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• Lua Alien Module - Trouble using WriteProcessMemory function, unsure on types (unit32)

  - by jefferysanders

  require "alien" --the address im trying to edit in the Mahjong game on Win7 local SCOREREF = 0x0744D554 --this should give me full access to the process local ACCESS = 0x001F0FFF --this is my process ID for my open window of Mahjong local PID = 1136 --function to open proc local op = alien.Kernel32.OpenProcess op:types{ ret = "pointer", abi = "stdcall"; "int", "int", "int"} --function to write to proc mem local wm = alien.Kernel32.WriteProcessMemory wm:types{ ret = "long", abi = "stdcall"; "pointer", "pointer", "pointer", "long", "pointer" } local pRef = op(ACCESS, true, PID) local buf = alien.buffer("99") -- ptr,uint32,byte arr (no idea what to make this),int, ptr print( wm( pRef, SCOREREF, buf, 4, nil)) --prints 1 if success, 0 if failed So that is my code. I am not even sure if I have the types set correctly. I am completely lost and need some guidance. I really wish there was more online help/documentation for alien, it confuses my poor brain. What utterly baffles me is that it WriteProcessMemory will sometimes complete successfully (though it does nothing at all, to my knowledge) and will also sometimes fail to complete successfully. As I've stated, my brain hurts. Any help appreciated.

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• iphone encryption not working

  - by Futur

  I have this encryption/decryption implemented and executes with no error, but i am unable to decrypt the data and im not sure whether the data is encrypted, kindly help. - (NSData *)AES256EncryptWithKey:(NSString *)key { char keyPtr[kCCKeySizeAES256+1]; bzero(keyPtr, sizeof(keyPtr)); [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding]; NSUInteger dataLength = [strData length]; data = [[NSData alloc] init]; data = [strData dataUsingEncoding:NSUTF8StringEncoding]; size_t bufferSize = dataLength + kCCBlockSizeAES128; void *pribuffer = malloc(bufferSize); size_t numBytesEncrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding, keyPtr, kCCKeySizeAES256, NULL /* initialization vector (optional) */, [data bytes], dataLength, /* input */ [data bytes], bufferSize, /* output */ &numBytesEncrypted); if (cryptStatus == kCCSuccess) { return [NSData dataWithBytesNoCopy:data length:numBytesEncrypted]; }} The decryption is : -(NSData *)AES256DecryptWithKey:(NSString *)key andForData:(NSData *)objDataObject { char keyPtr[kCCKeySizeAES256+1]; bzero(keyPtr, sizeof(keyPtr)); [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding]; NSUInteger dataLength = [objDataObject length]; size_t bufferSize = dataLength + kCCBlockSizeAES128; void *buffer = malloc(bufferSize); size_t numBytesDecrypted = 0; CCCryptorStatus cryptStatus = CCCrypt(kCCDecrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding, keyPtr, kCCKeySizeAES256, NULL, [objDataObject bytes], dataLength, [objDataObject bytes], bufferSize, &numBytesDecrypted); if (cryptStatus == kCCSuccess) { return [NSData dataWithBytesNoCopy:objDataObject length:numBytesDecrypted]; } } i call the above methods like this: CryptoClass *obj = [CryptoClass new]; NSData *objData = [obj AES256EncryptWithKey:@"hell"]; NSData *val = [obj AES256DecryptWithKey:@"hell" andForData:objData ]; NSLog(@"decrypted string is : %@ AND LENGTH IS %d",[val description],[val length]); Decryption doesnt seem to happen at all and the encryption - i am not sure about it, kindly help me here.

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• Retrieve Flash file post in ASP.NET

  - by Quandary

  Question: In ASP.NET, I retrieve a JPEG-file as Flash post data like this Sub ProcessRequest(ByVal context As HttpContext) Implements IHttpHandler.ProcessRequest context.Response.ContentType = "text/plain" ' Retrieve a bytearray from the post buffer Dim myBuffer As Byte() = context.Request.BinaryRead(Convert.ToInt32(context.Request.InputStream.Length)) System.IO.File.WriteAllBytes("c:\temp\test.jpg", myBuffer) End Sub In Flash, I send it to an asp.net handler like this var jpgSource:BitmapData = cPrint.TakeSnapshot(MovieClip(cGlobals.ccPlanZoomView)); var bmpThisBitmap:Bitmap = new Bitmap(jpgSource); var nQuality:Number = 100; var jpgEncoder:JPGEncoder = new JPGEncoder(nQuality); var jpgStream:ByteArray = jpgEncoder.encode(jpgSource); var header:URLRequestHeader = new URLRequestHeader ("Content-type", "application/octet-stream"); // Make sure to use the correct path to jpg_encoder_download.php var strFileName:String="test.jpg"; var jpgURLRequest:URLRequest = new URLRequest("http://localhost/raumplaner_new/raumplaner_new/cgi-bin/SavePDF.ashx"); //var scriptVars:URLVariables = new URLVariables(); //scriptVars.fn = strFileName; //var myarr:Array= new Array(); //myarr.push(jpgStream); //scriptVars.Files = myarr; jpgURLRequest.requestHeaders.push(header); jpgURLRequest.method = URLRequestMethod.POST; //jpgURLRequest.data = scriptVars; jpgURLRequest.data = jpgStream; var loader:URLLoader = new URLLoader(); loader.dataFormat = URLLoaderDataFormat.BINARY; loader.load(jpgURLRequest); It works but I want to send a few additional variables along, via scriptVars (commented out here). How do I retrieve the JPEG file in that case ? Because if I use parameters, there is no more BinaryRead... Aspecially, how would I read an array of jpeg files (several files) ?

