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  • Make Browsing Safer for Children in Google Chrome

    - by Asian Angel
    If you are worried about the websites that your children could accidentally visit while browsing, then you may want to have a look at the Kid Safe – LinkExtend extension for Google Chrome. Kid Safe – LinkExtend in Action Before going any further you may want to have a quick look at the options. Everything is enabled by default but it is recommended that you disable the “Allow entering unsafe sites Option”. For our first example we visited “chatroulette.com”. As you can see in the screenshot WOT and McAfee SiteAdvisor gave the website a “green rating” but when it came specifically to its’ level of appropriateness for children LinkExtend gave it a “yellow rating”. Our second example was “hotbabes.com”…obviously not a good website for any child to visit. You can see that the entire window area has been totally “blacked out” and the available information for this site from each of the six ratings sources. The “Toolbar Button” is also displaying a “red rating”… Notice the two links at the bottom of the ratings screen…both will be visible if the “Allow entering unsafe sites Option” is not disabled (see Options above). You can see the difference for the links at the bottom of the ratings screen if you have the “Allow entering unsafe sites Option” disabled. Definitely much much better… Clicking on the “Find Kids Sites Link” will navigate the tab to the Yahoo! Kids website. The extension will also place “ratings buttons” beside search results at Google. As you can see in the screenshot below not all of the results had information available for them at this time. But it is certainly a lot better than nothing at all when it comes to keeping your children safe. A close-up look at the ratings for one of the search results. Conclusion While no browser add-in makes for a perfect solution the Kid Safe – LinkExtend extension will definitely be a helpful addition to your family’s Chrome browser. Links Download the Kid Safe – LinkExtend extension (Google Chrome Extensions) Similar Articles Productive Geek Tips How to Make Google Chrome Your Default BrowserAccess Browsing History in Google Chrome the Easy WayFocused New Tabs Quick-Fix for Google ChromeVisually Browse Through Your Open Tabs in Google ChromeSubscribe to RSS Feeds in Chrome with a Single Click TouchFreeze Alternative in AutoHotkey The Icy Undertow Desktop Windows Home Server – Backup to LAN The Clear & Clean Desktop Use This Bookmarklet to Easily Get Albums Use AutoHotkey to Assign a Hotkey to a Specific Window Latest Software Reviews Tinyhacker Random Tips DVDFab 6 Revo Uninstaller Pro Registry Mechanic 9 for Windows PC Tools Internet Security Suite 2010 Awe inspiring, inter-galactic theme (Win 7) Case Study – How to Optimize Popular Wordpress Sites Restore Hidden Updates in Windows 7 & Vista Iceland an Insurance Job? Find Downloads and Add-ins for Outlook Recycle !

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  • MongoDB usage best practices

