A subprocess command builder/runner with a focus on enforcing limits to runtime, memory use, CPU use, and command output.

Add this line to your application's Gemfile:

gem 'comlim'

And then execute:

$ bundle

Or install it yourself as:

$ gem install comlim

(Then get upset when you realise I haven't pushed this to the masses yet).

Limit stdout and stderr to a total of 1KiB.

QuietRunner = Comlim.output(1024)

Limit it to 32MiB of memory.

MemLimitedRunner = QuietRunner.memory(1024 * 1024 * 32)

2 seconds of CPU should be plenty:

CpuMemLimitedRunner = MemLimitedRunner.cputime(2)

4 seconds of runtime, followed by summary execution:

RestrictedRunner = CpuMemLimitedRunner.walltime(4)

Use it to run inline Ruby:

RubyRunner = RestrictedRunner.command('ruby').arg('-e')

And finally use it to run some potentially runaway process:

result = RubyRunner.arg('loop { puts "SMASH THE STATE!" }')
pp result
# => #<struct Comlim::Result
# => pid=95544,
# => status=#<Process::Status: pid 95544 exit 1>,
# => exitstatus=1,
# => exitreason=Comlim::ExitReason::OutputExceeded,
# => stdout=
# =>  "SMASH THE STATE!\n" +
# =>  "SMASH THE STATE!\n" +
# =>  ...
# =>  [SUBVERSIVE MESSAGE REDACTED]
# => stderr="",
# => walltime=0.1225816321093589>

Bwahahaha. Ahem.

Eh, it probably mostly works on my machine. I guess?

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/Freaky/comlim.

The gem is available as open source under the terms of the MIT License.