Minidump constructor treats displayName as a file path when creating CachedMemoryReader

[egraff]

There is a code path in the Minidump constructor that passes displayName to the CachedMemoryReader's dumpPath parameter:

clrmd/src/Microsoft.Diagnostics.Runtime/Windows/Minidump.cs

Line 134 in bfbcda6

memoryReader = new CachedMemoryReader(segments, displayName, fs, cacheSize, technology, PointerSize, leaveOpen);

The CachedMemoryReader constructor does:

clrmd/src/Microsoft.Diagnostics.Runtime/Windows/CachedMemoryReader.cs

Lines 37 to 40 in bfbcda6

	public CachedMemoryReader(ImmutableArray<MinidumpSegment> segments, string dumpPath, FileStream stream, long maxCacheSize, CacheTechnology cacheTechnology, int pointerSize, bool leaveOpen)
	{
	PointerSize = pointerSize;
	DumpPath = dumpPath;

and importantly, has this method, which expects DumpPath to actually be a valid file path:

clrmd/src/Microsoft.Diagnostics.Runtime/Windows/CachedMemoryReader.cs

Lines 93 to 101 in bfbcda6

	public override int ReadFromRva(ulong rva, Span<byte> buffer)
	{
	lock (_rvaLock)
	{
	_rvaStream ??= File.OpenRead(DumpPath);
	_rvaStream.Position = (long)rva;
	return _rvaStream.Read(buffer);
	}
	}

However, this breaks the data contract from DataTarget.LoadDump:

clrmd/src/Microsoft.Diagnostics.Runtime/DataTarget.cs

Lines 261 to 269 in bfbcda6

	/// <summary>
	/// Loads a dump stream. Currently supported formats are Mach-O coredump, ELF coredump, and Windows Minidump formats.
	/// </summary>
	/// <param name="displayName">The name of this DataTarget, might be used in exceptions.</param>
	/// <param name="stream">The stream that should be used.</param>
	/// <param name="leaveOpen">True whenever the given stream should be leaved open when the DataTarget is disposed.</param>
	/// <param name="options">The options to use when loading the dump.</param>
	/// <returns>A <see cref="DataTarget"/> for the given dump.</returns>
	public static DataTarget LoadDump(string displayName, Stream stream, bool leaveOpen = false, DataTargetOptions? options = null)

where the caller is allowed to pass in a Stream and a display name of their own choice (which, importantly, is not specified to have to be a file path).

The Minidump constructor should maybe pass fs.Name instead to the CachedMemoryReader? Or, the API contract must be changed.