puppetlabs-stdlib/lib/puppet/parser/functions/validate_absolute_path.rb

module Puppet::Parser::Functions
  newfunction(:validate_absolute_path, :doc => <<-'ENDHEREDOC') do |args|
    Validate the string represents an absolute path in the filesystem.  This function works
    for windows and unix style paths.

    The following values will pass:

        $my_path = 'C:/Program Files (x86)/Puppet Labs/Puppet'
        validate_absolute_path($my_path)
        $my_path2 = '/var/lib/puppet'
        validate_absolute_path($my_path2)
        $my_path3 = ['C:/Program Files (x86)/Puppet Labs/Puppet','C:/Program Files/Puppet Labs/Puppet']
        validate_absolute_path($my_path3)
        $my_path4 = ['/var/lib/puppet','/usr/share/puppet']
        validate_absolute_path($my_path4)

    The following values will fail, causing compilation to abort:

        validate_absolute_path(true)
        validate_absolute_path('../var/lib/puppet')
        validate_absolute_path('var/lib/puppet')
        validate_absolute_path([ 'var/lib/puppet', '/var/foo' ])
        validate_absolute_path([ '/var/lib/puppet', 'var/foo' ])
        $undefined = undef
        validate_absolute_path($undefined)

    ENDHEREDOC

    require 'puppet/util'

    unless args.length > 0 then
      raise Puppet::ParseError, ("validate_absolute_path(): wrong number of arguments (#{args.length}; must be > 0)")
    end

    args.each do |arg|
      # put arg to candidate var to be able to replace it
      candidates = arg
      # if arg is just a string with a path to test, convert it to an array
      # to avoid test code duplication
      unless arg.is_a?(Array) then
        candidates = Array.new(1,arg)
      end
      # iterate over all pathes within the candidates array
      candidates.each do |path|
        # This logic was borrowed from
        # [lib/puppet/file_serving/base.rb](https://github.com/puppetlabs/puppet/blob/master/lib/puppet/file_serving/base.rb)
        # Puppet 2.7 and beyond will have Puppet::Util.absolute_path? Fall back to a back-ported implementation otherwise.
        if Puppet::Util.respond_to?(:absolute_path?) then
          unless Puppet::Util.absolute_path?(path, :posix) or Puppet::Util.absolute_path?(path, :windows)
            raise Puppet::ParseError, ("#{path.inspect} is not an absolute path.")
          end
        else
          # This code back-ported from 2.7.x's lib/puppet/util.rb Puppet::Util.absolute_path?
          # Determine in a platform-specific way whether a path is absolute. This
          # defaults to the local platform if none is specified.
          # Escape once for the string literal, and once for the regex.
          slash = '[\\\\/]'
          name = '[^\\\\/]+'
          regexes = {
            :windows => %r!^(([A-Z]:#{slash})|(#{slash}#{slash}#{name}#{slash}#{name})|(#{slash}#{slash}\?#{slash}#{name}))!i,
            :posix => %r!^/!,
          }
          rval = (!!(path =~ regexes[:posix])) || (!!(path =~ regexes[:windows]))
          rval or raise Puppet::ParseError, ("#{path.inspect} is not an absolute path.")
        end
      end
    end
  end
end