From: quintus@...
Date: 2014-09-29T14:05:51+00:00
Subject: [ruby-core:65320] [ruby-trunk - Feature #10305] [Open] Method for resolving all autoload statements / Add warning on autoload when used with chroot

Issue #10305 has been reported by Marvin G��lker.

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Feature #10305: Method for resolving all autoload statements / Add warning on autoload when used with chroot
https://bugs.ruby-lang.org/issues/10305

* Author: Marvin G��lker
* Status: Open
* Priority: Normal
* Assignee: 
* Category: core
* Target version: 
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Hi everyone,

I���m currently trying to make my way to create a chrooted process using Dir.chroot. However, once these lines are executed:

~~~ ruby
Dir.chroot("/some/path/here")
Dir.chdir("/")
~~~

all libraries that use the #autoload method (which are quite a lot) fail with LoadErrors everywhere. This is natural, because after being locked into the chroot the referenced paths are simply gone. I could live with that if there was a method to load all the files referenced by #autoload immediately, which I would then simply call before I lock the process into the chroot. However, it appears there is not even a way to get a list of all constants that are to be autoloaded; the #autoload? method only allows checks for specific constants I simply do not have at hand without digging through all the library code, which is infeasable.

Therefore, I suggest do add one of the following methods to Ruby:

1. Kernel#load_autoloads that loads all modules referenced with #autoload right now.
2. Kernel#autoload_list that returns a list of symbols for the constants that are to be autoloaded.

The methods could probably also be on Module rather than on the Kernel module, but I guess this is topic for discussion.

I also suggest that when calling Dir::chroot() and there are constants that are marked as autoloadable, a warning should be printed that the referenced files cannot be loaded if the constants are ever used.

Steps to reproduce the LoadError problem after chroot:

Create a file "foo.rb" with this content:

~~~~~~~~~~~ ruby
autoload :Bar, File.join(Dir.pwd, "bar.rb")

Dir.chroot "/var/empty"
Dir.chdir "/"

Bar.new
~~~~~~~~~~~

Create a file "bar.rb" with this content:

~~~~~~~~~ ruby
class Bar
end
~~~~~~~~~

Ensure you have the directory "/var/empty", and it is empty.

Execute "foo.rb" with root rights.

~~~~~~~~~~~
$ sudo ruby foo.rb
foo.rb:6:in `<main>': cannot load such file -- /home/quintus/foo/bar.rb (LoadError)
~~~~~~~~~~~

Valete,
Marvin



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