    - by andresv
    The project I'm working on uses MongoDB for some stuff so I'm creating some documents to help developers speedup the learning curve and also avoid mistakes and help them write clean & reliable code. This is my first version of it, so I'm pretty sure I will be adding more stuff to it, so stay tuned! C# Official driver notes The 10gen official MongoDB driver should always be referenced in projects by using NUGET. Do not manually download and reference assemblies in any project. C# driver quickstart guide: http://www.mongodb.org/display/DOCS/CSharp+Driver+Quickstart Reference links C# Language Center: http://www.mongodb.org/display/DOCS/CSharp+Language+Center MongoDB Server Documentation: http://www.mongodb.org/display/DOCS/Home MongoDB Server Downloads: http://www.mongodb.org/downloads MongoDB client drivers download: http://www.mongodb.org/display/DOCS/Drivers MongoDB Community content: http://www.mongodb.org/display/DOCS/CSharp+Community+Projects Tutorials Tutorial MongoDB con ASP.NET MVC - Ejemplo Práctico (Spanish):http://geeks.ms/blogs/gperez/archive/2011/12/02/tutorial-mongodb-con-asp-net-mvc-ejemplo-pr-225-ctico.aspx MongoDB and C#:http://www.codeproject.com/Articles/87757/MongoDB-and-C C# driver LINQ tutorial:http://www.mongodb.org/display/DOCS/CSharp+Driver+LINQ+Tutorial C# driver reference: http://www.mongodb.org/display/DOCS/CSharp+Driver+Tutorial Safe Mode Connection The C# driver supports two connection modes: safe and unsafe. Safe connection mode (only applies to methods that modify data in a database like Inserts, Deletes and Updates. While the current driver defaults to unsafe mode (safeMode == false) it's recommended to always enable safe mode, and force unsafe mode on specific things we know aren't critical. When safe mode is enabled, the driver internal code calls the MongoDB "getLastError" function to ensure the last operation is completed before returning control the the caller. For more information on using safe mode and their implicancies on performance and data reliability see: http://www.mongodb.org/display/DOCS/getLastError+Command If safe mode is not enabled, all data modification calls to the database are executed asynchronously (fire & forget) without waiting for the result of the operation. This mode could be useful for creating / updating non-critical data like performance counters, usage logging and so on. It's important to know that not using safe mode implies that data loss can occur without any notification to the caller. As with any wait operation, enabling safe mode also implies dealing with timeouts. For more information about C# driver safe mode configuration see: http://www.mongodb.org/display/DOCS/CSharp+getLastError+and+SafeMode The safe mode configuration can be specified at different levels: Connection string: mongodb://hostname/?safe=true Database: when obtaining a database instance using the server.GetDatabase(name, safeMode) method Collection: when obtaining a collection instance using the database.GetCollection(name, safeMode) method Operation: for example, when executing the collection.Insert(document, safeMode) method Some useful SafeMode article: http://stackoverflow.com/questions/4604868/mongodb-c-sharp-safemode-official-driver Exception Handling The driver ensures that an exception will be thrown in case of something going wrong, in case of using safe mode (as said above, when not using safe mode no exception will be thrown no matter what the outcome of the operation is). As explained here https://groups.google.com/forum/?fromgroups#!topic/mongodb-user/mS6jIq5FUiM there is no need to check for any returned value from a driver method inserting data. With updates the situation is similar to any other relational database: if an update command doesn't affect any records, the call will suceed anyway (no exception thrown) and you manually have to check for something like "records affected". For MongoDB, an Update operation will return an instance of the "SafeModeResult" class, and you can verify the "DocumentsAffected" property to ensure the intended document was indeed updated. Note: Please remember that an Update method might return a null instance instead of an "SafeModeResult" instance when safe mode is not enabled. Useful Community Articles Comments about how MongoDB works and how that might affect your application: http://ethangunderson.com/blog/two-reasons-to-not-use-mongodb/ FourSquare using MongoDB had serious scalability problems: http://mashable.com/2010/10/07/mongodb-foursquare/ Is MongoDB a replacement for Memcached? http://www.quora.com/Is-MongoDB-a-good-replacement-for-Memcached/answer/Rick-Branson MongoDB Introduction, shell, when not to use, maintenance, upgrade, backups, memory, sharding, etc: http://www.markus-gattol.name/ws/mongodb.html MongoDB Collection level locking support: https://jira.mongodb.org/browse/SERVER-1240 MongoDB performance tips: http://www.quora.com/MongoDB/What-are-some-best-practices-for-optimal-performance-of-MongoDB-particularly-for-queries-that-involve-multiple-documents Lessons learned migrating from SQL Server to MongoDB: http://www.wireclub.com/development/TqnkQwQ8CxUYTVT90/read MongoDB replication performance: http://benshepheard.blogspot.com.ar/2011/01/mongodb-replication-performance.html

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  • Java AtomicInteger: what are the differences between compareAndSet and weakCompareAndSet?

