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Answer 1

A:

See http://en.wikipedia.org/wiki/DEFLATE#Encoder_implementations

It lists a number of software implementations, including gzip, so that should work. Did you try just running gzip on the file? Does it not recognize the format automatically?

How do you know it is compressed using DEFLATE? What tool was used to compress the file?

Marc van Kempen 2010-07-05 10:01:22

felixge 2010-07-05 10:07:07

Ah ok, so the data is compressed using the zlib library, then it stands to reason you can uncompress using zlib too! You could try a ruby, perl or other binding to wip up a simple deflate script. Or if you're not afraid to try your hands at compiling a c program, try this:http://www.zlib.net/zlib_how.html

Marc van Kempen 2010-07-05 10:20:56

NB I just tried it and zpipe.c works on git objects, compile with 'gcc -o zpipe zpipe.c -I/path/to/zlib.h -L/path/to/zlib -lz'use:./zpipe -d < .git/objects/83/535d1693580f04824a2ddd22bd241fd00533d8(use -d for decompression)

Marc van Kempen 2010-07-05 12:09:18

Answer 2

+1 A:

If I understand the hint in the Wikipedia article mentioned by Marc van Kempen, you can use puff.c from zlib directly.

mkluwe 2010-07-05 10:08:21

Yeah, I looked at that. But I would definitely prefer a commonly packaged tool.

felixge 2010-07-05 10:10:53

Choosing this as the "right" answer as it is the closest. Otherwise those SO folks who complain about my low acceptance rate will get their forks out again : ).I'm actually using a little PHP script now : /

felixge 2010-07-05 20:53:54

@fekixge: Well, thanks. I tried it yesterday on an gzipped file (stripping the gzip header away) but it crashed, unluckily. I'm debugging now as this is quite interesting to me.

mkluwe 2010-07-06 09:48:42

Answer 3

A:

Why don't you just use git's tools to access the data? This should be able to read any git object:

git show --pretty=raw <object SHA-1>

igorw 2010-07-05 10:22:47

I'm preparing for a little git-workshop I'm going to give soon. One of the examples involves showing what 'git add' does by hand.De-compressing the blob using git itself doesn't make sense since I want to show the underlaying functionality. I will probably end up using ruby or perl, but I was hoping I could stick with a simple bash oneliner.

felixge 2010-07-05 10:58:26

Or `git cat-file -p c0fb67ab3fda7909000da003f4b2ce50a53f43e7`

Jakub Narębski 2010-07-05 12:51:49

Answer 4

A:

It has a header on it - before you deflate it you'll need to strip everything before and including the first null byte from the data, btw.

Scott Chacon 2010-07-05 14:10:48

I think the header is compressed using DEFLATE as well. That is unless the example I'm learning from is wrong: http://progit.org/book/ch9-2.html : )

felixge 2010-07-05 20:52:11

haha - you're right. I should really read my own stuff before I comment on things.

Scott Chacon 2010-07-06 15:28:47

Answer 5

A:

Something like the following will print the raw content, including the "$type $length\0" header:

perl -MCompress::Zlib -e 'undef $/; print uncompress(<>)' < .git/objects/27/de0a1dd5a89a94990618632967a1c86a82d577

araqnid 2010-07-06 10:17:37

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Deflate command line tool

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