this is true and it is onaly a problem with an ! at the end of the name. there are quite some places where we discover jar urls like

my.jar!/script.rb
file:my.jar!/script.rb
jar:file:my.jar!/script.rb

by looking for !/
since this feature is more a legacy feature I think it can be more restrictive by looking for .jar!/ instead

To give more detail, I found the problem in the context of digital preservation in a library. We get sets of files with all kinds of bizarre (to me) naming convention/directory structures coming from our various units. In particular our archive unit is likely to get weird stuff and want to preserve it as is. I think the particular case I found was something like ../../PLUS!/../...

So if a general solution is possible I'd certainly be appreciative, but I do bear in mind that I wouldn't be the one doing it.

Also I'm a little confused by the idea that it is a legacy feature - is there equivalent functionality for Pathname#relative_path_from elsewhere in ruby or the stdlib?

Thanks,
Howard

the legacy feature is to allow such jar like paths with file: or jar:file: or no protocol prefix at all. I will have a look and please feel free to report any other pathname/directory-name which gives you problems.

Thanks. I was getting another (different) error that went away when I hacked around this issue, but I'll see if I can reproduce it and see if it is a jruby issue or not.

I found the other problem. Let me know if you'd like me to open another ticket for it. This time it's when the path involves some unicode characters:

jruby-9.0.0.0 :007 > x = "joe"
=> "joe"
jruby-9.0.0.0 :008 > y = "joe/⸀䐀攀氀攀琀攀䴀攀/fred"
=> "joe/⸀䐀攀氀攀琀攀䴀攀/fred"
jruby-9.0.0.0 :009 > Pathname.new(y).relative_path_from(Pathname.new(x))
TypeError: no implicit conversion from nil to integer
from org/jruby/RubyString.java:2870:in []' from /services/medusa/.rvm/rubies/jruby-9.0.0.0/lib/ruby/stdlib/pathname.rb:48:inchop_basename'
from /services/medusa/.rvm/rubies/jruby-9.0.0.0/lib/ruby/stdlib/pathname.rb:113:in cleanpath_aggressive' from /services/medusa/.rvm/rubies/jruby-9.0.0.0/lib/ruby/stdlib/pathname.rb:91:incleanpath'
from /services/medusa/.rvm/rubies/jruby-9.0.0.0/lib/ruby/stdlib/pathname.rb:493:in relative_path_from' from (irb):9:in'
from org/jruby/RubyKernel.java:979:in eval' from org/jruby/RubyKernel.java:1292:inloop'
from org/jruby/RubyKernel.java:1099:in catch' from org/jruby/RubyKernel.java:1099:incatch'
from /services/medusa/.rvm/rubies/jruby-9.0.0.0/bin/irb:13:in `'

Here's the MRI version, which works:

2.2.3 :006 > x = "joe"
=> "joe"
2.2.3 :007 > y = "joe/⸀䐀攀氀攀琀攀䴀攀/fred"
=> "joe/⸀䐀攀氀攀琀攀䴀攀/fred"
2.2.3 :008 > Pathname.new(y).relative_path_from(Pathname.new(x))
=> #Pathname:⸀䐀攀氀攀琀攀䴀攀/fred

please file a second issue since it is really something else going wrong ;)
thanx

Okay, filed as issue #3396.