disable preview for binary files (closes issue #157)

lua/fzf-lua/previewer/builtin.lua

@@ -257,6 +257,13 @@ function Previewer.buffer_or_file:populate_preview_buf(entry_str)
     self.preview_bufloaded = true
     -- make sure the file is readable (or bad entry.path)
     if not vim.loop.fs_stat(entry.path) then return end
+    if utils.file_is_binary(entry.path) then
+      vim.api.nvim_buf_set_lines(self.preview_bufnr, 0, -1, false, {
+        "Preview is not supported for binary files."
+      })
+      self:preview_buf_post(entry)
+      return
+    end
     -- read the file into the buffer
     utils.read_file_async(entry.path, vim.schedule_wrap(function(data)
       if not vim.api.nvim_buf_is_valid(self.preview_bufnr) then

lua/fzf-lua/utils.lua

@@ -78,6 +78,16 @@ function M.sk_escape(str)
   end)
 end
 
+M.file_is_binary = function(filepath)
+  filepath = vim.fn.expand(filepath)
+  if vim.fn.executable("file") ~= 1 or
+     not vim.loop.fs_stat(filepath) then
+    return false
+  end
+  local out = M.io_system("file --dereference --mime " ..  filepath)
+  return out:match("charset=binary") ~= nil
+end
+
 M.read_file = function(filepath)
   local fd = vim.loop.fs_open(filepath, "r", 438)
   if fd == nil then return '' end