Close tmp in-memory file after usage

lib/asciinema/file_store.ex

@@ -4,4 +4,7 @@ defmodule Asciinema.FileStore do
 
   @doc "Opens the given path in store"
   @callback open(path :: String.t) :: {:ok, File.io_device} | {:error, File.posix}
+
+  @doc "Opens the given path in store, executes given fn and closes the file"
+  @callback open(path :: String.t, function :: (File.io_device -> res)) :: {:ok, res} | {:error, File.posix} when res: var
 end

lib/asciinema/file_store/local.ex

@@ -22,6 +22,9 @@ defmodule Asciinema.FileStore.Local do
   def open(path) do
     File.open(base_path() <> path, [:binary, :read])
   end
+  def open(path, function) do
+    File.open(base_path() <> path, [:binary, :read], function)
+  end
 
   defp config do
     Application.get_env(:asciinema, Asciinema.FileStore.Local)

lib/asciinema/file_store/s3.ex

@@ -19,12 +19,16 @@ defmodule Asciinema.FileStore.S3 do
     |> redirect(external: url)
   end
 
-  def open(path) do
+  def open(path, function \\ nil) do
     response = S3.get_object(bucket(), base_path() <> path) |> ExAws.request(region: region())
 
     case response do
       {:ok, %{body: body}} ->
-        File.open(body, [:ram, :binary, :read])
+        if function do
+          File.open(body, [:ram, :binary, :read], function)
+        else
+          File.open(body, [:ram, :binary, :read])
+        end
       {:error, reason} ->
         {:error, reason}
     end

lib/asciinema/png_generator/a2png.ex

@@ -65,12 +65,12 @@ defmodule Asciinema.PngGenerator.A2png do
       Integer.to_string(png_params.scale)
     ]
 
-    with {:ok, file} <- file_store().open(path),
-         {:ok, _} <- :file.copy(file, json_path),
-         process <- Porcelain.spawn(bin_path(), args, err: :string),
-         {:ok, %{status: 0}} <- Porcelain.Process.await(process, @a2png_timeout) do
-      {:ok, png_path}
-    else
+    {:ok, {:ok, _}} = file_store().open(path, &(:file.copy(&1, json_path)))
+    process = Porcelain.spawn(bin_path(), args, err: :string)
+
+    case Porcelain.Process.await(process, @a2png_timeout) do
+      {:ok, %{status: 0}} ->
+        {:ok, png_path}
       {:ok, %Porcelain.Result{} = result} ->
         {:error, result}
       otherwise ->