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• Project Euler 7 Scala Problem

  - by Nishu

  I was trying to solve Project Euler problem number 7 using scala 2.8 First solution implemented by me takes ~8 seconds def problem_7:Int = { var num = 17; var primes = new ArrayBuffer[Int](); primes += 2 primes += 3 primes += 5 primes += 7 primes += 11 primes += 13 while (primes.size < 10001){ if (isPrime(num, primes)) primes += num if (isPrime(num+2, primes)) primes += num+2 num += 6 } return primes.last; } def isPrime(num:Int, primes:ArrayBuffer[Int]):Boolean = { // if n == 2 return false; // if n == 3 return false; var r = Math.sqrt(num) for (i <- primes){ if(i <= r ){ if (num % i == 0) return false; } } return true; } Later I tried the same problem without storing prime numbers in array buffer. This take .118 seconds. def problem_7_alt:Int = { var limit = 10001; var count = 6; var num:Int = 17; while(count < limit){ if (isPrime2(num)) count += 1; if (isPrime2(num+2)) count += 1; num += 6; } return num; } def isPrime2(n:Int):Boolean = { // if n == 2 return false; // if n == 3 return false; var r = Math.sqrt(n) var f = 5; while (f <= r){ if (n % f == 0) { return false; } else if (n % (f+2) == 0) { return false; } f += 6; } return true; } I tried using various mutable array/list implementations in Scala but was not able to make solution one faster. I do not think that storing Int in a array of size 10001 can make program slow. Is there some better way to use lists/arrays in scala?

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• C# Error reading two dates from a binary file

  - by Jamie

  Hi all, When reading two dates from a binary file I'm seeing the error below: "The output char buffer is too small to contain the decoded characters, encoding 'Unicode (UTF-8)' fallback 'System.Text.DecoderReplacementFallback'. Parameter name: chars" My code is below: static DateTime[] ReadDates() { System.IO.FileStream appData = new System.IO.FileStream( appDataFile, System.IO.FileMode.Open, System.IO.FileAccess.Read); List<DateTime> result = new List<DateTime>(); using (System.IO.BinaryReader br = new System.IO.BinaryReader(appData)) { while (br.PeekChar() > 0) { result.Add(new DateTime(br.ReadInt64())); } br.Close(); } return result.ToArray(); } static void WriteDates(IEnumerable<DateTime> dates) { System.IO.FileStream appData = new System.IO.FileStream( appDataFile, System.IO.FileMode.Create, System.IO.FileAccess.Write); List<DateTime> result = new List<DateTime>(); using (System.IO.BinaryWriter bw = new System.IO.BinaryWriter(appData)) { foreach (DateTime date in dates) bw.Write(date.Ticks); bw.Close(); } } What could be the cause? Thanks

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• Export Multiple Crystal Reports ASP.NET

