vsa Engine) at JScript 0.Global Code() at JScript Main.Main(String[] ) I have tried doing an explicit cast both to AsyncCallback and to the base MulticastDelegate and Delegate types to no avail. Delegates are supposed to be created automatically, obviating the need for creating a new AsyncCallback explicitly, eg: BeginRead( ... new AsyncDelegate( readFileCallback), object ); And in fact if you try to create the delegate explicitly the compiler issues an error. I must be missing something here.

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• XML serialization of a collection in C#

  - by Archana R

  I have two classes as follows: public class Info { [XmlAttribute] public string language; public int version; public Book book; public Info() { } public Info(string l, int v, string author, int quantity, int price) { this.language = l; this.version = v; book = new Book(author, quantity, price); } } public class Book { [XmlAttribute] public string author; public int quantity; public int price; [XmlIgnore]public int total; public NameValueCollection nvcollection = new NameValueCollection(); public Book() { } public Book(string author, int quantity, int price) { this.author = author; this.quantity = quantity; this.price = price; total = quantity * price; nvcollection.Add(author, price.ToString()); } } I have created an ArrayList which adds the two instances of Info class as follows: FileStream fs = new FileStream("SerializedInfo.XML", FileMode.Create); List<Info> arrList = new List<Info>(); XmlSerializer xs = new XmlSerializer(typeof(List<Info>)); Info pObj = new Info("ABC", 3, "DEF", 2, 6); Info pObj1 = new Info("GHI", 4, "JKL", 2, 8); arrList.Add(pObj); arrList.Add(pObj1); xs.Serialize(fs, arrList); fs.Close(); But when I try to serialize, I get an exception as "There was an error reflecting type 'System.Collections.Generic.List`1[ConsoleApplicationSerialization.Info]'." Can anyone help me with it? Also, instead of namevaluecollection, which type of structure can i use?

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• F#, Linux and makefiles

  - by rwallace

  I intend to distribute an F# program as both binary and source so the user has the option of recompiling it if desired. On Windows, I understand how to do this: provide .fsproj and .sln files, which both Visual Studio and MSBuild can understand. On Linux, the traditional solution for C programs is a makefile. This depends on gcc being directly available, which it always is. The F# compiler can be installed on Linux and works under Mono, so that's fine so far. However, as far as I can tell, it doesn't create a scenario where fsc runs the compiler, instead the command is mono ...path.../fsc.exe. This is also fine, except I don't know what the path is going to be. So the full command to run the compiler in my case could be mono ~/FSharp-2.0.0.0/bin/fsc.exe types.fs tptp.fs main.fs -r FSharp.PowerPack.dll except that I'm not sure where fsc.exe will actually be located on the user's machine. Is there a way to find that out within a makefile, or would it be better to fall back on just explaining the above in the documentation and relying on the user to modify the command according to his setup?

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• Cast errors with IXmlSerializable

  - by Nathan

  I am trying to use the IXmlSerializable interface to deserialize an Object (I am using it because I need specific control over what gets deserialized and what does not. See my previous question for more information). However, I'm stumped as to the error message I get. Below is the error message I get (I have changed some names for clarity): An unhandled exception of type 'System.InvalidCastException' occurred in App.exe Additional information: Unable to cast object of type 'System.Xml.XmlNode[]' to type 'MyObject'. MyObject has all the correct methods defined for the interface, and regardless of what I put in the method body for ReadXml() I still get this error. It doesn't matter if it has my implementation code or if it's just blank. I did some googling and found an error that looks similar to this involving polymorphic objects that implement IXmlSerializable. However, my class does not inherit from any others (besides Object). I suspected this may be an issue because I never reference XmlNode any other time in my code. Microsoft describes a solution to the polymorphism error: https://connect.microsoft.com/VisualStudio/feedback/details/422577/incorrect-deserialization-of-polymorphic-type-that-implements-ixmlserializable?wa=wsignin1.0#details The code the error occurs at is as follows. The object to be read back in is an ArrayList of "MyObjects" IO::FileStream ^fs = gcnew IO::FileStream(filename, IO::FileMode::Open); array<System::Type^>^ extraTypes = gcnew array<System::Type^>(1); extraTypes[0] = MyObject::typeid; XmlSerializer ^xmlser = gcnew XmlSerializer(ArrayList::typeid, extraTypes); System::Object ^obj; obj = xmlser->Deserialize(fs); fs->Close(); ArrayList ^al = safe_cast<ArrayList^>(obj); MyObject ^objs; for each(objs in al) //Error occurs here { //do some processing } Thanks for reading and for any help.

