zhangyoufu’s gists

zhangyoufu / gist:eb429891f07d593a956476cf483e3944

Created January 28, 2026 07:18

generate random subnet from fc00::/7 ULA prefix

	import ipaddress
	import random

	def generate_random_ula_prefix(prefix_length: int, L: int = 1) -> ipaddress.IPv6Network:
	return ipaddress.IPv6Network((((0xfc\|L)<<120)\|(random.getrandbits(prefix_length-8)<<(128-prefix_length)), prefix_length))

	for prefix_length in range(8, 129):
	print(generate_random_ula_prefix(prefix_length))

zhangyoufu / pppd-lcp-rtt-log-parser.py

Created January 25, 2026 06:30

A Python script to parse and monitor Round-Trip Time (RTT) log files produced by pppd's `lcp-rtt-file` configuration directive.

zhangyoufu / ctypes_from_readonly_buffer.py

Created January 24, 2026 16:37

CPython: fake readwrite buffer from readonly buffer

	import ctypes
	import mmap

	# https://stackoverflow.com/a/34096544
	def fake_readwrite_buffer(obj: object) -> memoryview:
	address = ctypes.c_void_p()
	length = ctypes.c_ssize_t()
	ctypes.pythonapi.PyObject_AsReadBuffer(ctypes.py_object(obj), ctypes.byref(address), ctypes.byref(length))
	return ctypes.memoryview_at(address.value, length, readonly=False)

zhangyoufu / itertools.go

Created January 5, 2026 03:26

itertools-like Cycle and Take in Go

	package main

	import "iter"

	func Cycle[T any](items []T) func(func(T) bool) {
	return func(yield func(T) bool) {
	for {
	for _, item := range items {
	if !yield(item) {
	return

zhangyoufu / find_wifi_channel.py

Created December 28, 2025 02:48

find country code in regdb-wireless

	#!/usr/bin/env python3
	from typing import Optional, TypeAlias
	import dbparse
	import enum

	class Flags(enum.IntFlag):
	NO_OFDM = 1<<0
	NO_CCK = 1<<1
	NO_INDOOR = 1<<2
	NO_OUTDOOR = 1<<3

zhangyoufu / detect-x86-64-abi-version.sh

Created December 12, 2025 02:05

detect x86-64 ABI version on Linux, using /proc/cpuinfo

	#!/bin/bash

	# Note on hybrid CPUs (P-cores/E-cores):
	# Linux /proc/cpuinfo reports only features common to ALL cores.
	# This script will correctly detect the lowest ISA level supported
	# across all core types, which matches glibc's behavior.

	get_x86_64_abi_version() {
	local FLAGS
	local DETECTED_LEVEL

zhangyoufu / log_init.go

Created November 12, 2025 09:54

if stdout is tty: log text to stderr; else: log json to stdout

	import "github.com/mattn/go-isatty"

	func init() {
	if isatty.IsTerminal(os.Stdout.Fd()) {
	slog.SetDefault(slog.New(slog.NewJSONHandler(os.Stdout, nil)))
	}
	}

zhangyoufu / nvme-shutdown.sh

Created October 24, 2025 07:41

zhangyoufu / userChrome.css

Created October 22, 2025 15:19

Firefox UI Customization: Compact Vertical Tab Bar

	@media -moz-pref("sidebar.verticalTabs") {
	:root {
	--tab-block-margin: 0 !important;
	--tab-min-height: 24px !important;
	}
	}

	#tabbrowser-tabs[orient="vertical"] {
	.tabbrowser-tab {
	padding-block: 0 !important;

zhangyoufu / cksum.sh

Created September 14, 2025 08:05

Calculate multiple checksum for a single file

Youfu Zhang zhangyoufu