  - by AProgrammer

  Hey all, I want to export 2 different reports when I click an Export button. The problem is the routine only fires once and I only get one report to print out. Am I doing something wrong? I think it has something to do with the HTTPResponse, but I'm not sure. Here's my code: Dim badgeSize As Integer = 0 'Drop Down selection Dim badgeData As New DataSet 'Visitor Badge Data Dim badgeEmployeeData As New DataSet 'Employee Badge Data Dim badgeTotals As Integer = 0 'Totals for both badgeSize = ddlBadgeSize.SelectedValue ' Get Visitor Data badgeData = _DatabaseAccess.GetProjectReportData(sessionInfo.myEventID, sessionInfo.EventCreator) ' Get Employee Data badgeEmployeeData = _DatabaseAccess.GetProjectReportEmployeeData(sessionInfo.myEventID, sessionInfo.EventCreator) 'Obtain Totals badgeTotals = badgeData.Tables(0).Rows.Count + badgeEmployeeData.Tables(0).Rows.Count If badgeTotals = 0 Then ShowMessage("There are no badges to print.") Exit Sub End If If badgeSize.Equals(0) Then 'Small If badgeEmployeeData.Tables(0).Rows.Count > 0 Then If badgeEmployeeData.Tables(0).Rows.Count >= 6 Then PrintProjectBadges(badgeEmployeeData, "Employee", badgeSize) Else PrintStandardDymo(badgeEmployeeData, "Employee", 1) End If End If If badgeData.Tables(0).Rows.Count > 0 Then If badgeData.Tables(0).Rows.Count >= 6 Then PrintProjectBadges(badgeData, "Visitor", badgeSize) Else PrintStandardDymo(badgeData, "Visitor", 1) End If End If else 'do somethign else endif And the Report Code: Private Sub PrintProjectBadges(ByVal theData As DataSet, ByVal badgeType As String, ByVal badgeSize As Integer) Dim ourReport As New ReportDocument Dim crConnectionInfo As New ConnectionInfo(SetCrystalConnection) If badgeSize = 0 Then Try If badgeType = "Visitor" Then ourReport.Load(Server.MapPath("SmallProjectBadge.rpt"), OpenReportMethod.OpenReportByDefault) 'LIVE SERVER USE Else ourReport.Load(Server.MapPath("SmallProjectEmployeeBadge.rpt"), OpenReportMethod.OpenReportByDefault) 'LIVE SERVER USE End If Catch ex As Exception Dim TraceList As New ArrayList TraceList.Add("DBLog") DatabaseAccess.WriteToErrorLog("Visitor Registration", "Printing Project Badges", ex.Message, TraceEventType.Information, 1, TraceList) Exit Sub End Try ourReport.SetDataSource(theData.Tables("Project")) Else 'Do somethign else... End If Response.Buffer = True 'Clear the response content and headers Response.ClearContent() Response.ClearHeaders() SetLogon(ourReport, crConnectionInfo) 'Export the Report to Response stream in PDF format and file name Customers ourReport.ExportToHttpResponse(ExportFormatType.PortableDocFormat, Response, True, "Visitor_Badges") Response.End() 'Response.Close() End Sub Any Help would be much appreciated.

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• Convert function to read from string instead of file in C

  - by Dusty

  I've been tasked with updating a function which currently reads in a configuration file from disk and populates a structure: static int LoadFromFile(FILE *Stream, ConfigStructure *cs) { int tempInt; ... if ( fscanf( Stream, "Version: %d\n",&tempInt) != 1 ) { printf("Unable to read version number\n"); return 0; } cs->Version = tempInt; ... } to one which allows us to bypass writing the configuration to disk and instead pass it directly in memory, roughly equivalent to this: static int LoadFromString(char *Stream, ConfigStructure *cs) A few things to note: The current LoadFromFile function is incredibly dense and complex, reading dozens of versions of the config file in a backward compatible manner, which makes duplication of the overall logic quite a pain. The functions that generate the config file and those that read it originate in totally different parts of the old system and therefore don't share any data structures so I can't pass those directly. I could potentially write a wrapper, but again, it would need to handle any structure passed in in a backwards compatible manner. I'm tempted to just pass the file as is in as a string (as in the prototype above) and convert all the fscanf's to sscanf's but then I have to handle incrementing the pointer along (and potentially dealing with buffer overrun errors) manually. This has to remain in C, so no C++ functionality like streams can help here Am I missing a better option? Is there some way to create a FILE * that actually just points to a location in memory instead of on disk? Any pointers, suggestions or other help is greatly appreciated.

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• Is there a standard mapping between JSON and Protocol Buffers?

  - by Daniel Earwicker

  From a comment on the announcement blog post: Regarding JSON: JSON is structured similarly to Protocol Buffers, but protocol buffer binary format is still smaller and faster to encode. JSON makes a great text encoding for protocol buffers, though -- it's trivial to write an encoder/decoder that converts arbitrary protocol messages to and from JSON, using protobuf reflection. This is a good way to communicate with AJAX apps, since making the user download a full protobuf decoder when they visit your page might be too much. It may be trivial to cook up a mapping, but is there a single "obvious" mapping between the two that any two separate dev teams would naturally settle on? If two products supported PB data and could interoperate because they shared the same .proto spec, I wonder if they would still be able to interoperate if they independently introduced a JSON reflection of the same spec. There might be some arbitrary decisions to be made, e.g. should enum values be represented by a string (to be human-readable a la typical JSON) or by their integer value? So is there an established mapping, and any open source implementations for generating JSON encoder/decoders from .proto specs?

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• even PHP has 'bugs' with IE

  - by silversky

  It's not a real bug BUT for sure it is not what you would expect. I have this sample code to upload images: <?php if($type=="image/jpg" || $type=="image/jpeg" || $type=="image/pjpeg" || $type=="image/tiff" || $type=="image/gif" || $type=="image/png") { // make upload else echo "Incorect format ...."; ?> The problem is that that if I modify the extention of an image, let's say to .jpgq or even .jpg% and i try to upload it FF and Chrome will say that the file"s type is "application/octet-stream" and normaly the condition will be false BUT since IE is 'smarter' that other brow. it will say that the file is "image/pjeg and the condition will be true and the file will be uploaded and of course latter any brow. will not be able to read / view the image. It is not a bug because on msdn.microsoft.com it says that: "If the "suggested" (server-provided) MIME type is unknown (not known and not ambiguous), FindMimeFromData immediately returns this MIME type" and "If the server-provided MIME type is either known or ambiguous, the buffer is scanned in an attempt to verify or obtain a MIME type from the actual content." plus others 'inovative solutions from Microsoft'. SO my questions are: Why is IE so 'smart' and when I upload the file to server it knows the real MIME type BUT it will fail to read it from the server ? How can i work around this issue (if the file doesn't have the right extention the condition has to be false)? Is it wise to check the extention format (and not the MIME type)? is any of the above extention not recomended to use ? Should I add others?

