Validate Ruby Syntax using Ruby











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0
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I need to validate that a given string is valid Ruby syntax, programmatically, using Ruby. I imagine one way I can do this is by running the code in an EVAL statement, and detecting syntax errors that way.



What's a more proper, safer way I can accomplish this?






ruby validation syntax







share|improve this question
























  • Instead of running the code with EVAL, perhaps just run ruby -c?
    – lurker
    Nov 19 at 17:07










  • I need to do this programmatically in the controller action that receives the form submission, and I'd prefer not to use programmatically access the filesystem or command line to do so, unless I'm misunderstanding. Thanks for your help.
    – choey
    Nov 19 at 17:13






  • 3




    This sounds extremely dangerous. Is there any way to do this other than by posting and running raw Ruby code? What's the actual objective here? There's really no "safe" way to run arbitrary code. Shopify has made an effort to contain Ruby in a sandbox so you may want to consider that approach.
    – tadman
    Nov 19 at 17:26












  • Definitely, executing the code, as in an eval, would be extremely dangerous, which is why I'd rather a different solution. The goal here is to ensure a string has valid ruby syntax, without executing any arbitrary code.
    – choey
    Nov 19 at 17:32






  • 1




    @sawa thank you for clarifying this - I'll remove the rails references from the question.
    – choey
    yesterday















up vote
0
down vote

favorite












I need to validate that a given string is valid Ruby syntax, programmatically, using Ruby. I imagine one way I can do this is by running the code in an EVAL statement, and detecting syntax errors that way.



What's a more proper, safer way I can accomplish this?






ruby validation syntax







share|improve this question
























  • Instead of running the code with EVAL, perhaps just run ruby -c?
    – lurker
    Nov 19 at 17:07










  • I need to do this programmatically in the controller action that receives the form submission, and I'd prefer not to use programmatically access the filesystem or command line to do so, unless I'm misunderstanding. Thanks for your help.
    – choey
    Nov 19 at 17:13






  • 3




    This sounds extremely dangerous. Is there any way to do this other than by posting and running raw Ruby code? What's the actual objective here? There's really no "safe" way to run arbitrary code. Shopify has made an effort to contain Ruby in a sandbox so you may want to consider that approach.
    – tadman
    Nov 19 at 17:26












  • Definitely, executing the code, as in an eval, would be extremely dangerous, which is why I'd rather a different solution. The goal here is to ensure a string has valid ruby syntax, without executing any arbitrary code.
    – choey
    Nov 19 at 17:32






  • 1




    @sawa thank you for clarifying this - I'll remove the rails references from the question.
    – choey
    yesterday













up vote
0
down vote

favorite









up vote
0
down vote

favorite











I need to validate that a given string is valid Ruby syntax, programmatically, using Ruby. I imagine one way I can do this is by running the code in an EVAL statement, and detecting syntax errors that way.



What's a more proper, safer way I can accomplish this?






ruby validation syntax







share|improve this question















I need to validate that a given string is valid Ruby syntax, programmatically, using Ruby. I imagine one way I can do this is by running the code in an EVAL statement, and detecting syntax errors that way.



What's a more proper, safer way I can accomplish this?






ruby validation syntax




ruby validation syntax






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited yesterday

























asked Nov 19 at 17:01









choey

218




218












  • Instead of running the code with EVAL, perhaps just run ruby -c?
    – lurker
    Nov 19 at 17:07










  • I need to do this programmatically in the controller action that receives the form submission, and I'd prefer not to use programmatically access the filesystem or command line to do so, unless I'm misunderstanding. Thanks for your help.
    – choey
    Nov 19 at 17:13






  • 3




    This sounds extremely dangerous. Is there any way to do this other than by posting and running raw Ruby code? What's the actual objective here? There's really no "safe" way to run arbitrary code. Shopify has made an effort to contain Ruby in a sandbox so you may want to consider that approach.
    – tadman
    Nov 19 at 17:26












