GNU bug report logs - #38766
bug: "gzip -l" truncates reported decompressed size to 32 bits

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Package: gzip;

Reported by: Jason Mancini <jayrusman <at> hotmail.com>

Date: Fri, 27 Dec 2019 23:19:01 UTC

Severity: normal

Merged with 17804, 29089, 30935, 30936, 42965, 48424, 52227

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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Report forwarded to bug-gzip <at> gnu.org:
bug#38766; Package gzip. (Fri, 27 Dec 2019 23:19:01 GMT) Full text and rfc822 format available.
Acknowledgement sent to Jason Mancini <jayrusman <at> hotmail.com>:
New bug report received and forwarded. Copy sent to bug-gzip <at> gnu.org. (Fri, 27 Dec 2019 23:19:01 GMT) Full text and rfc822 format available.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jason Mancini <jayrusman <at> hotmail.com>
To: "bug-gzip <at> gnu.org" <bug-gzip <at> gnu.org>
Subject: bug: "gzip -l" truncates reported decompressed size to 32 bits
Date: Fri, 27 Dec 2019 20:35:13 +0000

As title states.

openSUSE Tumbleweed 20191216 (x86_64)
gzip 1.10

(Number delimiters manually added for clarity below.)

# zcat backup.bin.gz | wc -c
67,645,849,600
# gzip -l backup.bin.gz
compressed        uncompressed  ratio uncompressed_name
9,458,450,396    3,221,340,160 -193.6% backup.bin
#

67,645,849,600 => 0xf_c001_c000 => truncate => 0xc001_c000 => 3,221,340,160

Thanks!
Jason Mancini
Information forwarded to bug-gzip <at> gnu.org:
bug#38766; Package gzip. (Sat, 28 Dec 2019 16:37:02 GMT) Full text and rfc822 format available.

Message #8 received at 38766 <at> debbugs.gnu.org (full text, mbox):

From: Antonio Diaz Diaz <antonio <at> gnu.org>
To: Jason Mancini <jayrusman <at> hotmail.com>
Cc: 38766 <at> debbugs.gnu.org
Subject: Re: bug#38766: bug: "gzip -l" truncates reported decompressed size
 to 32 bits
Date: Sat, 28 Dec 2019 17:36:44 +0100

Jason Mancini wrote:
> # zcat backup.bin.gz | wc -c
> 67,645,849,600
> # gzip -l backup.bin.gz
> compressed        uncompressed  ratio uncompressed_name
> 9,458,450,396    3,221,340,160 -193.6% backup.bin

This is a known limitation of the gzip format, and is documented in the manual:

http://www.gnu.org/software/gzip/manual/gzip.html#Invoking-gzip

"The gzip format represents the input size modulo 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:
zcat file.gz | wc -c"


Best regards,
Antonio.
Merged 17804 29089 30935 30936 38766 42965 48424 52227. Request was from Paul Eggert <eggert <at> cs.ucla.edu> to control <at> debbugs.gnu.org. (Wed, 01 Dec 2021 23:34:01 GMT) Full text and rfc822 format available.
bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Thu, 13 Jan 2022 12:24:04 GMT) Full text and rfc822 format available.
This bug report was last modified 2 years and 102 days ago.

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