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• Best approach to storing image pixels in bottom-up order in Java

  - by finnw

  I have an array of bytes representing an image in Windows BMP format and I would like my library to present it to the Java application as a BufferedImage, without copying the pixel data. The main problem is that all implementations of Raster in the JDK store image pixels in top-down, left-to-right order whereas BMP pixel data is stored bottom-up, left-to-right. If this is not compensated for, the resulting image will be flipped vertically. The most obvious "solution" is to set the SampleModel's scanlineStride property to a negative value and change the band offsets (or the DataBuffer's array offset) to point to the top-left pixel, i.e. the first pixel of the last line in the array. Unfortunately this does not work because all of the SampleModel constructors throw an exception if given a negative scanlineStride argument. I am currently working around it by forcing the scanlineStride field to a negative value using reflection, but I would like to do it in a cleaner and more portable way if possible. e.g. is there another way to fool the Raster or SampleModel into arranging the pixels in bottom-up order but without breaking encapsulation? Or is there a library somewhere that will wrap the Raster and SampleModel, presenting the pixel rows in reverse order? I would prefer to avoid the following approaches: Copying the whole image (for performance reasons. The code must process hundreds of large (= 1Mpixels) images per second and although the whole image must be available to the application, it will normally access only a tiny (but hard-to-predict) portion of the image.) Modifying the DataBuffer to perform coordinate transformation (this actually works but is another "dirty" solution because the buffer should not need to know about the scanline/pixel layout.) Re-implementing the Raster and/or SampleModel interfaces from scratch (but I have a hunch that I will be unable to avoid this.)

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• Can you force a crash if a write occurs to a given memory location with finer than page granularity?

  - by Joseph Garvin

  I'm writing a program that for performance reasons uses shared memory (alternatives have been evaluated, and they are not fast enough for my task, so suggestions to not use it will be downvoted). In the shared memory region I am writing many structs of a fixed size. There is one program responsible for writing the structs into shared memory, and many clients that read from it. However, there is one member of each struct that clients need to write to (a reference count, which they will update atomically). All of the other members should be read only to the clients. Because clients need to change that one member, they can't map the shared memory region as read only. But they shouldn't be tinkering with the other members either, and since these programs are written in C++, memory corruption is possible. Ideally, it should be as difficult as possible for one client to crash another. I'm only worried about buggy clients, not malicious ones, so imperfect solutions are allowed. I can try to stop clients from overwriting by declaring the members in the header they use as const, but that won't prevent memory corruption (buffer overflows, bad casts, etc.) from overwriting. I can insert canaries, but then I have to constantly pay the cost of checking them. Instead of storing the reference count member directly, I could store a pointer to the actual data in a separate mapped write only page, while keeping the structs in read only mapped pages. This will work, the OS will force my application to crash if I try to write to the pointed to data, but indirect storage can be undesirable when trying to write lock free algorithms, because needing to follow another level of indirection can change whether something can be done atomically. Is there any way to mark smaller areas of memory such that writing them will cause your app to blow up? Some platforms have hardware watchpoints, and maybe I could activate one of those with inline assembly, but I'd be limited to only 4 at a time on 32-bit x86 and each one could only cover part of the struct because they're limited to 4 bytes. It'd also make my program painful to debug ;)

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• Disassembling with python - no easy solution?

  - by Abc4599

  Hi, I'm trying to create a python script that will disassemble a binary (a Windows exe to be precise) and analyze its code. I need the ability to take a certain buffer, and extract some sort of struct containing information about the instructions in it. I've worked with libdisasm in C before, and I found it's interface quite intuitive and comfortable. The problem is, its Python interface is available only through SWIG, and I can't get it to compile properly under Windows. At the availability aspect, diStorm provides a nice out-of-the-box interface, but it provides only the Mnemonic of each instruction, and not a binary struct with enumerations defining instruction type and what not. This is quite uncomfortable for my purpose, and will require a lot of what I see as spent time wrapping the interface to make it fit my needs. I've also looked at BeaEngine, which does in fact provide the output I need, a struct with binary info concerning each instruction, but its interface is really odd and counter-intuitive, and it crashes pretty much instantly when provided with wrong arguments. The CTypes sort of ultimate-death-to-your-python crashes. So, I'd be happy to hear about other solutions, which are a little less time consuming than messing around with djgcc or mingw to make SWIGed libdisasm, or writing an OOP wrapper for diStorm. If anyone has some guidance as to how to compile SWIGed libdisasm, or better yet, a compiled binary (pyd or dll+py), I'd love to hear/have it. :) Thanks ahead.

