ComStream indicate that inner IStream is not readable/writeable incorrectly

[zhuxb711]

Construct the ComStream with this constructor

Vanara/Core/InteropServices/ComStream.cs

Lines 20 to 22 in 4904128

	/// <summary>Initializes a new instance of the ComStream class.</summary>
	/// <param name="stream">A ComTypes.IStream</param>
	public ComStream(IStream stream) => comStream = stream;

However, CanSeek/CanRead/CanWrite are all false (Only consider netStream)

Vanara/Core/InteropServices/ComStream.cs

Lines 35 to 49 in 4904128

	/// <summary>Gets a value indicating whether this instance can read.</summary>
	/// <value><see langword="true"/> if this instance can read; otherwise, <see langword="false"/>.</value>
	public override bool CanRead => netStream?.CanRead ?? false;
	/// <summary>Gets a value indicating whether this instance can seek.</summary>
	/// <value><see langword="true"/> if this instance can seek; otherwise, <see langword="false"/>.</value>
	public override bool CanSeek => netStream?.CanSeek ?? false;
	/// <summary>Gets a value indicating whether this instance can timeout.</summary>
	/// <value><see langword="true"/> if this instance can timeout; otherwise, <see langword="false"/>.</value>
	public override bool CanTimeout => netStream?.CanTimeout ?? false;
	/// <summary>Gets a value indicating whether this instance can write.</summary>
	/// <value><see langword="true"/> if this instance can write; otherwise, <see langword="false"/>.</value>
	public override bool CanWrite => netStream?.CanWrite ?? false;

Should use IStream.Stat(out STATSTG pstatstg, int grfStatFlag) to get STATSTG.grfMode and check whether the stream is readable/writeable instead of simply return false.

For IStream, I think CanSeek should always true & CanTimeout should always false

// grfMode reference
STGM_READ // readonly
STGM_WRITE // writeonly
STGM_READWRITE // read/write

[dahall]

Given:

STGM_READ = 0x00000000,
STGM_WRITE = 0x00000001,
STGM_READWRITE = 0x00000002,

I think the following is correct given different values of STATSTG:

public override bool CanRead => (GetStats().grfMode & 0x00000003) is 0 or 2;
public override bool CanSeek => netStream?.CanSeek ?? true;
public override bool CanTimeout => netStream?.CanTimeout ?? false;
public override bool CanWrite => (GetStats().grfMode & 0x00000003) is 1 or 2;

Do you agree?

[zhuxb711]

I would prefer use IsFlagSet to check the flags

Vanara/Core/Extensions/EnumExtensions.cs

Line 99 in 4a8854b

public static bool IsFlagSet<T>(this T flags, T flag) where T : struct, Enum

Anyway, it looks good. Thanks~

[zhuxb711]

By the way, would you release the next version in the near future?

[dahall]

Yes, I plan to push 4.0.5 by the end of the month.