vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

macshome

How to Defang macOS System Protections

If you want to change things on the root drive of a Mac you will need to take some steps to disable the built in security of the system. Most of these steps are the same regardless if you are on Intel or Apple Silicon. If there is a difference it is noted.

Note that all of these things put a Mac into an unsupported and less secure state.

Make sure you either perform these steps in a VM or that you reset the protections after you are done poking around

Protections and Terms

(This list is not exahustive on the details of each. Check the links at the end for more info.)

panzi

// "License": Public Domain
// I, Mathias Panzenböck, place this file hereby into the public domain. Use it at your own risk for whatever you like.
// In case there are jurisdictions that don't support putting things in the public domain you can also consider it to
// be "dual licensed" under the BSD, MIT and Apache licenses, if you want to. This code is trivial anyway. Consider it
// an example on how to get the endian conversion functions on different platforms.

#ifndef PORTABLE_ENDIAN_H__
#define PORTABLE_ENDIAN_H__

#if (defined(_WIN16) || defined(_WIN32) || defined(_WIN64)) && !defined(__WINDOWS__)

domenic

Auto-deploying built products to gh-pages with GitHub Actions

This is a set up for projects which want to check in only their source files, but have their gh-pages branch automatically updated with some compiled output every time they push.

A file below this one contains the steps for doing this with Travis CI. However, these days I recommend GitHub Actions, for the following reasons:

• It is much easier and requires less steps, because you are already authenticated with GitHub, so you don't need to share secret keys across services like you do when coordinate Travis CI and GitHub.
• It is free, with no quotas.
• Anecdotally, builds are much faster with GitHub Actions than with Travis CI, especially in terms of time spent waiting for a builder.

dropmeaword

Browser histories

Unless you are using Safari on OSX, most browsers will have some kind of free plugin that you can use to export the browser's history. So that's probably the easiest way. The harder way, which seems to be what Safari wants is a bit more hacky but it will also work for other browsers. Turns out that most of them, including Safari, have their history saved in some kind of sqlite database file somewhere in your home directory.

The OSX Finder cheats a little bit and doesn't show us all the files that actually exist on our drive. It tries to protect us from ourselves by hiding some system and application-specific files. You can work around this by either using the terminal (my preferred method) or by using the Cmd+Shft+G in Finder.

Once you locate the file containing the browser's history, copy it to make a backup just in case we screw up.

matthewaveryusa

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <linux/input.h>
#include <time.h>
#include <stdint.h>

int main(int argc, char* argv[]){ 
  sleep(1);

ccbrown

#include <stdio.h>

void DumpHex(const void* data, size_t size) {
	char ascii[17];
	size_t i, j;
	ascii[16] = '\0';
	for (i = 0; i < size; ++i) {
		printf("%02X ", ((unsigned char*)data)[i]);
		if (((unsigned char*)data)[i] >= ' ' && ((unsigned char*)data)[i] <= '~') {
			ascii[i % 16] = ((unsigned char*)data)[i];

saelo

|=-----------------------------------------------------------------------=|
|=-------------=[ 3 Years of Attacking JavaScript Engines ]=-------------=|
|=-----------------------------------------------------------------------=|
|=------------------------------=[ saelo ]=------------------------------=|
|=-----------------------------------------------------------------------=|

The following are some brief notes about the changes that have taken place
since the release of the "Attacking JavaScript Engines" paper [1]. In
general, no big conceptional changes have happened since. Mitigations have
been added to break some of the presented techniques and, as expected, a

mosquito

def ip2hex(cidr, router):
    addr, mask = cidr.split("/")
    mask = int(mask)
    addr = [("%2s" % hex(int(i))[2:]).replace(" ", "0") for i in addr.split(".") if i != "0"]
    parts = mask/8 - len(addr)
    if mask%8 > 0:
        parts += 1
    if parts > 0:
        for i in range(int(parts)):
            addr.append("00")

briancroom

I am trying to determine if it is possible to build a Swift dynamic library which is itself composed of one of more private modules, without needing to expose to that fact to outside users. My hope was that I could build the private module as a static library, which would be linked into the primary (dynamic) library. The dylib could then be deployed together with its swiftmodule and swiftdoc and be imported, with the private module and its symbols not being exposed at all.

Unfortunately, what I'm currently observing seems to indicate that the private module's swiftmodule also has to be available for the primary library to be successfully imported.

This can be reproduced as follows. I have the following directory structure:

./Greeter/Logger/Logger.swift:

public func log(_ message: String) {