Merge 9009302 into 7453538

lib/xgit/repository/working_tree.ex

@@ -140,6 +140,40 @@ defmodule Xgit.Repository.WorkingTree do
     end
   end
 
+  @typedoc ~S"""
+  Error code reasons returned by `reset_dir_cache/1`.
+  """
+  @type reset_dir_cache_reason :: WriteIndexFile.to_iodevice_reason()
+
+  @doc ~S"""
+  Reset the dir cache to empty and rewrite the index file accordingly.
+
+  ## Return Values
+
+  `:ok` if successful.
+
+  `{:error, reason}` if unable. The relevant reason codes may come from:
+
+  * `Xgit.Repository.WorkingTree.WriteIndexFile.to_iodevice/2`.
+  """
+  @spec reset_dir_cache(working_tree :: t) ::
+          :ok | {:error, reset_dir_cache_reason}
+  def reset_dir_cache(working_tree) when is_pid(working_tree),
+    do: GenServer.call(working_tree, :reset_dir_cache)
+
+  defp handle_reset_dir_cache(%{work_dir: work_dir} = state) do
+    index_path = Path.join([work_dir, ".git", "index"])
+
+    with {:ok, iodevice}
+         when is_pid(iodevice) <- TrailingHashDevice.open_file_for_write(index_path),
+         :ok <- WriteIndexFile.to_iodevice(DirCache.empty(), iodevice),
+         :ok <- File.close(iodevice) do
+      cover {:reply, :ok, state}
+    else
+      {:error, reason} -> cover {:reply, {:error, reason}, state}
+    end
+  end
+
   @typedoc ~S"""
   Error code reasons returned by `update_dir_cache/3`.
   """
@@ -167,7 +201,7 @@ defmodule Xgit.Repository.WorkingTree do
   `{:ok, dir_cache}` where `dir_cache` is the original `dir_cache` with the new
   entries added (and properly sorted) and targeted entries removed.
 
-  `{:error, :reason}` if unable. The relevant reason codes may come from:
+  `{:error, reason}` if unable. The relevant reason codes may come from:
 
   * `Xgit.Core.DirCache.add_entries/2`
   * `Xgit.Core.DirCache.remove_entries/2`
@@ -213,6 +247,8 @@ defmodule Xgit.Repository.WorkingTree do
 
   def handle_call(:dir_cache, _from, state), do: handle_dir_cache(state)
 
+  def handle_call(:reset_dir_cache, _from, state), do: handle_reset_dir_cache(state)
+
   def handle_call({:update_dir_cache, add, remove}, _from, state),
     do: handle_update_dir_cache(add, remove, state)
 

test/xgit/repository/working_tree/reset_dir_cache_test.exs

@@ -0,0 +1,173 @@
+defmodule Xgit.Repository.WorkingTree.ResetDirCacheTest do
+  use Xgit.GitInitTestCase, async: true
+
+  alias Xgit.Core.DirCache
+  alias Xgit.Repository
+  alias Xgit.Repository.OnDisk
+  alias Xgit.Repository.WorkingTree
+
+  import FolderDiff
+
+  describe "reset_dir_cache/1" do
+    test "happy path: can generate correct empty index file",
+         %{ref: ref, xgit: xgit} do
+      # An initialized git repo doesn't have an index file at all.
+      # Adding and removing a file generates an empty index file.
+
+      {_output, 0} =
+        System.cmd(
+          "git",
+          [
+            "update-index",
+            "--add",
+            "--cacheinfo",
+            "100644",
+            "18832d35117ef2f013c4009f5b2128dfaeff354f",
+            "hello.txt"
+          ],
+          cd: ref
+        )
+
+      {_output, 0} =
+        System.cmd(
+          "git",
+          [
+            "update-index",
+            "--remove",
+            "hello.txt"
+          ],
+          cd: ref
+        )
+
+      assert :ok = OnDisk.create(xgit)
+      {:ok, repo} = OnDisk.start_link(work_dir: xgit)
+      working_tree = Repository.default_working_tree(repo)
+
+      assert :ok = WorkingTree.reset_dir_cache(working_tree)
+
+      assert_folders_are_equal(ref, xgit)
+    end
+
+    test "can reset an index file when entries existed",
+         %{ref: ref, xgit: xgit} do
+      {_output, 0} =
+        System.cmd(
+          "git",
+          [
+            "update-index",
+            "--add",
+            "--cacheinfo",
+            "100644",
+            "18832d35117ef2f013c4009f5b2128dfaeff354f",
+            "hello.txt"
+          ],
+          cd: ref
+        )
+
+      {_output, 0} =
+        System.cmd(
+          "git",
+          [
+            "update-index",
+            "--add",
+            "--cacheinfo",
+            "100644",
+            "d670460b4b4aece5915caf5c68d12f560a9fe3e4",
+            "test_content.txt"
+          ],
+          cd: ref
+        )
+
+      assert :ok = OnDisk.create(xgit)
+      {:ok, repo} = OnDisk.start_link(work_dir: xgit)
+      working_tree = Repository.default_working_tree(repo)
+
+      assert :ok =
+               WorkingTree.update_dir_cache(
+                 working_tree,
+                 [
+                   %DirCache.Entry{
+                     assume_valid?: false,
+                     ctime: 0,
+                     ctime_ns: 0,
+                     dev: 0,
+                     extended?: false,
+                     gid: 0,
+                     ino: 0,
+                     intent_to_add?: false,
+                     mode: 0o100644,
+                     mtime: 0,
+                     mtime_ns: 0,
+                     name: 'hello.txt',
+                     object_id: "18832d35117ef2f013c4009f5b2128dfaeff354f",
+                     size: 0,
+                     skip_worktree?: false,
+                     stage: 0,
+                     uid: 0
+                   },
+                   %DirCache.Entry{
+                     assume_valid?: false,
+                     ctime: 0,
+                     ctime_ns: 0,
+                     dev: 0,
+                     extended?: false,
+                     gid: 0,
+                     ino: 0,
+                     intent_to_add?: false,
+                     mode: 0o100644,
+                     mtime: 0,
+                     mtime_ns: 0,
+                     name: 'test_content.txt',
+                     object_id: "d670460b4b4aece5915caf5c68d12f560a9fe3e4",
+                     size: 0,
+                     skip_worktree?: false,
+                     stage: 0,
+                     uid: 0
+                   }
+                 ],
+                 []
+               )
+
+      assert_folders_are_equal(ref, xgit)
+
+      {_output, 0} =
+        System.cmd(
+          "git",
+          [
+            "update-index",
+            "--remove",
+            "hello.txt"
+          ],
+          cd: ref
+        )
+
+      {_output, 0} =
+        System.cmd(
+          "git",
+          [
+            "update-index",
+            "--remove",
+            "test_content.txt"
+          ],
+          cd: ref
+        )
+
+      assert :ok = WorkingTree.reset_dir_cache(working_tree)
+
+      assert_folders_are_equal(ref, xgit)
+    end
+
+    test "error: can't replace malformed index file", %{xgit: xgit} do
+      git_dir = Path.join(xgit, '.git')
+      File.mkdir_p!(git_dir)
+
+      index = Path.join(git_dir, 'index')
+      File.mkdir_p!(index)
+
+      {:ok, repo} = OnDisk.start_link(work_dir: xgit)
+      working_tree = Repository.default_working_tree(repo)
+
+      assert {:error, :eisdir} = WorkingTree.reset_dir_cache(working_tree)
+    end
+  end
+end