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• Passing IDisposable objects through constructor chains

  - by Matt Enright

  I've got a small hierarchy of objects that in general gets constructed from data in a Stream, but for some particular subclasses, can be synthesized from a simpler argument list. In chaining the constructors from the subclasses, I'm running into an issue with ensuring the disposal of the synthesized stream that the base class constructor needs. Its not escaped me that the use of IDisposable objects this way is possibly just dirty pool (plz advise?) for reasons I've not considered, but, this issue aside, it seems fairly straightforward (and good encapsulation). Codes: abstract class Node { protected Node (Stream raw) { // calculate/generate some base class properties } } class FilesystemNode : Node { public FilesystemNode (FileStream fs) : base (fs) { // all good here; disposing of fs not our responsibility } } class CompositeNode : Node { public CompositeNode (IEnumerable some_stuff) : base (GenerateRaw (some_stuff)) { // rogue stream from GenerateRaw now loose in the wild! } static Stream GenerateRaw (IEnumerable some_stuff) { var content = new MemoryStream (); // molest elements of some_stuff into proper format, write to stream content.Seek (0, SeekOrigin.Begin); return content; } } I realize that not disposing of a MemoryStream is not exactly a world-stopping case of bad CLR citizenship, but it still gives me the heebie-jeebies (not to mention that I may not always be using a MemoryStream for other subtypes). It's not in scope, so I can't explicitly Dispose () it later in the constructor, and adding a using statement in GenerateRaw () is self-defeating since I need the stream returned. Is there a better way to do this? Preemptive strikes: yes, the properties calculated in the Node constructor should be part of the base class, and should not be calculated by (or accessible in) the subclasses I won't require that a stream be passed into CompositeNode (its format should be irrelevant to the caller) The previous iteration had the value calculation in the base class as a separate protected method, which I then just called at the end of each subtype constructor, moved the body of GenerateRaw () into a using statement in the body of the CompositeNode constructor. But the repetition of requiring that call for each constructor and not being able to guarantee that it be run for every subtype ever (a Node is not a Node, semantically, without these properties initialized) gave me heebie-jeebies far worse than the (potential) resource leak here does.

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• How would i down-sample a .wav file then reconstruct it using nyquist? - in MATLAB

  - by Andrew

  This is all done in MATLAB 2010 My objective is to show the results of: undersampling, nyquist rate/ oversampling First i need to downsample the .wav file to get an incomplete/ or impartial data stream that i can then reconstuct. Heres the flow chart of what im going to be doing So the flow is analog signal - sampling analog filter - ADC - resample down - resample up - DAC - reconstruction analog filter what needs to be achieved: F= Frequency F(Hz=1/s) E.x. 100Hz = 1000 (Cyc/sec) F(s)= 1/(2f) Example problem: 1000 hz = Highest frequency 1/2(1000hz) = 1/2000 = 5x10(-3) sec/cyc or a sampling rate of 5ms This is my first signal processing project using matlab. what i have so far. % Fs = frequency sampled (44100hz or the sampling frequency of a cd) [test,fs]=wavread('test.wav'); % loads the .wav file left=test(:,1); % Plot of the .wav signal time vs. strength time=(1/44100)*length(left); t=linspace(0,time,length(left)); plot(t,left) xlabel('time (sec)'); ylabel('relative signal strength') **%this is were i would need to sample it at the different frequecys (both above and below and at) nyquist frequency.*I think.*** soundsc(left,fs) % shows the resaultant audio file , which is the same as original ( only at or above nyquist frequency however) Can anyone tell me how to make it better, and how to do the sampling at verious frequencies?

