yushijinhun

C++26 Modules Cheat Sheet

Disclaimer: this cheat sheet is generated by Codex, based on BrickSim, an open-source project that uses this setup in the real world.

Pragmatic patterns for building C++ modules with CMake, Clang, and import std;.

This is a standalone, copy-pastable note aimed at real projects, not a language-lawyer overview. The emphasis is on the setup that tends to work in practice:

• put module interface units in .cppm files
• register them with CMake as a CXX_MODULES file set

yushijinhun

#!/usr/bin/python3
import argparse
from bcc import BPF
import pyroute2

def main():
    parser = argparse.ArgumentParser(description='Redirect traffic to another interface with VLAN')
    subparsers = parser.add_subparsers(dest='command')
    load_parser = subparsers.add_parser('load')
    load_parser.add_argument('--iface-in', required=True, help='Name of interface to attach BPF program')

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/**
 * ra_prefix_filter.c - eBPF program to filter prefixes in IPv6 RA
 * Copyright (C) 2023  Haowei Wen <yushijinhun@gmail.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,

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import { parseIp, stringifyIp } from "ip-bigint";

/**
 * @typedef { { version: 4 | 6; address: bigint; mask: number; } } CIDR
 */

/**
 * @param {string} str
 * @returns {CIDR}
 */

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#include "ring_buffer.h"
#include <string.h>
#include <sys/param.h>

void ringbuf_init(ringbuf_t *rb, uint8_t *buf, size_t buf_size) {
	rb->buf = buf;
	rb->size = buf_size;
	rb->begin = rb->end = 0;
}

yushijinhun

Steps

Check your host IP address on LXD network interface:

$ lxc network show lxdbr0
config:
  ipv4.address: 172.17.233.1/24 # <--- IP address is 172.17.233.1
...

Edit /etc/systemd/resolved.conf.d/lxdbr0.conf:

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Steps

First, create a LXD profile named forward-desktop:

lxc profile create forward-desktop

Edit the profile:

lxc profile forward-desktop

Replace config: {} and devices: {} with:

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• Retrieve keys of those who trust you

  gpg --recv-keys $(gpg --with-colons --no-expensive-trust-checks --list-sigs <your_id> | grep 'User ID not found' | cut -d: -f5 | sort | uniq | xargs)`

• List all keys signed by a given key

  # params: long_keyid
  # 
  function gpg_list_keys_signed_by() {

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// - Adds '--enable-preview' parameter

application {
	applicationDefaultJvmArgs << '--enable-preview'
}

compileJava {
	options.compilerArgs << '--enable-preview'
}

yushijinhun

// - Adds modularity support to Buildship

// Code is originally from https://github.com/java9-modularity/gradle-modules-plugin/issues/33#issue-376998502

apply plugin: 'eclipse'

eclipse {
	classpath {
		file {
			whenMerged {