From ce65f8c11be13b51f242890cabdf15f4e0d1b12a Mon Sep 17 00:00:00 2001 From: Kiplangatkorir Date: Wed, 4 Mar 2026 11:15:45 +0300 Subject: [PATCH] fix: add size limit to ReadFileTool to prevent OOM MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit ReadFileTool had no file size check — reading a multi-GB file would load everything into memory and crash the process. Now: - Rejects files over ~512KB at the byte level (fast stat check) - Truncates at 128K chars with a notice if content is too long - Guides the agent to use exec with head/tail/grep for large files This matches the protection already in ExecTool (10KB) and WebFetchTool (50KB). --- nanobot/agent/tools/filesystem.py | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/nanobot/agent/tools/filesystem.py b/nanobot/agent/tools/filesystem.py index bbdd49c..7b0b867 100644 --- a/nanobot/agent/tools/filesystem.py +++ b/nanobot/agent/tools/filesystem.py @@ -26,6 +26,8 @@ def _resolve_path( class ReadFileTool(Tool): """Tool to read file contents.""" + _MAX_CHARS = 128_000 # ~128 KB — prevents OOM from reading huge files into LLM context + def __init__(self, workspace: Path | None = None, allowed_dir: Path | None = None): self._workspace = workspace self._allowed_dir = allowed_dir @@ -54,7 +56,16 @@ class ReadFileTool(Tool): if not file_path.is_file(): return f"Error: Not a file: {path}" + size = file_path.stat().st_size + if size > self._MAX_CHARS * 4: # rough upper bound (UTF-8 chars ≤ 4 bytes) + return ( + f"Error: File too large ({size:,} bytes). " + f"Use exec tool with head/tail/grep to read portions." + ) + content = file_path.read_text(encoding="utf-8") + if len(content) > self._MAX_CHARS: + return content[: self._MAX_CHARS] + f"\n\n... (truncated — file is {len(content):,} chars, limit {self._MAX_CHARS:,})" return content except PermissionError as e: return f"Error: {e}"