Nico Weber nico

## write_cmyk_ycck_jpegs.cc
// A short demo program that uses libjpeg to write cmyk/ycck jpeg files.
// It's possible to write ycck jpegs using ImageMagick's convert and Photoshop's Save As.
// I haven't found a good way to write subsampled true cmyk jpegs using any of cjpeg, convert, Photoshop, or GIMP though.
// (GIMP 2.99.16 has in-progress cmyk saving support, and by picking 4:2:0 subsampling it writes a 2111 CMYK file.
// But 2111 CMYK files don't make any sense, and 4:2:0 is a YCC term and applying it to CMYK is fairly silly.
// Anyways, I wasn't able to create a 2112 CMYK file, which is what is sometimes seen in pratice -- not that
// having C have more resolution than MY makes a ton of sense either.)
//
// compile with:
//     clang++ -std=c++11 write_cmyk_ycck_jpegs.cc -I ~/Downloads/libjpeg-turbo-3.0.1 -I ~/Downloads/libjpeg-turbo-3.0.1/build -ljpeg -L ~/Downloads/libjpeg-turbo-3.0.1/build

## kpc_demo.c
// =============================================================================
// XNU kperf/kpc demo
// Available for 64-bit Intel/Apple Silicon, macOS/iOS, with root privileges
//
//
// Demo 1 (profile a function in current thread):
// 1. Open directory '/usr/share/kpep/', find your CPU PMC database.
//    For M1 (Pro/Max), the database file is '/usr/share/kpep/a14.plist'.
// 2. Select a few events that you are interested in,
//    add their names to the `profile_events` array below.

## .sh
% cat minimal.txt
package "example"
version "0.0.1"

% ~/Downloads/gengetopt-2.23/src/gengetopt < minimal.txt
% cat cmdline.h
/** @file cmdline.h
 *  @brief The header file for the command line option parser
 *  generated by GNU Gengetopt version 2.23
 *  http://www.gnu.org/software/gengetopt.

## quine.py
  File "quine.py", line 1
    File "quine.py", line 1
    ^
IndentationError: unexpected indent

## c_inline.md

      
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                nico
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              Last active
              July 25, 2023 18:43
            
              
                C vs C++ inline function semantics, and ODR vs /arch:
              
          
    The semantics of inline are one of the areas where C and C++ are pretty different. This post is about the C++ semantics, but the history is interesting, so here's a short summary of it.
The meaning of "inline" is intuitively easy to understand: It gives the compiler a hint that it'd be nice if a function could be inlined. It gets a bit complicated because of two issues:

If the function ends up not being inlined,
where should the definition of the function
be emitted?
If the inline function contains a static local
variable, should that be inlined? Should there
be several copies of the static local, or just one?


## blocks.txt
General Punctuation
U+201x ‐ ‒ – — ― ‖ ‗ ‘ ’ ‚ ‛ “ ” „ ‟
U+202x † ‡ • ‣ ․ ‥ … ‧
U+203x ‰ ‱ ′ ″ ‴ ‵ ‶ ‷ ‸ ‹ › ※ ‼ ‽ ‾ ‿
U+204x ⁀ ⁁ ⁂ ⁃ ⁄ ⁅ ⁆ ⁇ ⁈ ⁉ ⁊ ⁋ ⁌ ⁍ ⁎ ⁏
U+205x ⁐ ⁑ ⁒ ⁓ ⁔ ⁕ ⁖ ⁗ ⁘ ⁙ ⁚ ⁛ ⁜ ⁝ ⁞

Arrows
U+219x ← ↑ → ↓ ↔ ↕ ↖ ↗ ↘ ↙ ↚ ↛ ↜ ↝ ↞ ↟
U+21Ax ↠ ↡ ↢ ↣ ↤ ↥ ↦ ↧ ↨ ↩ ↪ ↫ ↬ ↭ ↮ ↯

## makewinsysroot.bat
@ech off

REM Creates "myroot" which can be used with `clang-cl /winsysroot myroot`

setlocal

REM Adjust this one accordingly:
set VSInstallDir="%ProgramFiles(x86)%\Microsoft Visual Studio\2019\Professional"
set WinSdkDir="%ProgramFiles(x86)%\Windows Kits"

## gist:5bd81b9f887abd48e29f70cdb0978b0c
#!/bin/bash

inotifywait -m -e create -r $1 | while read dir action file; do
  # Coalese additional queued up events, if any
  # If events keep arriving faster than we can read them off stdin here,
  # we'll never run the script! If you're worried about that, set
  # SECONDS to 0 before this loop and make the conditional also check that
  # $SECONDS is smaller than some timeout to make sure that the script runs
  # every now and then. The stdin pipe buffer size means there won't be an
  # unbounded buildup on stdin -- instead inotifywait will block writing

## jpegfuzz.patch
commit 0c783ec6a639401153d96de1f4bc6ec8117c409c
Author: Nico Weber <thakis@chromium.org>
Date:   Sun Jul 19 19:49:54 2020 -0400

    fix one ppm fuzzer issue and two jpeg issues, all harmless DoS

diff --git a/Libraries/LibGfx/JPGLoader.cpp b/Libraries/LibGfx/JPGLoader.cpp
index 57772534d..03f7b2822 100644
--- a/Libraries/LibGfx/JPGLoader.cpp
+++ b/Libraries/LibGfx/JPGLoader.cpp

