-- Array of file names indicating root directory. Modify to your liking.
local root_names = { '.git', 'Makefile', '.svn', '.hg' }

-- Cache to use for speed up (at cost of possibly outdated results)
local root_cache = {}

local set_root = function()
  -- Get directory path to start search from
  local path = vim.api.nvim_buf_get_name(0)
  if path == "" then return end
  path = vim.fs.dirname(path)

  -- Try cache and resort to searching upward for root directory
  local root = root_cache[path]
  if root == nil then
	local root_file = vim.fs.find(root_names, { path = path, upward = true })[1]
	if root_file == nil then return end
	root = vim.fs.dirname(root_file)
	root_cache[path] = root
  end

  -- Set current directory
  vim.fn.chdir(root)
end

local root_augroup = vim.api.nvim_create_augroup('MyAutoRoot', {})
vim.api.nvim_create_autocmd('BufEnter', { group = root_augroup, callback = set_root })