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  • Write PEM encoded certificate in file - java

    - by user1349407
    Good day. I recently create X.509 certificate by using bouncy castle API. I need to save the certificate result rather than display the result. I tried to use FileOutputStream, but it does not work. regards the result is like follows -----BEGIN CERTIFICATE----- MIICeTCCAeKgAwIBAgIGATs8OWsXMA0GCSqGSIb3DQEBCwUAMBsxGTAXBgNVBAMT... -----END CERTIFICATE----- The code is belows import java.io.FileOutputStream; //example of a basic CA public class PKCS10CertCreateExample { public static X509Certificate[] buildChain() throws Exception { //create the certification request KeyPair pair = chapter7.Utils.generateRSAKeyPair(); PKCS10CertificationRequest request = PKCS10ExtensionExample.generateRequest(pair); //create a root certificate KeyPair rootPair=chapter7.Utils.generateRSAKeyPair(); X509Certificate rootCert = X509V1CreateExample.generateV1Certificate (rootPair); //validate the certification request if(!request.verify("BC")) { System.out.println("request failed to verify!"); System.exit(1); } //create the certificate using the information in the request X509V3CertificateGenerator certGen = new X509V3CertificateGenerator(); certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis())); certGen.setIssuerDN(rootCert.getSubjectX500Principal()); certGen.setNotBefore(new Date(System.currentTimeMillis())); certGen.setNotAfter(new Date(System.currentTimeMillis()+50000)); certGen.setSubjectDN(request.getCertificationRequestInfo().getSubject()); certGen.setPublicKey(request.getPublicKey("BC")); certGen.setSignatureAlgorithm("SHA256WithRSAEncryption"); certGen.addExtension(X509Extensions.AuthorityKeyIdentifier, false, new AuthorityKeyIdentifierStructure(rootCert)); certGen.addExtension(X509Extensions.SubjectKeyIdentifier, false, new SubjectKeyIdentifierStructure(request.getPublicKey("BC"))); certGen.addExtension(X509Extensions.BasicConstraints, true, new BasicConstraints(false)); //certGen.addExtension(X509Extensions.KeyUsage, true, new BasicConstraints(false)); certGen.addExtension(X509Extensions.KeyUsage, true, new KeyUsage(KeyUsage.digitalSignature | KeyUsage.keyEncipherment)); certGen.addExtension(X509Extensions.ExtendedKeyUsage, true, new ExtendedKeyUsage(KeyPurposeId.id_kp_serverAuth)); //extract the extension request attribute ASN1Set attributes = request.getCertificationRequestInfo().getAttributes(); for(int i=0;i!=attributes.size();i++) { Attribute attr = Attribute.getInstance(attributes.getObjectAt(i)); //process extension request if(attr.getAttrType().equals(PKCSObjectIdentifiers.pkcs_9_at_extensionRequest)) { X509Extensions extensions = X509Extensions.getInstance(attr.getAttrValues().getObjectAt(0)); Enumeration<?> e = extensions.oids(); while(e.hasMoreElements()) { DERObjectIdentifier oid = (DERObjectIdentifier)e.nextElement(); X509Extension ext = extensions.getExtension(oid); certGen.addExtension(oid, ext.isCritical(), ext.getValue().getOctets()); } } } X509Certificate issuedCert = certGen.generateX509Certificate(rootPair.getPrivate()); return new X509Certificate[]{issuedCert, rootCert}; } public static void main(String[] args) throws Exception { X509Certificate[] chain = buildChain(); PEMWriter pemWrt = new PEMWriter(new OutputStreamWriter(System.out)); pemWrt.writeObject(chain[0]); //pemWrt.writeObject(chain[1]); pemWrt.close(); //write it out //FileOutputStream fOut = new FileOutputStream("pkcs10req.req"); //fOut.write(chain[0].toString()); //fOut.write() //System.out.println(chain[0].toString()); //fOut.close(); } }

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  • OpenGL texture misaligned on quad

    - by user308226
    I've been having trouble with this for a while now, and I haven't gotten any solutions that work yet. Here is the problem, and the specifics: I am loading a 256x256 uncompressed TGA into a simple OpenGL program that draws a quad on the screen, but when it shows up, it is shifted about two pixels to the left, with the cropped part appearing on the right side. It has been baffling me for the longest time, people have suggested clamping and such, but somehow I think my problem is probably something really simple, but I just can't figure out what it is! Here is a screenshot comparing the TGA (left) and how it appears running in the program (right) for clarity. Also take note that there's a tiny black pixel on the upper right corner, I'm hoping that's related to the same problem. Here's the code for the loader, I'm convinced that my problem lies in the way that I'm loading the texture. Thanks in advance to anyone who can fix my problem. bool TGA::LoadUncompressedTGA(char *filename,ifstream &texturestream) { cout << "G position status:" << texturestream.tellg() << endl; texturestream.read((char*)header, sizeof(header)); //read 6 bytes into the file to get the tga header width = (GLuint)header[1] * 256 + (GLuint)header[0]; //read and calculate width and save height = (GLuint)header[3] * 256 + (GLuint)header[2]; //read and calculate height and save bpp = (GLuint)header[4]; //read bpp and save cout << bpp << endl; if((width <= 0) || (height <= 0) || ((bpp != 24) && (bpp !=32))) //check to make sure the height, width, and bpp are valid { return false; } if(bpp == 24) { type = GL_RGB; } else { type = GL_RGBA; } imagesize = ((bpp/8) * width * height); //determine size in bytes of the image cout << imagesize << endl; imagedata = new GLubyte[imagesize]; //allocate memory for our imagedata variable texturestream.read((char*)imagedata,imagesize); //read according the the size of the image and save into imagedata for(GLuint cswap = 0; cswap < (GLuint)imagesize; cswap += (bpp/8)) //loop through and reverse the tga's BGR format to RGB { imagedata[cswap] ^= imagedata[cswap+2] ^= //1st Byte XOR 3rd Byte XOR 1st Byte XOR 3rd Byte imagedata[cswap] ^= imagedata[cswap+2]; } texturestream.close(); //close ifstream because we're done with it cout << "image loaded" << endl; glGenTextures(1, &texID); // Generate OpenGL texture IDs glBindTexture(GL_TEXTURE_2D, texID); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); glTexImage2D(GL_TEXTURE_2D, 0, type, width, height, 0, type, GL_UNSIGNED_BYTE, imagedata); delete imagedata; return true; } //Public loading function for TGA images. Opens TGA file and determines //its type, if any, then loads it and calls the appropriate function. //Returns: TRUE on success, FALSE on failure bool TGA::loadTGA(char *filename) { cout << width << endl; ifstream texturestream; texturestream.open(filename,ios::binary); texturestream.read((char*)header,sizeof(header)); //read 6 bytes into the file, its the header. //if it matches the uncompressed header's first 6 bytes, load it as uncompressed LoadUncompressedTGA(filename,texturestream); return true; }

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  • How can I create a Searchstring for a Google AJAX Search API?