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• File Locked by Services (after service code reading the text file)

  - by rvpals

  I have a windows services written in C# .NET. The service is running on a internal timer, every time the interval hits, it will go and try to read this log file into a String. My issue is every time the log file is read, the service seem to lock the log file. The lock on that log file will continue until I stop the windows service. At the same time the service is checking the log file, the same log file needs to be continuously updated by another program. If the file lock is on, the other program could not update the log file. Here is the code I use to read the text log file. private string ReadtextFile(string filename) { string res = ""; try { System.IO.FileStream fs = new System.IO.FileStream(filename, System.IO.FileMode.Open, System.IO.FileAccess.Read); System.IO.StreamReader sr = new System.IO.StreamReader(fs); res = sr.ReadToEnd(); sr.Close(); fs.Close(); } catch (System.Exception ex) { HandleEx(ex); } return res; } Thank you.

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• Why is F# member not found when used in subclass

  - by James Black

  I have a base type that I want to inherit from, for all my DAO objects, but this member gets the error further down about not being defined: type BaseDAO() = member v.ExecNonQuery2(conn)(sqlStr) = let comm = new MySqlCommand(sqlStr, conn, CommandTimeout = 10) comm.ExecuteNonQuery |> ignore comm.Dispose |> ignore I inherit in this type: type CreateDatabase() = inherit BaseDAO() member private self.createDatabase(conn) = self.ExecNonQuery2 conn "DROP DATABASE IF EXISTS restaurant" This is what I see when my script runs in the interactive shell: --> Referenced 'C:\Program Files\MySQL\MySQL Connector Net 6.2.3\Assemblies\MySql.Data.dll' [Loading C:\Users\jblack\Documents\Visual Studio 2010\Projects\RestaurantService\RestaurantDAO\BaseDAO.fs] namespace FSI_0106.RestaurantServiceDAO type BaseDAO = class new : unit -> BaseDAO member ExecNonQuery2 : conn:MySql.Data.MySqlClient.MySqlConnection -> sqlStr:string -> unit member execNonQuery : sqlStr:string -> unit member execQuery : sqlStr:string * selectFunc:(MySql.Data.MySqlClient.MySqlDataReader -> 'a list) -> 'a list member f : x:obj -> string member Conn : MySql.Data.MySqlClient.MySqlConnection end [Loading C:\Users\jblack\Documents\Visual Studio 2010\Projects\RestaurantService\RestaurantDAO\CreateDatabase.fs] C:\Users\jblack\Documents\Visual Studio 2010\Projects\RestaurantService\RestaurantDAO\CreateDatabase.fs(56,14): error FS0039: The field, constructor or member 'ExecNonQuery2' is not defined I am curious what I am doing wrong. I have tried not inheriting, and just instantiating the BaseDAO type in the function, but I get the same error. I started on this path because I had a property that had the same error, so it seems there may be a problem with how I am defining my BaseDAO type, but it compiles with no error, which further confuses me about this problem.

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• net send command program debugging in C#

  - by riad

  Dear all, I write a program to execute and send msg using windows net send command.Its working fine for single receptor.But the problem happen when i want to send message in many receptors. i use a for loop to take receptor name from a list box. Here all message go to the first receptor.The problem happen on process execution.So far i guess the process is not clear or dead on the time. Can any body guide me how i can send the msg to multiple users at a time? my code below: string sendingMessage = messageRichTextBox.Text; string[] recepentAddressArray = new string[recepentAddressListBox.Items.Count]; for (int j = 0; j < recepentAddressListBox.Items.Count; j++) // Getting address from list box { recepentAddressArray[j] = recepentAddressListBox.Items[j].ToString(); string recepantAddress = recepentAddressArray[j]; try { string strLine = "net send " + recepantAddress + " " + sendingMessage + " >C:netsend.log"; FileStream fs = new FileStream("c:netsend.bat", FileMode.Create, FileAccess.Write); StreamWriter streamWriter = new StreamWriter(fs); streamWriter.BaseStream.Seek(0, SeekOrigin.End); streamWriter.Write(strLine); streamWriter.Flush(); streamWriter.Close(); fs.Close(); Process p = new Process(); p.StartInfo.FileName = "C:netsend.bat"; p.StartInfo.WindowStyle = ProcessWindowStyle.Hidden; p.Start(); p.WaitForExit(); p.Close(); FileStream fsOutput = new FileStream("C:netsend.log", FileMode.Open, FileAccess.Read); StreamReader reader = new StreamReader(fsOutput); reader.BaseStream.Seek(0, SeekOrigin.Begin); string strOut = reader.ReadLine(); reader.Close(); fsOutput.Close(); } catch (Exception) { MessageBox.Show("ERROR"); } }

