Implementation:Trailofbits Fickling Find File Properties

Knowledge Sources	Fickling
Domains	Security, File_Format, Supply_Chain
Last Updated	2026-02-14 14:00 GMT

Overview

Concrete tool for discovering structural properties of PyTorch files provided by the Fickling library.

Description

find_file_properties opens a file and runs multiple structural checks to produce a boolean properties dictionary. It checks PyTorch ZIP magic numbers, tar headers, pickle validity, NumPy headers, and ZIP archive contents (data.pkl, constants.pkl, version, model.json, attributes.pkl).

Usage

Use this as the first step in format identification. Pass the resulting dict to identify_pytorch_file_format or check_for_corruption.

Code Reference

Source Location

• Repository: fickling
• File: fickling/polyglot.py
• Lines: L111-167

Signature

def find_file_properties(
    file_path: str,
    print_properties: bool = False
) -> dict:
    """Discover structural properties of a file.

    Args:
        file_path: Path to the file to inspect.
        print_properties: Print discovered properties to stdout.

    Returns:
        Dict with boolean keys: is_torch_zip, is_tar,
        is_valid_pickle, is_numpy, is_numpy_pickle,
        is_standard_zip, is_standard_not_torch,
        has_constants_pkl, has_data_pkl, has_version,
        has_model_json, has_attributes_pkl.
    """

Import

from fickling.polyglot import find_file_properties

I/O Contract

Inputs

Name	Type	Required	Description
file_path	str	Yes	Path to the file to inspect
print_properties	bool	No	Print discovered properties to stdout (default: False)

Outputs

Name	Type	Description
(return)	dict	Boolean properties dict with 12 keys describing file structure

Usage Examples

Inspect File Properties

from fickling.polyglot import find_file_properties

properties = find_file_properties("model.pt", print_properties=True)

if properties["is_torch_zip"] and properties["has_data_pkl"]:
    print("Standard PyTorch v1.3 format")
elif properties["is_valid_pickle"]:
    print("Legacy stacked pickle format")

Related Pages

Implements Principle

• Principle:Trailofbits_Fickling_File_Property_Discovery

Requires Environment

• Environment:Trailofbits_Fickling_PyTorch