Add ability to enable Read Sharing when Writing to files

[eFail]

What

This change adds a new LocalFileAbstraction.ReadShareWhenWriting property. By default, this property is false, resulting in no change in code flow. If a library user chooses to optionally enable it, then the WriteStream created by LocalFileAbstraction will use FileShare.Read, meaning that other processes can continue to read the file while it is being written to.

Currently, this change is only needed/useful when working with MP3 files. It will throw a NotSupportedException() if used anywhere else.

Why

A common scenario when editing ID3 tags is that a user uses one application (something like Mp3tag) to edit tags, while they use another application (something like WinAmp) to simultaneously listen to the MP3 files for which tags are being edited. This scenario works perfectly fine with most application mixes like the ones mentioned above. The only "side-effect" is a slight audio glitch that occurs after the tag of a playing song gets updated.

Using the example applications mentioned above, if Mp3tag were to be implemented using taglib-sharp, the above scenario no longer becomes possible. A user plays a song to determine what Genre it should be. Then, while they continue to listen to the song, they attempt to set the Genre in its ID3 tag. But they can't, because the MP3 file is already in use.

How Tested?

• The scenario mentioned above didn't work before, now it does.
• A new unit test was created to cover this new property.

[eFail]

@dotnet-policy-service agree

[Copilot]

Pull Request Overview

This PR adds a new ReadShareWhenWriting property to the IFileAbstraction interface that allows files to be read by other processes while being written to. The primary use case is enabling MP3 file editing while the file is being played by another application.

• Adds ReadShareWhenWriting boolean property to IFileAbstraction interface
• Implements the property in LocalFileAbstraction to control FileShare.Read behavior
• Adds comprehensive unit tests to verify the functionality works as expected

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/TaglibSharp/File.cs	Core implementation adding the interface property and LocalFileAbstraction logic
src/TaglibSharp/Tiff/Rw2/IFDReader.cs	Stub implementation throwing NotSupportedException
src/TaglibSharp.Tests/Helpers.cs	Test helper stub implementation throwing NotSupportedException
examples/ReadFromUri/ReadFromUri.cs	Example code stub implementation throwing NotSupportedException
src/TaglibSharp.Tests/FileFormats/Id3BothFormatTest.cs	Unit test validating the new functionality

Comments suppressed due to low confidence (1)

src/TaglibSharp/File.cs:196

• The field name read_share_when_writing uses snake_case which is inconsistent with C# naming conventions. It should be readShareWhenWriting or better yet, this appears to be unused since the property is implemented in LocalFileAbstraction.

		public bool read_share_when_writing;

[Copilot]

[nitpick] Consider using FileShare.None explicitly instead of the default parameter to make the intent clearer, or add a comment explaining why FileShare.None is the default behavior.

[Copilot]

The discarded task should be awaited or stored in a variable to handle potential exceptions. Consider using var backgroundTask = Task.Run(...) and awaiting it at the end of the test.

Suggested change

	_ = Task.Run (async () => {
	var playbackTask = Task.Run (async () => {

[Copilot]

[nitpick] Consider using FileMode.Open constant instead of the fully qualified name for consistency with the rest of the codebase, and the variable name fileToPlay could be more descriptive like readOnlyFileStream.

Suggested change

	using (var fileToPlay = System.IO.File.Open (tmp_file, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.ReadWrite)) {
	using (var readOnlyFileStream = System.IO.File.Open (tmp_file, FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.ReadWrite)) {