Extract embedded data from a MachO executable at runtime.

Bundle+EmbeddedData.swift

//
//  Bundle+EmbeddedData.swift
//  
//
//  Created by Stephan Casas on 6/26/24.
//

import Foundation;

extension Bundle {
    
    /// Get the raw bytes of an executable-embedded entity stored in the given segment and identified by the given section.
    /// - Parameters:
    ///   - section: The name of the section in which the entity is stored.
    ///   - segment: The name of the segment in which the section is partitioned.
    /// - Returns: The embedded entity's raw bytes as `Data`.
    static func getEmbeddedDataForSection(_ section: String, in segment: String = "__TEXT") -> Data? {
        guard let ownExecPtr = dlopen(nil, RTLD_NOW) else {
            return nil;
        }
        
        defer { dlclose(ownExecPtr) }
        
        guard let machHeaderOpaquePtr = dlsym(ownExecPtr, MH_EXECUTE_SYM) else {
            return nil;
        }
        
        let machHeaderPtr = machHeaderOpaquePtr.assumingMemoryBound(
            to: mach_header_64.self);
        
        var dataSize: UInt = 0;
        guard let dataPtr = getsectiondata(machHeaderPtr, segment, section, &dataSize) else {
            return nil;
        }
        
        return .init(bytes: dataPtr, count: .init(dataSize));
    }
    
}