How to determine if a directory is read only in C#?

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My goal in this part of my application is to warn the user if they select a directory/folder for use as a report depot that is read only, not accessible to them.
Based on several solutions from this web site and others, I have tried the following

DirectoryInfo di = new DirectoryInfo(sConnectionFolder);
if ((di.Attributes & FileAttributes.ReadOnly) == FileAttributes.ReadOnly)
{
// WARN THE USER

My problem is, when testing with a read-only folder, the di.Attributes property's value is merely 'Directory', and does not contain the flag/component for read-only.
from the debugger:
di.Attributes = Directory
So my warning code is never executed.

What I have tried:

Other attempts:

if (di.Attributes.HasFlag(FileAttributes.ReadOnly))

// and steering clear of DirectoryInfo, just using FileInfo:
FileAttributes file_attr = (new FileInfo(sConnectionFolder)).Attributes;

// and lastly, using File class to get the attributes:
FileAttributes fa = File.GetAttributes(sConnectionFolder);

// all with the same result: Directory for the attribute value

// Why is the read-only flag not present?

Posted 11-Apr-20 9:05am

uniqman

Updated 11-Apr-20 12:16pm

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2 solutions

Solution 1

Try the DirectoryInfo.GetAccessControl Method (System.IO) | Microsoft Docs[^] - it should tell you what you want (possibly by throwing an access violation exception, I can't tell ATM, i'm on a tablet).

Posted 11-Apr-20 9:25am

OriginalGriff

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uniqman 11-Apr-20 19:48pm

Thanks for replying. I tried this just now and it does not throw an exception, and the folder is such that I cannot create a text file in it (via File Explorer). I was thinking I will just have to do a trial file create (like the solution below), but I was hoping there was a more sophisticated method.

Dave Kreskowiak 11-Apr-20 22:13pm

There isn't a direct method because the Security system is pretty complex, having to deal with impersonation. The "current user" may be obvious to you sitting at the keyboard, but in the real world, that's not a simple concept. Throw various levels of impersonation into the mix and things get complex real quick.

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Dave Kreskowiak · Accepted Answer · 2020-04-11T12:16:00

Solution 2

Attributes is never going to tell you.

The really quick'n'easy way to figure it out is to attempt to create a file in that folder and see what happens. If it succeeds, the user running your code has the permissions to do save there. If not, well, you tell the user to pick another folder.

Posted 11-Apr-20 12:16pm

Dave Kreskowiak

Comments

uniqman 11-Apr-20 19:53pm

Thanks, that is what I will do. But I am surprised there isn't a .NET method that would provide the answer.