bugfix: empty file strings from archive readers (#2027)

* bugfix: empty file strings from archive readers

Empty files in archives are sometimes possible (we just ran into this with TGZ), but is never a valid file to extract. So remove it and discount it altogether. Changed structure to support testing of these global calls.

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>

* lint and rebuild

Signed-off-by: Dominik Richter <dominik.richter@gmail.com>

lib/inspec/file_provider.rb

@@ -97,9 +97,10 @@ module Inspec
       @path = path
       @contents = {}
       @files = []
-      ::Zip::InputStream.open(@path) do |io|
+      walk_zip(@path) do |io|
         while (entry = io.get_next_entry)
-          @files.push(entry.name.sub(%r{/+$}, ''))
+          name = entry.name.sub(%r{/+$}, '')
+          @files.push(name) unless name.empty?
         end
       end
     end
@@ -110,10 +111,14 @@ module Inspec
 
     private
 
+    def walk_zip(path, &callback)
+      ::Zip::InputStream.open(path, &callback)
+    end
+
     def read_from_zip(file)
       return nil unless @files.include?(file)
       res = nil
-      ::Zip::InputStream.open(@path) do |io|
+      walk_zip(@path) do |io|
         while (entry = io.get_next_entry)
           next unless file == entry.name
           res = io.read
@@ -131,8 +136,8 @@ module Inspec
       @path = path
       @contents = {}
       @files = []
-      Gem::Package::TarReader.new(Zlib::GzipReader.open(@path)) do |tar|
-        @files = tar.map(&:full_name)
+      walk_tar(@path) do |tar|
+        @files = tar.map(&:full_name).find_all { |x| !x.empty? }
       end
     end
 
@@ -142,11 +147,15 @@ module Inspec
 
     private
 
+    def walk_tar(path, &callback)
+      Gem::Package::TarReader.new(Zlib::GzipReader.open(path), &callback)
+    end
+
     def read_from_tar(file)
       return nil unless @files.include?(file)
       res = nil
       # NB `TarReader` includes `Enumerable` beginning with Ruby 2.x
-      Gem::Package::TarReader.new(Zlib::GzipReader.open(@path)) do |tar|
+      walk_tar(@path) do |tar|
         tar.each do |entry|
           next unless entry.file? && file == entry.full_name
           res = entry.read

test/unit/file_provider_test.rb

@@ -98,6 +98,28 @@ describe Inspec::ZipProvider do
       subject.read('inspec.yml').must_match(/^name: complete$/)
     end
   end
+
+  describe 'applied to a zip with an empty filename' do
+    # Just a placeholder, it will be ignored anyway:
+    let(:cls) {
+      class MockZipProvider < Inspec::ZipProvider
+        Entry = Struct.new(:name)
+        class List < Array
+          alias :get_next_entry :pop
+        end
+        private
+        def walk_zip(path, &callback)
+          list = List.new([Entry.new(''), Entry.new('zipzip'), Entry.new('')])
+          callback.call(list)
+        end
+      end
+      MockZipProvider
+    }
+
+    it 'must contain all files' do
+      cls.new(rand.to_s).files.must_equal %w{zipzip}
+    end
+  end
 end
 
 
@@ -143,6 +165,24 @@ describe Inspec::TarProvider do
       subject.read('inspec.yml').must_match(/^name: complete$/)
     end
   end
+
+  describe 'applied to a tar with an empty filename' do
+    # Just a placeholder, it will be ignored anyway:
+    let(:cls) {
+      class MockTarProvider < Inspec::TarProvider
+        Entry = Struct.new(:full_name)
+        private
+        def walk_tar(path, &callback)
+          callback.call([Entry.new(''), Entry.new('tartar'), Entry.new('')])
+        end
+      end
+      MockTarProvider
+    }
+
+    it 'must contain all files' do
+      cls.new(rand.to_s).files.must_equal %w{tartar}
+    end
+  end
 end
 
 describe Inspec::RelativeFileProvider do