Satish Bhat bhattisatish

macOS Internals

Understand your Mac and iPhone more deeply by tracing the evolution of Mac OS X from prelease to Swift. John Siracusa delivers the details.

Starting Points

How to use this gist

You've got two main options:

I have an updated version of this on my blog here: https://chrisamico.com/blog/2023-01-14/python-setup/.

Python

This is my recommended Python setup, as of Fall 2022. The Python landscape can be a confusing mess of overlapping tools that sometimes don't work well together. This is an effort to standardize our approach and environments.

Tools and helpful links:

Python docs: https://docs.python.org/3/
Python Standard Library: - Start here when you're trying to solve a specific problem

Setup

Edit package.json Jest configuration as shown below. The big points are to ensure you have a json reporter and to ensure your coverage is stored in a unique directory for unit tests (in this config its coverage/unit. Also, add the development dependencies shown as they are required for the merge script.
Edit your e2e configuration (test/jest-e2e.json) as shown below. The required "trick" was to ensure that rootDir's subtree includes paths for the e2e tests as well as an source you want to generate coverage for. Using the parent directory includes both test and src so this works. I tried many other methods, like setting collectCoverageFrom to ../src, none of them worked. It appears you must use the parent directory and exclude everything you don't want. Note that it also uses a unique directory for its generated coverage data (coverage/e2e).
Add merge-coverage.ts shown below to your project and run it after you've ran both test sets generating coverage.

Poor Man's Global Traffic Manager

Sometimes we need to add redundancy to some service or server which happen to be a public-facing entry point of our infrastructure. For example, imagine we want to add a high availability pair for a load balancer which sits on the edge of network and forwards traffic to alive backend servers.

                                             ┌─────────────┐
                                             │             │
                                      ┌─────►│  Backend 1  │
                                      │      │             │
                                      │      └─────────────┘

Introduction
Standards
Common combinations
Conversion
Verification/Inspection
Tips for recognising

Introduction

It happens that there are many standards for storing cryptography materials (key, certificate, ...) and it isn't always obvious to know which standard is used by just looking at file name extension or file content. There are bunch of questions on stackoverflow asking about how to convert from PEM to PKCS#8 or PKCS#12, while many tried to answer the questions, those answers may not help because the correct answer depends on the content inside the PEM file. That is, a PEM file can contain many different things, such as an X509 certificate, a PKCS#1 or PKCS#8 private key. The worst-case scenario is that someone just store a non-PEM content in "something.pem" file.

Pure ESM package

The package that linked you here is now pure ESM. It cannot be require()'d from CommonJS.

This means you have the following choices:

Use ESM yourself. (preferred)
Use import foo from 'foo' instead of const foo = require('foo') to import the package. You also need to put "type": "module" in your package.json and more. Follow the below guide.
If the package is used in an async context, you could use await import(…) from CommonJS instead of require(…).
Stay on the existing version of the package until you can move to ESM.

	$ grep -P "^[ABCDEFabcdefOoIi]{6,6}$" /usr/share/dict/words \| tr 'OoIi' '0011' \| tr '[:lower:]' '[:upper:]' \| awk '{print "#" $0}'
	#ACAD1A
	#B0BB1E
	#DEBB1E
	#AB1DED
	#ACAC1A
	#ACCEDE
	#AC1D1C
	#BAB1ED
	#BA0BAB

	#include <string>
	#include <dlfcn.h>
	#include <stdio.h>
	#include <sys/mman.h>
	#include <unistd.h>
	#include <errno.h>
	#include <stdlib.h>

	using namespace std::literals;

	-- DateDiff function that returns the difference between two timestamps in the given date_part (weeks, months, etc) as an integer
	-- This behaves like the DateDiff function in warehouses like Redshift and Snowflake, which count the boundaries between date_parts
	CREATE OR REPLACE FUNCTION datediff (date_part VARCHAR(30), start_t TIMESTAMP, end_t TIMESTAMP)
	RETURNS INT AS $diff$

	DECLARE
	years INT = 0;
	days INT = 0;
	hours INT = 0;
	minutes INT = 0;

	#!/bin/bash

	gdb -p "$1" -batch -ex 'set {short}$rip = 0x050f' -ex 'set $rax=231' -ex 'set $rdi=0' -ex 'cont'