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• create and write to a text file in vb.net

  - by woolardz

  I'm creating a small vb.net application, and I'm trying trying to write a list of results from a listview to a text file. I've looked online and found the code to open the save file dialog and write the text file. When I click save on the save file dialog, I receive an IOException with the message "The process cannot access the file 'C:\thethe.txt' because it is being used by another process." The text file is created in the correct location, but is empty. The application quits at this line "Dim fs As New FileStream(saveFileDialog1.FileName, FileMode.OpenOrCreate, FileAccess.Write)" Thanks in advance for any help. Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click Dim myStream As Stream Dim saveFileDialog1 As New SaveFileDialog() saveFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*" saveFileDialog1.FilterIndex = 2 saveFileDialog1.RestoreDirectory = True If saveFileDialog1.ShowDialog() = DialogResult.OK Then myStream = saveFileDialog1.OpenFile() If (myStream IsNot Nothing) Then Dim fs As New FileStream(saveFileDialog1.FileName, FileMode.OpenOrCreate, FileAccess.Write) Dim m_streamWriter As New StreamWriter(fs) m_streamWriter.Flush() 'Write to the file using StreamWriter class m_streamWriter.BaseStream.Seek(0, SeekOrigin.Begin) 'write each row of the ListView out to a tab-delimited line in a file For i As Integer = 0 To Me.ListView1.Items.Count - 1 m_streamWriter.WriteLine(((ListView1.Items(i).Text & vbTab) + ListView1.Items(i).SubItems(0).ToString() & vbTab) + ListView1.Items(i).SubItems(1).ToString()) Next myStream.Close() End If End If End Sub

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• Apples, oranges, and pointers to the most derived c++ class

  - by Matthew Lowe

  Suppose I have a bunch of fruit: class Fruit { ... }; class Apple : public Fruit { ... }; class Orange: public Fruit { ... }; And some polymorphic functions that operate on said fruit: void Eat(Fruit* f, Pesticide* p) { } void Eat(Apple* f, Pesticide* p) { ingest(f,p); } void Eat(Orange* f, Pesticide* p) { peel(f,p); ingest(f,p); } OK, wait. Stop right there. Note at this point that any sane person would make Eat() a virtual member function of the Fruit classes. But that's not an option, because I am not a sane person. Also, I don't want that Pesticide* in the header file for my fruit class. Sadly, what I want to be able to do next is exactly what member functions and dynamic binding allow: typedef list<Fruit*> Fruits; Fruits fs; ... for(Fruits::iterator i=fs.begin(), e=fs.end(); i!=e; ++i) Eat(*i); And obviously, the problem here is that the pointer we pass to Eat() will be a Fruit*, not an Apple* or an Orange*, therefore nothing will get eaten and we will all be very hungry. So what I really want to be able to do instead of this: Eat(*i); is this: Eat(MAGIC_CAST_TO_MOST_DERIVED_CLASS(*i)); But to my limited knowledge, such magic does not exist, except possibly in the form of a big nasty if-statement full of calls to dynamic_cast. So is there some run-time magic of which I am not aware? Or should I implement and maintain a big nasty if-statement full of dynamic_casts? Or should I suck it up, quit thinking about how I would implement this in Ruby, and allow a little Pesticide to make its way into my fruit header?

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• Is this method of static file serving safe in node.js? (potential security hole?)

  - by MikeC8

  I want to create the simplest node.js server to serve static files. Here's what I came up with: fs = require('fs'); server = require('http').createServer(function(req, res) { res.end(fs.readFileSync(__dirname + '/public/' + req.url)); }); server.listen(8080); Clearly this would map http://localhost:8080/index.html to project_dir/public/index.html, and similarly so for all other files. My one concern is that someone could abuse this to access files outside of project_dir/public. Something like this, for example: http://localhost:8080/../../sensitive_file.txt I tried this a little bit, and it wasn't working. But, it seems like my browser was removing the ".." itself. Which leads me to believe that someone could abuse my poor little node.js server. I know there are npm packages that do static file serving. But I'm actually curious to write my own here. So my questions are: Is this safe? If so, why? If not, why not? And, if further, if not, what is the "right" way to do this? My one constraint is I don't want to have to have an if clause for each possible file, I want the server to serve whatever files I throw in a directory.

