Class: Cirron::Injector

Inherits:
Object
  • Object
show all
Defined in:
lib/injector.rb

Constant Summary collapse

VALID_ACTIONS = 
[
  'error', 'retval', 'signal', 'syscall', 'delay_enter', 'delay_exit',
  'poke_enter', 'poke_exit', 'when'
].freeze

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Injector

Returns a new instance of Injector.



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# File 'lib/injector.rb', line 13

def initialize
  @rules = []
end

Instance Method Details

#inject(syscall, action, value, when_condition = nil) ⇒ Object 



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# File 'lib/injector.rb', line 17

def inject(syscall, action, value, when_condition = nil)
  unless VALID_ACTIONS.include?(action)
    raise ArgumentError, "Invalid action: #{action}. Valid actions are: #{VALID_ACTIONS.join(', ')}"
  end

  @rules << Rule.new(syscall, action, value, when_condition)
end

#run(timeout = 10) ⇒ Object 



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# File 'lib/injector.rb', line 25

def run(timeout = 10)
  trace_file = Tempfile.new('cirron_inject')
  trace_file_path = trace_file.path
  trace_file.close
  trace_file.unlink
  parent_pid = Process.pid

  cmd = ["strace", "--quiet=attach,exit", "-f", "-o", trace_file_path, "-p", parent_pid.to_s]

  @rules.each do |rule|
    inject_arg = "inject=#{rule.syscall}:#{rule.action}=#{rule.value}"
    inject_arg += ":when=#{rule.when}" if rule.when
    cmd.concat(["-e", inject_arg])
  end

  strace_proc = spawn(*cmd, :out => "/dev/null", :err => "/dev/null")

  begin
    deadline = Time.now + timeout
    until File.exist?(trace_file_path)
      if Time.now > deadline
        raise Timeout::Error, "Failed to start strace within #{timeout}s."
      end
      sleep 0.1
    end

    sleep 0.1

    yield if block_given?
  ensure
    Process.kill('INT', strace_proc) rescue nil
    Process.wait(strace_proc) rescue nil
  end
end