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From: Martin Hansen on 18 May 2010 02:11
> Maybe you could reimplement the Perl code trying to decompress always
> and trapping the exception when the file is not compressed? Something
> like this:
>
> irb1.9 -rfacets/zlib -rzlib -rstringio
> irb(main):001:0> Zlib.decompress("plain text")
> Zlib::GzipFile::Error: not in gzip format

That is a good idea (I don't think you can rescue exceptions in Perl).
However, I am still uncertain if wise/possible and how to get a single
file handle on a stream from multiple files. I need to do
zipping/unzipping on the fly since I want to work on huge files.



Martin
--
Posted via http://www.ruby-forum.com/.

From: F. Senault on 18 May 2010 07:43
Le 18 mai � 08:11, Martin Hansen a �crit :

>> Maybe you could reimplement the Perl code trying to decompress always
>> and trapping the exception when the file is not compressed? Something
>> like this:
>>
>> irb1.9 -rfacets/zlib -rzlib -rstringio
>> irb(main):001:0> Zlib.decompress("plain text")
>> Zlib::GzipFile::Error: not in gzip format
>
> That is a good idea (I don't think you can rescue exceptions in Perl).
> However, I am still uncertain if wise/possible and how to get a single
> file handle on a stream from multiple files. I need to do
> zipping/unzipping on the fly since I want to work on huge files.

This should work :

require "zlib"

def openf(fn)
File.open(fn) do |f|
sig = f.read(3)
f.rewind
if sig.bytes.to_a == [31, 139, 8] # GZip file signature
gz = Zlib::GzipReader.new(f)
yield gz
gz.close rescue nil
else
yield f
end
end
end

>> openf("toto.gz") { |f| puts f.read }
aljezalkezajlkezaj
=> nil
>> openf("toto2.txt") { |f| puts f.read }
iappoeipozaipza
=> nil

(You'd want to work on the exception handling etc, of course.)

Fred
--
Although I may flirt With all kinds of dirt To the point of disease
Now I want release From all this decay Take it away
And somewhere There's someone who cares With a heart of gold
To have and to hold (Depeche Mode, To Have and to Hold)
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