Martin Gratzer mgratzer

Using LLVM's libfuzzer with Swift

Background

Of the many tools available for fuzzing, I've found that LLVM's libfuzzer is the easiest to use for Swift on macOS. Other tools seem to have a list of requirements taht are difficult to meet. libfuzzer on the other hand is built into LLVM and is available on macOS in the custom Swift toolchains: https://www.swift.org/download/

In this document I'll describe how to use libfuzzer with Swift and Swift Packages.

I used this setup to fuzz an SVG Renderer package that I am building. I was able to find and fix a number of bugs in my SVG parsing code using libfuzzer in basically no time at all.

Minimal APIs at a glance

This document now exists on the official ASP.NET core docs page.

Application
- WebApplication
- WebApplicationBuilder
Request Handling
- Routing
- Parameter Binding

How To Work With Multiple Github Accounts on a single Machine

Let suppose I have two github accounts, https://github.com/rahul-office and https://github.com/rahul-personal. Now i want to setup my mac to easily talk to both the github accounts.

NOTE: This logic can be extended to more than two accounts also. :)

The setup can be done in 5 easy steps:

Steps:

Step 1 : Create SSH keys for all accounts
Step 2 : Add SSH keys to SSH Agent

	[alias]
	# need llm CLI: https://llm.datasette.io/en/stable/
	# based on https://gist.github.com/karpathy/1dd0294ef9567971c1e4348a90d69285?permalink_comment_id=5167582#gistcomment-5167582
	commit-ai = "!f() { if [ -n \"$(git diff --cached)\" ]; then git commit -m \"$(git diff --cached \| llm -m '4o-mini' 'Below is a diff of all staged changes, coming from the command:\\n```\\ngit diff --cached\\n```\\nPlease generate a concise, two-sentence, maximum 100 characteres commit message for these changes. Do not mention project name.')\"; else echo 'No changes to commit'; fi }; f"

	import SwiftUI

	extension View {
	@MainActor
	func pdf(size: ProposedViewSize) -> Data {
	let renderer = ImageRenderer(content: self)
	renderer.proposedSize = size
	var pdfData = NSMutableData()
	renderer.render { size, render in
	var mediaBox = CGRect(origin: .zero, size: size)

	import Foundation

	// Here's a pretty typical scenario where you want to encode a polymorphic type -
	// in this case a Shape type that can be either a Square or Circle. Swift provides
	// a nice pattern for doing this in a type-safe way using enums:

	struct Circle: Codable {
	var radius: Int
	}

	import SwiftUI

	extension CGPoint {
	static func *(lhs: Self, rhs: CGFloat) -> Self {
	.init(x: lhs.x * rhs, y: lhs.y * rhs)
	}
	}

	// Idea: https://www.framer.com/showcase/project/lo2Qka8jtPXrjzZaPZdB/

	import SwiftUI

	@MainActor
	class PhotoStore: ObservableObject {
	@Published private(set) var isSaving: Bool = false

	// Made nonisolated because Playgrounds does not run on
	// @MainActor. There's probably a cleaner way of doing this
	nonisolated init() {}

	//
	// KeyCommand.swift
	// Adds Keyboard Shortcuts to SwiftUI on iOS 13
	// See https://steipete.com/posts/fixing-keyboardshortcut-in-swiftui/
	// License: MIT
	//
	// Usage: (wrap view in `KeyboardEnabledHostingController`)
	// Button(action: {
	// print("Button Tapped!!")
	// }) {

	@objc(PSTArchitecture) class Architecture: NSObject {
	/// Check if process runs under Rosetta 2.
	///
	/// Use to disable tests that use WebKit when running on Apple Silicon
	/// FB8920323: Crash in WebKit memory allocator on Apple Silicon when iOS below 14
	/// Crash is in JavaScriptCore: bmalloc::HeapConstants::HeapConstants(std::__1::lock_guard<bmalloc::Mutex> const&)
	@objc class var isRosettaEmulated: Bool {
	// Issue is specific to Simulator, not real devices
	#if targetEnvironment(simulator)
	return processIsTranslated() == EMULATED_EXECUTION