Appendix D: Compatibility Matrix

This appendix provides detailed compatibility information between libmagic-rs and other file identification tools, magic file formats, and system environments.

GNU file Compatibility

Command-Line Interface

Output Format Compatibility

Text Output

# GNU file
$ file example.elf
example.elf: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked

# rmagic (current)
$ rmagic example.elf
example.elf: ELF 64-bit LSB executable

# rmagic (planned)
$ rmagic example.elf
example.elf: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked

MIME Type Output

# GNU file
$ file -i example.pdf
example.pdf: application/pdf; charset=binary

# rmagic (planned)
$ rmagic --mime-type example.pdf
example.pdf: application/pdf; charset=binary

JSON Output

# GNU file (recent versions)
$ file --json example.elf
[{"filename":"example.elf","mime-type":"application/x-pie-executable","mime-encoding":"binary","description":"ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked"}]

# rmagic (current)
$ rmagic --json example.elf
{
  "filename": "example.elf",
  "description": "ELF 64-bit LSB executable",
  "mime_type": "application/x-executable",
  "confidence": 1.0
}

Magic File Format Compatibility

libmagic C Library Compatibility

API Compatibility

Flag Compatibility

Platform Compatibility

Operating Systems

Architectures

Rust Version Compatibility

File Format Support

Executable Formats

Archive Formats

Image Formats

Document Formats

Performance Comparison

Benchmark Results (Preliminary)

Note: Benchmarks are preliminary and may vary by system and file types.

Memory Usage

Migration Guide

From GNU file

Command Line Migration

# Old GNU file commands
file document.pdf
file -i document.pdf
file -b document.pdf
file -m custom.magic document.pdf

# New rmagic commands
rmagic document.pdf
rmagic --mime-type document.pdf     # Planned
rmagic --brief document.pdf         # Planned
rmagic --magic-file custom.magic document.pdf

Script Migration

#!/bin/bash
# Old script using GNU file
for f in *.bin; do
    type=$(file -b "$f")
    echo "File $f is: $type"
done

# New script using rmagic
for f in *.bin; do
    type=$(rmagic --brief "$f")  # Planned
    echo "File $f is: $type"
done

From libmagic C Library

C Code Migration

// Old libmagic C code
#include <magic.h>

magic_t magic = magic_open(MAGIC_MIME_TYPE);
magic_load(magic, NULL);
const char* result = magic_file(magic, "file.bin");
printf("MIME type: %s\n", result);
magic_close(magic);

#![allow(unused)]
fn main() {
// New Rust code
use libmagic_rs::{MagicDatabase, EvaluationConfig};

let mut config = EvaluationConfig::default();
config.output_format = OutputFormat::MimeType;  // Planned

let db = MagicDatabase::load_default()?;
let result = db.evaluate_file("file.bin")?;
println!("MIME type: {}", result.mime_type.unwrap_or_default());
}

Known Limitations

Current Limitations

1. Incomplete Magic File Support: Not all GNU file magic syntax is implemented
2. Limited File Format Coverage: Focus on common formats initially
3. No Compression Support: Cannot look inside compressed files yet
4. Basic MIME Type Support: Limited MIME type database
5. No Plugin System: Cannot extend with custom detectors

Planned Improvements

1. Complete Magic File Compatibility: Full GNU file magic syntax support
2. Comprehensive Format Support: Support for all major file formats
3. Advanced Features: Compression, encryption detection
4. Performance Optimization: Parallel processing, caching
5. Extended APIs: More flexible configuration options

Testing Compatibility

Test Suite Coverage

Compatibility Test Plan

1. Format Detection Tests: Validate against GNU file results
2. Magic File Tests: Test with real-world magic databases
3. Performance Tests: Compare speed and memory usage
4. API Tests: Validate library interface compatibility
5. Cross-platform Tests: Ensure consistent behavior across platforms

This compatibility matrix will be updated as development progresses and more features are implemented.