3 files changed, 44 insertions(+), 10 deletions(-)

M .rubocop.yml
M lib/dhall/resolve.rb
M test/test_resolve.rb

@@ 20,6 20,9 @@ Metrics/BlockLength:
   Exclude:
     - dhall.gemspec
 
+Metrics/ParameterLists:
+  CountKeywordArgs: false
+
 Metrics/ModuleLength:
   Enabled: false
 

@@ 150,8 150,9 @@ module Dhall
 		end
 
 		class ResolutionSet
-			def initialize(reader)
+			def initialize(reader, max_depth:)
 				@reader = reader
+				@max_depth = max_depth
 				@parents = []
 				@set = Hash.new { |h, k| h[k] = [] }
 			end


@@ 160,6 161,9 @@ module Dhall
 				p = Promise.new
 				if @parents.include?(source.canonical)
 					p.reject(ImportLoopException.new(source))
+				elsif @parents.length + 1 > @max_depth
+					msg = "Max import depth of #{@max_depth} exceeded"
+					p.reject(ImportFailedException.new(msg))
 				else
 					@set[source] << p
 				end


@@ 215,12 219,15 @@ module Dhall
 				path_reader: ReadPathSources,
 				http_reader: StandardReadHttpSources,
 				https_reader: http_reader,
-				environment_reader: ReadEnvironmentSources
+				environment_reader: ReadEnvironmentSources,
+				max_depth: Float::INFINITY
 			)
-				@path_resolutions = ResolutionSet.new(path_reader)
-				@http_resolutions = ResolutionSet.new(http_reader)
-				@https_resolutions = ResolutionSet.new(https_reader)
-				@env_resolutions = ResolutionSet.new(environment_reader)
+				@path_resolutions = ResolutionSet.new(path_reader, max_depth: max_depth)
+				@http_resolutions = ResolutionSet.new(http_reader, max_depth: max_depth)
+				@https_resolutions = ResolutionSet.new(https_reader, max_depth: max_depth)
+				@env_resolutions = ResolutionSet.new(
+					environment_reader, max_depth: max_depth
+				)
 				@deadline = Util::NoDeadline.new
 				@cache = {}
 			end


@@ 307,7 314,8 @@ module Dhall
 				http_reader: ReadHttpSources,
 				https_reader: http_reader,
 				environment_reader: ReadEnvironmentSources,
-				ipfs_public_gateway: "cloudflare-ipfs.com"
+				ipfs_public_gateway: "cloudflare-ipfs.com",
+				max_depth: 50
 			)
 				super(
 					path_reader: ReadPathAndIPFSSources.new(


@@ 317,7 325,7 @@ module Dhall
 						public_gateway: ipfs_public_gateway
 					),
 					http_reader: http_reader, https_reader: https_reader,
-					environment_reader: environment_reader
+					environment_reader: environment_reader, max_depth: max_depth
 				)
 			end
 		end


@@ 325,13 333,15 @@ module Dhall
 		class LocalOnly < Standard
 			def initialize(
 				path_reader: ReadPathSources,
-				environment_reader: ReadEnvironmentSources
+				environment_reader: ReadEnvironmentSources,
+				max_depth: 50
 			)
 				super(
 					path_reader:        path_reader,
 					environment_reader: environment_reader,
 					http_reader:        RejectSources,
-					https_reader:       RejectSources
+					https_reader:       RejectSources,
+					max_depth:          max_depth
 				)
 			end
 		end

@@ 1,6 1,7 @@
 # frozen_string_literal: true
 
 require "base64"
+require "securerandom"
 require "webmock/minitest"
 require "minitest/autorun"
 


@@ 132,6 133,26 @@ class TestResolve < Minitest::Test
 		)
 	end
 
+	def test_forever_no_loop
+		resolver = Dhall::Resolvers::LocalOnly.new(
+			path_reader: lambda do |sources|
+				sources.map do |_|
+					Promise.resolve(nil).then do
+						"./#{SecureRandom.hex}"
+					end
+				end
+			end
+		)
+
+		assert_raises Dhall::ImportFailedException do
+			Dhall.load(
+				"./start",
+				resolver: resolver,
+				timeout:  Float::INFINITY
+			).sync
+		end
+	end
+
 	def test_missing
 		expr = Dhall::Import.new(
 			Dhall::Import::IntegrityCheck.new,