    - by WizardOfOdds
    (note that this question is not about CAS, it's about the "May fail spuriously" Javadoc). The only difference in the Javadoc between these two methods from the AtomicInteger class is that the weakCompareAndSet contains the comment: "May fail spuriously". Now unless my eyes are cheated by some spell, both method do look to be doing exactly the same: public final boolean compareAndSet(int expect, int update) { return unsafe.compareAndSwapInt(this, valueOffset, expect, update); } /* ... * May fail spuriously. */ public final boolean weakCompareAndSet(int expect, int update) { return unsafe.compareAndSwapInt(this, valueOffset, expect, update); } So I realize that "May" doesn't mean "Must" but then why don't we all start adding this to our codebase: public void doIt() { a(); } /** * May fail spuriously */ public void weakDoIt() { a(); } I'm really confused with that weakCompareAndSet() that appears to do the same as the compareAndSet() yet that "may fail spuriously" while the other can't. Apparently the "weak" and the "spurious fail" are in a way related to "happens-before" ordering but I'm still very confused by these two AtomicInteger (and AtomicLong etc.) methods: because apparently they call exactly the same unsafe.compareAndSwapInt method. I'm particularly confused in that AtomicInteger got introduced in Java 1.5, so after the Java Memory Model change (so it is obviously not something that could "fail spuriously in 1.4" but whose behavior changed to "shall not fail spuriously in 1.5").

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  • Wrapping FUSE from Go

    - by Matt Joiner
    I'm playing around with wrapping FUSE with Go. However I've come stuck with how to deal with struct fuse_operations. I can't seem to expose the operations struct by declaring type Operations C.struct_fuse_operations as the members are lower case, and my pure-Go sources would have to use C-hackery to set the members anyway. My first error in this case is "can't set getattr" in what looks to be the Go equivalent of a default copy constructor. My next attempt is to expose an interface that expects GetAttr, ReadLink etc, and then generate C.struct_fuse_operations and bind the function pointers to closures that call the given interface. This is what I've got (explanation continues after code): package fuse // #include <fuse.h> // #include <stdlib.h> import "C" import ( //"fmt" "os" "unsafe" ) type Operations interface { GetAttr(string, *os.FileInfo) int } func Main(args []string, ops Operations) int { argv := make([]*C.char, len(args) + 1) for i, s := range args { p := C.CString(s) defer C.free(unsafe.Pointer(p)) argv[i] = p } cop := new(C.struct_fuse_operations) cop.getattr = func(*C.char, *C.struct_stat) int {} argc := C.int(len(args)) return int(C.fuse_main_real(argc, &argv[0], cop, C.size_t(unsafe.Sizeof(cop)), nil)) } package main import ( "fmt" "fuse" "os" ) type CpfsOps struct { a int } func (me *CpfsOps) GetAttr(string, *os.FileInfo) int { return -1; } func main() { fmt.Println(os.Args) ops := &CpfsOps{} fmt.Println("fuse main returned", fuse.Main(os.Args, ops)) } This gives the following error: fuse.go:21[fuse.cgo1.go:23]: cannot use func literal (type func(*_Ctype_char, *_Ctype_struct_stat) int) as type *[0]uint8 in assignment I'm not sure what to pass to these members of C.struct_fuse_operations, and I've seen mention in a few places it's not possible to call from C back into Go code. If it is possible, what should I do? How can I provide the "default" values for interface functions that acts as though the corresponding C.struct_fuse_operations member is set to NULL?

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  • Are Thread.stop and friends ever safe in Java?

    - by Stephen C
    The stop(), suspend(), and resume() in java.lang.Thread are deprecated because they are unsafe. The Sun recommended work around is to use Thread.interrupt(), but that approach doesn't work in all cases. For example, if you are call a library method that doesn't explicitly or implicitly check the interrupted flag, you have no choice but to wait for the call to finish. So, I'm wondering if it is possible to characterize situations where it is (provably) safe to call stop() on a Thread. For example, would it be safe to stop() a thread that did nothing but call find(...) or match(...) on a java.util.regex.Matcher? (If there are any Sun engineers reading this ... a definitive answer would be really appreciated.) EDIT: Answers that simply restate the mantra that you should not call stop() because it is deprecated, unsafe, whatever are missing the point of this question. I know that that it is genuinely unsafe in the majority of cases, and that if there is a viable alternative you should always use that instead. This question is about the subset cases where it is safe. Specifically, what is that subset?