    - by elmaso
    Hello, i have this code to get the search resutls from the api: querygoogle.php: <?php session_start(); // Here's the Google AJAX Search API url for curl. It uses Google Search's site:www.yourdomain.com syntax to search in a specific site. I used $_SERVER['HTTP_HOST'] to find my domain automatically. Change $_POST['searchquery'] to your posted search query $url = 'http://ajax.googleapis.com/ajax/services/search/web?rsz=large&v=1.0&start=20&q=' . urlencode('' . $_POST['searchquery']); // use fopen and fread to pull Google's search results $handle = fopen($url, 'rb'); $body = ''; while (!feof($handle)) { $body .= fread($handle, 8192); } fclose($handle); // now $body is the JSON encoded results. We need to decode them. $json = json_decode($body); // now $json is an object of Google's search results and we need to iterate through it. foreach($json->responseData->results as $searchresult) { if($searchresult->GsearchResultClass == 'GwebSearch') { $formattedresults .= ' <div class="searchresult"> <h3><a href="' . $searchresult->unescapedUrl . '">' . $searchresult->titleNoFormatting . '</a></h3> <p class="resultdesc">' . $searchresult->content . '</p> <p class="resulturl">' . $searchresult->visibleUrl . '</p> </div>'; } } $_SESSION['googleresults'] = $formattedresults; header('Location: ' . $_SERVER['HTTP_REFERER']); exit; ?> search.php <?php session_start(); ?> <form method="post" action="querygoogle.php"> <label for="searchquery"><span class="caption">Search this site</span> <input type="text" size="20" maxlength="255" title="Enter your keywords and click the search button" name="searchquery" /></label> <input type="submit" value="Search" /> </form> <?php if(!empty($_SESSION['googleresults'])) { echo $_SESSION['googleresults']; unset($_SESSION['googleresults']); } ?> but with this code, I cant add a searchstring.. how can i add a search string like search.php?search=keyword ? thanks

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  • How do I tie a cmbBox that selects all drives (local and network) into a treeNode VB

    - by jpavlov
    How do i tie in a selected item from a cmbBox with a treeView? I am looking to just obtain the value of the one selected drive Thanks. Imports System Imports System.IO Imports System.IO.File Imports System.Windows.Forms Public Class F_Treeview_Demo Private Sub F_Treeview_Demo_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load ' Initialize the local directory treeview Dim nodeText As String = "" Dim sb As New C_StringBuilder With My.Computer.FileSystem 'Read in the number of drives For i As Integer = 0 To .Drives.Count - 1 '** Build the drive's node text sb.ClearText() sb.AppendText(.Drives(i).Name) cmbDrives.Items.Add(sb.FullText) Next End With ListRootNodes() End Sub Private Sub btnExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnExit.Click Application.Exit() End Sub Private Sub tvwLocalFolders_AfterSelect(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) _ Handles tvwLocalFolders.AfterSelect ' Display the path for the selected node Dim folder As String = tvwLocalFolders.SelectedNode.Tag lblLocalPath.Text = folder ListView1.Items.Clear() Dim childNode As TreeNode = e.Node.FirstNode Dim parentPath As String = AddChar(e.Node.Tag) End Sub Private Sub AddToList(ByVal nodes As TreeNodeCollection) For Each node As TreeNode In nodes If node.Checked Then ListView1.Items.Add(node.Text) ListView1.Items.Add(Chr(13)) AddToList(node.Nodes) End If Next End Sub Private Sub tvwLocalFolders_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) _ Handles tvwLocalFolders.BeforeExpand ' Display the path for the selected node lblLocalPath.Text = e.Node.Tag ' Populate all child nodes below the selected node Dim parentPath As String = AddChar(e.Node.Tag) tvwLocalFolders.BeginUpdate() Dim childNode As TreeNode = e.Node.FirstNode 'this i added Dim smallNode As TreeNode = e.Node.FirstNode Do While childNode IsNot Nothing ListLocalSubFolders(childNode, parentPath & childNode.Text) childNode = childNode.NextNode ''this i added ListLocalFiles(smallNode, parentPath & smallNode.Text) Loop tvwLocalFolders.EndUpdate() tvwLocalFolders.Refresh() ' Select the node being expanded tvwLocalFolders.SelectedNode = e.Node ListView1.Items.Clear() AddToList(tvwLocalFolders.Nodes) ListView1.Items.Add(Environment.NewLine) End Sub Private Sub ListRootNodes() ' Add all local drives to the Local treeview Dim nodeText As String = "" Dim sb As New C_StringBuilder With My.Computer.FileSystem For i As Integer = 0 To .Drives.Count - 1 '** Build the drive's node text sb.ClearText() sb.AppendText(.Drives(i).Name) nodeText = sb.FullText nodeText = Me.cmbDrives.SelectedItem '** Add the drive to the treeview Dim driveNode As TreeNode driveNode = tvwLocalFolders.Nodes.Add(nodeText) 'driveNode.Tag = .Drives(i).Name '** Add the next level of subfolders 'ListLocalSubFolders(driveNode, .Drives(i).Name) ListLocalSubFolders(driveNode, nodeText) 'driveNode = Nothing Next End With End Sub Private Sub ListLocalFiles(ByVal ParentNode As TreeNode, ByVal PParentPath As String) Dim FileNode As String = "" Try For Each FileNode In Directory.GetFiles(PParentPath) Dim smallNode As TreeNode smallNode = ParentNode.Nodes.Add(FilenameFromPath(FileNode)) With smallNode .ImageIndex = 0 .SelectedImageIndex = 1 .Tag = FileNode End With smallNode = Nothing Next Catch ex As Exception End Try End Sub Private Sub ListLocalSubFolders(ByVal ParentNode As TreeNode, _ ByVal ParentPath As String) ' Add all local subfolders below the passed Local treeview node Dim FolderNode As String = "" Try For Each FolderNode In Directory.GetDirectories(ParentPath) Dim childNode As TreeNode childNode = ParentNode.Nodes.Add(FilenameFromPath(FolderNode)) With childNode .ImageIndex = 0 .SelectedImageIndex = 1 .Tag = FolderNode End With childNode = Nothing Next Catch ex As Exception End Try End Sub Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmbDrives.SelectedIndexChanged End Sub Private Sub lblLocalPath_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lblLocalPath.Click End Sub Private Sub grpLocalFileSystem_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles grpLocalFileSystem.Enter End Sub Private Sub btn1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btn1.Click ' lbl1.Text = End Sub Private Sub ListView1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ListView1.SelectedIndexChanged End Sub End Class

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  • Do you use an exception class in your Perl programs? Why or why not?

    - by daotoad
    I've got a bunch of questions about how people use exceptions in Perl. I've included some background notes on exceptions, skip this if you want, but please take a moment to read the questions and respond to them. Thanks. Background on Perl Exceptions Perl has a very basic built-in exception system that provides a spring-board for more sophisticated usage. For example die "I ate a bug.\n"; throws an exception with a string assigned to $@. You can also throw an object, instead of a string: die BadBug->new('I ate a bug.'); You can even install a signal handler to catch the SIGDIE psuedo-signal. Here's a handler that rethrows exceptions as objects if they aren't already. $SIG{__DIE__} = sub { my $e = shift; $e = ExceptionObject->new( $e ) unless blessed $e; die $e; } This pattern is used in a number of CPAN modules. but perlvar says: Due to an implementation glitch, the $SIG{DIE} hook is called even inside an eval(). Do not use this to rewrite a pending exception in $@ , or as a bizarre substitute for overriding CORE::GLOBAL::die() . This strange action at a distance may be fixed in a future release so that $SIG{DIE} is only called if your program is about to exit, as was the original intent. Any other use is deprecated. So now I wonder if objectifying exceptions in sigdie is evil. The Questions Do you use exception objects? If so, which one and why? If not, why not? If you don't use exception objects, what would entice you to use them? If you do use exception objects, what do you hate about them, and what could be better? Is objectifying exceptions in the DIE handler a bad idea? Where should I objectify my exceptions? In my eval{} wrapper? In a sigdie handler? Are there any papers, articles or other resources on exceptions in general and in Perl that you find useful or enlightening.