  • Definitely, executing the code, as in an eval, would be extremely dangerous, which is why I'd rather a different solution. The goal here is to ensure a string has valid ruby syntax, without executing any arbitrary code.
    – choey
    Nov 19 at 17:32






  • 1




    @sawa thank you for clarifying this - I'll remove the rails references from the question.
    – choey
    yesterday


















  • Instead of running the code with EVAL, perhaps just run ruby -c?
    – lurker
    Nov 19 at 17:07










  • I need to do this programmatically in the controller action that receives the form submission, and I'd prefer not to use programmatically access the filesystem or command line to do so, unless I'm misunderstanding. Thanks for your help.
    – choey
    Nov 19 at 17:13






  • 3




    This sounds extremely dangerous. Is there any way to do this other than by posting and running raw Ruby code? What's the actual objective here? There's really no "safe" way to run arbitrary code. Shopify has made an effort to contain Ruby in a sandbox so you may want to consider that approach.
    – tadman
    Nov 19 at 17:26












  • Definitely, executing the code, as in an eval, would be extremely dangerous, which is why I'd rather a different solution. The goal here is to ensure a string has valid ruby syntax, without executing any arbitrary code.
    – choey
    Nov 19 at 17:32






  • 1




    @sawa thank you for clarifying this - I'll remove the rails references from the question.
    – choey
    yesterday
















Instead of running the code with EVAL, perhaps just run ruby -c?
– lurker
Nov 19 at 17:07




Instead of running the code with EVAL, perhaps just run ruby -c?
– lurker
Nov 19 at 17:07












I need to do this programmatically in the controller action that receives the form submission, and I'd prefer not to use programmatically access the filesystem or command line to do so, unless I'm misunderstanding. Thanks for your help.
– choey
Nov 19 at 17:13




I need to do this programmatically in the controller action that receives the form submission, and I'd prefer not to use programmatically access the filesystem or command line to do so, unless I'm misunderstanding. Thanks for your help.
– choey
Nov 19 at 17:13




3




3




This sounds extremely dangerous. Is there any way to do this other than by posting and running raw Ruby code? What's the actual objective here? There's really no "safe" way to run arbitrary code. Shopify has made an effort to contain Ruby in a sandbox so you may want to consider that approach.
– tadman
Nov 19 at 17:26






This sounds extremely dangerous. Is there any way to do this other than by posting and running raw Ruby code? What's the actual objective here? There's really no "safe" way to run arbitrary code. Shopify has made an effort to contain Ruby in a sandbox so you may want to consider that approach.
– tadman
Nov 19 at 17:26














Definitely, executing the code, as in an eval, would be extremely dangerous, which is why I'd rather a different solution. The goal here is to ensure a string has valid ruby syntax, without executing any arbitrary code.
– choey
Nov 19 at 17:32




Definitely, executing the code, as in an eval, would be extremely dangerous, which is why I'd rather a different solution. The goal here is to ensure a string has valid ruby syntax, without executing any arbitrary code.
– choey
Nov 19 at 17:32




1




1




@sawa thank you for clarifying this - I'll remove the rails references from the question.
– choey
yesterday




@sawa thank you for clarifying this - I'll remove the rails references from the question.
– choey
yesterday












2 Answers
2






active

oldest

votes

















up vote
1
down vote



accepted










Let the code string be code. The standard way is to do something like this:



begin

  RubyVM::InstructionSequence.compile(code)

  nil

rescue Exception => e

  ... # Put code here to return `e` itself, print its message, or whatever you like

end


If an error is raised and is rescued, that error will display the syntax error. If not (and nil is returned), then code is syntactically valid Ruby code (which does not guarantee that it is free of other types of errors).



