All Questions
56
questions
0
votes
1
answer
76
views
Storing NTFS File Attributes in a Zip Archive
I have recently written a DEFLATE compressor and decompressor. As far as I understand the fstream Windows gives you does not include NTFS attributes as these are found in the $MFT. I need to go over ...
- 115
0
votes
1
answer
164
views
Is the DEFLATE compression algorithm in ZIP and GZip formats based on LZ77 or LZSS?
Wikipedia states that the DEFLATE algorithm (used among others by the ZIP and the GZip compression formats, but also by the PNG image format) is based on the LZ77 algorithm :
Deflate is a lossless ...
- 381
0
votes
1
answer
50
views
How does a decompressor know the huffman tree that was used by the compressor?
From what i understood Deflate is LZ77 and Huffman encoding but i have been looking at the structure of .zip file but i haven't seen where to extract information about Huffman tree that was used in ...
0
votes
0
answers
19
views
Compression Discrepancy in BMEcat XML Files Generated via Talend vs. eprocat
Hello Stack Overflow community,
I am currently working on a project where I generate a BMEcat XML catalog (version 1.2) using Talend Studio. I have encountered a peculiar issue related to file ...
- 1
0
votes
0
answers
67
views
zlib.js Error code: "Z_DATA_ERROR" errno: -3
When i try to extract one file using node.js with package node-stream-zip its getting error like
code: "Z_DATA_ERROR"
errno: -3
message: "too many length or distance symbols"
stack:...
- 11
1
vote
1
answer
48
views
Heuristics to improve brute forcing the location of a DEFLATE block
I work in the data recovery industry. Sometimes a document (.docx) has the beginning overwritten but most of the file might still be intact. A 'docx' is really just a zip file, and the primary ...
- 618
-1
votes
3
answers
726
views
Compression Gzip/7Zip [closed]
When I calculate the entropy values of files compressed with Gzip, PKZIP, 7ZIP and Winrar, I find that the compression rate of Gzip is higher than the others. The entropy value is higher (indicating ...
- 47
0
votes
3
answers
270
views
Maximum size of compressed data using Python's zlib
I'm writing a Python library that makes ZIP files in a streaming way. If the uncompressed or compressed data of a member of the zip is 4GiB or bigger, then it has to use a particular extension to the ...
- 26.6k
0
votes
2
answers
295
views
Test that a ZIP doesn't require zip64 support
I'm looking to test some Python code makes zip files that dynamically chooses zip32 or zip64, and I would like to assert that in certain cases it really does create valid zip32 files by opening it in ...
- 26.6k
0
votes
2
answers
126
views
Write deflated byte[] into zip file
my data is stored deflated in a database.
You can donwload this data inflated as .txt via app.
Now it should be possible to download the data as .zip
I'm looking for a solution without decompressing ...
- 1,835
1
vote
1
answer
315
views
DEFLATE Block Header
I had a few questions regarding the header of a DEFLATE block, specifically concerning this section:
5 Bits: HLIT, # of Literal/Length codes - 257 (257 - 286)
5 Bits: ...
1
vote
1
answer
261
views
When to form a new DEFLATE block?
When compressing a file or directory into a zip file using DEFLATE, when should a new DEFLATE block be formed? Furthermore, since the maximum code length is 15 bits in DEFLATE, should a new block be ...
0
votes
1
answer
213
views
Deflate Compression Specification
I'm currently looking through the DEFLATE compression specification and am confused about this part:
0 - 15: Represent code lengths of 0 - 15
16: Copy the previous ...
0
votes
2
answers
538
views
Original ZIP size limits 2^32 vs 2^32 - 1. Is there an off by 1 error in Wikipedia?
According to https://en.wikipedia.org/wiki/ZIP_(file_format)#ZIP64
The original .ZIP format had a 4 GB (2^32 bytes) limit on various things (uncompressed size of a file, compressed size of a file, ...
- 26.6k
1
vote
1
answer
353
views
How to get zlib (or another library) to create Type 01 DEFLATE block
I'm writing a DEFLATE uncompressor (in Python), and wanting to test it with Type 01 blocks (i.e. with the fixed Huffman code in of 3.2.6. of RFC 1951.
I know I can create them myself, but I would like ...
- 26.6k