gzip -l does not deal correctly with large files

[Knappke, Christian]

Hi,

I used gzip to compress a database backup file.
Afterwards gzip -l says:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> gzip -l compressed_file.gz
         compressed        uncompressed  ratio uncompressed_name
          869130362           411041792 -111.4% compressed_file
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
which is nonsense.

The real uncompressed size is:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> gzip -c -d compressed_file.gz | wc -c
4706009088
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

I use the following gzip release on Windows XP professional:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> gzip -V
gzip 1.3.12
Copyright (C) 2007 Free Software Foundation, Inc.
Copyright (C) 1993 Jean-loup Gailly.
This is free software.  You may redistribute copies of it under the terms of
the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.

Written by Jean-loup Gailly.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Best regards
Christian

________________________________
Christian Knappke
Senior Support Consultant
Active Global Support - Technology
SAP AG
Dietmar-Hopp-Allee 16
D-69190 Walldorf
T   [phone]
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mailto:christian.knappke@...
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[Paul Eggert]

The gzip documentation says:

The @command{gzip} format represents the input size modulo
@math{2^32}, so the uncompressed size and compression ratio are listed
incorrectly for uncompressed files 4 GiB and larger.  To work around
this problem, you can use the following command to discover a large
uncompressed file's true size:

@example
zcat file.gz | wc -c
@end example