[BUG] Blob FromStream is not GC safe

[jeremy-visionaid]

Description

If GC runs after the blob is created, the managed array memory might be moved resulting in a crash,

Code

By inspection:

	public static unsafe Blob FromStream (Stream stream)
	{
		// TODO: check to see if we can avoid the second copy (the ToArray)


		using var ms = new MemoryStream ();
		stream.CopyTo (ms);
		var data = ms.ToArray ();


		fixed (byte* dataPtr = data) {
			return new Blob ((IntPtr)dataPtr, data.Length, MemoryMode.ReadOnly, () => ms.Dispose ());
		}
	}

Expected Behavior

Should copy via an UnmanagedMemoryStream:

		public static unsafe Blob FromStream (Stream stream)
		{
			var length = (int)(stream.Length - stream.Position);

			var dataPtr = Marshal.AllocCoTaskMem (length);

			using var ums = new UnmanagedMemoryStream ((byte*)dataPtr, length, length, FileAccess.ReadWrite);
			stream.CopyTo (ums);

			return new Blob (dataPtr, length, MemoryMode.ReadOnly, () => Marshal.FreeCoTaskMem (dataPtr));
		}

Actual Behavior

No response

Version of SkiaSharp

3.116.0 (Current)

Last Known Good Version of SkiaSharp

2.88.9 (Previous)

IDE / Editor

Visual Studio (Windows)

Platform / Operating System

All

Platform / Operating System Version

No response

Devices

No response

Relevant Screenshots

No response

Relevant Log Output

Code of Conduct

• I agree to follow this project's Code of Conduct

[github-actions]

Triage Summary

Labels will be applied to highlight issues related to reliability (due to potential crashes), the SkiaSharp library, and the Windows Classic operating system.

This issue is not specifically identified as a regression based on the provided information.

Additional remarks:

• The issue addresses a crash related to garbage collection in memory management, particularly within the SkiaSharp library's functionalities.

Detailed Summary and Actions

Summary of the triage:

• The issue describes a potential crash caused by garbage collection affecting memory management, which raises reliability concerns.
• The bug is associated with the 'Blob FromStream' functionality within the SkiaSharp library.
• The context of the issue is reported within Visual Studio on the Windows Classic operating system.
• The problem particularly highlights memory management issues in SkiaSharp's Blob creation process.

Summary of the actions that will be performed:

Action	Item	Description
Apply Label	tenet/reliability	The issue describes a potential crash due to memory management, indicating concerns over reliability.
Apply Label	area/SkiaSharp	The issue relates to a bug in the 'Blob FromStream' functionality within the SkiaSharp library.
Apply Label	os/Windows-Classic	The issue is reported in the context of Visual Studio on the Windows Classic operating system.
Apply Label	backend/SkiaSharp	The issue involves a bug related to memory management during the Blob creation process in SkiaSharp.

This entire triage process was automated by AI and mistakes may have been made. Please let us know so we can continue to improve.

[jeremy-visionaid]

@mattleibow This should also improve performance since it removes the redundant copy