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  • Jumping into argv?

    - by jth
    Hi, I`am experimenting with shellcode and stumbled upon the nop-slide technique. I wrote a little tool that takes buffer-size as a parameter and constructs a buffer like this: [ NOP | SC | RET ], with NOP taking half of the buffer, followed by the shellcode and the rest filled with the (guessed) return address. Its very similar to the tool aleph1 described in his famous paper. My vulnerable test-app is the same as in his paper: int main(int argc, char **argv) { char little_array[512]; if(argc>1) strcpy(little_array,argv[1]); return 0; } I tested it and well, it works: jth@insecure:~/no_nx_no_aslr$ ./victim $(./exploit 604 0) $ exit But honestly, I have no idea why. Okay, the saved eip was overwritten as intended, but instead of jumping somewhere into the buffer, it jumped into argv, I think. gdb showed up the following addresses before strcpy() was called: (gdb) i f Stack level 0, frame at 0xbffff1f0: eip = 0x80483ed in main (victim.c:7); saved eip 0x154b56 source language c. Arglist at 0xbffff1e8, args: argc=2, argv=0xbffff294 Locals at 0xbffff1e8, Previous frame's sp is 0xbffff1f0 Saved registers: ebp at 0xbffff1e8, eip at 0xbffff1ec Address of little_array: (gdb) print &little_array[0] $1 = 0xbfffefe8 "\020" After strcpy(): (gdb) i f Stack level 0, frame at 0xbffff1f0: eip = 0x804840d in main (victim.c:10); saved eip 0xbffff458 source language c. Arglist at 0xbffff1e8, args: argc=-1073744808, argv=0xbffff458 Locals at 0xbffff1e8, Previous frame's sp is 0xbffff1f0 Saved registers: ebp at 0xbffff1e8, eip at 0xbffff1ec So, what happened here? I used a 604 byte buffer to overflow little_array, so he certainly overwrote saved ebp, saved eip and argc and also argv with the guessed address 0xbffff458. Then, after returning, EIP pointed at 0xbffff458. But little_buffer resides at 0xbfffefe8, that`s a difference of 1136 byte, so he certainly isn't executing little_array. I followed execution with the stepi command and well, at 0xbffff458 and onwards, he executes NOPs and reaches the shellcode. I'am not quite sure why this is happening. First of all, am I correct that he executes my shellcode in argv, not little_array? And where does the loader(?) place argv onto the stack? I thought it follows immediately after argc, but between argc and 0xbffff458, there is a gap of 620 bytes. How is it possible that he successfully "lands" in the NOP-Pad at Address 0xbffff458, which is way above the saved eip at 0xbffff1ec? Can someone clarify this? I have actually no idea why this is working. My test-machine is an Ubuntu 9.10 32-Bit Machine without ASLR. victim has an executable stack, set with execstack -s. Thanks in advance.

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  • opening and viewing a file in php

    - by Christian Burgos
    how do i open/view for editing an uploaded file in php? i have tried this but it doesn't open the file. $my_file = 'file.txt'; $handle = fopen($my_file, 'r'); $data = fread($handle,filesize($my_file)); i've also tried this but it wont work. $my_file = 'file.txt'; $handle = fopen($my_file, 'w') or die('Cannot open file: '.$my_file); $data = 'This is the data'; fwrite($handle, $data); what i have in mind is like when you want to view an uploaded resume,documents or any other ms office files like .docx,.xls,.pptx and be able to edit them, save and close the said file. edit: latest tried code... <?php // Connects to your Database include "configdb.php"; //Retrieves data from MySQL $data = mysql_query("SELECT * FROM employees") or die(mysql_error()); //Puts it into an array while($info = mysql_fetch_array( $data )) { //Outputs the image and other data //Echo "<img src=localhost/uploadfile/images".$info['photo'] ."> <br>"; Echo "<b>Name:</b> ".$info['name'] . "<br> "; Echo "<b>Email:</b> ".$info['email'] . " <br>"; Echo "<b>Phone:</b> ".$info['phone'] . " <hr>"; //$file=fopen("uploadfile/images/".$info['photo'],"r+"); $file=fopen("Applications/XAMPP/xamppfiles/htdocs/uploadfile/images/file.odt","r") or exit("unable to open file");; } ?> i am getting the error: Warning: fopen(Applications/XAMPP/xamppfiles/htdocs/uploadfile/images/file.odt): failed to open stream: No such file or directory in /Applications/XAMPP/xamppfiles/htdocs/uploadfile/view.php on line 17 unable to open file the file is in that folder, i don't know it wont find it.

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  • Displaying an Image in an activity using URI

    - by evkwan
    Hi, I'm writing an application that uses Intent(MediaStore.ACTION_IMAGE_CAPTURE) to capture and image. On the process of capturing the image, I noted the output of the image's URI. Right after finishing the camera activity, I wish to display the image using this specific URI. The method I used to capture images is: private void saveFullImage() { Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); File file = new File(Environment.getExternalStorageDirectory(), "test.jpg"); outputFileUri = Uri.fromFile(file); intent.putExtra(MediaStore.EXTRA_OUTPUT, outputFileUri); startActivityForResult(intent, TAKE_PICTURE); } Which is a method taken from Reto Meier's book Professional Android 2 Application Development. The method works fine, and I assume that the URI of the picture I just took is stored in the outputFileUri variable. Then at this point of the code is where I want to display the picture: @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == TAKE_PICTURE) { //I want to display the picture I just took here //using the URI } } I'm not sure how to do it. I tried creating a new layout object and a new ImageView object using the method setImageURI(outputFileUri). My main layout (xml) did not have a ImageView object. But even when I set the contentView to the new layout with the ImageView attached to it, it doesn't display anything. I tried creating a Bitmap object from the URI and set it to the ImageView, but I get an unexpected error and forced exit. I have seen examples from here here which creates a Bitmap from URI, but it's not displaying it? My question is just how to display an image in the middle of a running activity? Do I need to get the File Path (like this) in order to display it? If I make a Bitmap out of the URI, how do I display the Bitmap? I'm just probably missing something simple...so any help would be a greatly appreciated! Also additional question for thought: If I were to take multiple pictures, would you recommend me to use the SimpleCursorAdapter instead? Thanks!

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  • Thread sleep and thread join.