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• Can't catch KEY_VALUE_BASIC_INFORMATION.Name in CmRegisterCallback

  - by alex

  I want to hide in registry name of key value. I write driver, that using CmRegisterCallback. But I can't catch name of key value that I need. When I DbgPrint PKEY_VALUE_BASIC_INFORMATION-Name I get only symbols [ , u . Where is my mistake? Can anybody help me?My RegistryCallback source: NTSTATUS RegistryCallback(PVOID CallbackContext, PVOID Argument1, PVOID Argument2) { PDEVICE_CONTEXT pContext = (PDEVICE_CONTEXT) CallbackContext; REG_NOTIFY_CLASS Action = (REG_NOTIFY_CLASS) Argument1; UNICODE_STRING regKeyNameValueToHide = {0}; try { switch (Action) { case RegNtEnumerateValueKey: { PREG_ENUMERATE_VALUE_KEY_INFORMATION pInfo = (PREG_ENUMERATE_VALUE_KEY_INFORMATION) Argument2; //DbgPrint(pInfo->ValueName->Buffer); RtlInitUnicodeString(&regKeyNameValueToHide,L"alex-56328943333"); if(pInfo->KeyValueInformationClass == KeyValueBasicInformation) { PKEY_VALUE_BASIC_INFORMATION pKeyValueBasicInfirmation = (PKEY_VALUE_BASIC_INFORMATION) pInfo->KeyValueInformation; UNICODE_STRING regKeyNameValue = {0}; RtlInitUnicodeString(&regKeyNameValue,pKeyValueBasicInfirmation->Name); if (RtlEqualUnicodeString(&regKeyNameValue, &regKeyNameValueToHide, 1)) { return STATUS_CALLBACK_BYPASS; } } else if(pInfo->KeyValueInformationClass == KeyValueFullInformation) { PKEY_VALUE_FULL_INFORMATION pKeyValueFullInfirmation = (PKEY_VALUE_FULL_INFORMATION) pInfo->KeyValueInformation; UNICODE_STRING regKeyNameValue = {0}; RtlInitUnicodeString(&regKeyNameValue,pKeyValueFullInfirmation->Name); if (RtlEqualUnicodeString(&regKeyNameValue, &regKeyNameValueToHide, 1)) { return STATUS_CALLBACK_BYPASS; } } break; } default: { return STATUS_SUCCESS break; } } } except (EXCEPTION_EXECUTE_HANDLER) { DbgPrint("Exception in RegistryCallback!!!"); } return STATUS_SUCCESS; }

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• Overlaying 2D paths on UIImage without scaling artifacts

  - by tat0

  I need to draw a path along the shape of an image in a way that it is always matching its position on the image independent of the image scale. Think of this like the hybrid view of Google Maps where streets names and roads are superimposed on top of the aerial pictures. Furthermore, this path will be drawn by the user's finger movements and I need to be able to retrieve the path keypoints on the image pixel coordinates. The user zooms-in in order to more precisely set the paths location. I manage to somehow make it work using this approach: -Create a custom UIView called CanvasView that handles touches interaction and delivers scaling, rotation, translation values to either the UIImageView or PathsView (see bellow) depending on a flag: deliverToImageOrPaths. -Create a UIImageView holding the base image. This is set as a children of CanvasView -Create a custom UIView called PathsView that keeps track of the 2D paths geometry and draws itself with a custom drawRect. This is set as children of the UIImageView. So hierarchy: CanvasView - UIImageView -PathsView In this way when deliverToImageOrPaths is YES, finger gestures transforms both the UIImageView and its child PathsView. When deliverToImageOrPaths is NO the gestures affect only the PathsView altering its geometry. So far so good. QUESTION: The problem I have is that when scaling the base UIImageView (via its .transform property) the PathsView is scaled with aliasing artifacts. drawRect is still being called on the PathsView but I guess it's performing the drawing using the original buffer size and then interpolating. How can I solve this issue? Are there better ways to implement these features? PS: I tried changing the PathsView layer class to CATiledLayer with levelsOfDetailBias 4 and levelsOfDetail 4. It solves the aliasing problem to some extent but it's unacceptable slow to render.

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• Q on Python serialization/deserialization

  - by neil

  What chances do I have to instantiate, keep and serialize/deserialize to/from binary data Python classes reflecting this pattern (adopted from RFC 2246 [TLS]): enum { apple, orange } VariantTag; struct { uint16 number; opaque string<0..10>; /* variable length */ } V1; struct { uint32 number; opaque string[10]; /* fixed length */ } V2; struct { select (VariantTag) { /* value of selector is implicit */ case apple: V1; /* VariantBody, tag = apple */ case orange: V2; /* VariantBody, tag = orange */ } variant_body; /* optional label on variant */ } VariantRecord; Basically I would have to define a (variant) class VariantRecord, which varies depending on the value of VariantTag. That's not that difficult. The challenge is to find a most generic way to build a class, which serializes/deserializes to and from a byte stream... Pickle, Google protocol buffer, marshal is all not an option. I made little success with having an explicit "def serialize" in my class, but I'm not very happy with it, because it's not generic enough. I hope I could express the problem. My current solution in case VariantTag = apple would look like this, but I don't like it too much import binascii import struct class VariantRecord(object): def __init__(self, number, opaque): self.number = number self.opaque = opaque def serialize(self): out = struct.pack('>HB%ds' % len(self.opaque), self.number, len(self.opaque), self.opaque) return out v = VariantRecord(10, 'Hello') print binascii.hexlify(v.serialize()) >> 000a0548656c6c6f Regards

