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PROTECTING PATHS IN MACRO EXPANSIONS BY EXTENDING UTF-8

March 05, 2024
nullprogram.com/blog/2024/03/05/

> After a year I’ve finally came up with an elegant solution to a vexing
> u-config problem. The pkg-config format uses macros to generate build flags
> through recursive expansion. Some flags embed file system paths, but to the
> macro system it’s all strings. The output is also ultimately just one big
> string, which the receiving shell splits into fields. If a path contains
> spaces, or shell metacharacters, u-config must escape them so that shells
> treat them as part of a token. But how can u-config itself distinguish
> incidental spaces in paths from deliberate spaces between flags? What about
> other shell metacharacters in paths? My solution is to extend UTF-8 to encode
> metadata that survives macro expansion.

[…]
 * c
 * trick


AN IMPROVED CHKSTK FUNCTION ON WINDOWS

February 05, 2024
nullprogram.com/blog/2024/02/05/

> If you’ve spent much time developing with Mingw-w64 you’ve likely seen the
> symbol ___chkstk_ms, perhaps in an error message. It’s a little piece of
> runtime provided by GCC via libgcc which ensures enough of the stack is
> committed for the caller’s stack frame. The “function” uses a custom ABI and
> is implemented in assembly. So is the subject of this article, a slightly
> improved implementation soon to be included in w64devkit as libchkstk
> (-lchkstk).

[…]
 * c
 * cpp
 * win32
 * rant


TWO HANDY GDB BREAKPOINT TRICKS

January 28, 2024
nullprogram.com/blog/2024/01/28/

> Over the past couple months I’ve discovered a couple of handy tricks for
> working with GDB breakpoints. I figured these out on my own, and I’ve not seen
> either discussed elsewhere, so I really ought to share them.

[…]
 * c
 * cpp


SO YOU WANT CUSTOM ALLOCATOR SUPPORT IN YOUR C LIBRARY

December 17, 2023
nullprogram.com/blog/2023/12/17/

> This article was discussed on Hacker News and on reddit.
> 
> Users of mature C libraries conventionally get to choose how memory is
> allocated — that is, when it cannot be avoided entirely. The C standard never
> laid down a convention — perhaps for the better — so each library re-invents
> an allocator interface. Not all are created equal, and most repeat a few
> fundamental mistakes. Often the interface is merely a token effort, to check
> off that it’s “supported” without actual consideration to its use. This
> article describes the critical features of a practical allocator interface,
> and demonstrates why they’re important.

[…]
 * c


MY PERSONAL C CODING STYLE AS OF LATE 2023

October 08, 2023
nullprogram.com/blog/2023/10/08/

> This article was discussed on Hacker News and on reddit.
> 
> This has been a ground-breaking year for my C skills, and paradigm shifts in
> my technique has provoked me to reconsider my habits and coding style. It’s
> been my largest personal style change in years, so I’ve decided to take a
> snapshot of its current state and my reasoning. These changes have produced
> significant productive and organizational benefits, so while most is certainly
> subjective, it likely includes a few objective improvements. I’m not saying
> everyone should write C this way, and when I contribute code to a project I
> follow their local style. This is about what works well for me.

[…]
 * c


A SIMPLE, ARENA-BACKED, GENERIC DYNAMIC ARRAY FOR C

October 05, 2023
nullprogram.com/blog/2023/10/05/

> Previously I presented an arena-friendly hash map applicable to any
> programming language where one might use arena allocation. In this third
> article I present a generic, arena-backed dynamic array. The details are
> specific to C, as the most appropriate mechanism depends on the language (e.g.
> templates, generics). Just as in the previous two articles, the goal is to
> demonstrate an idea so simple that a full implementation fits on one terminal
> pager screen — a concept rather than a library.

[…]
 * c


AN EASY-TO-IMPLEMENT, ARENA-FRIENDLY HASH MAP

September 30, 2023
nullprogram.com/blog/2023/09/30/

> My last article had tips for for arena allocation. This next article
> demonstrates a technique for building bespoke hash maps that compose nicely
> with arena allocation. In addition, they’re fast, simple, and automatically
> scale to any problem that could reasonably be solved with an in-memory hash
> map. To avoid resizing — both to better support arenas and to simplify
> implementation — they have slightly above average memory requirements. The
> design, which we’re calling a hash-trie, is the result of fruitful
> collaboration with NRK, whose sibling article includes benchmarks. It’s my new
> favorite data structure, and has proven incredibly useful. With a couple
> well-placed acquire/release atomics, we can even turn it into a lock-free
> concurrent hash map.

[…]
 * c
 * optimization


ARENA ALLOCATOR TIPS AND TRICKS

September 27, 2023
nullprogram.com/blog/2023/09/27/

> This article was discussed on Hacker News.
> 
> Over the past year I’ve refined my approach to arena allocation. With
> practice, it’s effective, simple, and fast; typically as easy to use as
> garbage collection but without the costs. Depending on need, an allocator can
> weigh just 7–25 lines of code — perfect when lacking a runtime. With the core
> details of my own technique settled, now is a good time to document and share
> lessons learned. This is certainly not the only way to approach arena
> allocation, but these are practices I’ve worked out to simplify programs and
> reduce mistakes.

[…]
 * c


HOW TO LINK IDENTICAL FUNCTION NAMES FROM DIFFERENT DLLS

August 27, 2023
nullprogram.com/blog/2023/08/27/

> For the typical DLL function call you declare the function prototype (via
> header file), you inform the link editor (ld, link) that the DLL exports a
> symbol with that name (import library), it matches the declared name with this
> export, and it becomes an import in your program’s import table. What happens
> when two different DLLs export the same symbol? The link editor will pick the
> first found. But what if you want to use both exports? If they have the same
> name, how could program or link editor distinguish them? In this article I’ll
> demonstrate a technique to resolve this by creating a program which links with
> and directly uses two different C runtimes (CRTs) simultaneously.

[…]
 * c
 * win32


EVERYTHING YOU NEVER WANTED TO KNOW ABOUT WIN32 ENVIRONMENT BLOCKS

August 23, 2023
nullprogram.com/blog/2023/08/23/

> In an effort to avoid programming by superstition, I did a deep dive into the
> Win32 “environment block,” the data structure holding a process’s environment
> variables, in order to better understand it. Along the way I discovered
> implied and undocumented behaviors. (The environment block must not to be
> confused with the Process Environment Block (PEB) which is different.) Because
> I cannot possibly retain all the quirky details in my head for long, I’m
> writing them down for future reference. I ran my tests on different Windows
> versions as far back as Windows XP SP3 in order to fill in gaps where
> documentation is ambiguous, incomplete, or wrong. Overall conclusion: Correct,
> direct manipulation of an environment block is impossible in the general case
> due to under-specified and incorrect documentation. This has important
> consequences mainly for programming language runtimes.

[…]
 * c
 * win32


NULL PROGRAM


CHRIS WELLONS

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