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https://github.com/zerkman/zzlib
zlib-compressed file depacking library in Lua
https://github.com/zerkman/zzlib
deflate extract gzip lua wtfpl zip zlib
Last synced: 3 months ago
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zlib-compressed file depacking library in Lua
- Host: GitHub
- URL: https://github.com/zerkman/zzlib
- Owner: zerkman
- License: wtfpl
- Created: 2016-08-30T13:14:50.000Z (over 8 years ago)
- Default Branch: master
- Last Pushed: 2024-01-07T18:35:54.000Z (about 1 year ago)
- Last Synced: 2024-07-30T21:09:13.729Z (6 months ago)
- Topics: deflate, extract, gzip, lua, wtfpl, zip, zlib
- Language: Lua
- Size: 24.4 KB
- Stars: 83
- Watchers: 5
- Forks: 20
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
- License: COPYING
Awesome Lists containing this project
README
# zzlib
Copyright (c) 2019-2024 by François Galea (fgalea à free.fr)
This is a pure Lua implementation of a depacker for the zlib DEFLATE(RFC1951)/GZIP(RFC1952) file format.
zzlib also allows the decoding of zlib-compressed data (RFC1950).
Also featured is basic support for extracting files from DEFLATE-compressed ZIP archives
(no support for encryption).
The implementation is pretty fast. It makes use of the built-in bit32 (PUC-Rio
Lua) or bit (LuaJIT) libraries for bitwise operations. Typical run times to
depack lua-5.3.3.tar.gz on a single Core i7-6600U are 0.87s with Lua ≤ 5.2,
0.50s with Lua 5.3, and 0.17s with LuaJIT 2.1.0.
zzlib is distributed under the WTFPL licence. See the COPYING file
or http://www.wtfpl.net/ for more details.
## Usage
There are various ways of using the library.
### Stream from a GZIP file
```
-- import the zzlib library
zzlib = require("zzlib")
-- get the unpacked contents of the file in the 'output' string
local output,err = zzlib.gunzipf("input.gz")
if not output then error(err) end
```
### Read GZIP/zlib data from a string
Read a file into a string, call the depacker, and get a string with the unpacked file contents, as follows:
```
-- import the zzlib library
zzlib = require("zzlib")
...
if use_gzip then
-- unpack the gzip input data to the 'output' string
output = zzlib.gunzip(input)
else
-- unpack the zlib input data to the 'output' string
output = zzlib.inflate(input)
end
```
### Extract a file from a ZIP archive stored in a string
Read a file into a string, call the depacker, and get a string with the unpacked contents of the chosen file, as follows:
```
-- import the zzlib library
zzlib = require("zzlib")
...
-- extract a specific file from the input zip file
output = zzlib.unzip(input,"lua-5.3.4/README")
```
### Process the list of files from a ZIP archive stored in a string
The `zzlib.files()` iterator function allows you to span the whole list of files in a ZIP archive, as follows:
```
for _,name,offset,size,packed,crc in zzlib.files(input) do
print(string.format("%10d",size),name)
end
```
During such a loop, the `packed` boolean variable is set to `true` if the current file is packed. You may then decide to unpack it using this function call:
```
output = zzlib.unzip(input,offset,crc)
```
If the file is not packed, then you can directly extract its contents using `string.sub`:
```
output = input:sub(offset,offset+size-1)
```