Merge pull request #3670 from Nexus-Mods/fix-3668

Fixed: Unrecognised AppImage environment variable after handler fix.

Author: erri120

src/NexusMods.CrossPlatform/Process/AOSInterop.cs

@@ -86,12 +86,15 @@ public virtual Task OpenFileInDirectory(AbsolutePath filePath, bool logOutput =
     }
 
     /// <inheritdoc />
-    public virtual AbsolutePath GetOwnExe()
+    public virtual AbsolutePath GetOwnExe() => FileSystem.Shared.FromUnsanitizedFullPath(GetOwnExeUnsanitized());
+
+    /// <inheritdoc />
+    public virtual string GetOwnExeUnsanitized()
     {
         var processPath = Environment.ProcessPath;
         Debug.Assert(processPath is not null);
 
-        return FileSystem.Shared.FromUnsanitizedFullPath(processPath);
+        return processPath;
     }
 
     /// <inheritdoc />

src/NexusMods.CrossPlatform/Process/IOSInterop.cs

@@ -39,6 +39,17 @@ public interface IOSInterop
     /// </summary>
     AbsolutePath GetOwnExe();
 
+    /// <summary>
+    /// Get the path to the current executable as an unsanitized string.
+    /// This preserves the original path without conversion through the paths library.
+    /// </summary>
+    /// <remarks>
+    /// Do not use in production *unless you have a very good reason to do so*.
+    /// This API exists to resolve an edge case with protocol registration on Linux,
+    /// https://github.com/Nexus-Mods/NexusMods.Paths/issues/71
+    /// </remarks>
+    string GetOwnExeUnsanitized();
+
     /// <summary>
     /// Gets all file system mounts.
     /// </summary>

src/NexusMods.CrossPlatform/Process/OSInteropLinux.cs

@@ -69,14 +69,14 @@ private async ValueTask<OpenUriPortal> GetPortal()
     protected override Command CreateCommand(Uri uri) => throw new UnreachableException("Should never be called");
 
     /// <inheritdoc />
-    public override AbsolutePath GetOwnExe()
+    public override string GetOwnExeUnsanitized()
     {
         // https://docs.appimage.org/packaging-guide/environment-variables.html#type-2-appimage-runtime
         // APPIMAGE: (Absolute) path to AppImage file (with symlinks resolved)
         var appImagePath = Environment.GetEnvironmentVariable("APPIMAGE", EnvironmentVariableTarget.Process);
-        if (appImagePath is null) return base.GetOwnExe();
+        if (appImagePath is not null) return appImagePath;
 
-        return _fileSystem.FromUnsanitizedFullPath(appImagePath);
+        return base.GetOwnExeUnsanitized();
     }
 
     /// <inheritdoc />

src/NexusMods.CrossPlatform/ProtocolRegistration/ProtocolRegistrationLinux.cs

@@ -118,12 +118,6 @@ private async Task CreateDesktopFile(AbsolutePath applicationsDirectory, Cancell
 
         var text = await sr.ReadToEndAsync(cancellationToken);
 
-        // Note(sewer): For `processPath` we're temporarily using `_osInterop.GetOwnExe()` because
-        //              paths library will replace backslashes in folder names with forward slashes.
-        //              Backslashes are valid on Linux (& macOS), so we're avoiding 
-        //              breaking the App here.
-        // https://github.com/Nexus-Mods/NexusMods.Paths/issues/71
-
         // Note(sewer): xdg-utils has issues with the 'generic' fallback for `.desktop` files
         //              which will be used in non-mainstream DEs like Hyprland, Sway, i3, etc.
         //              We'll use a hack to work around this.
@@ -146,7 +140,13 @@ private async Task CreateDesktopFile(AbsolutePath applicationsDirectory, Cancell
         // I also added an extra 'safety' rule: 
         //  - The wrapper will only be used if the path requires escaping.
         //  - IF Path requires escaping AND `XDG_DATA_HOME` needs escaping, we log a warning.
-        var processPath = Environment.ProcessPath!;
+        
+        // Note(sewer): We use GetOwnExeUnsanitized() instead of GetOwnExe()
+        //              because the backslashes \ are unfortunately valid filename
+        //              characters on Linux. The Paths library converts \ to /
+        //              which breaks the path, so we must avoid this.
+        //              https://github.com/Nexus-Mods/NexusMods.Paths/issues/71
+        var processPath = _osInterop.GetOwnExeUnsanitized();
         var wrapperScriptPath = await CreateWrapperScriptIfNeeded(applicationsDirectory, processPath, cancellationToken);
 
         text = text.Replace(ExecuteParameterPlaceholder, wrapperScriptPath.ToString());