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  • How important do you find exception safety to be in your C++ code?

    - by Kai
    Every time I consider making my code strongly exception safe, I justify not doing it because it would be so time consuming. Consider this relatively simple snippet: Level::Entity* entity = new Level::Entity(); entity->id = GetNextId(); entity->AddComponent(new Component::Position(x, y)); entity->AddComponent(new Component::Movement()); entity->AddComponent(new Component::Render()); allEntities.push_back(entity); // std::vector entityById[entity->id] = entity; // std::map return entity; To implement a basic exception guarantee, I could use a scoped pointer on the new calls. This would prevent memory leaks if any of the calls were to throw an exception. However, let's say I want to implement a strong exception guarantee. At the least, I would need to implement a shared pointer for my containers (I'm not using Boost), a nothrow Entity::Swap for adding the components atomically, and some sort of idiom for atomically adding to both the Vector and Map. Not only would these be time consuming to implement, but they would be expensive since it involves a lot more copying than the exception unsafe solution. Ultimately, it feels to me like that time spent doing all of that wouldn't be justified just so that the a simple CreateEntity function is strongly exception safe. I probably just want the game to display an error and close at that point anyway. How far do you take this in your own game projects? Is it generally acceptable to write exception unsafe code for a program that can just crash when there is an exception?

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  • How to fix legacy code that uses <string.h> unsafely?

    - by Snowbody
    We've got a bunch of legacy code, written in straight C (some of which is K&R!), which for many, many years has been compiled using Visual C 6.0 (circa 1998) on an XP machine. We realize this is unsustainable, and we're trying to move it to a modern compiler. Political issues have said that the most recent compiler allowed is VC++ 2005. When compiling the project, there are many warnings about the unsafe string manipulation functions used (sprintf(), strcpy(), etc). Reviewing some of these places shows that the code is indeed unsafe; it does not check for buffer overflows. The compiler warning recommends that we move to using sprintf_s(), strcpy_s(), etc. However, these are Microsoft-created (and proprietary) functions and aren't available on (say) gcc (although we're primarily a Windows shop we do have some clients on various flavors of *NIX) How ought we to proceed? I don't want to roll our own string libraries. I only want to go over the code once. I'd rather not switch to C++ if we can help it.

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  • Is there a good way to convert between BitmapSource and Bitmap?

    - by JohannesH
    As far as I can tell the only way to convert from BitmapSource to Bitmap is through unsafe code... Like this (from Lesters WPF blog): myBitmapSource.CopyPixels(bits, stride, 0); unsafe { fixed (byte* pBits = bits) { IntPtr ptr = new IntPtr(pBits); System.Drawing.Bitmap bitmap = new System.Drawing.Bitmap( width, height, stride, System.Drawing.Imaging.PixelFormat.Format32bppPArgb,ptr); return bitmap; } } To do the reverse: System.Windows.Media.Imaging.BitmapSource bitmapSource = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap( bitmap.GetHbitmap(), IntPtr.Zero, Int32Rect.Empty, System.Windows.Media.Imaging.BitmapSizeOptions.FromEmptyOptions()); Is there an easier way in the framework? And what is the reason it isn't in there (if it's not)? I would think it's fairly usable. The reason I need it is because I use AForge to do certain image operations in an WPF app. WPF wants to show BitmapSource/ImageSource but AForge works on Bitmaps.