    - by Dhruv Gairola
    hi guys, if i put a thread to sleep in a loop, netbeans gives me a caution saying Invoking Thread.sleep in loop can cause performance problems. However, if i were to replace the sleep with join, no such caution is given. Both versions compile and work fine tho. My code is below (check the last few lines for "Thread.sleep() vs t.join()"). public class Test{ //Display a message, preceded by the name of the current thread static void threadMessage(String message) { String threadName = Thread.currentThread().getName(); System.out.format("%s: %s%n", threadName, message); } private static class MessageLoop implements Runnable { public void run() { String importantInfo[] = { "Mares eat oats", "Does eat oats", "Little lambs eat ivy", "A kid will eat ivy too" }; try { for (int i = 0; i < importantInfo.length; i++) { //Pause for 4 seconds Thread.sleep(4000); //Print a message threadMessage(importantInfo[i]); } } catch (InterruptedException e) { threadMessage("I wasn't done!"); } } } public static void main(String args[]) throws InterruptedException { //Delay, in milliseconds before we interrupt MessageLoop //thread (default one hour). long patience = 1000 * 60 * 60; //If command line argument present, gives patience in seconds. if (args.length > 0) { try { patience = Long.parseLong(args[0]) * 1000; } catch (NumberFormatException e) { System.err.println("Argument must be an integer."); System.exit(1); } } threadMessage("Starting MessageLoop thread"); long startTime = System.currentTimeMillis(); Thread t = new Thread(new MessageLoop()); t.start(); threadMessage("Waiting for MessageLoop thread to finish"); //loop until MessageLoop thread exits while (t.isAlive()) { threadMessage("Still waiting..."); //Wait maximum of 1 second for MessageLoop thread to //finish. /*******LOOK HERE**********************/ Thread.sleep(1000);//issues caution unlike t.join(1000) /**************************************/ if (((System.currentTimeMillis() - startTime) > patience) && t.isAlive()) { threadMessage("Tired of waiting!"); t.interrupt(); //Shouldn't be long now -- wait indefinitely t.join(); } } threadMessage("Finally!"); } } As i understand it, join waits for the other thread to complete, but in this case, arent both sleep and join doing the same thing? Then why does netbeans throw the caution?

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  • Avoiding explicit recursion in Haskell

    - by Travis Brown
    The following simple function applies a given monadic function iteratively until it hits a Nothing, at which point it returns the last non-Nothing value. It does what I need, and I understand how it works. lastJustM :: (Monad m) => (a -> m (Maybe a)) -> a -> m a lastJustM g x = g x >>= maybe (return x) (lastJustM g) As part of my self-education in Haskell I'm trying to avoid explicit recursion (or at least understand how to) whenever I can. It seems like there should be a simple non-explicitly recursive solution in this case, but I'm having trouble figuring it out. I don't want something like a monadic version of takeWhile, since it could be expensive to collect all the pre-Nothing values, and I don't care about them anyway. I checked Hoogle for the signature and nothing shows up. The m (Maybe a) bit makes me think a monad transformer might be useful here, but I don't really have the intuitions I'd need to come up with the details (yet). It's probably either embarrassingly easy to do this or embarrassingly easy to see why it can't or shouldn't be done, but this wouldn't be the first time I've used self-embarrassment as a pedagogical strategy. Background: Here's a simplified working example for context: suppose we're interested in random walks in the unit square, but we only care about points of exit. We have the following step function: randomStep :: (Floating a, Ord a, Random a) => a -> (a, a) -> State StdGen (Maybe (a, a)) randomStep s (x, y) = do (a, gen') <- randomR (0, 2 * pi) <$> get put gen' let (x', y') = (x + s * cos a, y + s * sin a) if x' < 0 || x' > 1 || y' < 0 || y' > 1 then return Nothing else return $ Just (x', y') Something like evalState (lastJustM (randomStep 0.01) (0.5, 0.5)) <$> newStdGen will give us a new data point.

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  • Redirecting one file to another using dub2 and strtok

    - by Sergiy Zakharov
    OK, here goes. I have to write a program, in which I need to use strtok and dup2 to redirect one file to another, but I need to also have the user to actually put the command cat < file1 file2, but not from the shell, but instead by using my program. That's why I need strtok. And the reason my program doesn't work is probably because of that, because I don't really understand how strtok works. I found a similar program on the internet, but they just take the ls command and redirect it to the file. That's it. My program is much more complicated. I mean, it would've been easier just to say in shell cat < file1 file2, but for some reason they want us to do it this way. So, anyways, here is what I have so far (here I just combined what I have found on the internet with what I already had from before. We had to do something similar but then the user would just go ls or ls -l. Very simple stuff. This is much harder, for me, at least.) #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <errno.h> #include <sys/wait.h> #include <string.h> int main() { pid_t pid; char line[256]; char *args[129]; int i; int fd; int status; char *temp; while (1) { printf(">"); if (fgets(line, 256, stdin) == 0) { exit(0); } else { pid = fork(); if (pid == 0) { i = 0; temp = strtok("<",line); while (temp != NULL) { args[i++] = temp; temp = strtok(">",line); args[i] = '\0'; } fd = open("hello", O_RDONLY); dup2(fd, STDIN_FILENO); fd = open("world", O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU); dup2(fd, STDOUT_FILENO ); close(fd); execvp(args[0], args); } else { close(fd); wait(&status); } } } } Any help would be greatly appreciated.

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  • assignment not working in a dll exported C++ class

    - by Jim Jones
    Using VS 2008 Have a C++ class in which I'm calling functions from a 3rd party dll. The definition in the header file is as follows: namespace OITImageExport { class ImageExport { private: SCCERR seResult; /* Error code returned. */ VTHDOC hDoc; /* Input doc handle returned by DAOpenDocument(). */ VTHEXPORT hExport; /* Handle to the export returned by EXOpenExport(). */ VTDWORD dwFIFlags; /* Used in setting the SCCOPT_FIFLAGS option. */ VTCHAR szError[256]; /* Error string buffer. */ VTDWORD dwOutputId; /* Output Format. */ VTDWORD dwSpecType; public: ImageExport(const char* outputId, const char* specType); void ProcessDocument(const char* inputPath, const char* outputPath); ~ImageExport(); }; } In the constructor I initialize two of the class fields having values which come from enumerations in the 3rd party dll: ImageExport::ImageExport(const char* outputId, const char* specType) { if(outputId == "jpeg") { dwOutputId = FI_JPEGFIF; } if(specType == "ansi") { dwSpecType = IOTYPE_ANSIPATH; } seResult = DAInit(); if (seResult != SCCERR_OK) { DAGetErrorString(seResult, szError, sizeof(szError)); fprintf(stderr, "DAInit() failed: %s (0x%04X)\n", szError, seResult); exit(seResult); } } When I use this class inside of a console app, with a main method in another file (all in the same namespace), instantiating the class object and calling the methods, it works like a champ. So, now that I know the basic code works, I open a dll project using the class header and code file. Course I have to add the dll macro, namely: #ifdef IMAGEDLL_EXPORTS #define DLL __declspec(dllexport) #else #define DLL __declspec(dllimport) #endif and changed the class definition to "class DLL ImageExport". Compiled nicely to a dll and .lib file (No errors, No warnings). Now to test this dll I open another console project using the same main method as before and linking to the (dll) lib file. Had problems, which when tracked down were the result of the two fields not being set; both had values of 0. Went back to the first console app and printed out the values: dwOutputId was 1535 (#define FI_JPEGFIF 1535) and dwSpecType was 2 (#define IOTYPE_ANSIPATH 2). Now if I was assigning these values outside of the class, I can see how the visibility could be different, but why is the assignment in the dll not working? Is it something about having a class in the dll?

