squashfs-tools-ng VS SDL

... except that that is also subtly broken.

It works if you write multiple UTF-8 code-units in one go, but breaks if you send them in several writes, or if you use the ANSI API (with the A suffix). Guess what the Windows implementation of stdio (printf and friends) does.

I already had some fun with this: https://github.com/AgentD/squashfs-tools-ng/issues/96#issuec...

And we didn't even discuss command line argument passing yet :-)

I tried to test it with the only other two languages I know besides English: German and Mandarin. Specifically also, because the later requires multi-byte characters to work. Getting this to work at all in a Windows terminal on an existing, German Windows 7 installation was an adventure on it's own.

Turns out, trying to write language agnostic command line applications on Windows is a PITA.

IIRC fanalyzer is a fairly recent addition to gcc. Has it become reasonable usable yet?

I recall getting a bit excited when I first read about it, but the results I got where rather bizarre (e.g. every single function that allocated memory and returned a pointer to it was labeled as leaking memory).

It did the fun exercise myself once to riffle through the gcc manpage, cobble together warning flags and massage them into autoconf[1][2].

There is a very handy m4 script in the util-linux source for testing supported warning flags[3].

[1] https://git.infradead.org/mtd-utils.git/blob/HEAD:/configure...

[2] https://github.com/AgentD/squashfs-tools-ng/blob/master/conf...

[3] https://github.com/karelzak/util-linux/blob/master/m4/compil...

> Honestly I think you could be a little more respectful of the project that inspired yours.

I do. I had a lot of great "Huh? That's clever!" moments while reverse engineering the format and formed a mental image of a clearly brilliant programmer who managed to squeeze the last bits out of some data structures using really clever tricks that I myself probably wouldn't have come up with. During that time I gained a lot of respect for the project and the author.

Also, please don't forget: the whole project is the filesystem, the tools are just a part of that. I care about this project, which is why I decided to start this effort in the first place. Which I explicitly did not advertise as a replacement, but an augmentation (see [2]).

> I'd be angry too ... Definitely understandable.

Yes, I agree! And I can understand why in the heat of the moment you might write something angry and threatening. But certainly not if you've had a few weeks time to calm down and think things over.

> And you plagiarized part of his readme.

https://github.com/plougher/squashfs-tools/blob/master/RELEA...

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/lin...

https://github.com/AgentD/squashfs-tools-ng/blob/master/READ...

Oh yes? Which part?

> ... calling it spaghetti code (which isn't immediately verifiable)

Here you go, have fun: https://github.com/plougher/squashfs-tools/blob/master/squas...

However, I cannot blame anyone here, I totally get how those things happen and have witnessed it myself in action:

You write a simple tool supporting a larger project. It's written by the seat of your pants without much planning, since it's not big and does one simple job. Then it gets used in production, eventually requirements change, other people pile on patches, but try to keep the diff small, so it's reviewable and it receives maybe a little less care than the actual project it supports. Nobody bothers to overhaul it or write documentation because, hey, it works, and any large changes might risk breaking things.

Even if nobody is to blame for it, the end result is still the same: an undocumented mess that is hard to wrap your head around if you aren't the original author, who is the only one with the bigger picture.

I tried for roughly a week to pull the code (there are some more files than this and some of the inter dependencies are nasty) apart into stacked utility libraries and a pure command line parsing front end, with the hopes to maybe get this upstream once it is done. I gave up and decided that at this point I understood enough about the format to start afresh and not touch what I believed to be an unmaintained mess.

FWIW there is an on various BSDs that contains "beXXtoh", "leXXtoh", "htobeXX", "htoleXX" where XX is a number of bits (16, 32, 64).

That header is also available on Linux, but glibc (and compatible libraries) put named it instead.

See: man 3 endian (https://linux.die.net/man/3/endian)

Of course it gets a bit hairier if the code is also supposed to run on other systems.

MacOS has OSSwapHostToLittleIntXX, OSSwapLittleToHostIntXX, OSSwapHostToBigIntXX and OSSwapBigToHostIntXX in .

I'm not sure if Windows has something similar, or if it even supports running on big endian machines (if you know, please tell).

My solution for achieving some portability currently entails cobbling together a "compat.h" header that defines macros for the MacOS functions and including the right headers. Something like this:

https://github.com/AgentD/squashfs-tools-ng/blob/master/incl...

This is usually my go-to-solution for working with low level on-disk or on-the-wire binary data structures that demand a specific endianness. In C I use "load/store" style functions that memcpy the data from a buffer into a struct instance and do the endian swapping. The copying is also necessary because the struct in the buffer may not have proper alignment.

