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Re: big file warning if compressed
From: |
Kevin Rodgers |
Subject: |
Re: big file warning if compressed |
Date: |
Tue, 05 Dec 2006 10:30:14 -0700 |
User-agent: |
Thunderbird 1.5.0.8 (Windows/20061025) |
Richard Stallman wrote:
> That is because Emacs has no way of telling how big it is
> until after uncompressing it.
That's not really true: GNU zip has the --list option, which generates
output like:
compressed uncompr. ratio uncompressed_name
12574759 58689536 78.5% foo.txt
1. How long does that take? Does it get the info instantly
or does it have to effectively uncompress the data to get the info?
gzip --list is fast: On that file, it took 15.9 seconds real time (3.0
user, 9.2 system) to run 1,000 iterations, compared to 7.1 seconds real
(6.3 user, 1.0 sys) for 1 iteration of gunzip --stdout | wc -l.
2. What about other compression formats?
According to http://www.gnu.org/software/gzip/manual/html_node/gzip_4.html
The uncompressed size is given as `-1' for files not in gzip
format, such as compressed `.Z' files
As far as the other compression programs supported by jka-compr.el,
neither compress/uncompress nor bzip2/bunzip2 seem to have this
feature.
You can try working on this, but I'd rather save it for after the
release.
OK. (I've already got an untested patch to add support for it.)
--
Kevin