Marshal.PtrToStringUni with non null-terminated string (linux x64)

build.sh

#!/usr/bin/env sh
gcc -shared -fPIC -o libnullterm.so nullterm.c
LD_LIBRARY_PATH=$(pwd) dotnet run

# output looks like this:
# value: foo1
# length: 4
# value: foo2⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪⨪
# length: 32

nullterm.c

// Linux with C11 compiler
#include <stdio.h>

#define DLLEXPORT __attribute__((visibility("default")))

DLLEXPORT
const void* getstrWithNullTerminator(char* in)
{
   // foo1
   char bytes[] = {0x66, 0x00, 0x6f, 0x00, 0x6f, 0x00, 0x31, 0x00, 0x00, 0x00};
   int i = 0;
   while (i < 10)
   {
      *(in + i) = *(bytes + i);
      ++i;
   }
   return in;
}

DLLEXPORT
const void* getstrWithoutNullTerminator(char* in)
{
   // foo2
   char bytes[] = {0x66, 0x00, 0x6f, 0x00, 0x6f, 0x00, 0x32, 0x00};
   int i = 0;
   while (i < 8)
   {
      *(in + i) = *(bytes + i);
      ++i;
   }
   return in;
}

nullterm.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net5.0</TargetFramework>
    <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
  </PropertyGroup>

</Project>

Program.cs

using System;
using System.Runtime.InteropServices;

unsafe class Program
{
    [DllImport("libnullterm")]
    private static extern IntPtr getstrWithNullTerminator(byte* inArray);

    [DllImport("libnullterm")]
    private static extern IntPtr getstrWithoutNullTerminator(byte* inArray);

    static void Main()
    {
        var bytes = new byte[64];
        Array.Fill(bytes, (byte)42);
        fixed (byte* b = bytes)
        {
            string x = Marshal.PtrToStringUni(getstrWithNullTerminator(b));
            Console.WriteLine("value: {0}\nlength: {1}", x, x.Length);
        }

        Array.Fill(bytes, (byte)42);
        fixed (byte* b = bytes)
        {
            string x = Marshal.PtrToStringUni(getstrWithoutNullTerminator(b));
            Console.WriteLine("value: {0}\nlength: {1}", x, x.Length);
        }
    }
}