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• How to replace same text in a text file

  - by user1688220

  i created a c# windows login form and i am saving username or password to a text file but every time i use same username or password that i have saved before it takes new place in that text file. But What i want is to replace the same username or password that is already saved in that text file. this is my code: private void button1_Click(object sender, EventArgs e) { try { FileStream fs = new FileStream("data.txt", FileMode.Append, FileAccess.Write); StreamWriter sw = new StreamWriter(fs); sw.Write("Email ID: "); sw.WriteLine(textBox1.Text); sw.Write("Password: "); sw.Write(textBox2.Text); sw.WriteLine(); sw.WriteLine(); sw.Flush(); sw.Close(); fs.Close(); } catch (Exception) { MessageBox.Show("Error", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); this.Close(); } MessageBox.Show("DONE", "Done", MessageBoxButtons.OK, MessageBoxIcon.Information); textBox1.Clear(); textBox2.Clear(); }

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• How do I trust a self signed cert using https?

  - by dave

  Edit: I originally thought the server's certificate was self signed. Turns out it was signed by a self-signed CA certificate. I'm trying to write a Node.js application that accesses an HTTPS site that's protected using a self-signed certificate certificate signed by a private, self-signed CA certificate. I'd also like to not completely disable certificate checking. I tried putting the self signed certificate server's certificate in the request options, but that doesn't seem to be working. Anyone know how to do this? I expect the following code to print statusCode 200, but instead it prints [Error: SELF_SIGNED_CERT_IN_CHAIN]. I've tried similar code with request with the same results. var https = require('https'); var fs = require('fs'); var opts = { hostname: host, port: 443, path: '/', method: 'GET', ca: fs.readFileSync(serverCertificateFile, 'utf-8') }; var req = https.request(opts, function (res) { console.log('statusCode', res.statusCode); }); req.end(); req.on('error', function (err) { console.error(err); });

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• RHEL - blocked FC remote port time out: saving binding

