Add Pleroma.Utils.command_available?/1 and use where appropriate

lib/pleroma/upload/filter/exiftool.ex

@@ -9,8 +9,15 @@ defmodule Pleroma.Upload.Filter.Exiftool do
   """
   @behaviour Pleroma.Upload.Filter
 
+  require Logger
+
   def filter(%Pleroma.Upload{tempfile: file, content_type: "image" <> _}) do
-    System.cmd("exiftool", ["-overwrite_original", "-gps:all=", file], parallelism: true)
+    if Pleroma.Utils.command_available?("exiftool") do
+      System.cmd("exiftool", ["-overwrite_original", "-gps:all=", file], parallelism: true)
+    else
+      Logger.warn("exiftool is not available, filter #{__MODULE__} skipped")
+    end
+
     :ok
   end
 

lib/pleroma/utils.ex

@@ -9,4 +9,19 @@ defmodule Pleroma.Utils do
     |> Enum.map(&Path.join(dir, &1))
     |> Kernel.ParallelCompiler.compile()
   end
+
+  @doc """
+  POSIX-compliant check if command is available in the system
+
+  ## Examples
+      iex> command_available?("git")
+      true
+      iex> command_available?("wrongcmd")
+      false
+
+  """
+  @spec command_available?(String.t()) :: boolean()
+  def command_available?(command) do
+    match?({_output, 0}, System.cmd("sh", ["-c", "command -v #{command}"]))
+  end
 end