Moving structure as preparation for docs

src/AMWD.Protocols.Modbus.Serial/Exceptions/UnixIOException.cs

@@ -0,0 +1,83 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Runtime.Serialization;
+using AMWD.Protocols.Modbus.Serial.Utils;
+#if NETSTANDARD
+using System.Security.Permissions;
+#endif
+
+namespace AMWD.Protocols.Modbus.Serial
+{
+	/// <summary>
+	/// Represents a unix specific IO exception.
+	/// </summary>
+	/// <remarks>
+	/// See StackOverflow answer: <see href="https://stackoverflow.com/a/10388107"/>.
+	/// </remarks>
+	[Serializable]
+	[System.Diagnostics.CodeAnalysis.ExcludeFromCodeCoverage]
+	public class UnixIOException : ExternalException
+	{
+		/// <summary>
+		/// Initializes a new instance of the <see cref="UnixIOException"/> class.
+		/// </summary>
+#if NETSTANDARD
+		[SecurityPermission(SecurityAction.Demand, UnmanagedCode = true)]
+#endif
+		public UnixIOException()
+			: this(Marshal.GetLastWin32Error())
+		{ }
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="UnixIOException"/> class.
+		/// </summary>
+		/// <param name="errorCode">The native error code.</param>
+#if NETSTANDARD
+		[SecurityPermission(SecurityAction.Demand, UnmanagedCode = true)]
+#endif
+		public UnixIOException(int errorCode)
+			: this(GetErrorMessage(errorCode), errorCode)
+		{ }
+
+		/// <summary>
+		/// Initializes a new instance of the <see cref="UnixIOException"/> class.
+		/// </summary>
+		/// <param name="message">The message that describes the error.</param>
+#if NETSTANDARD
+		[SecurityPermission(SecurityAction.Demand, UnmanagedCode = true)]
+#endif
+		public UnixIOException(string message)
+			: base(message)
+		{ }
+
+		/// <inheritdoc/>
+		public UnixIOException(string message, Exception inner)
+			: base(message, inner)
+		{ }
+
+		/// <inheritdoc/>
+		public UnixIOException(string message, int errorCode)
+			: base(message, errorCode)
+		{ }
+
+#if ! NET8_0_OR_GREATER
+		/// <inheritdoc/>
+		protected UnixIOException(SerializationInfo info, StreamingContext context)
+			: base(info, context)
+		{ }
+#endif
+
+		private static string GetErrorMessage(int errorCode)
+		{
+			try
+			{
+				nint ptr = UnsafeNativeMethods.StrError(errorCode);
+				return Marshal.PtrToStringAnsi(ptr);
+			}
+			catch
+			{
+				return $"Unknown error: 0x{errorCode:x}";
+			}
+		}
+	}
+}