  - by Dev G

  My Server went into a faulty state since the database could not write on the partition. I found out that the partition went into Read Only mode. Finally to fix it, I had to do a hard reboot. Linux 2.6.18-164.el5PAE #1 SMP Tue Aug 18 15:59:11 EDT 2009 i686 i686 i386 GNU/Linux /var/log/messages Oct 31 00:56:45 ota3g1 Had[17275]: VCS ERROR V-16-1-10214 Concurrency Violation:CurrentCount increased above 1 for failover group sg_network Oct 31 00:57:05 ota3g1 Had[17275]: VCS CRITICAL V-16-1-50086 CPU usage on ota3g1.mtsallstream.com is 100% Oct 31 01:01:47 ota3g1 Had[17275]: VCS ERROR V-16-1-10214 Concurrency Violation:CurrentCount increased above 1 for failover group sg_network Oct 31 01:06:50 ota3g1 Had[17275]: VCS ERROR V-16-1-10214 Concurrency Violation:CurrentCount increased above 1 for failover group sg_network Oct 31 01:11:52 ota3g1 Had[17275]: VCS ERROR V-16-1-10214 Concurrency Violation:CurrentCount increased above 1 for failover group sg_network Oct 31 01:12:10 ota3g1 kernel: lpfc 0000:29:00.1: 1:1305 Link Down Event x2 received Data: x2 x20 x80000 x0 x0 Oct 31 01:12:10 ota3g1 kernel: lpfc 0000:29:00.1: 1:1303 Link Up Event x3 received Data: x3 x1 x10 x1 x0 x0 0 Oct 31 01:12:12 ota3g1 kernel: lpfc 0000:29:00.1: 1:1305 Link Down Event x4 received Data: x4 x20 x80000 x0 x0 Oct 31 01:12:40 ota3g1 kernel: rport-8:0-0: blocked FC remote port time out: saving binding Oct 31 01:12:40 ota3g1 kernel: lpfc 0000:29:00.1: 1:(0):0203 Devloss timeout on WWPN 20:25:00:a0:b8:74:f5:65 NPort x0000e4 Data: x0 x7 x0 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 38617577 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 283532153 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 90825 Oct 31 01:12:40 ota3g1 kernel: Aborting journal on device dm-16. Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 868841 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: Aborting journal on device dm-10. Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 37759889 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 283349449 Oct 31 01:12:40 ota3g1 kernel: printk: 6 messages suppressed. Oct 31 01:12:40 ota3g1 kernel: Aborting journal on device dm-12. Oct 31 01:12:40 ota3g1 kernel: EXT3-fs error (device dm-12) in ext3_reserve_inode_write: Journal has aborted Oct 31 01:12:40 ota3g1 kernel: Buffer I/O error on device dm-16, logical block 1545 Oct 31 01:12:40 ota3g1 kernel: lost page write due to I/O error on dm-16 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 12745 Oct 31 01:12:40 ota3g1 kernel: Buffer I/O error on device dm-10, logical block 1545 Oct 31 01:12:40 ota3g1 kernel: EXT3-fs error (device dm-16) in ext3_reserve_inode_write: Journal has aborted Oct 31 01:12:40 ota3g1 kernel: lost page write due to I/O error on dm-10 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 37749121 Oct 31 01:12:40 ota3g1 kernel: Buffer I/O error on device dm-12, logical block 0 Oct 31 01:12:40 ota3g1 kernel: lost page write due to I/O error on dm-12 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: EXT3-fs error (device dm-12) in ext3_dirty_inode: Journal has aborted Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 37757897 Oct 31 01:12:40 ota3g1 kernel: Buffer I/O error on device dm-12, logical block 1097 Oct 31 01:12:40 ota3g1 kernel: lost page write due to I/O error on dm-12 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 283337089 Oct 31 01:12:40 ota3g1 kernel: Buffer I/O error on device dm-16, logical block 0 Oct 31 01:12:40 ota3g1 kernel: lost page write due to I/O error on dm-16 Oct 31 01:12:40 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:40 ota3g1 kernel: EXT3-fs error (device dm-16) in ext3_dirty_inode: Journal has aborted Oct 31 01:12:40 ota3g1 kernel: end_request: I/O error, dev sdi, sector 37749121 Oct 31 01:12:40 ota3g1 kernel: Buffer I/O error on device dm-12, logical block 0 Oct 31 01:12:41 ota3g1 kernel: lost page write due to I/O error on dm-12 Oct 31 01:12:41 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 Oct 31 01:12:41 ota3g1 kernel: end_request: I/O error, dev sdi, sector 283337089 Oct 31 01:12:41 ota3g1 kernel: Buffer I/O error on device dm-16, logical block 0 Oct 31 01:12:41 ota3g1 kernel: lost page write due to I/O error on dm-16 Oct 31 01:12:41 ota3g1 kernel: sd 8:0:0:4: SCSI error: return code = 0x00010000 df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/cciss-root 4.9G 730M 3.9G 16% / /dev/mapper/cciss-home 9.7G 1.2G 8.1G 13% /home /dev/mapper/cciss-var 9.7G 494M 8.8G 6% /var /dev/mapper/cciss-usr 15G 2.6G 12G 19% /usr /dev/mapper/cciss-tmp 3.9G 153M 3.6G 5% /tmp /dev/sda1 996M 43M 902M 5% /boot tmpfs 5.9G 0 5.9G 0% /dev/shm /dev/mapper/cciss-product 25G 16G 7.4G 68% /product /dev/mapper/cciss-opt 20G 4.5G 14G 25% /opt /dev/mapper/dg_db1-vol_db1_system 18G 2.2G 15G 14% /database/OTADB/sys /dev/mapper/dg_db1-vol_db1_undo 18G 5.8G 12G 35% /database/OTADB/undo /dev/mapper/dg_db1-vol_db1_redo 8.9G 4.3G 4.2G 51% /database/OTADB/redo /dev/mapper/dg_db1-vol_db1_sgbd 8.9G 654M 7.8G 8% /database/OTADB/admin /dev/mapper/dg_db1-vol_db1_arch 98G 24G 69G 26% /database/OTADB/arch /dev/mapper/dg_db1-vol_db1_indexes 240G 14G 214G 6% /database/OTADB/index /dev/mapper/dg_db1-vol_db1_data 275G 47G 215G 18% /database/OTADB/data /dev/mapper/dg_dbrman-vol_db_rman 8.9G 351M 8.1G 5% /database/RMAN /dev/mapper/dg_app1-vol_app1 151G 113G 31G 79% /files/ota /etc/fstab /dev/cciss/root / ext3 defaults 1 1 /dev/cciss/home /home ext3 defaults 1 2 /dev/cciss/var /var ext3 defaults 1 2 /dev/cciss/usr /usr ext3 defaults 1 2 /dev/cciss/tmp /tmp ext3 defaults 1 2 LABEL=/boot /boot ext3 defaults 1 2 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 /dev/cciss/swap swap swap defaults 0 0 /dev/cciss/product /product ext3 defaults 1 2 /dev/cciss/opt /opt ext3 defaults 1 2 /dev/dg_db1/vol_db1_system /database/OTADB/sys ext3 defaults 1 2 /dev/dg_db1/vol_db1_undo /database/OTADB/undo ext3 defaults 1 2 /dev/dg_db1/vol_db1_redo /database/OTADB/redo ext3 defaults 1 2 /dev/dg_db1/vol_db1_sgbd /database/OTADB/admin ext3 defaults 1 2 /dev/dg_db1/vol_db1_arch /database/OTADB/arch ext3 defaults 1 2 /dev/dg_db1/vol_db1_indexes /database/OTADB/index ext3 defaults 1 2 /dev/dg_db1/vol_db1_data /database/OTADB/data ext3 defaults 1 2 /dev/dg_dbrman/vol_db_rman /database/RMAN ext3 defaults 1 2 /dev/dg_app1/vol_app1 /files/ota ext3 defaults 1 2 Thanks for all the help.