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  • How to install system_timer gem on Windows 7

    - by user280405
    I got problem "Processing environment.rb: Pre Initialisation Phase (using rails 2.3.5)" "Processing environment.rb: Main Initialisation Phase" C:/Ruby/bin/rake: No such file or directory - svnversion [memcache-client] Could not load SystemTimer gem, falling back to Ruby's slower/unsafe timeout library: no such file to load -- system_timer rake aborted! unable to find server during initialization. C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2383:in `raw_load_rakefile' I dunno how to install this gem, because when i exec gem install system_timer i receiving: "Processing environment.rb: Pre Initialisation Phase (using rails 2.3.5)" "Processing environment.rb: Main Initialisation Phase" C:/Ruby/bin/rake: No such file or directory - svnversion [memcache-client] Could not load SystemTimer gem, falling back to Ruby's slower/unsafe timeout library: no such file to load -- system_timer rake aborted! unable to find server during initialization. C:/Ruby/lib/ruby/gems/1.8/gems/rake-0.8.7/lib/rake.rb:2383:in `raw_load_rakefile' Anybody, help please!

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  • UInt32 to IntPtr

    - by ffenix
    I have the following problem: public class ListenThread : SocketInvoke { [DllImport("Ws2_32", CharSet = CharSet.Auto)] public unsafe static extern UInt32 WSAWaitForMultipleEvents(UInt32 cEvents, IntPtr hEventObject, UInt32 fWaitAll, UInt32 dwTimeout, Boolean fAlertable); public void ListenConnections(NetSharedData data) { while (true) { unsafe { if (WSAWaitForMultipleEvents((UInt32)1, data.signal, (UInt32)0, (UInt32)100, false) != WSA_WAIT_TIMEOUT) { } } } } data.signal is a UInt32 how i can cast it to IntPtr?, i try: IntPtr signal = (IntPtr)data.signal; but it doesn't work because i need a pointer to data.signal (UInt32) type and not the int value as an pointer, that will make a memory exception. An C++ example of what i need: int signal = 0; int* psignal = &signal;

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  • How does c# type safety affect the garbage collection?

    - by Indeera
    I'm dealing with code that handles large buffers ( 100MB) and manipulation of these is done in unsafe blocks. I'd like to refactor these to avoid unsafe code. I'm wondering about the likely memory performance gains (positive/negative/neutral) before I embark on that. I assert that if the compiler can verify types, it could possibly generate better code and that could also mean good GC performance. Is this a valid assertion? What is your experience? Thanks.

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  • When we run an aspx page with client side scripting on IIS, we get an ActiveX control error?

    - by Ananya
    we have implemented the code for installing the messenger theme pack using the client side scripting in a web page. We are creating an object of the messenger using the classid .Using this object we call the installcontent() method and try to install the messenger theme pack hosted at following path: http://www.messengerexpressions.com/assets/worldCup/cabs/en-gb.cab Our code initially checks whether the messenger is installed on the user machine or not. Then it checks for the user login ,once the messenger is installed on the machine. And if the user is signed-in , the messenger theme pack is installed. The code currently when hosted on IIS checks the “Sign-In of the user” but when it tries to install the theme pack an error is thrown “An ActiveX control on this page is unsafe.Your current security settings prohibit running unsafe control on this page.As a result,this page may not be display as intended.” Please let us know if any setting is required on IIS for running this piece of codeor anything that we are missing out.

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  • Multi-Threaded Application vs. Single Threaded Application

