Bug 143782

Oh, I forgot to say, that it seems, that the problem was introduced 
with rpm 4.4.x, because my rebuild using rpm 4.3.x went fine. Hope
that helps you.

Ptr to *.src.rpm please.

http://labs.linuxnetz.de/bugzilla/mod_perl-1.99_19-0.src.rpm
MD5SUM: 1098a7880088a9b4585fb88a42cdd502

[03:26:51] < jbj> rsc: #143782 solved. turns out libmagic equiv of 
file -z is a bit dain bread, nuking MAGIC_COMPRESS fixes mod_perl. 
perhaps connection_cycle.dia needs re-compress. no matter what, 
libmagic is a bit stupid about partial block uncompresses. 
[13:48:57] < jbj> rsc_: rpm-4.4.1 was attempting equivalent of 
file(1) -z to identify what was compressed. doesn't work, don't do 
that was the fix.

Changelog of rpm-4.4.1-0.5 contains:
- revert MAGIC_COMPRESS, real fix is in libmagic (#143782).

So does a bug report for libmagic exist?

Re-assigned to file.

file -z .../connection_cycle.dia (from the mod_perl package)
is a reproducer, look for " ... ERROR: ..." in the output.

Well, what kind of files are these? There sth rotten. I've renamed the
files to unzip them. First let's see that the bug is still here

# file *.gz
bucket_brigades.dia.gz:  gzip compressed data, from Unix
connection_cycle.dia.gz: gzip compressed data, from Unix

# file -z *.gz
bucket_brigades.dia.gz:  XML document text (gzip compressed data, from
Unix)
connection_cycle.dia.gz: ERROR: gzip compressed data, from Unix

And now unzip .. Seems to be broken..

# gunzip connection_cycle.dia.gz
gunzip: connection_cycle.dia.gz: invalid compressed data--crc error
gunzip: connection_cycle.dia.gz: invalid compressed data--length error

Hmm, but I can view the file in midnight commander so I tried

# zcat connection_cycle.dia.gz

some xml stuff, but at the end I can still see this

zcat: connection_cycle.dia.gz: invalid compressed data--crc error
zcat: connection_cycle.dia.gz: invalid compressed data--length error

So writing the data to another file

# zcat connection_cycle.dia.gz > test.dia
zcat: connection_cycle.dia.gz: invalid compressed data--crc error
zcat: connection_cycle.dia.gz: invalid compressed data--length error

Zipping it

# gzip test.dia
# file -z test.dia.gz
test.dia.gz: XML document text (gzip compressed data, was "test.dia",
from Unix)

Here I go, the `file` seems to be fine but the file seems broken to me. 

Rebuilding of MAKEDEV-3.3.12.3-1.src.rpm (from Red Hat Enterprise 
Linux 3 or clones) using rpm-4.4.1-0.7 also fails with the same error, 
but here at the file /var/tmp/MAKEDEV-root/dev/adbmouse :-(

zcat (from gzip) and zlib are similar but different forms of
compression. Don't be tricked.

You are almost certainly correct that the file is strangely
compressed.

However,  the real issue is file and -z handling through libmagic, not
the strangely compressed file. file has flip-flopped from using a gzip
pipe to using zlib several times over the years.

zlib is arguably more efficient than a gzip pipe.

And "ERROR" should not be returned in-band within the libmagic buffer
no matter whether gzip pipe or zlib linkage is used by file.

Does that clarify the problem?

Ignore comment #8 please, this is bug #146623 - but with the same
error message.

I think the file output is correct so I don't see a problem here. The
ERROR is returned because the file which it is trying to uncompress is
broken - what kind of output do you expect here while it has to say
that there's sth rotten in the file.