12 ms·
How are zlib, gzip and zip related?
- encom 3y ago(2013)
- melagonster 3y agoFor people who first read this: the sweet part is in the comments :)
- dcow 3y agoWhat’s even more sad is that the SO community has since consequently destroyed SO as the home for this type of info. This post would now be considered off topic as it’s “not a good format for a Q&A site”. You’d never see it happen today. Truly sad.
- barrkel 3y agoThing is, it could only be that way in its early days, when the vanguard of users came to it from word of mouth, from following Joel Spolsky or Coding Horror or their joint podcast. The audience is much bigger now and with the long tail of people, the number willing to put effort into good questions is too low, and on-topicness is a simple quality bar which can improve the signal to noise ratio.
- dcow 3y agoExcept, I doubt anybody would argue that a lower signal to noise ratio has improved the site. (Plus, has the actual metric even improved and how is it measured?) And, did anybody ever stop to ask whether S:N should even be the champion metric in the first place, at a product level? With a philosophy of “Google is our homepage”, I honestly don’t understand why S:N even matters since search pretty effectively cuts out noise. I guess it makes a mod’s life easier though. The site is less useful today than it’s ever been. The road to hell…
- Dalewyn 3y agoVery broadly, I find the quality/value of a given thing is inversely proportional to how many people are involved. So with regards to the internet: The 90s and early 00s were great, then the internet became mainstream and it all just became Cable TV 2.0.
- s_dev 3y agoThey had a voting system. By having mods decide what was and what wasn't a 'good' question undermined the whole point of the voting system. Mods should use their powers to filter out hate/spam/trolling/egregiously off topic issues not determine relevance/usefulness. As others have pointed out SO was a site with great answers but awful for asking questions. This is why ChatGPT is eating SO for breakfast. Even if a question was super similar to one that was previously asked has value in exactly that it might be phrased slightly better and be a closer match to what people were Googling.
- twic 3y agoA rephrasing of this might be on-topic on retrocomputing: https://retrocomputing.stackexchange.com/q/3083/21450 https://retrocomputing.stackexchange.com/q/3083/21450 But almost nobody reads that.
- zxt_tzx 3y agoRelatedly, I have seen the graph showing the dip in SO traffic by ~30% if I'm not wrong (and the corresponding hot takes that attribute that to the rise of LLMs). I know most people are pessimistic that LLMs will lead to SO and the web in general to be overrun by hallucinated content and AI-training-on-AI-ouroboros, but I wonder if it might instead allow for curious people to query an endlessly patient AI assistant about exactly this kind of information. (A custom GPT perhaps?)
- dcow 3y agoGPT info tools will fully replace SO in most dev workflows if it hasn’t already.
- norenh 3y agoAnd what will GPT info tools learn from, once the public curated sources are gone?
- dylan604 3y agoBy then, AGI will be ready, right?
- dcow 3y agoProbably the great swaths of documentation out there that for most use cases people need not waste time sifting through if a computer can do it faster...
- hawski 3y agoIsn't it fun, that ChatGPT's success poisoned the well for everyone else? :)
- BeetleB 3y agoThis is somewhat revisionist. They would mark stuff like this as off topic even in the early days.
- miyuru 3y agoHis stackexchange profile is a gold mine itslef. https://stackexchange.com/users/1136690/mark-adler#top-answers-container https://stackexchange.com/users/1136690/mark-adler#top-answe...
- stavros 3y agoHah, imagine asking Mark Adler for gzip history references.
- ctur 3y agoWhat a great historical summary. Compression has moved on now but having grown up marveling at PKZip and maximizing usable space on very early computers, as well as compression in modems (v42bis ftw!), this field has always seemed magical. These days it generally is better to prefer Zstandard to zlib/gzip for many reasons. And if you need seekable format, consider squashfs as a reasonable choice. These stand on the shoulders of the giants of zlib and zip but do indeed stand much higher in the modern world.
- michaelrpeskin 3y agoI had forgotten about modem compression. Back in the BBS days when you had to upload files to get new files, you usually had a ratio (20 bytes download for every byte you uploaded). I would always use the PKZIP no compression option for the archive to upload because Z-Modem would take care of compression over the wire. So I didn't burn my daily time limit by uploading a large file and I got more credit for my download ratios. I was a silly kid.
- EvanAnderson 3y agoThat's really clever and likely would have gone unnoticed by a lot of sysops!
- cpeterso 3y agoAnother download ratio trick was to use a file transfer client like Leech Modem, an XMODEM-compatible client that would, after downloading the final data block, tell the server the file transfer failed so it wouldn’t count against your download limit. https://en.m.wikipedia.org/wiki/LeechModem https://en.m.wikipedia.org/wiki/LeechModem
- michaelrpeskin 3y agoThat's awesome! I totally would have used that as a young punk if I knew about it.
- 3y ago
- dustypotato 3y agoFound this hilarious: > This post is packed with so much history and information that I feel like some citations need be added > I am the reference (extracted a part of the conversation)
- FartyMcFarter 3y ago"I'm the one who knocks".
- matheusmoreira 3y ago"I am the hype."
- tyingq 3y agoMaybe a spoiler, but the "I" in "I am the reference" is Mark Adler: https://en.wikipedia.org/wiki/Mark_Adler https://en.wikipedia.org/wiki/Mark_Adler
- signaru 3y agoIt's awesome how he is active on stack overflow for almost anything DEFLATE related. I once tried stuffing deflate compressed vector graphics into PDFs. Among other things, it turns out an Adler-32 checksum is necessary for compliance (some newer PDF viewers will ignore its absence though).