    Why would we use a multi threaded application vs. a single threaded application? First we must define multithreading. Multithreading is a feature of an operating system that allows programs to run subcomponents or threads in parallel. Typically most applications only need to use one thread because they do not perform time consuming tasks. The use of multiple threads allows an application to distribute long running tasks so that they can be executed in parallel. This gives the user the perceived appearance that the application is working faster due to the fact that while one thread is waiting on an IO process the remaining tasks can make use of the available CPU. The allows working threads to execute in tandem so that they can be competed sooner. Multithreading Benefits Improved responsiveness — Users usually report improved responsiveness compared to single thread applications. Faster applications — Multiple threads can lead to improved application performance. Prioritization — Threads can be assigned a priority which would allow higher priority tasks to take precedence over lower priority tasks. Single Threading Benefits Programming and debugging —These activities are easier compared to multithreaded applications due to the reduced complexity Less Overhead — Threads add overhead to an application When developing multi-threaded applications, the following must be considered. Deadlocks occur when two threads hold a monitor that the other one requires. In essence each task is blocking the other and both tasks are waiting for the other monitor to be released. This forces an application to hang or deadlock. Resource allocation is used to prevent deadlocks because the system determines if approving the resource request will render the system in an unsafe state. An unsafe state could result in a deadlock. The system only approves requests that will lead to safe states. Thread Synchronization is used when multiple threads use the same instance of an object. The threads accessing the object can then be locked and then synchronized so that each task can interact with the static object on at a time.

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  • Unable to access other Volume in Vaio E series

    - by Rahul Ravi Kumar Shah
    Error mounting /dev/sda6 at /media/ravi/New Volume: mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sda6" "/media/ravi/New Volume" Exited with: non-zero exit status 14: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount '/dev/sda6': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.

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  • Unable to access “105 GB Volume”

    - by user170924
    Error mounting /dev/sda2 at /media/fehr/8CBE6431BE6415CC: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sda2" "/media/fehr/8CBE6431BE6415CC"' exited with non-zero exit status 14: Windows is hibernated, refused to mount. Failed to mount '/dev/sda2': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.

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  • Does the Adblock Plus extension prevent malicious code from downloading/executing? [closed]

    - by nctrnl
    Firefox and Chrome are my favourite browsers. The main reason is an extension called Adblock Plus. Basically, it blocks all the ad networks if you subscribe to one of the lists, like EasyList. Does it also protect against malicious ads on completely legitimate websites? For instance, several news websites use ad services that may allow a malicious user to insert "evil code". This makes the web very unsafe, especially for those who lack a serious antivirus product.

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  • Libreoffice 3.5 won't launch from Desktop Shortcut: Ubuntu 11.10 Unity

    - by Aivard
    I've upgraded my Libreoffice to the recent 3.5 version. Before, I was using LO 3.45 and it had no problems on launching from the Desktop Shortcut. Anyways, when I upgraded and tried to create a shortcut from the launcher it reported this, "The application launcher "libreoffice3.5-base.desktop" has not been marked as trusted. If you do not know the source of this file, launching it may be unsafe." Any ideas of fixing this. Thanks in advance: Regards

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  • Effective Methods to Combat Cyber Stalking

    Cyber stalking can be a very frightening experience. Often individuals who are the victims of this occurrence feel invaded and unsafe even in their own home. A large number of people use the internet... [Author: Ed Opperman - Computers and Internet - June 14, 2010]

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  • Unable to access “430 GB Volume”

    - by user170924
    Error mounting /dev/sda3 at /media/fehr/D42CAFD92CAFB4C0: Command-line `mount -t "ntfs" -o "uhelper=udisks2,nodev,nosuid,uid=1000,gid=1000,dmask=0077,fmask=0177" "/dev/sda3" "/media/fehr/D42CAFD92CAFB4C0"' exited with non-zero exit status 14: The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Failed to mount '/dev/sda3': Operation not permitted The NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting), or mount the volume read-only with the 'ro' mount option.

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  • error LNK2019 for ZLib sample compare.