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• Best available technology for layered disk cache in linux

  - by SpliFF

  I've just bought a 6-core Phenom with 16G of RAM. I use it primarily for compiling and video encoding (and occassional web/db). I'm finding all activities get disk-bound and I just can't keep all 6 cores fed. I'm buying an SSD raid to sit between the HDD and tmpfs. I want to setup a "layered" filesystem where reads are cached on tmpfs but writes safely go through to the SSD. I want files (or blocks) that haven't been read lately on the SSD to then be written back to a HDD using a compressed FS or block layer. So basically reads: - Check tmpfs - Check SSD - Check HD And writes: - Straight to SSD (for safety), then tmpfs (for speed) And periodically, or when space gets low: - Move least frequently accessed files down one layer. I've seen a few projects of interest. CacheFS, cachefsd, bcache seem pretty close but I'm having trouble determining which are practical. bcache seems a little risky (early adoption), cachefs seems tied to specific network filesystems. There are "union" projects unionfs and aufs that let you mount filesystems over each other (USB device over a DVD usually) but both are distributed as a patch and I get the impression this sort of "transparent" mounting was going to become a kernel feature rather than a FS. I know the kernel has a built-in disk cache but it doesn't seem to work well with compiling. I see a 20x speed improvement when I move my source files to tmpfs. I think it's because the standard buffers are dedicated to a specific process and compiling creates and destroys thousands of processes during a build (just guessing there). It looks like I really want those files precached. I've read tmpfs can use virtual memory. In that case is it practical to create a giant tmpfs with swap on the SSD? I don't need to boot off the resulting layered filesystem. I can load grub, kernel and initrd from elsewhere if needed. So that's the background. The question has several components I guess: Recommended FS and/or block layer for the SSD and compressed HDD. Recommended mkfs parameters (block size, options etc...) Recommended cache/mount technology to bind the layers transparently Required mount parameters Required kernel options / patches, etc..

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• lsattr: Inappropriate ioctl for device While reading flags

  - by rchhe

  For one of our Linux servers running CentOS 6.0, if I do lsattr /home, I get something like this (as root): $lsattr /home lsattr: Inappropriate ioctl for device While reading flags on /home/user lsattr: Inappropriate ioctl for device While reading flags on /home/user lsattr: Inappropriate ioctl for device While reading flags on /home/DIR Now, I try to change something with chattr $chattr -R -i /home chattr: Inappropriate ioctl for device while reading flags on /home Mount returns: $mount /dev/mapper/VolGroup00-LogVol00 on / type ext3 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) /dev/sda3 on /boot type ext3 (rw) tmpfs on /dev/shm type tmpfs (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw) nfsd on /proc/fs/nfsd type nfsd (rw) I have no clue how to fix this. Could somebody help?

