Add hard links. Closes #11

lib/fakefs/fake/file.rb

@@ -1,16 +1,50 @@
 module FakeFS
   class FakeFile
-    attr_accessor :name, :parent, :content
+    attr_accessor :name, :parent
+
+    class Inode
+      def initialize(file_owner)
+        @content = ""
+        @links   = [file_owner]
+      end
+
+      attr_accessor :content
+      attr_accessor :links
+
+      def link(file)
+        links << file unless links.include?(file)
+        file.inode = self
+      end
+    end
 
     def initialize(name = nil, parent = nil)
-      @name = name
+      @name   = name
       @parent = parent
-      @content = ''
+      @inode  = Inode.new(self)
+    end
+
+    attr_accessor :inode
+
+    def content
+      @inode.content
+    end
+
+    def content=(str)
+      @inode.content = str
+    end
+
+    def links
+      @inode.links
+    end
+
+    def link(other_file)
+      @inode.link(other_file)
     end
 
     def clone(parent = nil)
       clone = super()
       clone.parent = parent if parent
+      clone.inode  = inode.clone
       clone
     end
 

lib/fakefs/file.rb

@@ -116,10 +116,22 @@ module FakeFS
     end
     
     def self.link(source, dest)
-      raise(Errno::ENOENT, "No such file or directory - #{source} or #{dest}") if !File.exists?(source)
-      raise(Errno::EEXIST, "File exists - #{source} or #{dest}")               if  File.exists?(dest)
+      if directory?(source)
+        raise Errno::EPERM, "Operation not permitted - #{source} or #{dest}"
+      end
+
+      if !exists?(source)
+        raise Errno::ENOENT, "No such file or directory - #{source} or #{dest}"
+      end
       
-      FileUtils.cp(source, dest)
+      if exists?(dest)
+        raise Errno::EEXIST, "File exists - #{source} or #{dest}"
+      end
+      
+      source = FileSystem.find(source)
+      dest = FileSystem.add(dest, source.entry.clone)
+      source.link(dest)
+
       0
     end
 
@@ -147,6 +159,10 @@ module FakeFS
       def directory?
         File.directory?(@file)
       end
+
+      def nlink
+        FileSystem.find(@file).links.size
+      end
     end
 
     attr_reader :path

test/fake/file_test.rb

@@ -0,0 +1,88 @@
+$LOAD_PATH.unshift File.join(File.dirname(__FILE__), '..', '..', 'lib')
+require 'fakefs/safe'
+require 'test/unit'
+
+class FakeFileTest < Test::Unit::TestCase
+  include FakeFS
+
+  def setup
+    FileSystem.clear
+    
+    @file = FakeFile.new
+  end
+
+  def test_fake_file_has_empty_content_by_default
+    assert_equal "", @file.content
+  end
+
+  def test_fake_file_can_read_and_write_to_content
+    @file.content = "foobar"
+    assert_equal "foobar", @file.content
+  end
+
+  def test_fake_file_has_1_link_by_default
+    assert_equal [@file], @file.links
+  end
+
+  def test_fake_file_can_create_link
+    other_file = FakeFile.new
+
+    @file.link(other_file)
+
+    assert_equal [@file, other_file], @file.links
+  end
+
+  def test_fake_file_wont_add_link_to_same_file_twice
+    other_file = FakeFile.new
+
+    @file.link other_file
+    @file.link other_file
+
+    assert_equal [@file, other_file], @file.links
+  end
+
+  def test_links_are_mutual
+    other_file = FakeFile.new
+  
+    @file.link(other_file)
+  
+    assert_equal [@file, other_file], other_file.links
+  end
+
+  def test_can_link_multiple_files
+    file_two   = FakeFile.new
+    file_three = FakeFile.new
+
+    @file.link file_two
+    @file.link file_three
+
+    assert_equal [@file, file_two, file_three], @file.links
+    assert_equal [@file, file_two, file_three], file_two.links
+    assert_equal [@file, file_two, file_three], file_three.links
+  end
+
+  def test_links_share_same_content
+    other_file = FakeFile.new
+
+    @file.link other_file
+
+    @file.content = "foobar"
+
+    assert_equal "foobar", other_file.content
+  end
+
+  def test_clone_creates_new_inode
+    clone = @file.clone
+    assert !clone.inode.equal?(@file.inode)
+  end
+
+  def test_cloning_does_not_use_same_content_object
+    clone = @file.clone
+
+    clone.content = "foo"
+    @file.content = "bar"
+
+    assert_equal "foo", clone.content
+    assert_equal "bar", @file.content
+  end
+end

test/fakefs_test.rb

@@ -957,6 +957,14 @@ class FakeFSTest < Test::Unit::TestCase
     assert_equal "some content", File.read("/bar")
   end
 
+  def test_hard_link_with_directory_raises_error
+    Dir.mkdir "/foo"
+
+    assert_raises(Errno::EPERM) do
+      File.link("/foo", "/bar")
+    end
+  end
+
   def test_file_stat_returns_file_stat_object
     FileUtils.touch("/foo")
     assert_equal File::Stat, File.stat("/foo").class

test/file/stat_test.rb

@@ -21,6 +21,10 @@ class FileStatTest < Test::Unit::TestCase
     Dir.mkdir(*args)
   end
 
+  def ln(*args)
+    File.link(*args)
+  end
+
   def test_file_stat_init_with_non_existant_file
     assert_raises(Errno::ENOENT) do
       File::Stat.new("/foo")
@@ -51,4 +55,16 @@ class FileStatTest < Test::Unit::TestCase
 
     assert File::Stat.new("/foo").directory?
   end
+
+  def test_one_file_has_hard_link
+    touch "testfile"
+    assert_equal 1, File.stat("testfile").nlink
+  end
+
+  def test_two_hard_links_show_nlinks_as_two
+    touch "testfile"
+    ln    "testfile", "testfile.bak"
+
+    assert_equal 2, File.stat("testfile").nlink
+  end
 end