BepInEx/BepInEx.Preloader.Core/PlatformUtils.cs

using System;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using MonoMod.Utils;

namespace BepInEx.Preloader.Core;

internal static class PlatformUtils
{
    [DllImport("libc.so.6", EntryPoint = "uname", CallingConvention = CallingConvention.Cdecl,
               CharSet = CharSet.Ansi)]
    private static extern IntPtr uname_linux(ref utsname_linux utsname);

    [DllImport("/usr/lib/libSystem.dylib", EntryPoint = "uname", CallingConvention = CallingConvention.Cdecl,
               CharSet = CharSet.Ansi)]
    private static extern IntPtr uname_osx(ref utsname_osx utsname);

    /// <summary>
    ///     Recreation of MonoMod's PlatformHelper.DeterminePlatform method, but with libc calls instead of creating processes.
    /// </summary>
    public static void SetPlatform()
    {
        var current = Platform.Unknown;

        // For old Mono, get from a private property to accurately get the platform.
        // static extern PlatformID Platform
        var p_Platform = typeof(Environment).GetProperty("Platform", BindingFlags.NonPublic | BindingFlags.Static);
        string platID;
        if (p_Platform != null)
            platID = p_Platform.GetValue(null, new object[0]).ToString();
        else
            // For .NET and newer Mono, use the usual value.
            platID = Environment.OSVersion.Platform.ToString();
        platID = platID.ToLowerInvariant();

        if (platID.Contains("win"))
            current = Platform.Windows;
        else if (platID.Contains("mac") || platID.Contains("osx"))
            current = Platform.MacOS;
        else if (platID.Contains("lin") || platID.Contains("unix")) current = Platform.Linux;

        if (Is(current, Platform.Linux) && Directory.Exists("/data") && File.Exists("/system/build.prop"))
            current = Platform.Android;
        else if (Is(current, Platform.Unix) && Directory.Exists("/System/Library/AccessibilityBundles"))
            current = Platform.iOS;

        // Is64BitOperatingSystem has been added in .NET Framework 4.0
        var m_get_Is64BitOperatingSystem =
            typeof(Environment).GetProperty("Is64BitOperatingSystem")?.GetGetMethod();
        if (m_get_Is64BitOperatingSystem != null)
            current |= (bool) m_get_Is64BitOperatingSystem.Invoke(null, new object[0]) ? Platform.Bits64 : 0;
        else
            current |= IntPtr.Size >= 8 ? Platform.Bits64 : 0;

        if ((Is(current, Platform.MacOS) || Is(current, Platform.Linux)) && Type.GetType("Mono.Runtime") != null)
        {
            string arch;
            IntPtr result;

            if (Is(current, Platform.MacOS))
            {
                var utsname_osx = new utsname_osx();
                result = uname_osx(ref utsname_osx);
                arch = utsname_osx.machine;
            }
            else
            {
                // Linux
                var utsname_linux = new utsname_linux();
                result = uname_linux(ref utsname_linux);
                arch = utsname_linux.machine;
            }

            if (result == IntPtr.Zero && (arch.StartsWith("aarch") || arch.StartsWith("arm")))
                current |= Platform.ARM;
        }
        else
        {
            // Detect ARM based on PE info or uname.
            typeof(object).Module.GetPEKind(out var peKind, out var machine);
            if (machine == (ImageFileMachine) 0x01C4 /* ARM, .NET Framework 4.5 */)
                current |= Platform.ARM;
        }

        PlatformHelper.Current = current;
    }

    private static bool Is(Platform current, Platform expected) => (current & expected) == expected;

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    public struct utsname_osx
    {
        private const int osx_utslen = 256;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = osx_utslen)]
        public string sysname;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = osx_utslen)]
        public string nodename;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = osx_utslen)]
        public string release;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = osx_utslen)]
        public string version;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = osx_utslen)]
        public string machine;
    }

    [StructLayout(LayoutKind.Sequential, Pack = 1)]
    public struct utsname_linux
    {
        private const int linux_utslen = 65;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = linux_utslen)]
        public string sysname;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = linux_utslen)]
        public string nodename;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = linux_utslen)]
        public string release;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = linux_utslen)]
        public string version;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = linux_utslen)]
        public string machine;

        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = linux_utslen)]
        public string domainname;
    }
}