Improve upload filter return values so we can identify when filters make no changes to the input

lib/pleroma/upload/filter.ex

@@ -15,7 +15,11 @@ defmodule Pleroma.Upload.Filter do
 
   require Logger
 
-  @callback filter(Pleroma.Upload.t()) :: :ok | {:ok, Pleroma.Upload.t()} | {:error, any()}
+  @callback filter(Pleroma.Upload.t()) ::
+              {:ok, :filtered}
+              | {:ok, :noop}
+              | {:ok, :filtered, Pleroma.Upload.t()}
+              | {:error, any()}
 
   @spec filter([module()], Pleroma.Upload.t()) :: {:ok, Pleroma.Upload.t()} | {:error, any()}
 
@@ -25,10 +29,13 @@ defmodule Pleroma.Upload.Filter do
 
   def filter([filter | rest], upload) do
     case filter.filter(upload) do
-      :ok ->
+      {:ok, :filtered} ->
         filter(rest, upload)
 
-      {:ok, upload} ->
+      {:ok, :filtered, upload} ->
+        filter(rest, upload)
+
+      {:ok, :noop} ->
         filter(rest, upload)
 
       error ->

lib/pleroma/upload/filter/anonymize_filename.ex

@@ -16,9 +16,11 @@ defmodule Pleroma.Upload.Filter.AnonymizeFilename do
   def filter(%Upload{name: name} = upload) do
     extension = List.last(String.split(name, "."))
     name = predefined_name(extension) || random(extension)
-    {:ok, %Upload{upload | name: name}}
+    {:ok, :filtered, %Upload{upload | name: name}}
   end
 
+  def filter(_), do: {:ok, :noop}
+
   @spec predefined_name(String.t()) :: String.t() | nil
   defp predefined_name(extension) do
     with name when not is_nil(name) <- Config.get([__MODULE__, :text]),

lib/pleroma/upload/filter/dedupe.ex

@@ -17,8 +17,8 @@ defmodule Pleroma.Upload.Filter.Dedupe do
       |> Base.encode16(case: :lower)
 
     filename = shasum <> "." <> extension
-    {:ok, %Upload{upload | id: shasum, path: filename}}
+    {:ok, :filtered, %Upload{upload | id: shasum, path: filename}}
   end
 
-  def filter(_), do: :ok
+  def filter(_), do: {:ok, :noop}
 end

lib/pleroma/upload/filter/exiftool.ex

@@ -9,22 +9,22 @@ defmodule Pleroma.Upload.Filter.Exiftool do
   """
   @behaviour Pleroma.Upload.Filter
 
-  @spec filter(Pleroma.Upload.t()) :: :ok | {:error, String.t()}
+  @spec filter(Pleroma.Upload.t()) :: {:ok, any()} | {:error, String.t()}
   def filter(%Pleroma.Upload{name: file, tempfile: path, content_type: "image" <> _}) do
     # webp is not compatible with exiftool at this time
     if Regex.match?(~r/\.(webp)$/i, file) do
-      :ok
+      {:ok, :noop}
     else
       strip_exif(path)
     end
   end
 
-  def filter(_), do: :ok
+  def filter(_), do: {:ok, :noop}
 
   defp strip_exif(path) do
     try do
       case System.cmd("exiftool", ["-overwrite_original", "-gps:all=", path], parallelism: true) do
-        {_response, 0} -> :ok
+        {_response, 0} -> {:ok, :filtered}
         {error, 1} -> {:error, error}
       end
     rescue

lib/pleroma/upload/filter/mogrifun.ex

@@ -38,16 +38,16 @@ defmodule Pleroma.Upload.Filter.Mogrifun do
     [{"fill", "yellow"}, {"tint", "40"}]
   ]
 
-  @spec filter(Pleroma.Upload.t()) :: :ok | {:error, String.t()}
+  @spec filter(Pleroma.Upload.t()) :: {:ok, atom()} | {:error, String.t()}
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
     try do
       Filter.Mogrify.do_filter(file, [Enum.random(@filters)])
-      :ok
+      {:ok, :filtered}
     rescue
       _e in ErlangError ->
         {:error, "mogrify command not found"}
     end
   end
 
