System.IO.File.SetAttributes() not clear Read-only attribute on a file

[ggaller]

Description

Hi!

In our build system we copy many Read-only files to the workspace for processing. We use File.Copy() method with overwrite=true and sometimes get UnauthorizedAccessException, because destination file exist and have Read-only attribute.

This is looks strange because after each copy to workspace we clear Read-only attribute by calling File.SetAttributes() method.

I started investigate this problem and wrote simple app CopyReadonlyFile.zip that stable reproduce this bug (after 20-40 sec of work).

Configuration

.Net Core:
   Version: 3.1.3
   Commit:  4a9f85e9f8

OS:
   OS Name: Microsoft Windows 10 Pro
   OS Version: 10.0.18363 N/A Build 18363
   System Type: x64-based PC

Stack trace

System.UnauthorizedAccessException: Access to the path '<some path to the file>' is denied.
    at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
    at System.IO.File.InternalCopy(String sourceFileName, String destFileName, Boolean overwrite, Boolean checkHost)
    at System.IO.File.Copy(String sourceFileName, String destFileName, Boolean overwrite)
    at FilesCopy.<>c__DisplayClass0_0.<Copy>b__0(FileObject f) in FilesCopy.cs:line 32

Workaround

I added try/catch for UnauthorizedAccessException and remove Read-only attribute again, after this all work fine.