Fix unsafe fixed buffer pointer handling in F1 telemetry extensions

GamesDat.Demo/Program.cs

@@ -12,7 +12,7 @@ internal class Program
     {
         static async Task Main(string[] args)
         {
-            //await CaptureF1SessionAsync();
+            await CaptureF1SessionAsync();
             //await ReadF1Session("./sessions/f1_20260210_220103.bin");
         }
 

GamesDat/Telemetry/Sources/Formula1/F12025/Participant.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
+using System.Text;
 
 namespace GamesDat.Core.Telemetry.Sources.Formula1.F12025
 {
@@ -14,8 +15,8 @@ public struct Participant
         public byte m_raceNumber;                       // Race number of the car
         public byte m_nationality;                      // Nationality of the driver
 
-        [MarshalAs(UnmanagedType.ByValTStr, SizeConst = 32)]
-        public string m_name;                           // Name of participant in UTF-8 format – null terminated
+        [MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
+        public byte[] m_name;                           // Name of participant in UTF-8 format – null terminated
                                                         // Will be truncated with ... (U+2026) if too long
         public byte m_yourTelemetry;                    // The player's UDP setting, 0 = restricted, 1 = public
         public byte m_showOnlineNames;                  // The player's show online names setting, 0 = off, 1 = on
@@ -26,5 +27,18 @@ public struct Participant
         [MarshalAs(UnmanagedType.ByValArray, SizeConst = 4)]
         public LiveryColour[] m_liveryColours;          // Colours for the car
 
+        /// <summary>
+        /// Gets the participant name as a decoded UTF-8 string
+        /// </summary>
+        public readonly string Name
+        {
+            get
+            {
+                if (m_name == null) return string.Empty;
+                int length = Array.IndexOf(m_name, (byte)0);
+                if (length < 0) length = m_name.Length;
+                return Encoding.UTF8.GetString(m_name, 0, length);
+            }
+        }
     }
 }

GamesDat/Telemetry/Sources/Formula1/F1TelemetryFrameExtensions.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 
 namespace GamesDat.Core.Telemetry.Sources.Formula1
@@ -31,7 +32,8 @@ public static unsafe T GetPacket<T>(this F1TelemetryFrame frame) where T : struc
                     $"Packet data too small. Expected {expectedSize} bytes for {packetType.Name}, got {frame.DataLength}");
             }
 
-            return Marshal.PtrToStructure<T>((IntPtr)frame.RawData);
+            void* ptr = Unsafe.AsPointer(ref frame.RawData[0]);
+            return Marshal.PtrToStructure<T>((IntPtr)ptr);
         }
 
         /// <summary>
@@ -49,7 +51,8 @@ public static unsafe T GetPacket<T>(this F1TelemetryFrame frame) where T : struc
                 throw new InvalidOperationException($"Packet data too small. Expected {expectedSize} bytes for {packetType.Name}, got {frame.DataLength}");
             }
 
-            var result = Marshal.PtrToStructure((IntPtr)frame.RawData, packetType);
+            void* ptr = Unsafe.AsPointer(ref frame.RawData[0]);
+            var result = Marshal.PtrToStructure((IntPtr)ptr, packetType);
             return result;
         }
 
@@ -59,7 +62,8 @@ public static unsafe T GetPacket<T>(this F1TelemetryFrame frame) where T : struc
         public static unsafe byte[] GetRawData(this F1TelemetryFrame frame)
         {
             var data = new byte[frame.DataLength];
-            Marshal.Copy((IntPtr)frame.RawData, data, 0, frame.DataLength);
+            void* ptr = Unsafe.AsPointer(ref frame.RawData[0]);
+            Marshal.Copy((IntPtr)ptr, data, 0, frame.DataLength);
             return data;
         }
     }