fix: support XL_PLATFORM as well (hopefully)

Dalamud.Common/Util/EnvironmentUtils.cs

@@ -0,0 +1,18 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace Dalamud.Common.Util;
+
+public static class EnvironmentUtils
+{
+    /// <summary>
+    /// Attempts to get an environment variable using the Try pattern.
+    /// </summary>
+    /// <param name="variableName">The env var to get.</param>
+    /// <param name="value">An output containing the env var, if present.</param>
+    /// <returns>A boolean indicating whether the var was present.</returns>
+    public static bool TryGetEnvironmentVariable(string variableName, [NotNullWhen(true)] out string? value)
+    {
+        value = Environment.GetEnvironmentVariable(variableName);
+        return value != null;
+    }
+}

Dalamud.Injector/EntryPoint.cs

@@ -11,6 +11,8 @@ using System.Text.RegularExpressions;
 
 using Dalamud.Common;
 using Dalamud.Common.Game;
+using Dalamud.Common.Util;
+
 using Newtonsoft.Json;
 using Reloaded.Memory.Buffers;
 using Serilog;
@@ -311,6 +313,10 @@ namespace Dalamud.Injector
             var unhandledExceptionStr = startInfo.UnhandledException.ToString().ToLowerInvariant();
             var troubleshootingData = "{\"empty\": true, \"description\": \"No troubleshooting data supplied.\"}";
 
+            // env vars are brought in prior to launch args, since args can override them.
+            if (EnvironmentUtils.TryGetEnvironmentVariable("XL_PLATFORM", out var xlPlatformEnv))
+                platformStr = xlPlatformEnv.ToLowerInvariant();
+
             for (var i = 2; i < args.Count; i++)
             {
                 if (args[i].StartsWith(key = "--dalamud-working-directory="))