🔍 FileChangeDetection

A lightweight Windows CLI tool written in C that snapshots a directory tree and compares it against a previously saved snapshot to detect added, modified, or deleted files.

---

Features

• Directory traversal — Recursively walks a directory tree and records its structure
• Snapshot saving — Persists a directory snapshot to a custom binary file with -o for later comparison
• Manual diffing — Compare a live directory scan against any saved snapshot file
• Diff reporting — Optionally show added/deleted files (-d) and write results to a file (-w)
• O(n) comparison — Uses hash tables for path lookups, so diffing two snapshots scales linearly with the number of entries
• Modular design — Logic cleanly split across traverse, utils, and types modules

---

Project Structure

FileChangeDetection/
├── main.c          # Entry point & CLI argument handling (argtable3)
├── traverse.c/.h   # Directory traversal logic
├── utils.c/.h      # Snapshot I/O, comparison, and stat output
├── types.h         # Shared type definitions
└── extern/         # External dependency: argtable3 and uthash

---

Getting Started

Prerequisites

• Windows (the project uses windows.h and Windows-specific APIs)
• MSVC (primary target) or MinGW
• The argtable3 and uthash are bundled in extern/

Build

git clone https://github.com/TheEugen/FileChangeDetection.git
cd FileChangeDetection

Open the project in Visual Studio, or compile manually with your preferred Windows C toolchain. Make sure extern/argtable3.h and its corresponding source file are included in your build.

---

Usage

FileChangeDetection <dir> [options]

Flag	Description
<dir>	Directory to scan
-o <saveFile>	Save the scanned directory structure to a binary snapshot file
<file>	Snapshot file to compare against
-c	Compare only (load both snapshots from files, no live scan)
-d	Show added and deleted files/directories in the diff
-w <file>	Write diff results to a file
--help	Display usage information
--version	Display version info

Examples

Take a snapshot:

FileChangeDetection C:\MyFolder -o snapshot.dat

Compare current state against a snapshot:

FileChangeDetection C:\MyFolder snapshot.dat -d

Compare two saved snapshots (no live scan):

FileChangeDetection C:\MyFolder -c snapshot.dat -d -w diff_output.txt

---

How It Works

The tool is entirely manual — there is no background process or polling loop. You control when snapshots are taken and compared:

1. Scan & save — Run with -o to traverse a directory and serialize its structure to a custom binary file (storing root path, total size, file count, per-file name/path/size/last-write time, and directory entries)
2. Scan & compare — Run with a snapshot file to traverse the directory again and immediately diff the live state against the saved snapshot
3. Compare only — Run with -c and a snapshot file to compare two previously saved snapshots without doing a live scan

Comparison uses hash tables for efficient path lookups. Diff output (added/deleted entries) can be printed to the console with -d and/or written to a file with -w.

---

License

This project is licensed under the MIT License.