From: "Michael W. Ryder" <_mwryder@...>
Date: 2007-06-13T16:00:12+09:00
Subject: Re: File.exists? ignores file extension on windows?

Luke Bayes wrote:
> I just wanted to check in with an issue I ran into last night.
> 
> I was trying to unpack a zip file using the following code which
> appears to be the recommended way to extract using this library.
> 
> ------------------------------8<------------------------------
> 
> Zip::ZipFile::open(zip_file) do |zf|
>   zf.each do |e|
>     fpath = File.join(dir, e.name)
>     FileUtils.mkdir_p(File.dirname(fpath))
>     zf.extract(e, fpath)
>   end
> end
> 
> ------------------------------>8------------------------------
> 
> Unfortunately for me, the archive I was extracting contained two
> sibling files:
> 
> 1) bin/fcsh.exe
> 2) bin/fcsh
> 
> One is obviously an executable and the other is an extension-free
> shell script that points at it.
> 
> The Zip archive was raising a ZipDestinationFileExistsError every time
> it encountered the second, extension-free file (I am attempting to
> build cross-platform tools and was testing in Cygwin and DOS on
> Windows XP).
> 
> As it turns out, the problem isn't in the Zip library at all, but is
> in the Windows version of Ruby File.exists?().
> 

The problem is in Cygwin I believe.  If you enter touch test.exe into 
Cygwin and then enter ls -l test it will show the test.exe file.
This behavior seems to be confined to Cygwin as I don't see the same 
behavior under AIX.


> ------------------------------8<------------------------------
> 
> I was able to faithfully reproduce the problem as follows:
> 
> FileUtils.touch('fcsh.exe')
> puts "exists?: #{File.exists?('fcsh')}"
> 
> # exists?: true
> 
> ------------------------------>8------------------------------
> 
> Another interesting issue was that File.move also raises when you
> attempt to move on top of what Ruby believes is an existing file,
> while File.copy doesn't seem to mind the 'existing' file.
> 
> It was also fascinating that even though File.exists? was returning
> true, if I tried to do anything with that 'existing' file, I would get
> FileNotFound exceptions.
> 
> As it turned out, this is the hack that I came up with at midnight
> last night, is there a different/better workaround that other folks
> know about?
> 
> ------------------------------8<------------------------------
> 
> Zip::ZipFile::open(zip_file) do |zf|
>   zf.each do |e|
>     fpath = File.join(dir, e.name)
>     FileUtils.mkdir_p(File.dirname(fpath))
>     if(File.exists?(fpath) && !File.directory?(fpath))
>       hackpath = fpath + 'hack'
>       zf.extract(e, hackpath)
>       File.copy(hackpath, fpath)
>       File.delete(hackpath)
>     else
>       zf.extract(e, fpath)
>     end
>   end
> end
> 
> ------------------------------>8------------------------------
> 
> I did some quick google searches for this problem and didn't find any
> mentions of it. Where do you folks search for answers to problems like
> this?
> 
> I know that with Java, C#, JavaScript and ActionScript, I'm usually
> able to just fire up google and put in the language and exception name
> - this usually brings me to someone with a similar problem. I haven't
> found that to be the case with Ruby.
> 
> Are there any websites or blogs you have found (or written) that are
> focused on developing cross platform ruby client code?
> 
> What resources do you keep at the top of your list for Ruby
> development?
> 
> 
> Thanks,
> 
> 
> Luke Bayes
> http://www.asserttrue.com
>