The comments saying it is dangerous to do, etc, does not seem to make sense.






share|improve this answer





















  • Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
    – choey
    2 days ago












  • Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
    – sawa
    2 days ago


















up vote
0
down vote













I'd consider checking this in the browser with Opal - https://github.com/opal/opal






share|improve this answer





















  • This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
    – choey
    2 days ago













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2 Answers
2






active

oldest

votes








2 Answers
2






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
1
down vote



accepted










Let the code string be code. The standard way is to do something like this:



begin

  RubyVM::InstructionSequence.compile(code)

  nil

rescue Exception => e

  ... # Put code here to return `e` itself, print its message, or whatever you like

end


If an error is raised and is rescued, that error will display the syntax error. If not (and nil is returned), then code is syntactically valid Ruby code (which does not guarantee that it is free of other types of errors).



The comments saying it is dangerous to do, etc, does not seem to make sense.






share|improve this answer





















  • Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
    – choey
    2 days ago












  • Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
    – sawa
    2 days ago















up vote
1
down vote



accepted










Let the code string be code. The standard way is to do something like this:



begin

  RubyVM::InstructionSequence.compile(code)

  nil

rescue Exception => e

  ... # Put code here to return `e` itself, print its message, or whatever you like

end


If an error is raised and is rescued, that error will display the syntax error. If not (and nil is returned), then code is syntactically valid Ruby code (which does not guarantee that it is free of other types of errors).



The comments saying it is dangerous to do, etc, does not seem to make sense.






share|improve this answer





















  • Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
    – choey
    2 days ago












  • Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
    – sawa
    2 days ago













up vote
1
down vote



accepted







up vote
1
down vote



accepted






Let the code string be code. The standard way is to do something like this:



begin

  RubyVM::InstructionSequence.compile(code)

  nil

rescue Exception => e

  ... # Put code here to return `e` itself, print its message, or whatever you like

end


If an error is raised and is rescued, that error will display the syntax error. If not (and nil is returned), then code is syntactically valid Ruby code (which does not guarantee that it is free of other types of errors).



The comments saying it is dangerous to do, etc, does not seem to make sense.






share|improve this answer












Let the code string be code. The standard way is to do something like this:



begin

  RubyVM::InstructionSequence.compile(code)

  nil

rescue Exception => e

  ... # Put code here to return `e` itself, print its message, or whatever you like

end


If an error is raised and is rescued, that error will display the syntax error. If not (and nil is returned), then code is syntactically valid Ruby code (which does not guarantee that it is free of other types of errors).



The comments saying it is dangerous to do, etc, does not seem to make sense.







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 26 at 6:36









sawa

128k27193297




128k27193297












  • Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
    – choey
    2 days ago












  • Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
    – sawa
    2 days ago


















  • Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
    – choey
    2 days ago












  • Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
    – sawa
    2 days ago
















Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
– choey
2 days ago






Beautiful - this is exactly what I was looking for. I had previously stated in the question that this code string is coming from the front-end via a ruby editor and ajax, which I later removed to simplify the question, but that is probably why there are comments saying the eval approach is dangerous. I didn't want to be executing arbitrary code coming from the internet, so this solution is much better.
– choey
2 days ago














Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
– sawa
2 days ago




Using eval may be dangerous, but the comments that I mentioned are those that do not mention eval but say that doing this is dangerous.
– sawa
2 days ago












up vote
0
down vote













I'd consider checking this in the browser with Opal - https://github.com/opal/opal






share|improve this answer





















  • This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
    – choey
    2 days ago

















up vote
0
down vote













I'd consider checking this in the browser with Opal - https://github.com/opal/opal






share|improve this answer





















  • This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
    – choey
    2 days ago















up vote
0
down vote










up vote
0
down vote









I'd consider checking this in the browser with Opal - https://github.com/opal/opal






share|improve this answer












I'd consider checking this in the browser with Opal - https://github.com/opal/opal







share|improve this answer












share|improve this answer



share|improve this answer










answered Nov 19 at 17:57









Andrzej Krzywda

1818




1818












  • This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
    – choey
    2 days ago




















  • This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
    – choey
    2 days ago


















This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
– choey
2 days ago






This is very cool, and I may use it for checking the syntax on the front-end, but I'm mainly looking for a back-end solution.
– choey
2 days ago




















 

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