Class: Facter::Core::Execution::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/facter/core/execution/base.rb

Direct Known Subclasses

Posix, Windows

Instance Method Summary collapse

Instance Method Details

#execute(command, options = {}) ⇒ Object 



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# File 'lib/facter/core/execution/base.rb', line 30

def execute(command, options = {})

  on_fail = options.fetch(:on_fail, :raise)

  # Set LC_ALL and LANG to force i18n to C for the duration of this exec; this ensures that any code that parses the
  # output of the command can expect it to be in a consistent / predictable format / locale
  with_env 'LC_ALL' => 'C', 'LANG' => 'C' do

    expanded_command = expand_command(command)

    if expanded_command.nil?
      if on_fail == :raise
        raise Facter::Core::Execution::ExecutionFailure.new, "Could not execute '#{command}': command not found"
      else
        return on_fail
      end
    end

    out = ''

    begin
      wait_for_child = true
      out = %x{#{expanded_command}}.chomp
      wait_for_child = false
    rescue => detail
      if on_fail == :raise
        raise Facter::Core::Execution::ExecutionFailure.new, "Failed while executing '#{expanded_command}': #{detail.message}"
      else
        return on_fail
      end
    ensure
      if wait_for_child
        # We need to ensure that if this command exits early then any spawned
        # children will be reaped. Process execution is frequently
        # terminated using Timeout.timeout but since the timeout isn't in
        # this scope we can't rescue the raised exception. The best that
        # we can do is determine if the child has exited, and if it hasn't
        # then we need to spawn a thread to wait for the child.
        #
        # Due to the limitations of Ruby 1.8 there aren't good ways to
        # asynchronously run a command and grab the PID of that command
        # using the standard library. The best we can do is blindly wait
        # on all processes and hope for the best. This issue is described
        # at https://tickets.puppetlabs.com/browse/FACT-150
        Thread.new { Process.waitall }
      end
    end

    out
  end
end

#with_env(values) ⇒ Object 



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# File 'lib/facter/core/execution/base.rb', line 3

def with_env(values)
  old = {}
  values.each do |var, value|
    # save the old value if it exists
    if old_val = ENV[var]
      old[var] = old_val
    end
    # set the new (temporary) value for the environment variable
    ENV[var] = value
  end
  # execute the caller's block, capture the return value
  rv = yield
# use an ensure block to make absolutely sure we restore the variables
ensure
  # restore the old values
  values.each do |var, value|
    if old.include?(var)
      ENV[var] = old[var]
    else
      # if there was no old value, delete the key from the current environment variables hash
      ENV.delete(var)
    end
  end
  # return the captured return value
  rv
end