From: nagachika00@...
Date: 2014-08-24T14:42:16+00:00
Subject: [ruby-core:64534] [ruby-trunk - Bug #10101] Zlib::GzipReader produce different outputs for different methods applied

Issue #10101 has been updated by Tomoyuki Chikanaga.

Backport changed from 2.0.0: UNKNOWN, 2.1: UNKNOWN to 2.0.0: REQUIRED, 2.1: REQUIRED

Hello, Rafael.
Thank you for your report.

I can reproduce with your sample on 2.0.0p433 and 2.1.3, and it can be easily reproduced similar case with large gzip'ed file as follows.

    $ dd if=/dev/zero of=foo count=5000
    $ gzip foo
    $ ruby test1.rb foo.gz
    Size of read: 2560000
    Size of each_byte: 2097151
    Size of readbyte: 2560000

In this case, only `each_byte' returns wrong value. I suspect there are several different cause.
I don't have time to investigate this right now.
And zlib has no maintainer according to https://bugs.ruby-lang.org/projects/ruby/wiki/MaintainersStdlib
Are there anyone who can handle this?

----------------------------------------
Bug #10101: Zlib::GzipReader produce different outputs for different methods applied
https://bugs.ruby-lang.org/issues/10101#change-48464

* Author: Rafael Manzo
* Status: Open
* Priority: Normal
* Assignee: 
* Category: ext
* Target version: 
* ruby -v: ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-linux]
* Backport: 2.0.0: REQUIRED, 2.1: REQUIRED
----------------------------------------
The methods `read`, `readbyte` and `each_byte` are producing different outputs. Comparing with the unziped file, only the result of readbyte is correct according to the size but comparing byte per byte with the original file sometimes gives differences at the same positions.

This part of the differences I couldn't reproduce in a way that I could share on the internet because the original file is a magnetic resonance image subject to confidentiality.

But fortunately I was able to reproduce the bug on input size. I've attached a script that illustrates the problem and here is the link for the file that I've used for the following sample output:

https://drive.google.com/file/d/0B3O0CbLN-q0TcmhGR0RGeWM2UHM/edit?usp=sharing

Sorry about the size, but I couldn't produce a smaller file.

<code>
[manzo@WALL-A gz_debug]$ ruby -v
ruby 2.1.2p95 (2014-05-08 revision 45877) [x86_64-linux]
[manzo@WALL-A gz_debug]$ ruby test1.rb sample.gz 
Size of read: 45102570
Size of each_byte: 4668
Size of readbyte: 45158752
</code>

I hope I'm right on this report and thank you a lot for your time!


---Files--------------------------------
test1.rb (316 Bytes)


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