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# frozen_string_literal: true
module Gitlab
class UntrustedRegexp
# This class implements support for Ruby syntax of regexps
# and converts that to RE2 representation:
# /<regexp>/<flags>
class RubySyntax
PATTERN = %r{^/(?<regexp>.*)/(?<flags>[ismU]*)$}.freeze
# Checks if pattern matches a regexp pattern
# but does not enforce it's validity
def self.matches_syntax?(pattern)
pattern.is_a?(String) && pattern.match(PATTERN).present?
end
# The regexp can match the pattern `/.../`, but may not be fabricatable:
# it can be invalid or incomplete: `/match ( string/`
def self.valid?(pattern, fallback: false)
!!self.fabricate(pattern, fallback: fallback)
end
def self.fabricate(pattern, fallback: false)
self.fabricate!(pattern, fallback: fallback)
rescue RegexpError
nil
end
def self.fabricate!(pattern, fallback: false)
raise RegexpError, 'Pattern is not string!' unless pattern.is_a?(String)
matches = pattern.match(PATTERN)
raise RegexpError, 'Invalid regular expression!' if matches.nil?
begin
create_untrusted_regexp(matches[:regexp], matches[:flags])
rescue RegexpError
raise unless fallback &&
Feature.enabled?(:allow_unsafe_ruby_regexp, default_enabled: false)
create_ruby_regexp(matches[:regexp], matches[:flags])
end
end
def self.create_untrusted_regexp(pattern, flags)
pattern.prepend("(?#{flags})") if flags.present?
UntrustedRegexp.new(pattern, multiline: false)
end
private_class_method :create_untrusted_regexp
def self.create_ruby_regexp(pattern, flags)
options = 0
options += Regexp::IGNORECASE if flags&.include?('i')
options += Regexp::MULTILINE if flags&.include?('m')
Regexp.new(pattern, options)
end
private_class_method :create_ruby_regexp
end
end
end
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