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@Earnestly
Earnestly / c99_ub_list.rst
Last active March 29, 2024 03:52
C99 List of Undefined Behavior (193 Cases)

C99 List of Undefined Behavior

From N1256: (See http://port70.net/~nsz/c/c99/n1256.html#J.2)

  • A "shall" or "shall not" requirement that appears outside of a constraint is violated (clause 4).
  • A nonempty source file does not end in a new-line character which is not immediately preceded by a backslash character or ends in a partial preprocessing token or comment (5.1.1.2).
  • Token concatenation produces a character sequence matching the syntax of a universal character name (5.1.1.2).
  • A program in a hosted environment does not define a function named main using one of the specified forms (5.1.2.2.1).
  • A character not in the basic source character set is encountered in a source file, except in an identifier, a character constant, a string literal, a header name, a comment, or a preprocessing token that is never converted to a token (5.2.1).
  • An identifier, comment, string literal, character constant, or header name contains an invalid multibyte character or does not
@shafik
shafik / WhatIsStrictAliasingAndWhyDoWeCare.md
Last active March 28, 2024 20:47
What is Strict Aliasing and Why do we Care?

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

@myusuf3
myusuf3 / delete_git_submodule.md
Created November 3, 2014 17:36
How effectively delete a git submodule.

To remove a submodule you need to:

  • Delete the relevant section from the .gitmodules file.
  • Stage the .gitmodules changes git add .gitmodules
  • Delete the relevant section from .git/config.
  • Run git rm --cached path_to_submodule (no trailing slash).
  • Run rm -rf .git/modules/path_to_submodule (no trailing slash).
  • Commit git commit -m "Removed submodule "
  • Delete the now untracked submodule files rm -rf path_to_submodule
@PixelSergey
PixelSergey / dump.md
Last active March 16, 2024 12:22
Dump games with godmode9

Dumping games with Godmode9

Dumping games is the act of taking a game from your system or gamecart and copying it into a readable format onto your SD card. Dumping is perfectly legal if you keep the dumps to yourself, however sharing these dumps is piracy and is illegal.

This guide will tell you how to dump games from various formats and for various purposes. Dumping 3DS cartriges as .cia files is good if you want to install them to your system. Dumping them as .3ds files is good for emulators. Installed titles cannot be dumped as .3ds files. NDS cartiges can only be dumped as .nds files and cannot be installed (however, you can play them with emulators or flashcarts).

Dumping the RomFS of a game is primarily for romhacking purposess.

@davidnunez
davidnunez / gist:1404789
Created November 29, 2011 13:20
list all installed packages in android adb shell
pm list packages -f
@rygorous
rygorous / gist:e0f055bfb74e3d5f0af20690759de5a7
Created May 8, 2016 06:54
A bit of background on compilers exploiting signed overflow
Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
mysterious cases where it helps?
A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
I think it's useful to know what compiler writers are accomplishing by this.
TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
fairly common cases. The signed overflow UB exploitation is an attempt to work around this.
@paragonie-scott
paragonie-scott / crypto-wrong-answers.md
Last active January 22, 2024 04:20
An Open Letter to Developers Everywhere (About Cryptography)
@eligrey
eligrey / object-watch.js
Created April 30, 2010 01:38
object.watch polyfill in ES5
/*
* object.watch polyfill
*
* 2012-04-03
*
* By Eli Grey, http://eligrey.com
* Public Domain.
* NO WARRANTY EXPRESSED OR IMPLIED. USE AT YOUR OWN RISK.
*/