saagarjha’s gists

saagarjha / a14.plist.txt

Created January 16, 2024 04:08

plutil -p /usr/share/kpep/a14.plist

	{
	"internal" => 0
	"name" => "a14"
	"system" => {
	"cpu" => {
	"aliases" => {
	"Cycles" => "FIXED_CYCLES"
	"Instructions" => "FIXED_INSTRUCTIONS"
	}
	"architecture" => "arm64"

saagarjha / file_drain.c

Created November 11, 2023 10:01

"Drain" files while they are processed to reduce free disk space requirements

	// Sometimes you have a large file on a small disk and would like to "transform"
	// it in some way: for example, by decompressing it. However, you might not have
	// enough space on disk to keep both the the compressed file and the
	// decompressed results. If the process can be done in a streaming fashion, it
	// would be nice if the file could be "drained"; that is, the file would be
	// sequentially deleted as it is consumed. At the start you'd have 100% of the
	// original file, somewhere in the middle you'd have about half of the original
	// file and half of your output, and by the end the original file will be gone
	// and you'll be left with just the results. If you do it this way, you might
	// be able to do the entire operation without extra space!

saagarjha / mmap_vs_read.c

Created September 29, 2023 10:42

Test whether mmap or read is faster on your computer

	// As seen on:
	// https://federated.saagarjha.com/notice/AaEMQpJBSbxhLyxYzg
	// https://twitter.com/_saagarjha/status/1707423903969341949

	// Compiling: gcc mmap_vs_read.c -O3 -o mmap_vs_read
	// Usage: ./mmap_vs_read <bigfile> <mmap\|read>

	#include <fcntl.h>
	#include <stddef.h>
	#include <stdio.h>

saagarjha / MetadataExtractor.js

Created February 17, 2023 09:36

Apple's metadata extraction code for link previews in Messages, taken from macOS Ventura 13.3 Beta (22E5219e)

	//
	// LinkPresentation
	// Copyright © 2015-2020 Apple Inc. All rights reserved.
	//

	// FIXME: Twitter equivalents?

	(function () {

	var MetadataExtractor = {

saagarjha / FB11988552.html

Created February 12, 2023 16:44

Leak memory in Safari from a website

	<!DOCTYPE html>
	<html>
	<head>
	<script>
	var database;

	async function foo() {
	let key = await window.crypto.subtle.generateKey(
	{
	name: "HMAC",

saagarjha / crash_with_message.h

Created February 7, 2023 08:34

Poor man's replacement for abort_report_np (https://twitter.com/mraleph/status/1622598001855287300)

	// Usage should be fairly self-explanatory, just paste this in a header and use
	// CRASH_WITH_MESSAGE("foobar") in your function.
	// Example backtrace:
	// Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
	// 0 ??? 0x1022d8000 CRASHING IN test.c:20 (foobar) + 0
	// 1 a.out 0x1022d7f60 main + 24
	// 2 dyld 0x195f07e50 start + 2544

	#define STRINGIFY(a) #a
	#define CRASH_FUNCTION_NAME(file, line, message) "CRASHING IN " file ":" STRINGIFY(line) " (" message ")"

saagarjha / fix_FB11645580.mm

Last active January 1, 2024 04:09

Fix an Xcode hang caused by FB11645580 due to IDERunDestination registering thousands of duplicate KVO observers

	// https://gist.github.com/saagarjha/ed701e3369639410b5d5303612964557
	#import "swizzler.h"
	#import <Foundation/Foundation.h>
	#import <cstddef>
	#import <cstdlib>
	#import <dlfcn.h>
	#import <mach-o/dyld.h>
	#import <mutex>
	#import <string>
	#import <tuple>

saagarjha / binja_stripped_selector_stub_fixup.py

Last active October 22, 2023 17:33

Fix up objc_msgSend selector stubs in Binary Ninja

	for function in filter(lambda f: f.name == "_objc_msgSend", bv.functions):
	selector = function.lowest_address + 4
	selector = list(bv.get_code_refs_from(selector))[0]
	selector = list(bv.get_data_refs(selector))[0]
	selector = list(bv.get_data_refs_from(selector))[0]
	selector = bv.get_data_var_at(selector).value
	# objc_msgSend itself, probably
	if not selector:
	continue
	selector = selector[:-1].decode()

saagarjha / path_hook.mm

Created October 17, 2022 18:57

Some code I used to help write FB11698739. Very rough and posted as-is: don't copy things blindly from the internet, but that applies doubly so here!

	// clang path_hook.mm -shared -ldl -g -framework Foundation path_hook.o -L/usr/lib/swift

	#include <cassert>
	#include <cstdint>
	#include <dlfcn.h>
	#include <mach/arm/vm_param.h>
	#include <mach/kern_return.h>
	#include <mach/mach_init.h>
	#include <mach/vm_map.h>
	#include <mach/vm_prot.h>

saagarjha / watchOSURLSchemes.txt

Created June 19, 2022 00:18

watchOS app URL schemes

	// Generated via
	// grep -r -l CFBundleURLSchemes /Volumes/JupiterB19R570.N121bOS/ \| xargs -n1 sh -c '/usr/libexec/PlistBuddy -c "Print" "$0" > /dev/null 2>&1 && echo && echo "$0" && /usr/libexec/PlistBuddy -c "Print :CFBundleURLTypes" "$0"'
	// -[LSApplicationWorkspace openURL:configuration:completionHandler] is a good way to open these


	/Volumes/JupiterB19R570.N121bOS/System/Library/CoreServices/Carousel.app/Info.plist
	Array {
	Dict {
	CFBundleURLName = com.apple.carousel
	CFBundleURLSchemes = Array {

Saagar Jha saagarjha