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  • Multiple word Auttosuggest using Lucene.Net

    - by eric
    I am currently working on an search application which uses Lucene.Net to index the data from the database to Index file. I have a product catalog which has Name, short and long description, sku and other fields. The data is stored in Index using StandardAnalyzer. I am trying to add auto suggestion for a text field and using TermEnum to get all the keyword terms and its score from the Index. But the terms returned are of single term. For example, if I type for co, the suggestion returned are costume, count, collection, cowboy, combination etc. But I want the suggestion to return phrases. For exmaple, if I search for co, the suggestions should be cowboy costume, costume for adults, combination locks etc. The following is the code used to get the suggestions: public string[] GetKeywords(string strSearchExp) { IndexReader rd = IndexReader.Open(mIndexLoc); TermEnum tenum = rd.Terms(new Term("Name", strSearchExp)); string[] strResult = new string[10]; int i = 0; Dictionary<string, double> KeywordList = new Dictionary<string, double>(); do { //terms = tenum.Term(); if (tenum.Term() != null) { //strResult[i] = terms.text.ToString(); KeywordList.Add(tenum.Term().text.ToString(), tenum.DocFreq()); } } while (tenum.Next() && tenum.Term().text.StartsWith(strSearchExp) && tenum.Term().text.Length > 1); var sortedDict = (from entry in KeywordList orderby entry.Value descending select entry); foreach (KeyValuePair<string, double> data in sortedDict) { if (data.Key.Length > 1) { strResult[i] = data.Key; i++; } if (i >= 10) //Exit the for Loop if the count exceeds 10 break; } tenum.Close(); rd.Close(); return strResult; } Can anyone please give me directions to achive this? Thanks for looking into this.

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  • "Use of uninitialised value" despite of memset

    - by Framester
    Hi there, I allocate a 2d array and use memset to fill it with zeros. #include<stdio.h> #include<string.h> #include<stdlib.h> void main() { int m=10; int n =10; int **array_2d; array_2d = (int**) malloc(m*sizeof(int*)); if(array_2d==NULL) { printf("\n Could not malloc 2d array \n"); exit(1); } for(int i=0;i<m;i++) { ((array_2d)[i])=malloc(n*sizeof(int)); memset(((array_2d)[i]),0,sizeof(n*sizeof(int))); } for(int i=0; i<10;i++){ for(int j=0; j<10;j++){ printf("(%i,%i)=",i,j); fflush(stdout); printf("%i ", array_2d[i][j]); } printf("\n"); } } Afterwards I use valgrind [1] to check for memory errors. I get following error: Conditional jump or move depends on uninitialised value(s) for line 24 (printf("%i ", array_2d[i][j]);). I always thought memset is the function to initialize arrays. How can I get rid off this error? Thanks! Valgrind output: ==3485== Memcheck, a memory error detector ==3485== Copyright (C) 2002-2009, and GNU GPL'd, by Julian Seward et al. ==3485== Using Valgrind-3.5.0-Debian and LibVEX; rerun with -h for copyright info ==3485== Command: ./a.out ==3485== (0,0)=0 (0,1)===3485== Use of uninitialised value of size 4 ==3485== at 0x409E186: _itoa_word (_itoa.c:195) ==3485== by 0x40A1AD1: vfprintf (vfprintf.c:1613) ==3485== by 0x40A8FFF: printf (printf.c:35) ==3485== by 0x8048724: main (playing_with_valgrind.c:39) ==3485== ==3485== ==3485== ---- Attach to debugger ? --- [Return/N/n/Y/y/C/c] ---- ==3485== Conditional jump or move depends on uninitialised value(s) ==3485== at 0x409E18E: _itoa_word (_itoa.c:195) ==3485== by 0x40A1AD1: vfprintf (vfprintf.c:1613) ==3485== by 0x40A8FFF: printf (printf.c:35) ==3485== by 0x8048724: main (playing_with_valgrind.c:39) [1] valgrind --tool=memcheck --leak-check=yes --show-reachable=yes --num-callers=20 --track-fds=yes --db-attach=yes ./a.out [gcc-cmd] gcc -std=c99 -lm -Wall -g3 playing_with_valgrind.c

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  • Creating a binary file from an IntelHex in C#

    - by Allek
    I'm trying to create a binary file from a intelHex file. Iside the intelHex file I have data and address to which I should write the data inside the binary file. IntelHex file looks like that :10010000214601360121470136007EFE09D2190140 :100110002146017EB7C20001FF5F16002148011988 :10012000194E79234623965778239EDA3F01B2CAA7 :100130003F0156702B5E712B722B732146013421C7 :00000001FF So I have 4 lines here with data since the last one tells us thats the end of file. Here is what I'm doing to create the file while (!streamReader.EndOfStream) { string temp = String.Empty; int address = 0; line = streamReader.ReadLine(); // Get address for each data address = Convert.ToInt32(line.Substring(3, 4), 16); // Get data from each line temp = line.Substring(7, 2); if (temp == "01") break; else { temp = line.Substring(9, line.Length - 11); string[] array = new string[(temp.Length / 2)]; int j = 0; for (int i = 0; i < array.Length; ++i) { array[i] = temp[j].ToString() + temp[j + 1].ToString(); j = j + 2; } temp = String.Empty; for (int i = 0; i < array.Length; ++i) { temp = temp + Convert.ToChar(Convert.ToInt32(array[i], 16)); } } binaryWriter.Seek(address, SeekOrigin.Begin); binaryWriter.Write(temp); binaryWriter.Flush(); } Console.WriteLine("Done...\nPress any key to exit..."); The problem here is, that data in binary file in some places is not equal to data from the intelHex file. Looks like there is some random data added to the file and I do not know from where. First time I saw that there is an additional data before the data from the intelHex file. For instance first data line starts with 21, but in binary file I have a number 12 before the 21. I do not know what is wrong here. Hope someone can help me or guide me where I can find some usefull informations about creating binary files in C#

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  • How to reliably categorize HTTP sessions in proxy to corresponding browser' windows/tabs user is viewing?

    - by Jehonathan
    I was using the Fiddler core .Net library as a local proxy to record the user activity in web. However I ended up with a problem which seems dirty to solve. I have a web browser say Google Chrome, and the user opened like 10 different tabs each with different web URLs. The problem is that the proxy records all the HTTP session initiated by each pages separately, causing me to figure out using my intelligence the tab which the corresponding HTTP session belonged to. I understand that this is because of the stateless nature of HTTP protocol. However I am just wondering is there an easy way to do this? I ended up with below c# code for that in Fiddler. Still its not a reliable solution due to the heuristics. This is a modification of the sample project bundled with Fiddler core for .NET 4. Basically what it does is filtering HTTP sessions initiated in last few seconds to find the first request or switching to another page made by the same tab in browser. It almost works, but not seems to be a universal solution. Fiddler.FiddlerApplication.AfterSessionComplete += delegate(Fiddler.Session oS) { //exclude other HTTP methods if (oS.oRequest.headers.HTTPMethod == "GET" || oS.oRequest.headers.HTTPMethod == "POST") //exclude other HTTP Status codes if (oS.oResponse.headers.HTTPResponseStatus == "200 OK" || oS.oResponse.headers.HTTPResponseStatus == "304 Not Modified") { //exclude other MIME responses (allow only text/html) var accept = oS.oRequest.headers.FindAll("Accept"); if (accept != null) { if(accept.Count>0) if (accept[0].Value.Contains("text/html")) { //exclude AJAX if (!oS.oRequest.headers.Exists("X-Requested-With")) { //find the referer for this request var referer = oS.oRequest.headers.FindAll("Referer"); //if no referer then assume this as a new request and display the same if(referer!=null) { //if no referer then assume this as a new request and display the same if (referer.Count > 0) { //lock the sessions Monitor.Enter(oAllSessions); //filter further using the response if (oS.oResponse.MIMEType == string.Empty || oS.oResponse.MIMEType == "text/html") //get all previous sessions with the same process ID this session request if(oAllSessions.FindAll(a=>a.LocalProcessID == oS.LocalProcessID) //get all previous sessions within last second (assuming the new tab opened initiated multiple sessions other than parent) .FindAll(z => (z.Timers.ClientBeginRequest > oS.Timers.ClientBeginRequest.AddSeconds(-1))) //get all previous sessions that belongs to the same port of the current session .FindAll(b=>b.port == oS.port ).FindAll(c=>c.clientIP ==oS.clientIP) //get all previus sessions with the same referrer URL of the current session .FindAll(y => referer[0].Value.Equals(y.fullUrl)) //get all previous sessions with the same host name of the current session .FindAll(m=>m.hostname==oS.hostname).Count==0 ) //if count ==0 that means this is the parent request Console.WriteLine(oS.fullUrl); //unlock sessions Monitor.Exit(oAllSessions); } else Console.WriteLine(oS.fullUrl); } else Console.WriteLine(oS.fullUrl); Console.WriteLine(); } } } } };