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• Epoll in EPOLLET mode returning 2 EPOLLIN before reading from the socket

  - by Arkaitz Jimenez

  The epoll manpage says that a fd registered with EPOLLET(edge triggered) shouldn't notify twice EPOLLIN if no read has been done. So after an EPOLLIN you need to empty the buffer before epoll_wait being able to return a new EPOLLIN on new data. However I'm experiencing problems with this approach as I'm seeing duplicated EPOLLIN events for untouched fds. This is the strace output, 0x200 is EPOLLRDHUP that is not defined yet in my glibc headers but defined in the kernel. 30285 epoll_ctl(3, EPOLL_CTL_ADD, 9, {EPOLLIN|EPOLLPRI|EPOLLERR|EPOLLHUP|EPOLLET|0x2000, {u32=9, u64=9}}) = 0 30285 epoll_wait(3, {{EPOLLIN, {u32=9, u64=9}}}, 10, -1) = 1 30285 epoll_wait(3, {{EPOLLIN, {u32=9, u64=9}}}, 10, -1) = 1 30285 epoll_wait(3, <unfinished ...> 30349 epoll_ctl(3, EPOLL_CTL_DEL, 9, NULL) = 0 30306 recv(9, "7u\0\0\10\345\241\312\t\20\f\32\r\10\27\20\2\30\200\10 \31(C0\17\32\r\10\27\20\2\30"..., 20000, 0) = 20000 30349 epoll_ctl(3, EPOLL_CTL_DEL, 9, NULL) = -1 ENOENT (No such file or directory) 30305 recv(9, " \31(C0\17\32\r\10\27\20\2\30\200\10 \31(C0\17\32\r\10\27\20\2\30\200\10 \31("..., 20000, 0) = 10011 So, after adding fd number 9 I do receive 2 consecutive EPOLLIN events before having recving the file descriptor, the syscall trace shows how I do delete the fd before reading but it should only happen once, one per event. So either I am not reading the manpage properly or something is now working here.

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• rs232 communication, general timing question

  - by Sunny Dee

  Hi, I have a piece of hardware which sends out a byte of data representing a voltage signal at a frequency of 100Hz over the serial port. I want to write a program that will read in the data so I can plot it. I know I need to open the serial port and open an inputstream. But this next part is confusing me and I'm having trouble understanding the process conceptually: I create a while loop that reads in the data from the inputstream 1 byte at a time. How do I get the while loop timing so that there is always a byte available to be read whenever it reaches the readbyte line? I'm guessing that I can't just put a sleep function inside the while loop to try and match it to the hardware sample rate. Is it just a matter of continuing reading the inputstream in the while loop, and if it's too fast then it won't do anything (since there's no new data), and if it's too slow then it will accumulate in the inputstream buffer? Like I said, i'm only trying to understand this conceptually so any guidance would be much appreciated! I'm guessing the idea is independent of which programming language I'm using, but if not, assume it is for use in Java. Thanks!

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• being able to solve google code jam problem sets

  - by JPro

  This is not a homework question, but rather my intention to know if this is what it takes to learn programming. I keep loggin into TopCoder not to actually participate but to get the basic understand of how the problems are solved. But to my knowledge I don't understand what the problem is and how to translate the problem into an algorithm that can solve it. Just now I happen to look at ACM ICPC 2010 World Finals which is being held in china. The teams were given problem sets and one of them is this: Given at most 100 points on a plan with distinct x-coordinates, find the shortest cycle that passes through each point exactly once, goes from the leftmost point always to the right until it reaches the rightmost point, then goes always to the left until it gets back to the leftmost point. Additionally, two points are given such that the the path from left to right contains the first point, and the path from right to left contains the second point. This seems to be a very simple DP: after processing the last k points, and with the first path ending in point a and the second path ending in point b, what is the smallest total length to achieve that? This is O(n^2) states, transitions in O(n). We deal with the two special points by forcing the first path to contain the first one, and the second path contain the second one. Now I have no idea what I am supposed to solve after reading the problem set. and there's an other one from google code jam: Problem In a big, square room there are two point light sources: one is red and the other is green. There are also n circular pillars. Light travels in straight lines and is absorbed by walls and pillars. The pillars therefore cast shadows: they do not let light through. There are places in the room where no light reaches (black), where only one of the two light sources reaches (red or green), and places where both lights reach (yellow). Compute the total area of each of the four colors in the room. Do not include the area of the pillars. Input * One line containing the number of test cases, T. Each test case contains, in order: * One line containing the coordinates x, y of the red light source. * One line containing the coordinates x, y of the green light source. * One line containing the number of pillars n. * n lines describing the pillars. Each contains 3 numbers x, y, r. The pillar is a disk with the center (x, y) and radius r. The room is the square described by 0 = x, y = 100. Pillars, room walls and light sources are all disjoint, they do not overlap or touch. Output For each test case, output: Case #X: black area red area green area yellow area Is it required that people who program should be should be able to solve these type of problems? I would apprecite if anyone can help me interpret the google code jam problem set as I wish to participate in this years Code Jam to see if I can do anthing or not. Thanks.

