Copy symbolic links in the assets as actual files

Author: aYukiSekiguchi

lib/ex_doc/formatter/html.ex

@@ -306,7 +306,7 @@ defmodule ExDoc.Formatter.HTML do
 
         is_binary(dir_or_files) and File.dir?(dir_or_files) ->
           dir_or_files
-          |> File.cp_r!(target_dir)
+          |> File.cp_r!(target_dir, dereference_symlinks: true)
           |> Enum.map(&Path.relative_to(&1, output))
 
         is_binary(dir_or_files) ->

test/ex_doc/formatter/html_test.exs

@@ -816,4 +816,24 @@ defmodule ExDoc.Formatter.HTMLTest do
   after
     File.rm_rf!("test/tmp/html_assets")
   end
+
+  test "symbolic links in the assets should be resolved and copied as actual files",
+       %{tmp_dir: tmp_dir} = context do
+    File.mkdir_p!("test/tmp/html_assets/hello")
+    File.touch!("test/tmp/html_assets/hello/world")
+
+    File.ln_s("world", "test/tmp/html_assets/hello/symlink_world")
+
+    generate_docs(
+      doc_config(context,
+        assets: %{"test/tmp/html_assets" => "assets"}
+      )
+    )
+
+    assert File.regular?(tmp_dir <> "/html/assets/hello/world")
+    assert File.exists?(tmp_dir <> "/html/assets/hello/symlink_world")
+    assert File.read_link(tmp_dir <> "/html/assets/hello/symlink_world") == {:error, :einval}
+  after
+    File.rm_rf!("test/tmp/html_assets")
+  end
 end