- whalesalad 3y agoReminds me of when I was inadvertently arguing here on HN with the inventor of the actor model about what actors are
- demondemidi 3y agoThat sounds like something I’d do too. If that makes you feel better.
- chupasaurus 3y ago
- wiredfool 3y agoThe real question is: how are zlib and libz related?
- deleted 3y ago[deleted]
- deleted 3y ago[deleted]
- cout 3y agoInteresting -- I did not realize that the zip format supports lzma, bzip2, and zstd. What software supports those compression methods? Can Windows Explorer read zip files produced with those compression methods? (I have been using 7zip for about 15 years to produce archive files that have an index and can quickly extract a single file and can use multiple cores for compression, but I would love to have an alternative, if one exists).
- ForkMeOnTinder 3y ago7zip has a dropdown called "Compression method" in the "Add to Archive" dialog that lets you choose.
- pixl97 3y agoUntil windows 11, no, windows zip only seems to deal with COMPRESS/DEFLATE zip files.
- emmelaich 3y agoFun fact: in a sense. gzip can have multiple files, but not in a specially useful way ... $ echo meow >cat $ echo woof > dog $ gzip cat $ gzip dog $ cat cat.gz dog.gz >animals.gz $ gunzip animals.gz $ cat animals meow woof
- koolba 3y ago> ... but not in a specially useful way ... It can be very useful: https://github.com/google/crfs#introducing-stargz https://github.com/google/crfs#introducing-stargz
- DigiDigiorno 3y agoIt is specially useful, it is not especially/generally useful lol It could be a typo, though I think when we say something "isn't specially/specifically/particularly useful" we mean "compared to the set of all features, specifically this subset feature is not that useful" not that the feature isn't useful for specific things
- emmelaich 3y agoIndeed! I should have written "especially" not "specially"
- lxgr 3y agoWow, that's surprising (at least to me)! Is there a limit in the default gunzip implementation? I'm aware of the concept of ZIP/tar bombs, but I wouldn't have expected gunzip to ever produce more than one output file, at least when invoked without options.
- HexDecOctBin 3y agoIs there an archive format that supports appending diff's of an existing file, so that multiple versions of the same file are stored? PKZIP has a proprietary extension (supposedly), but I couldn't find any open version of that. (I was thinking of a creating a version control system whose .git directory equivalent is basically an archive file that can easily be emailed, etc.)
- pizza 3y agoNew versions of zstd allow you to produce patches using the trained dictionary feature
- raggi 3y agoThe answer is good, but is missing a key section: Salty form: They're all quite slow compared to modern competitors.
- levzettelin 3y agoWhat are some of those modern competitors?
- scq 3y agozstd is over 4x faster than zlib, while having a better compression ratio. http://facebook.github.io/zstd/ http://facebook.github.io/zstd/
- raggi 3y agoFor zlib compatible workloads, there are cloudflare patches and chromium forks, intel forks, and zlib-ng which are compatible but >50% faster. (I think the cloudflare patches eventually made it into upstream zlib, but you may not see that in your distro for a decade). lz4 and zstd have both been very popular since their release, they're similar and by the same author, though zstd has had more thorough testing and fuzzing, and is more featureful. lz4 maintains an extremely fast decompression speed. Snappy also performs very well, with zstd and snappy having very close performance with tuning to achieve comparable compression levels. In recent years Zstd has started to make heavy inroads in broader usage in OSS with a number of distro package managers moving to it and observing substantial benefits. There are HTTP extensions to make it available which Chrome originally resisted but I believe it's now finally coming there too (https://chromestatus.com/feature/6186023867908096 https://chromestatus.com/feature/6186023867908096). In gaming circles there's also Oodle and friends from RAD tools which are now available in Unreal engine as builtin compression offerings (since 4.27+). You could see the effects of this in for example Ark Survival Evolved (250GB) -> Ark Survival Ascended (75GB, with richer models & textures), and associated improved load times.
- exposition 3y agoThere's also pzip/punzip (https://github.com/ybirader https://github.com/ybirader) for those wanting more performant (concurrent) zip/unzip. Disclaimer: I'm the author.
- kissgyorgy 3y agoIf you are interested in implementation details, how to unpack/decompress them, check out these Python implementations: - https://github.com/onekey-sec/unblob/blob/main/unblob/handlers/archive/zip.py https://github.com/onekey-sec/unblob/blob/main/unblob/handle... - https://github.com/onekey-sec/unblob/blob/main/unblob/handlers/compression/gzip.py https://github.com/onekey-sec/unblob/blob/main/unblob/handle... - https://github.com/onekey-sec/unblob/blob/main/unblob/handlers/compression/zlib.py https://github.com/onekey-sec/unblob/blob/main/unblob/handle...
- Dwedit 3y agoSee a highly upvoted answer in a question about zlib related things, suspect it was probably posted by Mark Adler, and turn out to be correct.
- eYrKEC2 3y ago[flagged]
- readyplayernull 3y agogzip can be used to (de)compress directories recursively in a variable: FOO=$(tar cf - folderToCompress | gzip | base64) echo $FOO | base64 - d | zcat | tar xf -