HandleHunter

A lightweight Windows utility for managing file locks on the local machine, built with Pure C and Win32 API.

Features

• System Theme Support: Automatically detects and respects Windows dark/light mode settings
• Auto-Start: Automatically displays open files on the local machine when launched
• Multi-Select: Select and release multiple file locks at once (Ctrl+Click, Shift+Click)
• Search/Filter: Real-time filtering as you type
• DPI-Aware: Crisp display on high-resolution monitors (PerMonitorV2)
• Lightweight: ~134KB executable, no dependencies required
• Fast: Instant launch, no runtime overhead

Requirements

• Windows 7 or later
• Administrator privileges (required for NetFileEnum/NetFileClose)
• Visual Studio 2022 Build Tools (MSVC compiler) for building

Building

Prerequisites

1. Install Visual Studio 2022 Build Tools with C++ support:
   • Download from visualstudio.microsoft.com
   • Or use winget: winget install Microsoft.VisualStudio.2022.BuildTools
   • Select "Desktop development with C++" workload
2. Ensure vcvars64.bat is accessible (build script will locate it automatically)

Build Steps

1. Open PowerShell or Command Prompt in the project directory
2. Build: .\build_msvc.bat

The executable HandleHunter.exe will be created with:

• Application manifest embedded (UAC elevation + DPI awareness)
• Visual styles enabled (modern themed controls)
• Application icon embedded
• Fully CRT-free implementation (except minimal WinMain startup)

Clean Build

To remove all build artifacts:

.\build_msvc.bat clean

Usage

1. Run as Administrator: Right-click HandleHunter.exe → "Run as administrator"
2. The application automatically displays all open files on the local machine
3. Search: Use the search box to filter results by filename, path, or username
4. Refresh: Click "Refresh (F5)" or press F5 to update the list
5. Multi-Select: Use Ctrl+Click to select multiple files, Shift+Click for ranges
6. Release Locks: Select one or more files and click "Release Selected Lock(s)", press Del, or double-click
7. Navigate: Use Tab key to move between controls (search box, buttons, list)

Keyboard Shortcuts

• F5: Refresh file list
• Del: Release selected lock(s) (with confirmation)
• Ctrl+Click: Select multiple individual files
• Shift+Click: Select range of files
• Ctrl+A: Select all files
• Tab: Navigate between controls
• Double-click: Release selected lock(s) (with confirmation)

Troubleshooting

Access Denied Error

• Ensure you're running as Administrator
• Check Windows Firewall settings

Side-by-Side Configuration Error

• This should not occur with properly embedded manifest
• Try rebuilding: delete all .obj files and rebuild with build_msvc.bat

Project Structure

HandleHunter/
├── main.c              # Application entry point (WinMain)
├── gui.c               # GUI creation and window management
├── gui.h               # GUI function declarations
├── modern_ui.c         # Windows theme detection and styling
├── modern_ui.h         # Theme detection function declarations
├── netapi.c            # Windows NetAPI wrapper functions
├── netapi.h            # NetAPI function declarations
├── lockinfo.c          # Dynamic array implementation (CRT-free)
├── lockinfo.h          # Data structures (FileLockInfo, LockArray, AppState)
├── utilities.c         # CRT-free utility functions (MemCopy, StrSearch, etc.)
├── utilities.h         # CRT-free utility function declarations
├── resource.h          # Control IDs and resource identifiers
├── HandleHunter.rc     # Resource script (embeds manifest & icon)
├── manifest.xml        # UAC elevation and DPI awareness manifest
├── icon.ico            # Application icon
├── build_msvc.bat      # MSVC build script (VS Build Tools required)
└── README.md           # This file

Technical Details

• Language: Pure C (C99)
• Compiler: Microsoft Visual C++ (MSVC) from VS 2022 Build Tools
• API: Win32 API (no frameworks)
• Libraries: kernel32.lib, user32.lib, gdi32.lib, advapi32.lib, netapi32.lib, comctl32.lib, dwmapi.lib, uxtheme.lib
• Unicode: Full Unicode support (UTF-16)
• Memory Management: Windows Heap API (HeapAlloc/HeapFree) - completely CRT-free
• String Operations: Manual implementations (StrLen, StrSearch, StrToLower, StrCopyN, MemCopy, MemZero)
• Formatting: Windows API wsprintfW (user32.lib) instead of stdio.h swprintf
• Binary Size: ~137 KB with all features and optimizations
• DPI Aware: PerMonitorV2 (Windows 10+) with fallback
• Visual Styles: Uses standard Windows controls with system theme detection
• Modern Features: Conditional dark mode title bar (based on Windows theme), rounded corners (Windows 11)

License

This project is provided as-is for educational and practical use.

Contributing

Feel free to submit issues or pull requests for improvements!