    - by Nano HE
    Hello. I created win32 console application in vs2010 (without select the option of precompiled header). And I inserted the code below. but *.obj link failed. Could you provide me more information about the error. I searched MSDN, but still can't understand it. #include <stdio.h> #include "zlib.h" // Demonstration of zlib utility functions unsigned long file_size(char *filename) { FILE *pFile = fopen(filename, "rb"); fseek (pFile, 0, SEEK_END); unsigned long size = ftell(pFile); fclose (pFile); return size; } int decompress_one_file(char *infilename, char *outfilename) { gzFile infile = gzopen(infilename, "rb"); FILE *outfile = fopen(outfilename, "wb"); if (!infile || !outfile) return -1; char buffer[128]; int num_read = 0; while ((num_read = gzread(infile, buffer, sizeof(buffer))) > 0) { fwrite(buffer, 1, num_read, outfile); } gzclose(infile); fclose(outfile); } int compress_one_file(char *infilename, char *outfilename) { FILE *infile = fopen(infilename, "rb"); gzFile outfile = gzopen(outfilename, "wb"); if (!infile || !outfile) return -1; char inbuffer[128]; int num_read = 0; unsigned long total_read = 0, total_wrote = 0; while ((num_read = fread(inbuffer, 1, sizeof(inbuffer), infile)) > 0) { total_read += num_read; gzwrite(outfile, inbuffer, num_read); } fclose(infile); gzclose(outfile); printf("Read %ld bytes, Wrote %ld bytes, Compression factor %4.2f%%\n", total_read, file_size(outfilename), (1.0-file_size(outfilename)*1.0/total_read)*100.0); } int main(int argc, char **argv) { compress_one_file(argv[1],argv[2]); decompress_one_file(argv[2],argv[3]);} Output: 1>------ Build started: Project: zlibApp, Configuration: Debug Win32 ------ 1> zlibApp.cpp 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(15): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(25): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(40): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(36): warning C4715: 'decompress_one_file' : not all control paths return a value 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(57): warning C4715: 'compress_one_file' : not all control paths return a value 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzclose referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzread referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzopen referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzwrite referenced in function "int __cdecl compress_one_file(char *,char *)" (?compress_one_file@@YAHPAD0@Z) 1>D:\learning\cpp\cppVS2010\zlibApp\Debug\zlibApp.exe : fatal error LNK1120: 4 unresolved externals ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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  • error LNK2019 for ZLib sample code compiling.

    - by Nano HE
    Hello. I created win32 console application in vs2010 (without select the option of precompiled header). And I inserted the code below. but *.obj link failed. Could you provide me more information about the error. I searched MSDN, but still can't understand it. #include <stdio.h> #include "zlib.h" // Demonstration of zlib utility functions unsigned long file_size(char *filename) { FILE *pFile = fopen(filename, "rb"); fseek (pFile, 0, SEEK_END); unsigned long size = ftell(pFile); fclose (pFile); return size; } int decompress_one_file(char *infilename, char *outfilename) { gzFile infile = gzopen(infilename, "rb"); FILE *outfile = fopen(outfilename, "wb"); if (!infile || !outfile) return -1; char buffer[128]; int num_read = 0; while ((num_read = gzread(infile, buffer, sizeof(buffer))) > 0) { fwrite(buffer, 1, num_read, outfile); } gzclose(infile); fclose(outfile); } int compress_one_file(char *infilename, char *outfilename) { FILE *infile = fopen(infilename, "rb"); gzFile outfile = gzopen(outfilename, "wb"); if (!infile || !outfile) return -1; char inbuffer[128]; int num_read = 0; unsigned long total_read = 0, total_wrote = 0; while ((num_read = fread(inbuffer, 1, sizeof(inbuffer), infile)) > 0) { total_read += num_read; gzwrite(outfile, inbuffer, num_read); } fclose(infile); gzclose(outfile); printf("Read %ld bytes, Wrote %ld bytes, Compression factor %4.2f%%\n", total_read, file_size(outfilename), (1.0-file_size(outfilename)*1.0/total_read)*100.0); } int main(int argc, char **argv) { compress_one_file(argv[1],argv[2]); decompress_one_file(argv[2],argv[3]);} Output: 1>------ Build started: Project: zlibApp, Configuration: Debug Win32 ------ 1> zlibApp.cpp 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(15): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(25): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(40): warning C4996: 'fopen': This function or variable may be unsafe. Consider using fopen_s instead. To disable deprecation, use _CRT_SECURE_NO_WARNINGS. See online help for details. 1> c:\program files\microsoft visual studio 10.0\vc\include\stdio.h(234) : see declaration of 'fopen' 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(36): warning C4715: 'decompress_one_file' : not all control paths return a value 1>d:\learning\cpp\cppvs2010\zlibapp\zlibapp\zlibapp.cpp(57): warning C4715: 'compress_one_file' : not all control paths return a value 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzclose referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzread referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzopen referenced in function "int __cdecl decompress_one_file(char *,char *)" (?decompress_one_file@@YAHPAD0@Z) 1>zlibApp.obj : error LNK2019: unresolved external symbol _gzwrite referenced in function "int __cdecl compress_one_file(char *,char *)" (?compress_one_file@@YAHPAD0@Z) 1>D:\learning\cpp\cppVS2010\zlibApp\Debug\zlibApp.exe : fatal error LNK1120: 4 unresolved externals ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • The long road to bug-free software

