strip_metadata: skip BMP files

Not _yet_ supported as of exiftool 12.87, though
at first glance it seems like standard BMP files
can't store any metadata besides colour profiles

Fixes the specific case from
AkkomaGang/akkoma-fe#396
although the frontend shouldn’t get bricked regardless.

lib/pleroma/upload/filter/exiftool/strip_metadata.ex

@@ -18,6 +18,7 @@ defmodule Pleroma.Upload.Filter.Exiftool.StripMetadata do
 
   # Formats not compatible with exiftool at this time
   def filter(%Pleroma.Upload{content_type: "image/webp"}), do: {:ok, :noop}
+  def filter(%Pleroma.Upload{content_type: "image/bmp"}), do: {:ok, :noop}
   def filter(%Pleroma.Upload{content_type: "image/svg+xml"}), do: {:ok, :noop}
 
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do

test/pleroma/upload/filter/exiftool/strip_location_test.exs

@@ -115,6 +115,15 @@ test "verify webp files are skipped" do
     assert Filter.Exiftool.StripMetadata.filter(upload) == {:ok, :noop}
   end
 
+  test "verify bmp files are skipped" do
+    upload = %Pleroma.Upload{
+      name: "sample.bmp",
+      content_type: "image/bmp"
+    }
+
+    assert Filter.Exiftool.StripMetadata.filter(upload) == {:ok, :noop}
+  end
+
   test "verify svg files are skipped" do
     upload = %Pleroma.Upload{
       name: "sample.svg",