Add Directory.Copy extension method

[Copilot]

Ports Directory.Copy from Onova's DirectoryEx into PowerKit's DirectoryExtensions.

Changes

• Directory.Packages.props — updates PolyShim to 2.10.0 to gain portable File.GetUnixFileMode / File.SetUnixFileMode polyfills for net35 and netstandard2.0

• DirectoryExtensions.cs — adds Directory.Copy(sourcePath, destinationPath, overwrite = true):

  • Pre-creates all destination directories (including empty subdirectories) before opening any file streams
  • Opens destination files with exclusive locks before writing; concurrent readers may be blocked or fail with a sharing violation
  • Truncates destination files that are longer than their source counterpart
  • Preserves Unix file permissions on non-Windows platforms via File.GetUnixFileMode / File.SetUnixFileMode
  • Adapted for PowerKit's netstandard2.0 / net35 / net10.0 targets: replaces Path.GetRelativePath (NS2.1+) with a Substring approach; uses Disposable.Merge([.. sourceStreams, .. destinationStreams]).Dispose() in a finally block for safe stream disposal; uses File.OpenRead / File.OpenWrite / File.Open(FileMode.CreateNew) and a foreach/Zip loop

• DirectoryExtensionsTests.cs — 6 new tests covering flat copy, nested subdirectory copy, overwrite, no-overwrite (IOException), destination truncation, and Unix file mode preservation (skipped on Windows)

Directory.Copy(sourcePath, destinationPath);
Directory.Copy(sourcePath, destinationPath, overwrite: false); // throws IOException if file exists

[Tyrrrz]

@copilot we should also preserve Unix file modes. Update PolyShim to 2.10.0 in order to gain access to a portable implementation of File.Get/SetUnixMode().

[Copilot]

@copilot we should also preserve Unix file modes. Update PolyShim to 2.10.0 in order to gain access to a portable implementation of File.Get/SetUnixMode().

Done in f091558. Updated PolyShim to 2.10.0 and added Unix file mode preservation in the copy loop via File.GetUnixFileMode/File.SetUnixFileMode, guarded by !OperatingSystem.IsWindows(). Also added a Copy_UnixFileMode_Test that's skipped on Windows (via [SkippableFact] + Skip.If(OperatingSystem.IsWindows())).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.47%. Comparing base (431e52d) to head (f2e0129).
⚠️ Report is 1 commits behind head on prime.

Additional details and impacted files

@@            Coverage Diff             @@
##            prime      #38      +/-   ##
==========================================
+ Coverage   94.08%   94.47%   +0.39%     
==========================================
  Files          76       76              
  Lines        1470     1574     +104     
  Branches      125      131       +6     
==========================================
+ Hits         1383     1487     +104     
  Misses         65       65              
  Partials       22       22              

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[Tyrrrz]

@copilot run dotnet build to reformat everything

[Copilot]

@copilot run dotnet build to reformat everything

Done in 9b53bb3. CSharpier reformatted DirectoryExtensionsTests.cs and the build now succeeds cleanly.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

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