Force symlinks to be preserved

If the chosen adapter supports creation of symlinks, any symlink in
the git repo will be uploaded as a symlink. Otherwise, uploading of
that file will be skipped. Support has only been added to the SFTP
adapter so far.

lib/dandelion/adapter/noop.rb

@@ -9,6 +9,9 @@ def write(path, data)
 
       def delete(path)
       end
+
+      def symlink(path, data)
+      end
     end
   end
 end

lib/dandelion/adapter/sftp.rb

@@ -55,6 +55,19 @@ def delete(file)
         end
       end
 
+      def symlink(file, target)
+        begin
+          @sftp.symlink!(target, path(file))
+        rescue Net::SFTP::StatusException => e
+          if e.code == 2
+            mkdir_p(File.dirname(path(file)))
+          else
+            @sftp.remove!(path(file))
+          end
+          @sftp.symlink!(target, path(file))
+        end
+      end
+
       def to_s
         "sftp://#{@config['username']}@#{@config['host']}/#{@config['path']}"
       end

lib/dandelion/change.rb

@@ -1,6 +1,7 @@
 module Dandelion
   class Change
     attr_reader :path, :type
+    attr_accessor :type
 
     def initialize(path, type, read = nil)
       @path = path

lib/dandelion/changeset.rb

@@ -24,6 +24,7 @@ def each
           if change.type == :delete
             yield Change.new(path, change.type)
           else
+            change.type = :symlink if @tree.is_symlink?(change.path)
             read = -> { @tree.data(change.path) }
             yield Change.new(path, change.type, read)
           end

lib/dandelion/deployer.rb

@@ -50,6 +50,13 @@ def deploy_change!(change)
       when :delete
         log.debug("Deleting file: #{change.path}")  
         @adapter.delete(change.path)
+      when :symlink
+        if @adapter.respond_to?(:symlink)
+          log.debug("Creating symlink: #{change.path}")
+          @adapter.symlink(change.path, change.data)
+        else
+          log.debug("Skipped creating symlink:  #{change.path} -> #{change.data}")
+        end
       end
     end
 

lib/dandelion/tree.rb

@@ -7,6 +7,11 @@ def initialize(repo, commit)
       @commit = commit
     end
 
+    def is_symlink?(path)
+      # https://github.com/libgit2/libgit2/blob/development/include/git2/types.h
+      @commit.tree.path(path)[:filemode] == 0120000
+    end
+
     def data(path)
       submodule = @repo.submodules[path]
 
@@ -15,48 +20,21 @@ def data(path)
         nil
       else
         info, obj = object(path)
-        content(info, obj)
+        blob_content(obj)
       end
     end
 
     private
 
     def object(path)
-      object = @commit.tree
-      info = {}
-
-      path.split('/').each do |name|
-        info = object[name]
-        return nil unless info
-        return nil unless info[:type]
-
-        object = @repo.lookup(info[:oid])
-
-        return nil unless object
-      end
-
+      info = @commit.tree.path(path)
+      object = @repo.lookup(info[:oid])
       [info, object]
     end
 
-    def content(info, object)
-      # https://github.com/libgit2/libgit2/blob/development/include/git2/types.h
-      if info[:filemode] == 0120000
-        symlink_content(object)
-      else
-        blob_content(object)
-      end
-    end
-
     def blob_content(object)
       object.read_raw.data
     end
 
-    def symlink_content(object)
-      path = object.read_raw.data
-
-      result = data(path)
-      result ||= IO.binread(path) # external link
-      result
-    end
   end
 end

spec/dandelion/changeset_spec.rb

@@ -70,4 +70,30 @@
       end
     end
   end
+
+  context 'diff adds symlink' do
+    let(:changeset) { test_changeset_with_symlinks }
+
+    describe '#enumerable' do
+      let(:changes) { changeset.to_a }
+
+      it 'returns all changes' do
+        expect(changes).to be_a(Array)
+        expect(changes.length).to eq 1
+        expect(changes.map(&:path)).to eq ['link']
+        expect(changes.map(&:type)).to eq [:symlink]
+      end
+
+      it 'returns data for write changes' do
+        expect(changes.select { |c| c.type != :delete }.map(&:data)).to eq ["baz/bar"]
+      end
+    end
+
+    describe '#empty?' do
+      it 'returns false' do
+        expect(changeset.empty?).to eq false
+      end
+    end
+  end
+
 end

spec/dandelion/tree_spec.rb

@@ -16,8 +16,8 @@
       let(:repo) { test_repo('repo_symlink') }
       let(:tree) { test_tree(repo: repo, commit: repo.lookup('4c19bbe7ba04230a0ae2281c1abbc48a76a66550')) }
 
-      it 'returns content of link source path' do
-        expect(tree.data('link')).to eq "bar\n"
+      it 'returns target path of the symlink' do
+        expect(tree.data('link')).to eq "baz/bar"
       end
     end
 

spec/spec_helper.rb

@@ -27,6 +27,14 @@ def test_changeset(options = {})
   Dandelion::Changeset.new(test_tree, test_commits.first, options)
 end
 
+def test_changeset_with_symlinks(options = {})
+  repo = test_repo('repo_symlink')
+  commit0 = repo.lookup('3d9b743acb4a84dd99002d2c6f3fcf1a47e9f06b')
+  commit1 = repo.lookup('4c19bbe7ba04230a0ae2281c1abbc48a76a66550')
+  tree = test_tree(repo: repo, commit: commit1)
+  Dandelion::Changeset.new(tree, commit0, options)
+end
+
 def test_diff
   test_changeset.diff
 end