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• Resizing window causes black strips

  - by Paja

  I have a form, which sets these styles in constructor: this.SetStyle(ControlStyles.AllPaintingInWmPaint, true); this.SetStyle(ControlStyles.UserPaint, true); this.SetStyle(ControlStyles.ResizeRedraw, true); this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true); And I draw some rectangles in Paint event. There are no controls on the form. Hovewer, when I resize the form, there are black strips at right and bottom of the form. Is there any way to get rid of them? I've tried everything, listening for WM_ERASEBKGND in WndProc, manually drawing the form on WM_PAINT, implementing custom double buffer, etc. Is there anything else I could try? I've found this: https://connect.microsoft.com/VisualStudio/feedback/details/522441/custom-resizing-of-system-windows-window-flickers and it looks like it is a bug in DWM, but I just hope I can do some workaround. Please note that I must use double buffering, since I want to draw pretty intense graphic presentation in the Paint event. I develop in C# .NET 2.0, Win7.

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• Android:Playing bigger size audio wav sound file produces crash

  - by user187532

  Hi Android experts, I am trying to play the bigger size audio wav file(which is 20 mb) using the following code(AudioTrack) on my Android 1.6 HTC device which basically has less memory. But i found device crash as soon as it executes reading, writing and play. But the same code works fine and plays the lesser size audio wav files(10kb, 20 kb files etc) very well. P.S: I should play PCM(.wav) buffer sound, the reason behind why i use AudioTrack here. Though my device has lesser memory, how would i read bigger audio files bytes by bytes and play the sound to avoid crashing due to memory constraints. private void AudioTrackPlayPCM() throws IOException { String filePath = "/sdcard/myWav.wav"; // 8 kb file byte[] byteData = null; File file = null; file = new File(filePath); byteData = new byte[(int) file.length()]; FileInputStream in = null; try { in = new FileInputStream( file ); in.read( byteData ); in.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } int intSize = android.media.AudioTrack.getMinBufferSize(8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_8BIT); AudioTrack at = new AudioTrack(AudioManager.STREAM_MUSIC, 8000, AudioFormat.CHANNEL_CONFIGURATION_MONO, AudioFormat.ENCODING_PCM_8BIT, intSize, AudioTrack.MODE_STREAM); at.play(); at.write(byteData, 0, byteData.length); at.stop(); at.release(); } Could someone guide me please to play the AudioTrack code for bigger size wav files?

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• OpenGL behaving strangely

  - by Mk12

  OpenGL is acting very strangely for some reason. In my subclass of NSOpenGLView, I have the following code in -prepareOpenGL: - (void)prepareOpenGL { GLfloat lightAmbient[] = { 0.5f, 0.5f, 0.5f, 1.0f }; GLfloat lightDiffuse[] = { 1.0f, 1.0f, 1.0f, 1.0f }; GLfloat lightPosition[] = { 0.0f, 0.0f, 2.0f }; quality = 0; zCoord = -6; [self loadTextures]; glEnable(GL_LIGHTING); glEnable(GL_TEXTURE_2D); glShadeModel(GL_SMOOTH); glClearColor(0.2f, 0.2f, 0.2f, 0.0f); glClearDepth(1.0f); glEnable(GL_DEPTH_TEST); glDepthFunc(GL_LEQUAL); glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); glLightfv(GL_LIGHT1, GL_AMBIENT, lightAmbient); glLightfv(GL_LIGHT1, GL_DIFFUSE, lightDiffuse); glLightfv(GL_LIGHT1, GL_POSITION, lightPosition); glEnable(GL_LIGHT1); gameState = kGameStateRunning; int i = 0; // HERE ******** [NSTimer scheduledTimerWithTimeInterval:0.03f target:self selector:@selector(processKeys) userInfo:nil repeats:YES]; // Synchronize buffer swaps with vertical refresh rate GLint swapInt = 1; [[self openGLContext] setValues:&swapInt forParameter:NSOpenGLCPSwapInterval]; // Setup and start displayLink [self setupDisplayLink]; } I wanted to assign the timer that processes key input to an ivar so that I could invalidate it when the game is paused (and reinstantiate it on resume), however when I did that (as apposed to leaving it at [NSTimer scheduledTimer…), OpenGL doesn't display the cube I draw. When I take it away, it's fine. So i tried just adding a harmless statement, int i = 0; (maked // HERE *******), and that makes the lighting not work! When I take it away, everything is fine, but when I put it back, everything is dark. Can someone come up with a rational explanation for this? Thanks.