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  • How can I keep my MVC Views, models, and model binders as clean as possible?

    - by MBonig
    I'm rather new to MVC and as I'm getting into the whole framework more and more I'm finding the modelbinders are becoming tough to maintain. Let me explain... I am writing a basic CRUD-over-database app. My domain models are going to be very rich. In an attempt to keep my controllers as thin as possible I've set it up so that on Create/Edit commands the parameter for the action is a richly populated instance of my domain model. To do this I've implemented a custom model binder. As a result, though, this custom model binder is very specific to the view and the model. I've decided to just override the DefaultModelBinder that ships with MVC 2. In the case where the field being bound to my model is just a textbox (or something as simple), I just delegate to the base method. However, when I'm working with a dropdown or something more complex (the UI dictates that date and time are separate data entry fields but for the model it is one Property), I have to perform some checks and some manual data munging. The end result of this is that I have some pretty tight ties between the View and Binder. I'm architecturally fine with this but from a code maintenance standpoint, it's a nightmare. For example, my model I'm binding here is of type Log (this is the object I will get as a parameter on my Action). The "ServiceStateTime" is a property on Log. The form values of "log.ServiceStartDate" and "log.ServiceStartTime" are totally arbitrary and come from two textboxes on the form (Html.TextBox("log.ServiceStartTime",...)) protected override object GetPropertyValue(ControllerContext controllerContext, ModelBindingContext bindingContext, PropertyDescriptor propertyDescriptor, IModelBinder propertyBinder) { if (propertyDescriptor.Name == "ServiceStartTime") { string date = bindingContext.ValueProvider.GetValue("log.ServiceStartDate").ConvertTo(typeof (string)) as string; string time = bindingContext.ValueProvider.GetValue("log.ServiceStartTime").ConvertTo(typeof (string)) as string; DateTime dateTime = DateTime.Parse(date + " " + time); return dateTime; } if (propertyDescriptor.Name == "ServiceEndTime") { string date = bindingContext.ValueProvider.GetValue("log.ServiceEndDate").ConvertTo(typeof(string)) as string; string time = bindingContext.ValueProvider.GetValue("log.ServiceEndTime").ConvertTo(typeof(string)) as string; DateTime dateTime = DateTime.Parse(date + " " + time); return dateTime; } The Log.ServiceEndTime is a similar field. This doesn't feel very DRY to me. First, if I refactor the ServiceStartTime or ServiceEndTime into different field names, the text strings may get missed (although my refactoring tool of choice, R#, is pretty good at this sort of thing, it wouldn't cause a build-time failure and would only get caught by manual testing). Second, if I decided to arbitrarily change the descriptors "log.ServiceStartDate" and "log.ServiceStartTime", I would run into the same problem. To me, runtime silent errors are the worst kind of error out there. So, I see a couple of options to help here and would love to get some input from people who have come across some of these issues: Refactor any text strings in common between the view and model binders out into const strings attached to the ViewModel object I pass from controller to the aspx/ascx view. This pollutes the ViewModel object, though. Provide unit tests around all of the interactions. I'm a big proponent of unit tests and haven't started fleshing this option out but I've got a gut feeling that it won't save me from foot-shootings. If it matters, the Log and other entities in the system are persisted to the database using Fluent NHibernate. I really want to keep my controllers as thin as possible. So, any suggestions here are greatly welcomed! Thanks

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  • multi-thread access MySQL error

    - by user188916
    I have written a simple multi-threaded C program to access MySQL,it works fine except when i add usleep() or sleep() function in each thread function. i created two pthreads in the main method, int main(){ mysql_library_init(0,NULL,NULL); printf("Hello world!\n"); init_pool(&p,100); pthread_t producer; pthread_t consumer_1; pthread_t consumer_2; pthread_create(&producer,NULL,produce_fun,NULL); pthread_create(&consumer_1,NULL,consume_fun,NULL); pthread_create(&consumer_2,NULL,consume_fun,NULL); mysql_library_end(); } void * produce_fun(void *arg){ pthread_detach(pthread_self()); //procedure while(1){ usleep(500000); printf("producer...\n"); produce(&p,cnt++); } pthread_exit(NULL); } void * consume_fun(void *arg){ pthread_detach(pthread_self()); MYSQL db; MYSQL *ptr_db=mysql_init(&db); mysql_real_connect(); //procedure while(1){ usleep(1000000); printf("consumer..."); int item=consume(&p); addRecord_d(ptr_db,"test",item); } mysql_thread_end(); pthread_exit(NULL); } void addRecord_d(MYSQL *ptr_db,const char *t_name,int item){ char query_buffer[100]; sprintf(query_buffer,"insert into %s values(0,%d)",t_name,item); //pthread_mutex_lock(&db_t_lock); int ret=mysql_query(ptr_db,query_buffer); if(ret){ fprintf(stderr,"%s%s\n","cannot add record to ",t_name); return; } unsigned long long update_id=mysql_insert_id(ptr_db); // pthread_mutex_unlock(&db_t_lock); printf("add record (%llu,%d) ok.",update_id,item); } the program output errors like: [Thread debugging using libthread_db enabled] [New Thread 0xb7ae3b70 (LWP 7712)] Hello world! [New Thread 0xb72d6b70 (LWP 7713)] [New Thread 0xb6ad5b70 (LWP 7714)] [New Thread 0xb62d4b70 (LWP 7715)] [Thread 0xb7ae3b70 (LWP 7712) exited] producer... producer... consumer...consumer...add record (31441,0) ok.add record (31442,1) ok.producer... producer... consumer...consumer...add record (31443,2) ok.add record (31444,3) ok.producer... producer... consumer...consumer...add record (31445,4) ok.add record (31446,5) ok.producer... producer... consumer...consumer...add record (31447,6) ok.add record (31448,7) ok.producer... Error in my_thread_global_end(): 2 threads didn't exit [Thread 0xb72d6b70 (LWP 7713) exited] [Thread 0xb6ad5b70 (LWP 7714) exited] [Thread 0xb62d4b70 (LWP 7715) exited] Program exited normally. and when i add pthread_mutex_lock in function addRecord_d,the error still exists. So what exactly the problem is?

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  • What am I encrypting wrong here?