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• Hyper-V File Server Clustering - at my wit’s end

  - by René Kåbis

  I am at my wit’s end with File Server clustering under Hyper-V. I am hoping that someone might be able to help me figure out this Gordian Knot of a technology that seems to have dead ends (like forcing cluster VMs to use iSCSI drives where normally-attached VHDX drives could suffice) where logic and reason would normally provide a logical solution. My hardware: I will be running three servers (in the end), but right now everything is taking place on one server. One of the secondary servers will exist purely as a witness/quorum, and another slightly more powerful one will be acting as an emergency backup (with additional storage, just not redundant) to hold the secondary AD VM and the other halves of a set of clustered VMs: the SQL VM and the file system VM. Please note, these each are the depreciated nodes of a cluster, the main nodes will be on the most powerful first machine. My heavy lifter is a machine that also contains all of the truly redundant storage on the network. If this gives anyone the heebie-geebies, too bad. It has a 6TB (usable) RAID-10 array, and will (in the end) hold the primary nodes of both aforementioned clusters, but is right now holding all VMs. This is, right now: DC01, DC02, SQL01, SQL02, FS01 & FS02. Eventually, I will be adding additional VMs to handle Exchange, Sharepoint and Lync, but only to this main server (the secondary server won't be able to handle more than three or four VMs, so why burden it? The AD, SQL & FS VMs are the most critical for the business). If anyone is now saying, “wait, what about a SAN or a NAS for the file servers?”, well too bad. What exists on the main machine is what I have to deal with. I followed these instructions, but I seem to be unable to get things to work. In order to make the file server truly redundant, I cannot trust any one machine to hold the only data store on the network. Therefore, I have created a set of iSCSI drives on the VM-host of the main machine, and attached one to each file server VM. The end result is that I want my FS01 to sit on the heavy lifter, along with its iSCSI “drive”, and FS02 will sit on the secondary machine with its own iSCSI “drive” there as well. That is, neither iSCSI drive will end up sitting on the same machine as the other. As such, the clustered FS will utterly duplicate the contents of the iSCSI drives between each other, so that if one physical machine (or the FS VM) goes toes-up, the other has got a full copy of the data on its own iSCSI drive. My problem occurs when I try to apply the file server role within the failover cluster manager. Actually, it is even before that -- it occurs when adding the disks. Since I have added each disk preferentially to a specific VM (by limiting the initiator by DNS hostname, and by adding two-way CHAP authentication), this forces each VM to be in control of its own iSCSI disk. However, when I try to add the disks to the Disks section of Storage within Failover Cluster Manager, the entire process fails for a random disk of the pair. That is, one will get online, but the other will remain offline because it does not have the correct “owner node”. I mean, really -- WTF? Of course it doesn’t have the right owner node, both drives are showing the same node name!! I cannot seem to have one drive show up with one node name as owner, and the other drive show up with the other node name as owner. And because both drives are not “online”, I cannot create a pool to apply to a cluster role. Talk about getting stuck between a rock and a hard place! I’ve got more to add, but my work is closing for the day and I have to wrap things up. I will try to add more tomorrow morning when I get in. My main objective is to have a file server VM on each machine, the storage on each machine, but a transparent failover in case one physical machine fails. Essentially, a failover FS that doesn’t care which machine fails -- the storage contents are replicated equally on each machine. Am I even heading in the right direction?

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• grub-efi refuses to chainload Windows 8.1

  - by Alexei Averchenko

  I have installed LMDE (with grub in MBR) after I installed Windows 8.1. I then installed the grub-efi package and added the custom Windows options: #!/bin/sh exec tail -n +3 $0 menuentry "Windows" { search --fs-uuid --no-floppy --set=root A89A-7F4C chainloader (${root})/EFI/Boot/bkpbootx64.efi } menuentry "Windows (backup bootloader)" { search --fs-uuid --no-floppy --set=root A89A-7F4C chainloader (${root})/EFI/Microsoft/Boot/bkpbootmgfw.efi } These are basically a leftover from my older Ubuntu setup. However, grub is refusing to load them, complaining about the invalid signature. What do I do now?

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