Subject: bin/28581: gzip not compat w. RFC/GNU gzip on mtime values in header
To: None <,>
From: James Chacon <>
List: netbsd-bugs
Date: 12/07/2004 23:21:00
>Number:         28581
>Category:       bin
>Synopsis:       gzip not compat w. RFC/GNU gzip on mtime values in header
>Confidential:   no
>Severity:       serious
>Priority:       low
>Responsible:    bin-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Dec 07 23:21:00 +0000 2004
>Originator:     James Chacon
>Release:        NetBSD 2.0G
System: NetBSD quix 2.0G NetBSD 2.0G (QUIX) #3: Tue Aug 17 23:48:17 CDT 2004 roo
t@quix:/local0/src/sys/arch/i386/compile/QUIX i386
Architecture: i386
Machine: i386

RFC 1952 for gzip states the mtime value in the header comes from the mtime
of the file being compressed. 

If the data doesn't come from a file it should be set to the current time.

0 is only used if no time stamp is available (I'm guessing for systems which
cannot determine current time?).

In any case, GNU gzip honors all of these by the following:

1. For files passed on the command line, stat the file and use st_mtime
2. For data coming through stdin, fstat stdin and if IS_REG use st_mtime
3. For anything else use time(2) (i.e. pipline)

Ours fails #2 and #3 by assuming that anything redirecting stdout should put
mtime = 0 in the header.


gzip file > file.gz

and hexdump and look at the mtime. It'll be the current time and not the
mtime from the file.


Make handle_stdout take a time value in gzip.c