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• Replacing .NET WebBrowser control with a better browser, like Chrome?

  - by Sylverdrag

  Is there any relatively easy way to insert a modern browser into a .NET application? As far as I understand, the WebBrowser control is a wrapper for IE, which wouldn't be a problem except that it looks like it is a very old version of IE, with all that entails in terms of CSS screw-ups, potential security risks (if the rendering engine wasn't patched, can I really expect the zillion buffer overflow problems to be fixed?), and other issues. I am using Visual Studio C# (express edition - does it make any difference here?) I would like to integrate a good web browser in my applications. In some, I just use it to handle the user registration process, interface with some of my website's features and other things of that order, but I have another application in mind that will require more err... control. I need: A browser that can integrate inside a window of my application (not a separate window) A good support for CSS, js and other web technologies, on par with any modern browser Basic browser functions like "navigate", "back", "reload"... Liberal access to the page code and output. I was thinking about Chrome, since it comes under the BSD license, but I would be just as happy with a recent version of IE. As much as possible, I would like to keep things simple. The best would be if one could patch the existing WebBrowser control, which does already about 70% of what I need, but I don't think that's possible. I have found an activeX control for Mozilla (http://www.iol.ie/~locka/mozilla/control.htm) but it looks like it's an old version, so it's not necessarily an improvement. I am open to suggestions

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• copy a text file in C#

  - by melt

  I am trying to copy a text file in an other text file line by line. It seems that there is a buffer of 1024 character. If there is less than 1024 character in my file, my function will not copie in the other file. Also if there is more than 1024 character but less a factor of 1024, these exceeding characters will not be copied. Ex: 2048 character in initial file - 2048 copied 988 character in initial file - 0 copied 1256 character in initial file - 1024 copied Thks! private void button3_Click(object sender, EventArgs e) { // écrire code pour reprendre le nom du fichier sélectionné et //ajouter un suffix "_poly.txt" string ma_ligne; const int RMV_CARCT = 9; //délcaration des fichier FileStream apt_file = new FileStream(textBox1.Text, FileMode.Open, FileAccess.Read); textBox1.Text = textBox1.Text.Replace(".txt", "_mod.txt"); FileStream mdi_file = new FileStream(textBox1.Text, FileMode.OpenOrCreate,FileAccess.ReadWrite); //lecture/ecriture des fichiers en question StreamReader apt = new StreamReader(apt_file); StreamWriter mdi_line = new StreamWriter(mdi_file, System.Text.Encoding.UTF8, 16); while (apt.Peek() >= 0) { ma_ligne = apt.ReadLine(); //if (ma_ligne.StartsWith("GOTO")) //{ // ma_ligne = ma_ligne.Remove(0, RMV_CARCT); // ma_ligne = ma_ligne.Replace(" ",""); // ma_ligne = ma_ligne.Replace(",", " "); mdi_line.WriteLine(ma_ligne); //} } apt_file.Close(); mdi_file.Close(); }

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• Scala Interpreter scala.tools.nsc.interpreter.IMain Memory leak

  - by Peter

  I need to write a program using the scala interpreter to run scala code on the fly. The interpreter must be able to run an infinite amount of code without being restarted. I know that each time the method interpret() of the class scala.tools.nsc.interpreter.IMain is called, the request is stored, so the memory usage will keep going up forever. Here is the idea of what I would like to do: var interpreter = new IMain while (true) { interpreter.interpret(some code to be run on the fly) } If the method interpret() stores the request each time, is there a way to clear the buffer of stored requests? What I am trying to do now is to count the number of times the method interpret() is called then get a new instance of IMain when the number of times reaches 100, for instance. Here is my code: var interpreter = new IMain var counter = 0 while (true) { interpreter.interpret(some code to be run on the fly) counter = counter + 1 if (counter > 100) { interpreter = new IMain counter = 0 } } However, I still see that the memory usage is going up forever. It seems that the IMain instances are not garbage-collected by the JVM. Could somebody help me solve this issue? I really need to be able to keep my program running for a long time without restarting, but I cannot afford such a memory usage just for the scala interpreter. Thanks in advance, Pet

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• Do overlays work correctly in Emacs for Windows?

  - by Cheeso

  I'm using Flymake on C# code, emacs v22.2.1 on Windows. The Flymake stuff has been working well for me. For those who don't know, you can read an overview of flymake, but the quick story is that flymake repeatedly builds the source file you are currently working on in the background, for the purpose of doing syntax checking. It then highlights the compiler warnings and erros in the current buffer. Flymake didn't work for C# initially, but I "monkey-patched it" and it works nicely now. If you edit C# in emacs, I highly recommend using flymake. The only problem I have is with the UI. Flymake highlights the errors and warnings nicely, and then inserts "overlays" with the full error or warning text. IF I hover the mouse pointer over the highlighted line in code, the overlay pops up. But as you can see, the overlay is truncated, and it doesn't display correctly. Flymake seems to be doing the right thing, it's the overlay part that seems broken. Do overlays work correctly in emacs for Windows? Where do I look to fix this?

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