entityfs-users — Mailing list for EntityFS users.

Re: [Entityfs-users] Jar in Jar filesystem

[Karl G. <kar...@en...>]

Hi Jan,

Sorry for the late answer. You are probably working on something 
completely different by now.

Anyway. The reason for the FCTFileBacked requirement is that the file 
system implementation uses Java's JarFile object, which wants a File in 
its constructor.

It would be possible to base the file system implementation on At4J's 
Zip implementation instead. That only requires that the Zip or Jar file 
supports the FCRandomAccess capability, i.e. that a RandomAccess object 
can be opened on it. I think, without having looked into it, that would 
be possible for most nested Jar or Zip files, since files that are 
already compressed will probably be stored as STORED (i.e. not 
compressed once more) in a Jar or Zip file.

However, that would require the rewriting of the current Zip and Jar 
file system to use At4J instead.

Regards
/Karl

[Entityfs-users] Jar in Jar filesystem

[Finis, J. <jan...@ca...>]

Hello,

I am using EntityFS to build a jar/war analyzer which analyzes the files in jar/war files. With entityFS I can just use the JAR File like a normal file system. Great stuff, thanks for that!

However, I get this exception when trying to create a file system from a jar file in another jar file (since jars often contain other jars, this recursive jar analysis is necessary):
java.lang.IllegalArgumentException: The file implementation must support the FCTFileBacked capability
      at org.entityfs.jar.JarFileSystemBuilder.setJarFile(JarFileSystemBuilder.java:106)

It seems that it is just not allowed to create a file system from a jar in a jar (since it is not file backed). That is a pity :(. Am I doing something wrong, or is there a workaround? Or do I really have to unpack the outer jar to analyze the inner one (this would take away the elegance that entityFS offered).

Thanks for your help.

Best Regards
Jan Finis
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