In C++ code, all of this can of course be neatly stowed away in a special class with overloaded operators that transparently takes care of everything and "decays" into a single integer and exactly the above code after compilation, but is IMO somewhat cleaner to read and adds much needed type safety.

I once foolishly thought, I'll write a tar parser because, "how hard can it be" [1].

I simply tried to follow the tar(5) man page[2], and got a reference test set from another website posted previously on HN[3].

Along the way I discovered that NetBSD pax apparently cannot handle the PAX format[3] and my parser inadvertently uncovered that git-archive was doing the checksums wrong, but nobody noticed because other tar parsers were more lax about it[4].

As the article describes (as does the man page), tar is actually a really simple format, but there are just so many variants to choose from.

Turns out, if you strive for maximum compatibility, it's easiest to stick to what GNU tar does. If you think about it, IMO in many ways the GNU project ended up doing "embrace, extend, extinguish" with Unix.

[1] https://github.com/AgentD/squashfs-tools-ng/tree/master/lib/...

[2] https://www.freebsd.org/cgi/man.cgi?query=tar&sektion=5

[3] https://mgorny.pl/articles/portability-of-tar-features.html

[4] https://www.spinics.net/lists/git/msg363049.html

A while ago I did some simplistic SquashFS pack/unpack benchmarks[1][2]. I was primarily interested in looking at the behavior of my thread-pool based packer, but as a side effect I got a comparison of compressor speed & ratios over the various available compressors for my Debian test image.

I must say that LZ4 definitely stands out for both compression and uncompression speed, while still being able to cut the data size in half, making it probably quite suitable for life filesystems and network protocols. Particularly interesting was also comparing Zstd and LZ4[3], the former being substantially slower, but at the same time achieving a compression ratio somewhere between zlib and xz, while beating both in time (in my benchmark at least).

[1] https://github.com/AgentD/squashfs-tools-ng/blob/master/doc/...

[2] https://github.com/AgentD/squashfs-tools-ng/blob/master/doc/...

[3] https://github.com/AgentD/squashfs-tools-ng/blob/master/doc/...

Wayland works well on the Steam Deck because Valve controls the whole system. Because they have their own Wayland compositor (Gamescope), they're able to implement protocols to work around issues in Wayland without being delayed by the bureaucratic process of getting them approved. Here's an SDL pull request where a graphics developer at Valve discusses how two protocols necessary for good GPU performance haven't been added to Wayland yet so Valve added equivalent protocols to Gamescope as a workaround: https://github.com/libsdl-org/SDL/pull/9345

One thing to note is that the Steam Deck only uses Wayland for its fullscreen gaming mode. When you exit to its desktop mode (meant for running non-Steam software), it switches to X11.

The linked project doesn't use any ObjC files at all. SDL2 has a bunch of Cocoa files[1] so you did use Cocoa even if unknowingly.

[1] https://github.com/libsdl-org/SDL/tree/main/src/video/cocoa

Correct. It's explained here:

https://github.com/libsdl-org/SDL/pull/9345#issuecomment-201...

XWayland has special hooks into the compositors that normal wayland clients don't get.

Found about this through the release of SDL 3: https://github.com/libsdl-org/SDL/blob/main/build-scripts/SD...

https://github.com/libsdl-org/SDL/blob/main/include/SDL3/SDL_events.h

If that app ran in a 640x480 mode, memory accesses would be just as fast as the VGA applications 25 years ago, correct?

I think there's a lot more going on than that. Here's SDL's current pixel access code:

https://github.com/libsdl-org/SDL/blob/main/src/video/SDL_su...

We use the code examples throughout the article. The ellipsis characters "...." in the code were added by the author of the article. You can find the source files on the official GitHub of libsdl. In addition, each fragment has a reference to a specific area in the code. By the time this article is published, many errors will have already been fixed thanks to the issues we opened (for example, here and there). However, the links in the examples point exactly to the code you see in this article. Not only do we enjoy teasing developers but we also like making their projects a little bit better!

FetchContent_Declare(SDL2 GIT_REPOSITORY https://github.com/libsdl-org/SDL.git GIT_TAG release-2.28.3 ) FetchContent_MakeAvailable(SDL2)

It's not that difficult, I recently started learning to use graphics APIs myself. OpenGL is for linux, etc., directx for windows and vulkan for all platforms. I read through a bunch of forums yesterday and decided to go for vulkan (here is a link to the sdk) for my next small projects because it can run on all platforms. I would recommend to watch a basic tutorial series (like this one) for the graphics api itself to get an understanding of whats going on. And on top of that I use SDL2 for eventhandling and ImGui for the graphical user interface. Here is a link to a guide for setting up vulkan on your platform in case you would go for it.