Isolate Dir.chdir to a new process, or mutex

lib/git.rb

@@ -108,7 +108,7 @@ def self.export(repository, name, options = {})
     options.delete(:remote)
     repo = clone(repository, name, {:depth => 1}.merge(options))
     repo.checkout("origin/#{options[:branch]}") if options[:branch]
-    Dir.chdir(repo.dir.to_s) { FileUtils.rm_r '.git' }
+    FileUtils.rm_r(File.join(repo.dir.to_s, '.git'))
   end
 
   # Same as g.config, but forces it to be at the global level

lib/git/base.rb

@@ -3,6 +3,12 @@
 module Git
 
   class Base
+    # Adding a mutex to the class because each repo should be sharing the same mutex 
+    # in case we need to Dir.chdir and we don't have fork() support to isolate that
+    @chdir_semaphore = Mutex.new
+    class << self
+      attr_accessor :chdir_semaphore
+    end
 
     include Git::Base::Factory
 
@@ -92,18 +98,37 @@ def initialize(options = {})
       @index = options[:index] ? Git::Index.new(options[:index], false) : nil
     end
 
-    # changes current working directory for a block
-    # to the git working directory
+    # changes current working directory for a block to the git working directory.
+    #
+    # Note: If we can fork() or spawn(), Dir.chdir will happen in a new process
+    # otherwise, we will use a mutex to prevent threading errors
+    # See https://github.com/ruby-git/ruby-git/issues/355 for more info
     #
     # example
     #  @git.chdir do 
     #    # write files
     #    @git.add
     #    @git.commit('message')
     #  end
-    def chdir # :yields: the Git::Path
-      Dir.chdir(dir.path) do
-        yield dir.path
+    def chdir(&block) # :yields: the Git::Path
+      chdir_block = Proc.new do
+        Dir.chdir(dir.path) do
+          block.call(dir.path)
+        end
+      end
+
+      if Process.respond_to?(:fork)
+        # Forking this process so that we can be threadsafe
+        pid = Process.fork do
+          chdir_block.call
+        end
+        Process.wait(pid)
+      else
+        # JRuby and Windows don't support fork()
+        # let's use a mutex to prevent race conditions with threads
+        Git::Base.chdir_semaphore.synchronize do
+          chdir_block.call
+        end
       end
     end
 
@@ -144,9 +169,7 @@ def repo
 
     # returns the repository size in bytes
     def repo_size
-      Dir.chdir(repo.path) do
-        return `du -s`.chomp.split.first.to_i
-      end
+      return `du -s #{repo.path}`.chomp.split.first.to_i
     end
 
     def set_index(index_file, check = true)
@@ -348,7 +371,7 @@ def each_conflict(&block) # :yields: file, your_version, their_version
     #  @git.pull('upstream', 'develope')  # pulls from upstream/develop
     #
     def pull(remote='origin', branch='master')
-			self.lib.pull(remote, branch)
+      self.lib.pull(remote, branch)
     end
 
     # returns an array of Git:Remote objects

lib/git/lib.rb

@@ -8,6 +8,7 @@ class GitExecuteError < StandardError
   class Lib
 
     @@semaphore = Mutex.new
+    @@config_semaphore = Mutex.new
 
     def initialize(base = nil, logger = nil)
       @git_dir = nil
@@ -310,7 +311,7 @@ def branches_all
     def list_files(ref_dir)
       dir = File.join(@git_dir, 'refs', ref_dir)
       files = []
-      Dir.chdir(dir) { files = Dir.glob('**/*').select { |f| File.file?(f) } } rescue nil
+      files = Dir.glob(File.join(dir, '**/*')).select { |f| File.file?(f) } rescue nil
       files
     end
 
@@ -441,14 +442,16 @@ def config_remote(name)
     end
 
     def config_get(name)
-      do_get = lambda do |path|
-        command('config', ['--get', name])
-      end
+      @@config_semaphore.synchronize do
+        do_get = lambda do |path|
+          command('config', ['--get', name])
+        end
 
-      if @git_dir
-        Dir.chdir(@git_dir, &do_get)
-      else
-        do_get.call
+        if @git_dir
+          Dir.chdir(@git_dir, &do_get)
+        else
+          do_get.call
+        end
       end
     end
 
@@ -457,14 +460,16 @@ def global_config_get(name)
     end
 
     def config_list
-      build_list = lambda do |path|
-        parse_config_list command_lines('config', ['--list'])
-      end
+      @@config_semaphore.synchronize do
+        build_list = lambda do |path|
+          parse_config_list command_lines('config', ['--list'])
+        end
 
-      if @git_dir
-        Dir.chdir(@git_dir, &build_list)
-      else
-        build_list.call
+        if @git_dir
+          Dir.chdir(@git_dir, &build_list)
+        else
+          build_list.call
+        end
       end
     end
 

lib/git/status.rb

@@ -171,14 +171,14 @@ def construct_status
 
     def fetch_untracked
       ignore = @base.lib.ignored_files
-
-      Dir.chdir(@base.dir.path) do
-        Dir.glob('**/*', File::FNM_DOTMATCH) do |file|
-          next if @files[file] || File.directory?(file) ||
-                  ignore.include?(file) || file =~ %r{^.git\/.+}
-
-          @files[file] = { path: file, untracked: true }
-        end
+      root_base_dir_path_length = File.join(@base.dir.path, '/').length
+      Dir.glob(File.join(@base.dir.path, '**/*'), File::FNM_DOTMATCH) do |file|
+        # Strip off the `base.dir.path` to make these relative paths
+        relative_file_name = file.slice(root_base_dir_path_length..file.length)
+        next if @files[relative_file_name] || File.directory?(file) ||
+                ignore.include?(relative_file_name) || relative_file_name =~ %r{^.git\/.+}
+
+        @files[relative_file_name] = { path: relative_file_name, untracked: true }
       end
     end