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Uwp Cannot List or access .lnk or url files

Before I get into further details I wanted to point out that uwp can now know have system wide file access so this issue is not exactly related to that.
With that out of the way, the issue is rather simple to explain, uwp cannot query or access link (.lnk) or weblink files as well as possible other files that I dont know yet.
To be more specific the tools found both in the System.io and the Windows.Storage namespaces are incapable of listing .lnk and url files.
They simply never appear on Queries like the System.IO.Directory.GetFiles
StorageItemQueryResult.GetFiles()
While also direct access from path as allowed by functions like
StorageFile.GetFileFromPathAsync() or System.IO.File.Open()
will cause System.UnauthorizedAccessException: Access is denied.
I am posting knowing full well that this will probably never be answered, the only glimmer of hope is the fact the hidden build in uwp explorer can indeed list the affirmational files.

The .lnk file type has limitation to be accessed from UWP app since UWP app's sandboxed and user permission. You can not access this file type from path even using the broadFileSystemAccess Capability. But you can get the file by FileOpenPicker which lets the user choose and open files.

.net WPF application create a secure folder

I am working on one desktop application which is built by using .net WPF. I have some data inside the application like images,videos..
I want to make this folder secure, so nobody can access the data inside the folder after application installation. Only the application can read the data from that directory.
Even though administrator of that machine can not open that folder to check the content.
Is it possible to have this kind of security inside the WPF application.
Only motive it to keep the sensitive data protected from external copy from the application users.
Thanks,
Vijay

It depends on how you use the resources.
Actually you could encrypt all "protected" files, so that after the installation every one can copy but no one can use them unless your application decrypts the files.
When you encrypt files you should definitively test the performance (decryption takes some time).
Two links showing how you could do it:
What's the easiest way to encrypt a file in c#?
http://lukhezo.com/2011/11/06/encrypting-files-in-net-using-the-advanced-encryption-standard-aes/

Add the file you would like to strongly protect to you solution. Then right click each file, go to properties and set its "build action" to "embedded resource".
And for how to access the resource stream from within the exe for use with in your application, see link below
How to compile all files to one exe?
That way, your private files will not be copied to the installation folder but will instead reside inside your .exe file.

WPF is beside the point. Applications run with the permissions of the users that start them. If an application needs access to files, then the user will also need rights to those files.
In short, the answer is no, you cannot do exactly what you are asking.
The best you will be able to do is make it hard for a user to discover where the assets are coming from, but you will never be able to give access to your application without giving access to the application's user.

Quick Question: How can I make sure the current directory is not changed because of OpenFileDialog?

say my application is installed in C:\programfiles\xyz\ I've some setting & other data files (*.dat files) in this directory too.
My application uses OpenFileDialog to open an image. Problem is that when ever user browses to some directory (say MyPictures) for an image. The current working directory of the application becomes that directory (MyPictures in this case).
After user inputs the image. I do some processing over it and save some values to imagedata.dat which will be located in the path where original application is installed.(C:\programfiles\xyz here )
In my code I'm just using FileStream("imagedata.dat",...,...) without any path prefix before the filename. Problem here is that application is crashing because it is searching for imagedata.dat in 'MyPictures\imagedata.dat'.
How can I avoid this?

You should be using absolute path names when saving data to files. The current working directory is controlled by the user, not by you (for example, if they launch your process from a shortcut then the working directory could've been changed before your process even starts up).
Also, you should never save anything under C:\Program Files during normal use. Doing this means your program needs to be running as an administrator, and unless you're doing administrator-y things then you should be able to run it as a regular user.
The correct thing to do in your case is to use the Environment.GetFolderPath() function to get the location of the ApplicationData folder and save your data under there. Just choose a sub-directory based on your application's name.

You could save it to GetCurrentDirectory then restore with SetCurrentDirectory. However, I agree wih codeka that using the appropriate GetFolderPath (probably ApplicationData, CommonApplicationData or LocalApplicationData) is a better solution.

Writing drive C: in Windows 7/Vista

I am developing an application that saves its settings in the install folder. If I install the app in the Program Files on drive C: and attempt to write the settings file I get an exception and that's it.
I know that the User Account Control (UAC) migth be the one that is not letting my app modify the content of the file.
I need help with the following issues:
Do the file editing in such a way that at least an UAC warning should be shown and if I answer yes the file becomes writable
If there is no way to edit the file on drive C: I need a method to store data somewhe
A more generic question would be:
How to create a C# program that after installing it to C:\Program Files\MyProgram under Windows Vista can manipulate (create/edit/delete) an .ini file in the installation directory? This file should be the same for all users.

Why don't you store the settings in a user-specific location like C:\Users\Username\AppData?
That way different users can have different settings on the same machine. Also, this is the recommended location for settings and the like.

Building on the answer from Ben S, check out the Environment.GetFolderPath method.
This method allows you to abstract away the specific location and just use a known SpecialFolder path instead (ie SpecialFolder.ApplicationData).

The fact that you are getting an exception means that your program is Vista/7 aware somehow. I am not totally sure what setting (in a C# project) triggers that. But if you can make your app 'pretend' it is an XP application, Vista will let it write to a shadow file located elsewhere.
But the proper way to get a writeable path shared by all users:
string path = Environment.GetFolderPath(
Environment.SpecialFolder.CommonApplicationData);

I'm surprised it hasn't been mentioned yet, but a viable C# option is to ditch INI files (yuck) and embrace the Settings facilities provided by .Net. They work very well across all Windows versions, they are directly supported by Visual Studio, and finally they are overridable at both the User and Machine level.
We've had no real problems to speak of utilizing this feature (this includes XCopy deployments, Installed applications, Citrix, etc).

Building on the answers of Ben S and akmad, you should put the ini file in the appDataFolder.
If you want the settings to be unique to each user, create an ini file for each user and put it in their AppData folder, which can be retrieved with the following code:
Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData)
If you want the settings to be common to all users, but the ini file in the common AppData folder.
Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData)

List all applications that handle a specified file type

Is it possible to list all the applications on a machine that can open a specific file type, using only the files extension? for example if I have a text file (.txt), I want a list of all applications that can open .txt files.

Check out the HKEY_CLASSES_ROOT hive in your registry. It's all in there.

There is no master list of every application that can open a specific file that I am aware of.

I am assuming you are talking about Windows machines...
You can only go so far as listing the applications that are registered has to able of handling a specific file extension (the same applications that show up when you right click and select "Open With"). This is somewhere in the Windows Registry.
I would suggest you to check on the microsoft documentation, or open your registry and start searching for known extensions.