100 lines
2.0 KiB
Markdown
100 lines
2.0 KiB
Markdown
Requires
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========
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Ruby MRI or Ruby 1.9.
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Will not work with Rubinius! It does not support $SAFE.
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I do not know JRuby.
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Install
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=======
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gem install Safebox
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Usage
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=====
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First load the safebox:
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require 'safebox'
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The most things in your Safebox are possible:
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value = Safebox.eval "1+2**9" # => 513
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value = Safebox.eval {|| 1+2**8 } # => 257
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You can use a String or a Proc, also as argument:
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value = Safebox.eval lambda {|| 1+2**7 }
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More complex code with classes and everything else...
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value = Safebox.eval do
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class Mail
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attr_accessor :subject, :body, :to, :from
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def generate
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[ "To: #{@to}", "From: #{@from}",
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"Subject: #{@subject}", '', @body ].join "\n"
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end
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end
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mail = Mail.new
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mail.from, mail.to, mail.subject = "me", "root", "Plz install Ruby :)"
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mail.subject = "..."
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mail.generate
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end
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Only some good things are not possible:
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Safebox.eval "$stdout.puts 'I am OK!'" # not possible :(
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But, very bad code will not damage your system.
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Safebox.eval "class Unsecure;def self.code() system 'rm *' ; end end; Unsecure.code" # will fail :)
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This will raise a SecurityError.
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What is with raised exceptions, like SecurityError or others?
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Safebox.eval "raise Exception"
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This will print the Exception to Console.
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You want to get the Exception?
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ret = Safebox.run "raise Exception"
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ret # => [:exception, #<Exception>]
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What is *Safebox.run*?
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ret = Safebox.run "1+2**9"
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ret # => [:value, 513]
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It returns the value or the raised exception. -- Nothing else.
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You should know, Ruby is not stupid. I am very surprised,
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because this is not possible:
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aA = Safebox.eval do
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class A
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def to_s
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'Owned!'
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end
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end
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A.new
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end
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aA.to_s # => SecurityError: calling insecure method: to_s
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*A#to_s* is defined in our *Safebox*, so every call outside can be a security hole.
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But you can use #to_s in an other Safebox, withour any risk:
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Safebox.eval aA.method( :to_s) # => "Owned!" # Not really :)
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Behind Safebox
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==============
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It uses only a Thread, $SAFE=4 and some code for automatism.
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The real magic is Ruby itself.
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