buitin previewer: do not preview file size>10MB (configurable)

README.md

@@ -434,6 +434,7 @@ require'fzf-lua'.setup {
       syntax          = true,         -- preview syntax highlight?
       syntax_limit_l  = 0,            -- syntax limit (lines), 0=nolimit
       syntax_limit_b  = 1024*1024,    -- syntax limit (bytes), 0=nolimit
+      limit_b         = 1024*1024*10, -- preview limit (bytes), 0=nolimit
     },
   },
   -- provider setup

doc/fzf-lua.txt

@@ -476,6 +476,7 @@ Consult the list below for available settings:
           syntax          = true,         -- preview syntax highlight?
           syntax_limit_l  = 0,            -- syntax limit (lines), 0=nolimit
           syntax_limit_b  = 1024*1024,    -- syntax limit (bytes), 0=nolimit
+          limit_b         = 1024*1024*10, -- preview limit (bytes), 0=nolimit
         },
       },
       -- provider setup

lua/fzf-lua/config.lua

@@ -178,7 +178,8 @@ M.globals = {
       syntax          = true,
       syntax_delay    = 0,
       syntax_limit_l  = 0,
-      syntax_limit_b  = 1024*1024,
+      syntax_limit_b  = 1024*1024,    -- 1MB
+      limit_b         = 1024*1024*10, -- 10MB
       _ctor           = previewers.builtin.buffer_or_file,
     },
   },

lua/fzf-lua/previewer/builtin.lua

@@ -22,6 +22,7 @@ function Previewer.base:new(o, opts, fzf_win)
   self.syntax_delay = o.syntax_delay
   self.syntax_limit_b = o.syntax_limit_b
   self.syntax_limit_l = o.syntax_limit_l
+  self.limit_b = o.limit_b
   self.backups = {}
   return self
 end
@@ -304,16 +305,27 @@ function Previewer.buffer_or_file:populate_preview_buf(entry_str)
       entry.path = path.relative(vim.api.nvim_buf_get_name(entry.bufnr), vim.loop.cwd())
     end
     -- make sure the file is readable (or bad entry.path)
-    if not entry.path or not vim.loop.fs_stat(entry.path) then return end
+    local fs_stat = vim.loop.fs_stat(entry.path)
+    if not entry.path or not fs_stat then return end
     local tmpbuf = self:get_tmp_buffer()
-    if utils.perl_file_is_binary(entry.path) then
-      vim.api.nvim_buf_set_lines(tmpbuf, 0, -1, false, {
-        "Preview is not supported for binary files."
-      })
-      -- swap preview buffer with new one
-      self:set_preview_buf(tmpbuf)
-      self:preview_buf_post(entry)
-      return
+    do
+      local lines = nil
+      if utils.perl_file_is_binary(entry.path) then
+        lines = { "Preview is not supported for binary files." }
+      elseif tonumber(self.limit_b)>0 and fs_stat.size>self.limit_b then
+        lines = {
+          ("Preview file size limit (>%dMB) reached, file size %dMB.")
+            :format(self.limit_b/(1024*1024), fs_stat.size/(1024*1024)),
+          -- "(configured via 'previewers.builtin.limit_b')"
+        }
+      end
+      if lines then
+        vim.api.nvim_buf_set_lines(tmpbuf, 0, -1, false, lines)
+        -- swap preview buffer with new one
+        self:set_preview_buf(tmpbuf)
+        self:preview_buf_post(entry)
+        return
+      end
     end
     -- read the file into the buffer
     utils.read_file_async(entry.path, vim.schedule_wrap(function(data)