Crate magic_db 

magic-db: Precompiled Magic Rules Database

A precompiled database of file type detection rules based on the original libmagic project, optimized and adapted for use with pure-magic. This crate provides ready-to-use file type detection capabilities without requiring external rule files.

Features

• Precompiled Rules: Optimized database embedded directly in your binary
• No External Dependencies: All rules are included in the compiled crate
• Enhanced Rules: Improved and extended versions of the original libmagic rules
• Easy Integration: Simple one-line access to the compiled database

Optional Cargo Features

• global: Enables magic_db::global(), a lazily-initialized, process-wide MagicDb. This provides a convenient singleton but is optional. If you need explicit lifetime control or multiple independent instances, use magic_db::load() instead.

Installation

Add magic-db to your Cargo.toml:

[dependencies]
magic-db = "0.1"  # Replace with the latest version
pure-magic = "0.1"  # Required peer dependency

Usage

Manual lifecycle (default)

use std::fs::File;
use std::env::current_exe;

fn main() -> Result<(), pure_magic::Error> {
    // Open the precompiled database
    let db = magic_db::load()?;

    // Use it to detect file types
    let mut file = File::open(current_exe()?)?;
    let magic = db.first_magic(&mut file, None)?;
    assert!(!magic.is_default());

    println!("File type: {}", magic.message());
    println!("MIME type: {}", magic.mime_type());
    Ok(())
}

Global singleton (optional)

The crate provides a convenience global database via the global feature. This is process-wide, lazily initialized, and kept alive until program termination.

Enable it in Cargo.toml:

magic_db = { version = "0.1", features = ["global"] }

Then use it like this:

use magic_db::global;

let db = global().unwrap();

Note: Use the global feature only if you want a single, shared database. For multiple independent instances or explicit lifetime management, use magic_db::load().

About the Rules

This database contains slightly modified versions of the original libmagic rules that are available in the src/magdir directory of this repository.

Some of the rules have been:

• Adapted: Modified to work with the pure-magic parser
• Optimized: Performance improvements for common file types
• Extended: Additional rules were created
• Fixed: Corrections to inaccurate or problematic original rules

Rule Exclusions

The database intentionally excludes the der rules (ASN.1/DER encoding rules) because:

• The pure-magic parser doesn’t support (yet) the specific DER test types implemented in the original libmagic

Source Rules

The source magic rules are available in the repository at: src/magdir

You can:

1. Browse the rules to understand how file types are detected
2. Suggest improvements by opening issues or pull requests
3. Use these rules as a reference for creating your own custom rules

License

This project is licensed under the GPL-3.0 License.

See Also

• pure-magic: The core file type detection library
• magic-embed: The macro used to create this database
• magic: Expected magic rule format

Functions

globalglobal

Returns a process-wide read-only MagicDb initialized on first use.

load

Loads a MagicDb from the embedded, precompiled database.