Merge pull request #11 from badcel/ignore-null-termination-for-buffers

No automatic null termination in case of buffer scenario

readme.md

@@ -8,17 +8,24 @@ To work with WCharT data create a new instance of `WCharTString`:
 
 ```csharp
 //Read data from a byte*
-byte* pointer = NativeCal();
-var data = new WCharTString(pointer).GetString();
+byte* pointer = NativeCall();
+var str = new WCharTString(pointer).GetString();
 
 //Create a buffer for a native library and read the data after it was filled
 ReadOnlySpan<byte> data = new WCharTString(int bufferCharSize);
-NativeCall(data);
+NativeCall(...);
 var str = data.GetString();
 
 //Pass a string to a native library
 ReadOnlySpan<byte> data = new WCharTString(string str);
 NativeCall(data);
+
+//Can be used in fixed statements
+var data = new WCharTString(string str);
+fixed (byte* ptr = data)
+{
+    NativeCall(ptr);
+}
 ```
 
 ## Build

src/WCharT.Net.Tests/Tests.cs

@@ -1,5 +1,4 @@
 using System.Runtime.InteropServices;
-using System.Text;
 using FluentAssertions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -17,6 +16,17 @@ public void TestEncoding()
         str.GetString().Should().Be(text);
     }
 
+    [TestMethod]
+    public void BufferSizeIsRetained()
+    {
+        var bufferSize = 3;
+        var str = new WCharTString(bufferSize);
+
+        var result = str.GetString();
+        result.Should().Be(new string(new[] { char.MinValue, char.MinValue, char.MinValue }));
+        result.Length.Should().Be(bufferSize);
+    }
+
     [TestMethod]
     public void TestUnicode()
     {

src/WCharT.Net/Platforms/Unix.cs

@@ -7,7 +7,7 @@ internal static class Unix
     public static ReadOnlySpan<byte> CreateData(int chars)
     {
         var length = chars * sizeof(uint);
-        var data = new byte[length + sizeof(uint)]; //Null terminated
+        var data = new byte[length];
         return new ReadOnlySpan<byte>(data, 0, length);
     }
 

src/WCharT.Net/Platforms/Windows.cs

@@ -7,7 +7,7 @@ internal static class Windows
     public static ReadOnlySpan<byte> CreateData(int chars)
     {
         var length = chars * sizeof(ushort);
-        var data = new byte[length + sizeof(ushort)]; //Null terminated
+        var data = new byte[length];
         return new ReadOnlySpan<byte>(data, 0, length);
     }
 

src/WCharT.Net/WCharTString.cs

@@ -28,6 +28,7 @@ public unsafe WCharTString(byte* p)
     /// Creates an instance from a given string to be able to pass on the data later.
     /// </summary>
     /// <param name="str">A string which should be encoded into a wchar_t string.</param>
+    /// <remarks>The internal representation of the string is null terminated. Meaning it is possible to simply pass the pointer of the <see cref="ReadOnlySpan{T}"/> to native code without any length information. At the same time the length parameter of the <see cref="ReadOnlySpan{T}"/> does not include the null termination character. Meaning if an API requires the size of the data in bytes without the null termination character the length value of the <see cref="ReadOnlySpan{T}"/>can be used.</remarks>
     public WCharTString(string str)
     {
         data = Platform.CreateData(str);
@@ -37,6 +38,7 @@ public WCharTString(string str)
     /// Creates an instance for a given amount of wchar_t characters.
     /// </summary>
     /// <param name="length">The number of wchar_t characters which should be able to put into the instance.</param>
+    /// <remarks>This does not automatically add a character in case a null termination character is needed.</remarks>
     public WCharTString(int length)
     {
         data = Platform.CreateData(length);
@@ -46,6 +48,7 @@ public WCharTString(int length)
     /// Reads the current data and returns the contained string.
     /// </summary>
     /// <returns>The decoded wchar_t string from the data.</returns>
+    /// <remarks>The string has the size of the internal data block which can include null termination characters. If not needed those can be trimmed.</remarks>
     public string GetString()
     {
         return Platform.GetString(data);