    - by Katie Krueger
    So I have a wordplay project to do and I have to encrypt some characters. I am at the point where I am stuck, and when I run it and type 1 for encrypt it doesn't shift that many letters. It just prints the work over again. I am wondering what I could do to fix it where if I say "hello" it will print 1 character over and say "ifmmp" Thank you! import java.util.Scanner; public class WordPlayTester{ public static void main(String [] args){ String word, reverse=""; String original; int key= 0; String Menu= "1-Encrypt \n2-Decrypt \n3-Is Palindrome \n0-Quit \n-Select an option-"; Scanner in = new Scanner(System.in); System.out.println("-Type any word-"); word = in.nextLine(); System.out.println(Menu); int choice=in.nextInt(); if(choice==1) { System.out.println("Insert a Key number"); int select= in.nextInt(); for (int i=0; i < word.length(); i++) { char c = word.charAt(i); if (c >= 'A' && c <= 'Z') { c = (char)(c - 64); int n = c+1; n = n % 26; if (n < 0) { n = n + 26; } c = (char)(n + 65); } System.out.println(c); } } else if(choice==3) { int length = word.length(); for ( int i = length - 1 ; i >= 0 ; i-- ) reverse = reverse + word.charAt(i); if (word.equals(reverse)) System.out.println("Your word is a palindrome."); else System.out.println("Your word is not a palindrome."); } else if(choice==0) { System.exit(0); } else { System.out.println(Menu); } } }

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  • How to make item view render rich (html) text in PyQt?

    - by Giorgio Gelardi
    I'm trying to translate code from this thread in python: import sys from PyQt4.QtCore import * from PyQt4.QtGui import * __data__ = [ "Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.", "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.", "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.", "Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum." ] def get_html_box(text): return '''<table border="0" width="100%"><tr width="100%" valign="top"> <td width="1%"><img src="softwarecenter.png"/></td> <td><table border="0" width="100%" height="100%"> <tr><td><b><a href="http://www.google.com">titolo</a></b></td></tr> <tr><td>{0}</td></tr><tr><td align="right">88/88/8888, 88:88</td></tr> </table></td></tr></table>'''.format(text) class HTMLDelegate(QStyledItemDelegate): def paint(self, painter, option, index): model = index.model() record = model.listdata[index.row()] doc = QTextDocument(self) doc.setHtml(get_html_box(record)) doc.setTextWidth(option.rect.width()) painter.save() ctx = QAbstractTextDocumentLayout.PaintContext() ctx.clip = QRectF(0, option.rect.top(), option.rect.width(), option.rect.height()) dl = doc.documentLayout() dl.draw(painter, ctx) painter.restore() def sizeHint(self, option, index): model = index.model() record = model.listdata[index.row()] doc = QTextDocument(self) doc.setHtml(get_html_box(record)) doc.setTextWidth(option.rect.width()) return QSize(doc.idealWidth(), doc.size().height()) class MyListModel(QAbstractListModel): def __init__(self, parent=None, *args): super(MyListModel, self).__init__(parent, *args) self.listdata = __data__ def rowCount(self, parent=QModelIndex()): return len(self.listdata) def data(self, index, role=Qt.DisplayRole): return index.isValid() and QVariant(self.listdata[index.row()]) or QVariant() class MyWindow(QWidget): def __init__(self, *args): super(MyWindow, self).__init__(*args) # listview self.lv = QListView() self.lv.setModel(MyListModel(self)) self.lv.setItemDelegate(HTMLDelegate(self)) self.lv.setResizeMode(QListView.Adjust) # layout layout = QVBoxLayout() layout.addWidget(self.lv) self.setLayout(layout) if __name__ == "__main__": app = QApplication(sys.argv) w = MyWindow() w.show() sys.exit(app.exec_()) Element's size and position are not calculated correctly I guess, perhaps because I haven't understand at all the style related parts from original code. Can someone help me?

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  • How to write my own global lock / unlock functions for PostgreSQL

    - by rafalmag
    I have postgresql (in perlu) function getTravelTime(integer, timestamp), which tries to select data for specified ID and timestamp. If there are no data or if data is old, it downloads them from external server (downloading time ~300ms). Multiple process use this database and this function. There is an error when two process do not find data and download them and try to do an insert to travel_time table (id and timestamp pair have to be unique). I thought about locks. Locking whole table would block all processes and allow only one to proceed. I need to lock only on id and timestamp. pg_advisory_lock seems to lock only in "current session". But my processes uses their own sessions. I tried to write my own lock/unlock functions. Am I doing it right? I use active waiting, how can I omit this? Maybe there is a way to use pg_advisory_lock() as global lock? My code: CREATE TABLE travel_time_locks ( id_key integer NOT NULL, time_key timestamp without time zone NOT NULL, UNIQUE (id_key, time_key) ); ------------ -- Function: mylock(integer, timestamp) DROP FUNCTION IF EXISTS mylock(integer, timestamp) CASCADE; -- Usage: SELECT mylock(1, '2010-03-28T19:45'); -- function tries to do a global lock similar to pg_advisory_lock(key, key) CREATE OR REPLACE FUNCTION mylock(id_input integer, time_input timestamp) RETURNS void AS $BODY$ DECLARE rows int; BEGIN LOOP BEGIN -- active waiting here !!!! :( INSERT INTO travel_time_locks (id_key, time_key) VALUES (id_input, time_input); EXCEPTION WHEN unique_violation THEN CONTINUE; END; EXIT; END LOOP; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1; ------------ -- Function: myunlock(integer, timestamp) DROP FUNCTION IF EXISTS myunlock(integer, timestamp) CASCADE; -- Usage: SELECT myunlock(1, '2010-03-28T19:45'); -- function tries to do a global unlock similar to pg_advisory_unlock(key, key) CREATE OR REPLACE FUNCTION myunlock(id_input integer, time_input timestamp) RETURNS integer AS $BODY$ DECLARE BEGIN DELETE FROM ONLY travel_time_locks WHERE id_key=id_input AND time_key=time_input; RETURN 1; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1;

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  • How to store multiple variables from a File Input of unknown size in Java?

    - by AlphaOmegaStrife
    I'm a total beginner with my first programming assignment in Java. For our programming assignment, we will be given a .txt file of students like so: 3 345 Lisa Miller 890238 Y 2 <-(Number of classes) Mathematics MTH345 4 A Physics PHY357 3 B Bill Wilton 798324 N 2 English ENG378 3 B Philosophy PHL534 3 A Dandy Goat 746333 Y 1 History HIS101 3 A" The teacher will give us a .txt file on the day of turning it in with a list of unknown students. My problem is: I have a specific class for turning the data from the file into variables to be used for a different class in printing it to the screen. However, I do not know of a good way to get the variables from the input file for the course numbers, since that number is not predetermined. The only way I can think of to iterate over that unknown amount is using a loop, but that would just overwrite my variables every time. Also, the teacher has requested that we not use any JCL classes (I don't really know what this means.) Sorry if I have done a poor job of explaining this, but I can't think of a better way to conceptualize it. Let me know if I can clarify. Edit: public static void analyzeData() { Scanner inputStream = null; try { inputStream = new Scanner(new FileInputStream("Programming Assignment 1 Data.txt")); } catch (FileNotFoundException e) { System.out.println("File Programming Assignment 1 Data.txt could not be found or opened."); System.exit(0); } int numberOfStudents = inputStream.nextInt(); int tuitionPerHour = inputStream.nextInt(); String firstName = inputStream.next(); String lastname = inputStream.next(); String isTuitionPaid = inputStream.next(); int numberOfCourses = inputStream.nextInt(); String courseName = inputStream.next(); String courseNumber = inputStream.next(); int creditHours = inputStream.nextInt(); String grade = inputStream.next(); To show the methods I am using now, I am just using a Scanner to read from the file and for Scanner inputStream, I am using nextInt() or next() to get variables from the file. Obviously this will not work when I do not know exactly how many classes each student will have.

