Move checks to application startup

lib/pleroma/application.ex

@@ -47,6 +47,7 @@ def start(_type, _args) do
     Pleroma.ApplicationRequirements.verify!()
     setup_instrumenters()
     load_custom_modules()
+    check_system_commands()
     Pleroma.Docs.JSON.compile()
 
     adapter = Application.get_env(:tesla, :adapter)
@@ -249,4 +250,21 @@ defp http_children(Tesla.Adapter.Gun, _) do
   end
 
   defp http_children(_, _), do: []
+
+  defp check_system_commands do
+    filters = Config.get([Pleroma.Upload, :filters])
+
+    check_filter = fn filter, command_required ->
+      with true <- filter in filters,
+           false <- Pleroma.Utils.command_available?(command_required) do
+        Logger.error(
+          "#{filter} is specified in list of Pleroma.Upload filters, but the #{command_required} command is not found"
+        )
+      end
+    end
+
+    check_filter.(Pleroma.Upload.Filters.Exiftool, "exiftool")
+    check_filter.(Pleroma.Upload.Filters.Mogrify, "mogrify")
+    check_filter.(Pleroma.Upload.Filters.Mogrifun, "mogrify")
+  end
 end

lib/pleroma/upload/filter/exiftool.ex

@@ -9,11 +9,15 @@ defmodule Pleroma.Upload.Filter.Exiftool do
   """
   @behaviour Pleroma.Upload.Filter
 
+  @spec filter(Pleroma.Upload.t()) :: :ok | {:error, String.t()}
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
-    if Pleroma.Utils.command_available?("exiftool") do
-      System.cmd("exiftool", ["-overwrite_original", "-gps:all=", file], parallelism: true)
-      :ok
-    else
+    try do
+      case System.cmd("exiftool", ["-overwrite_original", "-gps:all=", file], parallelism: true) do
+        {_response, 0} -> :ok
+        {error, 1} -> {:error, error}
+      end
+    rescue
+      _e in ErlangError ->
         {:error, "exiftool command not found"}
     end
   end

lib/pleroma/upload/filter/mogrifun.ex

@@ -34,11 +34,13 @@ defmodule Pleroma.Upload.Filter.Mogrifun do
     [{"fill", "yellow"}, {"tint", "40"}]
   ]
 
+  @spec filter(Pleroma.Upload.t()) :: :ok | {:error, String.t()}
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
-    if Pleroma.Utils.command_available?("mogrify") do
+    try do
       Filter.Mogrify.do_filter(file, [Enum.random(@filters)])
       :ok
-    else
+    rescue
+      _e in ErlangError ->
         {:error, "mogrify command not found"}
     end
   end

lib/pleroma/upload/filter/mogrify.ex

@@ -8,13 +8,13 @@ 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()}
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
-    if Pleroma.Utils.command_available?("mogrify") do
-      filters = Pleroma.Config.get!([__MODULE__, :args])
-
-      do_filter(file, filters)
+    try do
+      do_filter(file, Pleroma.Config.get!([__MODULE__, :args]))
       :ok
-    else
+    rescue
+      _e in ErlangError ->
         {:error, "mogrify command not found"}
     end
   end