shafik

What is the Strict Aliasing Rule and Why do we care?

(OR Type Punning, Undefined Behavior and Alignment, Oh My!)

What is strict aliasing? First we will describe what is aliasing and then we can learn what being strict about it means.

In C and C++ aliasing has to do with what expression types we are allowed to access stored values through. In both C and C++ the standard specifies which expression types are allowed to alias which types. The compiler and optimizer are allowed to assume we follow the aliasing rules strictly, hence the term strict aliasing rule. If we attempt to access a value using a type not allowed it is classified as undefined behavior(UB). Once we have undefined behavior all bets are off, the results of our program are no longer reliable.

Unfortunately with strict aliasing violations, we will often obtain the results we expect, leaving the possibility the a future version of a compiler with a new optimization will break code we th

F21

This is a quick guide of the commands we use to sign someone's GPG key in a virtual key signing party.

Note: The steps cover only the technical aspects of signing someone's key. Before signing someone's key, you must verify their identity. This is usually done by showing government-issued ID and confirming the key's fingerprint

The commands will work for both GPG and GPG2.

I use Julian's key for the examples. His key id is 2AD3FAE3. You should substitute with the appropriate key id when running the commands.

Signing the key

1. List the keys currently in your keyring: gpg --list-keys.

bradrydzewski

#!/bin/bash
#
# Generates client and server certificates used to enable HTTPS
# remote authentication to a Docker daemon.
#
#     See http://docs.docker.com/articles/https/
#
# To start the Docker Daemon:
#
#     sudo docker -d                 \

fay59

Here's a list of mildly interesting things about the C language that I learned mostly by consuming Clang's ASTs. Although surprises are getting sparser, I might continue to update this document over time.

There are many more mildly interesting features of C++, but the language is literally known for being weird, whereas C is usually considered smaller and simpler, so this is (almost) only about C.

1. Combined type and variable/field declaration, inside a struct scope [https://godbolt.org/g/Rh94Go]

struct foo {
   struct bar {
 int x;

kj800x

preface: Posting these online since it sounds like these notes are somewhat interesting based on a few folks I've shared with. These are semi-rough notes that I basically wrote for myself in case I ever needed to revisit this fix, so keep that in mind.

I recently bought an LG ULTRAGEAR monitor secondhand off of a coworker. I really love it and it's been great so far, but I ran into some minor issues with it in Linux. It works great on both Mac and Windows, but on Linux it displays just a black panel until I use the second monitor to go in and reduce the refresh rate down to 60 Hz.

This has worked decent so far but there's some issues:

• It doesn't work while linux is booting up. The motherboards boot sequence is visible just fine, but as soon as control is handed over to Linux and I'd normally see a splash screen while I'm waiting for my login window, I see nothing.
• It doesn't work on the login screen. This would be fine if login consistently worked on my second screen, but I need to manually switch

munificent

#include <time.h> //  Robert Nystrom
#include <stdio.h> // @munificentbob
#include <stdlib.h> //     for Ginny
#define  r return    //    2008-2019
#define  l(a, b, c, d) for (i y=a;y\
<b; y++) for (int x = c; x < d; x++)
typedef int i;const i H=40;const i W
=80;i m[40][80];i g(i x){r rand()%x;
}void cave(i s){i w=g(10)+5;i h=g(6)
+3;i t=g(W-w-2)+1;i u=g(H-h-2)+1;l(u

kmorcinek

# The following command works for downloading when using Git for Windows:
# curl -LOf http://gist.githubusercontent.com/kmorcinek/2710267/raw/.gitignore
#
# Download this file using PowerShell v3 under Windows with the following comand:
# Invoke-WebRequest https://gist.githubusercontent.com/kmorcinek/2710267/raw/ -OutFile .gitignore
#
# or wget:
# wget --no-check-certificate http://gist.githubusercontent.com/kmorcinek/2710267/raw/.gitignore

# User-specific files

rcarmo

# in /etc/systemd/system
[Unit]
Description=Bluetooth Agent
[Service]
ExecStart=/usr/bin/bt-agent -c NoInputNoOutput
Type=simple
[Install]
WantedBy=multi-user.target

Tho85

Build your own private, encrypted, open-source Dropbox-esque sync folder

Prerequisites:

• One or more clients running a UNIX-like OS. Examples are given for Ubuntu 12.04 LTS, although all software components are available for other platforms as well (e.g. OS X). YMMV
• A cheap Ubuntu 12.04 VPS with storage. I recommend Backupsy, they offer 250GB storage for $5/month. Ask Google for coupon codes.

Software components used:

• Unison for file synchronization
• EncFS for folder encryption

jan-warchol

# Synchronize history between bash sessions
#
# Make history from other terminals available to the current one. However,
# don't mix all histories together - make sure that *all* commands from the
# current session are on top of its history, so that pressing up arrow will
# give you most recent command from this session, not from any session.
#
# Since history is saved on each prompt, this additionally protects it from
# terminal crashes.