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  • Split string in C every white space

    - by redsolja
    I want to write a program in C that displays each word of a whole sentence (taken as input) at a seperate line. This is what i have done so far: void manipulate(char *buffer); int get_words(char *buffer); int main(){ char buff[100]; printf("sizeof %d\nstrlen %d\n", sizeof(buff), strlen(buff)); // Debugging reasons bzero(buff, sizeof(buff)); printf("Give me the text:\n"); fgets(buff, sizeof(buff), stdin); manipulate(buff); return 0; } int get_words(char *buffer){ // Function that gets the word count, by counting the spaces. int count; int wordcount = 0; char ch; for (count = 0; count < strlen(buffer); count ++){ ch = buffer[count]; if((isblank(ch)) || (buffer[count] == '\0')){ // if the character is blank, or null byte add 1 to the wordcounter wordcount += 1; } } printf("%d\n\n", wordcount); return wordcount; } void manipulate(char *buffer){ int words = get_words(buffer); char *newbuff[words]; char *ptr; int count = 0; int count2 = 0; char ch = '\n'; ptr = buffer; bzero(newbuff, sizeof(newbuff)); for (count = 0; count < 100; count ++){ ch = buffer[count]; if (isblank(ch) || buffer[count] == '\0'){ buffer[count] = '\0'; if((newbuff[count2] = (char *)malloc(strlen(buffer))) == NULL) { printf("MALLOC ERROR!\n"); exit(-1); } strcpy(newbuff[count2], ptr); printf("\n%s\n",newbuff[count2]); ptr = &buffer[count + 1]; count2 ++; } } } Although the output is what i want, i have really many black spaces after the final word displayed, and the malloc() returns NULL so the MALLOC ERROR! is displayed in the end. I can understand that there is a mistake at my malloc() implementation but i do not know what it is. Is there another more elegant - generally better way to do it? Thanks in advance.

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  • DataGridView validating old value insted of new value.

    - by Scott Chamberlain
    I have a DataGridView that is bound to a DataTable, it has a column that is a double and the values need to be between 0 and 1. Here is my code private void dgvImpRDP_InfinityRDPLogin_CellValidating(object sender, DataGridViewCellValidatingEventArgs e) { if (e.ColumnIndex == dtxtPercentageOfUsersAllowed.Index) { double percentage; if(dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].Value.GetType() == typeof(double)) percentage = (double)dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].Value; else if (!double.TryParse(dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].Value.ToString(), out percentage)) { e.Cancel = true; dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].ErrorText = "The value must be between 0 and 1"; return; } if (percentage < 0 || percentage > 1) { e.Cancel = true; dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].ErrorText = "The value must be between 0 and 1"; } } } However my issue when dgvImpRDP_InfinityRDPLogin_CellValidating fires dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].Value will contain the old value before the edit, not the new value. For example lets say the old value was .1 and I enter 3. The above code runs when you exit the cell and dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].Value will be .1 for that run, the code validates and writes 3 the data to the DataTable. I click on it a second time, try to leave, and this time it behaves like it should, it raises the error icon for the cell and prevents me from leaving. I try to enter the correct value (say .7) but the the Value will still be 3 and there is now no way out of the cell because it is locked due to the error and my validation code will never push the new value. Any recommendations would be greatly appreciated. EDIT -- New version of the code based off of Stuart's suggestion and mimicking the style the MSDN article uses. Still behaves the same. private void dgvImpRDP_InfinityRDPLogin_CellValidating(object sender, DataGridViewCellValidatingEventArgs e) { if (e.ColumnIndex == dtxtPercentageOfUsersAllowed.Index) { dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].ErrorText = String.Empty; double percentage; if (!double.TryParse(dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].FormattedValue.ToString(), out percentage) || percentage < 0 || percentage > 1) { e.Cancel = true; dgvImpRDP_InfinityRDPLogin[e.ColumnIndex, e.RowIndex].ErrorText = "The value must be between 0 and 1"; return; } } }

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  • How to generalize a method call in Java (to avoid code duplication)

    - by dln385
    I have a process that needs to call a method and return its value. However, there are several different methods that this process may need to call, depending on the situation. If I could pass the method and its arguments to the process (like in Python), then this would be no problem. However, I don't know of any way to do this in Java. Here's a concrete example. (This example uses Apache ZooKeeper, but you don't need to know anything about ZooKeeper to understand the example.) The ZooKeeper object has several methods that will fail if the network goes down. In this case, I always want to retry the method. To make this easy, I made a "BetterZooKeeper" class that inherits the ZooKeeper class, and all of its methods automatically retry on failure. This is what the code looked like: public class BetterZooKeeper extends ZooKeeper { private void waitForReconnect() { // logic } @Override public Stat exists(String path, Watcher watcher) { while (true) { try { return super.exists(path, watcher); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } @Override public byte[] getData(String path, boolean watch, Stat stat) { while (true) { try { return super.getData(path, watch, stat); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } @Override public void delete(String path, int version) { while (true) { try { super.delete(path, version); return; } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } } (In the actual program there is much more logic and many more methods that I took out of the example for simplicity.) We can see that I'm using the same retry logic, but the arguments, method call, and return type are all different for each of the methods. Here's what I did to eliminate the duplication of code: public class BetterZooKeeper extends ZooKeeper { private void waitForReconnect() { // logic } @Override public Stat exists(final String path, final Watcher watcher) { return new RetryableZooKeeperAction<Stat>() { @Override public Stat action() { return BetterZooKeeper.super.exists(path, watcher); } }.run(); } @Override public byte[] getData(final String path, final boolean watch, final Stat stat) { return new RetryableZooKeeperAction<byte[]>() { @Override public byte[] action() { return BetterZooKeeper.super.getData(path, watch, stat); } }.run(); } @Override public void delete(final String path, final int version) { new RetryableZooKeeperAction<Object>() { @Override public Object action() { BetterZooKeeper.super.delete(path, version); return null; } }.run(); return; } private abstract class RetryableZooKeeperAction<T> { public abstract T action(); public final T run() { while (true) { try { return action(); } catch (KeeperException e) { // We will retry. } waitForReconnect(); } } } } The RetryableZooKeeperAction is parameterized with the return type of the function. The run() method holds the retry logic, and the action() method is a placeholder for whichever ZooKeeper method needs to be run. Each of the public methods of BetterZooKeeper instantiates an anonymous inner class that is a subclass of the RetryableZooKeeperAction inner class, and it overrides the action() method. The local variables are (strangely enough) implicitly passed to the action() method, which is possible because they are final. In the end, this approach does work and it does eliminate the duplication of the retry logic. However, it has two major drawbacks: (1) it creates a new object every time a method is called, and (2) it's ugly and hardly readable. Also I had to workaround the 'delete' method which has a void return value. So, here is my question: is there a better way to do this in Java? This can't be a totally uncommon task, and other languages (like Python) make it easier by allowing methods to be passed. I suspect there might be a way to do this through reflection, but I haven't been able to wrap my head around it.

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