## bmp fuzz.diff
commit c9d1d14e56d7ed3cb3d43053c06a86229dc9ca65
Author: Nico Weber <thakis@chromium.org>
Date:   Sat Jul 18 22:35:01 2020 -0400

    bmp loader does not validate data_offset, can use that for arbitrary read, with <canvas> can probably leak arbitrary user mem to js

diff --git a/Libraries/LibGfx/BMPLoader.cpp b/Libraries/LibGfx/BMPLoader.cpp
index a6c82ca15..91299749a 100644
--- a/Libraries/LibGfx/BMPLoader.cpp
+++ b/Libraries/LibGfx/BMPLoader.cpp
	// A short demo program that uses libjpeg to write cmyk/ycck jpeg files.
	// It's possible to write ycck jpegs using ImageMagick's convert and Photoshop's Save As.
	// I haven't found a good way to write subsampled true cmyk jpegs using any of cjpeg, convert, Photoshop, or GIMP though.
	// (GIMP 2.99.16 has in-progress cmyk saving support, and by picking 4:2:0 subsampling it writes a 2111 CMYK file.
	// But 2111 CMYK files don't make any sense, and 4:2:0 is a YCC term and applying it to CMYK is fairly silly.
	// Anyways, I wasn't able to create a 2112 CMYK file, which is what is sometimes seen in pratice -- not that
	// having C have more resolution than MY makes a ton of sense either.)
	//
	// compile with:
	// clang++ -std=c++11 write_cmyk_ycck_jpegs.cc -I ~/Downloads/libjpeg-turbo-3.0.1 -I ~/Downloads/libjpeg-turbo-3.0.1/build -ljpeg -L ~/Downloads/libjpeg-turbo-3.0.1/build
	// =============================================================================
	// XNU kperf/kpc demo
	// Available for 64-bit Intel/Apple Silicon, macOS/iOS, with root privileges
	//
	//
	// Demo 1 (profile a function in current thread):
	// 1. Open directory '/usr/share/kpep/', find your CPU PMC database.
	// For M1 (Pro/Max), the database file is '/usr/share/kpep/a14.plist'.
	// 2. Select a few events that you are interested in,
	// add their names to the `profile_events` array below.
	% cat minimal.txt
	package "example"
	version "0.0.1"

	% ~/Downloads/gengetopt-2.23/src/gengetopt < minimal.txt
	% cat cmdline.h
	/** @file cmdline.h
	* @brief The header file for the command line option parser
	* generated by GNU Gengetopt version 2.23
	* http://www.gnu.org/software/gengetopt.
	File "quine.py", line 1
	File "quine.py", line 1
	^
	IndentationError: unexpected indent
	General Punctuation
	U+201x ‐ ‒ – — ― ‖ ‗ ‘ ’ ‚ ‛ “ ” „ ‟
	U+202x † ‡ • ‣ ․ ‥ … ‧
	U+203x ‰ ‱ ′ ″ ‴ ‵ ‶ ‷ ‸ ‹ › ※ ‼ ‽ ‾ ‿
	U+204x ⁀ ⁁ ⁂ ⁃ ⁄ ⁅ ⁆ ⁇ ⁈ ⁉ ⁊ ⁋ ⁌ ⁍ ⁎ ⁏
	U+205x ⁐ ⁑ ⁒ ⁓ ⁔ ⁕ ⁖ ⁗ ⁘ ⁙ ⁚ ⁛ ⁜ ⁝ ⁞

	Arrows
	U+219x ← ↑ → ↓ ↔ ↕ ↖ ↗ ↘ ↙ ↚ ↛ ↜ ↝ ↞ ↟
	U+21Ax ↠ ↡ ↢ ↣ ↤ ↥ ↦ ↧ ↨ ↩ ↪ ↫ ↬ ↭ ↮ ↯
	@ech off

	REM Creates "myroot" which can be used with `clang-cl /winsysroot myroot`

	setlocal

	REM Adjust this one accordingly:
	set VSInstallDir="%ProgramFiles(x86)%\Microsoft Visual Studio\2019\Professional"
	set WinSdkDir="%ProgramFiles(x86)%\Windows Kits"
	#!/bin/bash

	inotifywait -m -e create -r $1 \| while read dir action file; do
	# Coalese additional queued up events, if any
	# If events keep arriving faster than we can read them off stdin here,
	# we'll never run the script! If you're worried about that, set
	# SECONDS to 0 before this loop and make the conditional also check that
	# $SECONDS is smaller than some timeout to make sure that the script runs
	# every now and then. The stdin pipe buffer size means there won't be an
	# unbounded buildup on stdin -- instead inotifywait will block writing
	commit 0c783ec6a639401153d96de1f4bc6ec8117c409c
	Author: Nico Weber <thakis@chromium.org>
	Date: Sun Jul 19 19:49:54 2020 -0400

	fix one ppm fuzzer issue and two jpeg issues, all harmless DoS

	diff --git a/Libraries/LibGfx/JPGLoader.cpp b/Libraries/LibGfx/JPGLoader.cpp
	index 57772534d..03f7b2822 100644
	--- a/Libraries/LibGfx/JPGLoader.cpp
	+++ b/Libraries/LibGfx/JPGLoader.cpp
	commit c9d1d14e56d7ed3cb3d43053c06a86229dc9ca65
	Author: Nico Weber <thakis@chromium.org>
	Date: Sat Jul 18 22:35:01 2020 -0400

	bmp loader does not validate data_offset, can use that for arbitrary read, with <canvas> can probably leak arbitrary user mem to js

	diff --git a/Libraries/LibGfx/BMPLoader.cpp b/Libraries/LibGfx/BMPLoader.cpp
	index a6c82ca15..91299749a 100644
	--- a/Libraries/LibGfx/BMPLoader.cpp
	+++ b/Libraries/LibGfx/BMPLoader.cpp