check.ps1

A PowerShell script to analyze how Windows Shell interprets various paths (local directories, \\wsl$, shell: URIs, etc.) by retrieving Shell attributes (SFGAO_*) via the Win32 API. It helps explain why some locations appear in folder picker dialogs (FOS_PICKFOLDERS) but not in regular file open/save dialogs.

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Table of Contents

• Overview
• Features
• How It Works
• Why SFGAO_FILESYSTEM Matters
• Requirements
• Usage

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Overview

In Windows, the Shell can treat different paths in different ways—some are recognized as “real” file system objects, others as “virtual” or “namespace” extensions. This check.ps1 script uses low-level Shell APIs (in particular, SHParseDisplayName) to parse a user-supplied path and report back critical SFGAO flags.

These flags determine whether a path is considered:

• A true filesystem object (SFGAO_FILESYSTEM),
• A file system ancestor (SFGAO_FILESYSANCESTOR),
• A folder-like container (SFGAO_FOLDER),
• Or something else entirely.

Key Insight:

• A location without SFGAO_FILESYSTEM but with SFGAO_FILESYSANCESTOR often does appear in a folder picker dialog but is hidden from classic file open/save dialogs, since the latter may require a full Win32 filesystem path.

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Features

• Retrieves Shell attributes (SFGAO_*) for a specified path using SHParseDisplayName.
• Highlights the difference between true filesystem objects (SFGAO_FILESYSTEM) and “virtual” or “namespace-only” folders (SFGAO_FILESYSANCESTOR).
• Explains why certain paths (e.g., \\wsl$, libraries like shell:PicturesLibrary, or network shares) behave differently in Windows UI.
• Interactive: prompts for a path, then shows the parsed attributes.

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How It Works

1. User inputs a path in PowerShell (e.g., \\wsl$\Ubuntu, C:\Windows, shell:PicturesLibrary, etc.).
2. The script calls SHParseDisplayName to parse the path into a PIDL (Pointer to an Item ID List).
3. Windows Shell returns flags (SFGAO_*) describing the item (is it a real FS object? is it an ancestor? a folder?).
4. The script displays these flags, clarifying how the Shell classifies that location.

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Why SFGAO_FILESYSTEM Matters

• SFGAO_FILESYSTEM indicates the path is part of the real file system in the Shell’s view.
• SFGAO_FILESYSANCESTOR means the path can lead to real file-system objects but isn’t itself a classic Win32 filesystem path.
• FOS_PICKFOLDERS (the folder picker dialog flag) often shows items with SFGAO_FILESYSANCESTOR, even without SFGAO_FILESYSTEM.
  • This is why WSL (\\wsl$) or shell:PicturesLibrary might appear in folder dialogs but remain hidden in a standard file open/save dialog.

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Requirements

• Windows 10/11 with standard Shell components
  (On Windows Server Core or minimal installations, the necessary Shell functionality may be absent or limited.)
• PowerShell 5.1+ or later.
• Sufficient permissions to run scripts (Set-ExecutionPolicy) or a signed script.

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Usage

1. Clone or download this repository.
2. Open a PowerShell session.
3. Navigate to the folder containing check.ps1.
4. Run the script:

   .\check.ps1