-  def filter(_), do: :ok
+  def filter(_), do: {:ok, :noop}
 end

lib/pleroma/upload/filter/mogrify.ex

@@ -8,18 +8,18 @@ defmodule Pleroma.Upload.Filter.Mogrify do
   @type conversion :: action :: String.t() | {action :: String.t(), opts :: String.t()}
   @type conversions :: conversion() | [conversion()]
 
-  @spec filter(Pleroma.Upload.t()) :: :ok | {:error, String.t()}
+  @spec filter(Pleroma.Upload.t()) :: {:ok, :atom} | {:error, String.t()}
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
     try do
       do_filter(file, Pleroma.Config.get!([__MODULE__, :args]))
-      :ok
+      {:ok, :filtered}
     rescue
       _e in ErlangError ->
         {:error, "mogrify command not found"}
     end
   end
 
-  def filter(_), do: :ok
+  def filter(_), do: {:ok, :noop}
 
   def do_filter(file, filters) do
     file

test/upload/filter/anonymize_filename_test.exs

@@ -24,18 +24,18 @@ defmodule Pleroma.Upload.Filter.AnonymizeFilenameTest do
 
   test "it replaces filename on pre-defined text", %{upload_file: upload_file} do
     Config.put([Upload.Filter.AnonymizeFilename, :text], "custom-file.png")
-    {:ok, %Upload{name: name}} = Upload.Filter.AnonymizeFilename.filter(upload_file)
+    {:ok, :filtered, %Upload{name: name}} = Upload.Filter.AnonymizeFilename.filter(upload_file)
     assert name == "custom-file.png"
   end
 
   test "it replaces filename on pre-defined text expression", %{upload_file: upload_file} do
     Config.put([Upload.Filter.AnonymizeFilename, :text], "custom-file.{extension}")
-    {:ok, %Upload{name: name}} = Upload.Filter.AnonymizeFilename.filter(upload_file)
+    {:ok, :filtered, %Upload{name: name}} = Upload.Filter.AnonymizeFilename.filter(upload_file)
     assert name == "custom-file.jpg"
   end
 
   test "it replaces filename on random text", %{upload_file: upload_file} do
-    {:ok, %Upload{name: name}} = Upload.Filter.AnonymizeFilename.filter(upload_file)
+    {:ok, :filtered, %Upload{name: name}} = Upload.Filter.AnonymizeFilename.filter(upload_file)
     assert <<_::bytes-size(14)>> <> ".jpg" = name
     refute name == "an… image.jpg"
   end

test/upload/filter/dedupe_test.exs

@@ -25,6 +25,7 @@ defmodule Pleroma.Upload.Filter.DedupeTest do
 
     assert {
              :ok,
+             :filtered,
              %Pleroma.Upload{id: @shasum, path: @shasum <> ".jpg"}
            } = Dedupe.filter(upload)
   end

test/upload/filter/exiftool_test.exs

@@ -21,7 +21,7 @@ defmodule Pleroma.Upload.Filter.ExiftoolTest do
       tempfile: Path.absname("test/fixtures/DSCN0010_tmp.jpg")
     }
 
-    assert Filter.Exiftool.filter(upload) == :ok
+    assert Filter.Exiftool.filter(upload) == {:ok, :filtered}
 
     {exif_original, 0} = System.cmd("exiftool", ["test/fixtures/DSCN0010.jpg"])
     {exif_filtered, 0} = System.cmd("exiftool", ["test/fixtures/DSCN0010_tmp.jpg"])

test/upload/filter/mogrifun_test.exs

@@ -36,7 +36,7 @@ defmodule Pleroma.Upload.Filter.MogrifunTest do
          save: fn _f, _o -> :ok end
        ]}
     ]) do
-      assert Filter.Mogrifun.filter(upload) == :ok
+      assert Filter.Mogrifun.filter(upload) == {:ok, :filtered}
     end
 
     Task.await(task)

test/upload/filter/mogrify_test.exs

@@ -33,7 +33,7 @@ defmodule Pleroma.Upload.Filter.MogrifyTest do
       custom: fn _m, _a -> :ok end,
       custom: fn m, a, o -> send(task.pid, {:apply_filter, {m, a, o}}) end,
       save: fn _f, _o -> :ok end do
-      assert Filter.Mogrify.filter(upload) == :ok
+      assert Filter.Mogrify.filter(upload) == {:ok, :filtered}
     end
 
     Task.await(task)