    - by Tony Davis
    The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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  • Encrypting an id in an URL in ASP.NET MVC

    - by Chuck Conway
    I'm attempting to encode the encrypted id in the Url. Like this: http://www.calemadr.com/Membership/Welcome/9xCnCLIwzxzBuPEjqJFxC6XJdAZqQsIDqNrRUJoW6229IIeeL4eXl5n1cnYapg+N However, it either doesn't encode correctly and I get slashes '/' in the encryption or I receive and error from IIS: The request filtering module is configured to deny a request that contains a double escape sequence. I've tried different encodings, each fails: HttpUtility.HtmlEncode HttpUtility.UrlEncode HttpUtility.UrlPathEncode HttpUtility.UrlEncodeUnicode Update The problem was I when I encrypted a Guid and converted it to a base64 string it would contain unsafe url characters . Of course when I tried to navigate to a url containing unsafe characters IIS(7.5/ windows 7) would blow up. Url Encoding the base64 encrypted string would raise and error in IIS (The request filtering module is configured to deny a request that contains a double escape sequence.). I'm not sure how it detects double encoded strings but it did. After trying the above methods to encode the base64 encrypted string. I decided to remove the base64 encoding. However this leaves the encrypted text as a byte[]. I tried UrlEncoding the byte[], it's one of the overloads hanging off the httpUtility.Encode method. Again, while it was URL encoded, IIS did not like it and served up a "page not found." After digging around the net I came across a HexEncoding/Decoding class. Applying the Hex Encoding to the encrypted bytes did the trick. The output is url safe. On the other side, I haven't had any problems with decoding and decrypting the hex strings.

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  • what exactly is the danger of an uninitialized pointer in C

    - by akh2103
    I am trying get a handle on C as I work my way thru Jim Trevor's "Cyclone: A safe dialect of C" for a PL class. Trevor and his co-authors are trying to make a safe version of C, so they eliminate uninitialized pointers in their language. Googling around a bit on uninitialized pointers, it seems like un-initialized pointers point to random locations in memory. It seems like this alone makes them unsafe. If you reference an un-itilialized pointer, you jump to an unsafe part of memory. Period. But the way Trevor talks about them seems to imply that it is more complex. He cites the following code, and explains that when the function FrmGetObjectIndex dereferences f, it isn’t accessing a valid pointer, but rather an unpredictable address — whatever was on the stack when the space for f was allocated. What does Trevor mean by "whatever was on the stack when the space for f was allocated"? Are "un-initialized" pointers initialized to random locations in memory by default? Or does their "random" behavior have to do with the memory allocated for these pointers getting filled with strange values (that are then referenced) because of unexpected behavior on the stack. Form *f; switch (event->eType) { case frmOpenEvent: f = FrmGetActiveForm(); ... case ctlSelectEvent: i = FrmGetObjectIndex(f, field); ... }

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