Add download script method - close #152

build_tests/typical/download.rb

@@ -0,0 +1,45 @@
+default do
+  download "https://github.com/holtrop/rscons/releases/download/v2.3.0/rscons",
+    "rscons-2.3.0",
+    sha256sum: "27a6e0f65b446d0e862d357a3ecd2904ebdfb7a9d2c387f08fb687793ac8adf8"
+  mtime = File.stat("rscons-2.3.0").mtime
+  sleep 1
+  download "https://github.com/holtrop/rscons/releases/download/v2.3.0/rscons",
+    "rscons-2.3.0",
+    sha256sum: "27a6e0f65b446d0e862d357a3ecd2904ebdfb7a9d2c387f08fb687793ac8adf8"
+  unless mtime == File.stat("rscons-2.3.0").mtime
+    raise "mtime changed"
+  end
+end
+
+task "badchecksum" do
+  download "https://github.com/holtrop/rscons/releases/download/v2.3.0/rscons",
+    "rscons-2.3.0",
+    sha256sum: "badbadbadbadbadbadbadbadbadbadbadbadbadbadbadbadbadbadbadbadbad0"
+  puts "continued"
+end
+
+task "nochecksum" do
+  File.binwrite("rscons-2.3.0", "hi")
+  download "https://github.com/holtrop/rscons/releases/download/v2.3.0/rscons",
+    "rscons-2.3.0"
+end
+
+task "redirectlimit" do
+  download "http://github.com/holtrop/rscons/releases/download/v2.3.0/rscons",
+    "rscons-2.3.0",
+    sha256sum: "27a6e0f65b446d0e862d357a3ecd2904ebdfb7a9d2c387f08fb687793ac8adf8",
+    redirect_limit: 0
+end
+
+task "badurl" do
+  download "https://github.com/holtrop/rscons/releases/download/v2.3.0/rscons.nope",
+    "rscons-2.3.0",
+    sha256sum: "27a6e0f65b446d0e862d357a3ecd2904ebdfb7a9d2c387f08fb687793ac8adf8"
+end
+
+task "badhost" do
+  download "http://ksfjliasjlaskdmflaskfmalisfjsd.com/foo",
+    "foo",
+    sha256sum: "27a6e0f65b446d0e862d357a3ecd2904ebdfb7a9d2c387f08fb687793ac8adf8"
+end

lib/rscons.rb

@@ -1,3 +1,5 @@
+require "net/http"
+require "digest"
 require_relative "rscons/ansi"
 require_relative "rscons/application"
 require_relative "rscons/basic_environment"

lib/rscons/script.rb

@@ -37,6 +37,62 @@ module Rscons
         end.sort
       end
 
+      # Download a file.
+      #
+      # @param url [String]
+      #   URL.
+      # @param dest [String]
+      #   Path to where to save the file.
+      # @param options [Hash]
+      #   Options.
+      # @option options [String] :sha256sum
+      #   Expected file checksum.
+      # @option options [Integer] :redirect_limit
+      #   Maximum number of times to allow HTTP redirection (default 5).
+      #
+      # @return [void]
+      def download(url, dest, options = {})
+        options[:redirect_limit] ||= 5
+        unless options[:redirected]
+          if File.exist?(dest) && options[:sha256sum]
+            if Digest::SHA2.hexdigest(File.binread(dest)) == options[:sha256sum]
+              # Destination file already exists and has the expected checksum.
+              return
+            end
+          end
+        end
+        uri = URI(url)
+        use_ssl = url.start_with?("https://")
+        response = nil
+        socketerror_message = ""
+        digest = Digest::SHA2.new
+        begin
+          Net::HTTP.start(uri.host, uri.port, use_ssl: use_ssl) do |http|
+            File.open(dest, "wb") do |fh|
+              response = http.get(uri.request_uri) do |data|
+                fh.write(data)
+                digest << data
+              end
+            end
+          end
+        rescue SocketError => e
+          raise RsconsError.new("Error downloading #{dest}: #{e.message}")
+        end
+        if response.is_a?(Net::HTTPRedirection)
+          if options[:redirect_limit] == 0
+            raise RsconsError.new("Redirect limit reached when downloading #{dest}")
+          else
+            return download(response["location"], dest, options.merge(redirect_limit: options[:redirect_limit] - 1, redirected: true))
+          end
+        end
+        unless response.is_a?(Net::HTTPSuccess)
+          raise RsconsError.new("Error downloading #{dest}")
+        end
+        if options[:sha256sum] && options[:sha256sum] != digest.hexdigest
+          raise RsconsError.new("Unexpected checksum on #{dest}")
+        end
+      end
+
       # Construct a task parameter.
       #
       # @param name [String]

spec/build_tests_spec.rb

@@ -2922,4 +2922,51 @@ EOF
     expect(result.stdout).to_not match /^\s*two\b/
   end
 
+  context "download script method" do
+    it "downloads the specified file unless it already exists with the expected checksum" do
+      test_dir "typical"
+      result = run_rscons(args: %w[-f download.rb])
+      expect(result.stderr).to eq ""
+      expect(result.status).to eq 0
+      expect(File.exist?("rscons-2.3.0")).to be_truthy
+    end
+
+    it "downloads the specified file if no checksum is given" do
+      test_dir "typical"
+      result = run_rscons(args: %w[-f download.rb nochecksum])
+      expect(result.stderr).to eq ""
+      expect(result.status).to eq 0
+      expect(File.exist?("rscons-2.3.0")).to be_truthy
+      expect(File.binread("rscons-2.3.0").size).to be > 100
+    end
+
+    it "exits with an error if the downloaded file checksum does not match the given checksum" do
+      test_dir "typical"
+      result = run_rscons(args: %w[-f download.rb badchecksum])
+      expect(result.stderr).to match /Unexpected checksum on rscons-2.3.0/
+      expect(result.status).to_not eq 0
+    end
+
+    it "exits with an error if the redirect limit is reached" do
+      test_dir "typical"
+      result = run_rscons(args: %w[-f download.rb redirectlimit])
+      expect(result.stderr).to match /Redirect limit reached when downloading rscons-2.3.0/
+      expect(result.status).to_not eq 0
+    end
+
+    it "exits with an error if the download results in an error" do
+      test_dir "typical"
+      result = run_rscons(args: %w[-f download.rb badurl])
+      expect(result.stderr).to match /Error downloading rscons-2.3.0/
+      expect(result.status).to_not eq 0
+    end
+
+    it "exits with an error if the download results in a socket error" do
+      test_dir "typical"
+      result = run_rscons(args: %w[-f download.rb badhost])
+      expect(result.stderr).to match /Error downloading foo: .*ksfjlias/
+      expect(result.status).to_not eq 0
+    end
+  end
+
 end