Merge pull request #7548 from ahopper/fix-32bit-linux-session-manger-pinvoke

fix 32 bit raspberry pi session manager seg fault

src/Avalonia.X11/SMLib.cs

@@ -1,3 +1,4 @@
+#nullable enable
 using System;
 using System.Runtime.InteropServices;
 
@@ -7,20 +8,19 @@ namespace Avalonia.X11
     {
         private const string LibSm = "libSM.so.6";
 
-        [DllImport(LibSm, CharSet = CharSet.Ansi)]
+        [DllImport(LibSm, CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
         public static extern IntPtr SmcOpenConnection(
-            [MarshalAs(UnmanagedType.LPWStr)] string networkId,
+            [MarshalAs(UnmanagedType.LPStr)] string? networkId,
             IntPtr content,
             int xsmpMajorRev,
             int xsmpMinorRev,
-            ulong mask,
+            nuint mask,
             ref SmcCallbacks callbacks,
-            [MarshalAs(UnmanagedType.LPWStr)] [Out]
-            out string previousId,
-            [MarshalAs(UnmanagedType.LPWStr)] [Out]
-            out string clientIdRet,
+            [MarshalAs(UnmanagedType.LPStr)] string? previousId,
+            ref IntPtr clientIdRet,
             int errorLength,
-            [Out] char[] errorStringRet);
+            [Out] byte[] errorStringRet
+        );
 
         [DllImport(LibSm, CallingConvention = CallingConvention.StdCall)]
         public static extern int SmcCloseConnection(

src/Avalonia.X11/X11PlatformLifetimeEvents.cs

@@ -1,5 +1,6 @@
 #nullable enable
 using System;
+using System.Text;
 using System.Collections.Concurrent;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -14,10 +15,10 @@ namespace Avalonia.X11
     internal unsafe class X11PlatformLifetimeEvents : IDisposable, IPlatformLifetimeEventsImpl
     {
         private readonly AvaloniaX11Platform _platform;
-        private const ulong SmcSaveYourselfProcMask = 1L;
-        private const ulong SmcDieProcMask = 2L;
-        private const ulong SmcSaveCompleteProcMask = 4L;
-        private const ulong SmcShutdownCancelledProcMask = 8L;
+        private const nuint SmcSaveYourselfProcMask = 1;
+        private const nuint SmcDieProcMask = 2;
+        private const nuint SmcSaveCompleteProcMask = 4;
+        private const nuint SmcShutdownCancelledProcMask = 8;
 
         private static readonly ConcurrentDictionary<IntPtr, X11PlatformLifetimeEvents> s_nativeToManagedMapper =
             new ConcurrentDictionary<IntPtr, X11PlatformLifetimeEvents>();
@@ -62,24 +63,24 @@ namespace Avalonia.X11
                 return;
             }
 
-            var errorBuf = new char[255];
-
-            var smcConn = SMLib.SmcOpenConnection(null!,
+            byte[] errorBuf = new byte[255];
+            IntPtr clientIdRet = IntPtr.Zero;
+            var smcConn = SMLib.SmcOpenConnection(null,
                 IntPtr.Zero, 1, 0,
                 SmcSaveYourselfProcMask |
                 SmcSaveCompleteProcMask |
                 SmcShutdownCancelledProcMask |
                 SmcDieProcMask,
                 ref s_callbacks,
-                out _,
-                out _,
+                null,
+                ref clientIdRet,
                 errorBuf.Length,
                 errorBuf);
 
             if (smcConn == IntPtr.Zero)
             {
                 Logger.TryGet(LogEventLevel.Warning, LogArea.X11Platform)?.Log(this,
-                    $"SMLib/ICELib reported a new error: {new string(errorBuf)}");
+                    $"SMLib/ICELib reported a new error: {Encoding.ASCII.GetString(errorBuf)}");
                 return;
             }