DotNetMetadata

A Swift library for reading and inspecting .NET metadata, including WinMD files, following the ECMA-335, Common Language Infrastructure (CLI) standard. Parsing IL is currently out of scope, but not off the table in the future.

Example

import DotNetMetadata

let context = AssemblyLoadContext()
let assembly = try context.load(path: #"C:\Windows\Microsoft.NET\Framework64\v4.0.30319\mscorlib.dll"#)
let typeDefinition = assembly.resolveTypeDefinition(fullName: "System.IDisposable")!
print("interface \(typeDefinition.name) {")
for method in typeDefinition.methods {
    print("  void \(method.name)()")
}
print("}")

Package.swift:

// swift-tools-version: 5.8
import PackageDescription

let package = Package(
    name: "MyPackage",
    dependencies: [
        .package(url: "https://github.com/tristanlabelle/swift-dotnetmetadata", branch: "main")
    ],
    targets: [
        .executableTarget(name: "MyTarget", dependencies: [
            .product(name: "DotNetMetadata", package: "swift-dotnetmetadata")
        ])
    ]
)

Architecture

The library consists in two layered modules:

• DotNetMetadata (logical layer): Provides an object model for .NET concepts of assemblies, types and members, including resolution of cross-assembly references, similar to the System.Reflection APIs.
• DotNetMetadataFormat (physical layer): Implements low-level decoding of the .NET portable executable file format and provides a strongly-typed view of the metadata tables, heaps and signatures.

The logical layer can represent a mock mscorlib assembly and its core types to support inspecting .winmd files, which reference an unresolvable mscorlib, Version=255.255.255.255.

Error Handling

The code currently makes liberal use of ! and fatalError, making it unsuitable for some production scenarios. The plan is to progressively transition to throwing errors as needed, and the expectation is that most of the logical layer API will be marked throws, to fail at a fine granularity in the presence of a few pieces of malformed data.