pygfried 0.15.0

Siegfried as a Python extension

Pygfried

pygfried is a CPython extension that brings siegfried - a powerful, signature-based file format identification tool written in Go - into the Python ecosystem.

Instead of reimplementing siegfried's logic, pygfried embeds the original Go code directly, making core siegfried functionality available to Python users without any changes to the underlying detection engine.

No animals were harmed in the making of this extension.

Usage

$ pip install pygfried
$ python -q
>>> import pygfried
>>> pygfried.version()
'1.11.2'
>>> pygfried.identify("example.png")
'fmt/11'
>>> pygfried.identify("example.png", detailed=True)
{'siegfried': '1.11.2', 'scandate': '2025-06-10T07:16:31+02:00', 'signature': 'default.sig', 'created': '2025-03-01T15:28:08+11:00', 'identifiers': [{'name': 'pronom', 'details': 'DROID_SignatureFile_V120.xml; container-signature-20240715.xml'}], 'files': [{'filename': 'example.png', 'filesize': 237675, 'modified': '2025-06-10T07:11:26+02:00', 'errors': '', 'matches': [{'ns': 'pronom', 'id': 'fmt/11', 'format': 'Portable Network Graphics', 'version': '1.0', 'mime': 'image/png', 'class': 'Image (Raster)', 'basis': 'extension match png; byte match at [[0 16] [237663 12]]', 'warning': ''}]}]}
>>> pygfried.identify_many(["example.png", "README.md"], workers=2)
{'siegfried': '1.11.2', ...}
>>> pygfried.identify_dir("samples", recursive=True, workers=2)
{'siegfried': '1.11.2', ...}

Batch and directory scans

Use identify_many when you already have a list of paths, or identify_dir when you want pygfried to scan a directory for you. Both functions return the same detailed result shape as identify(..., detailed=True).

>>> from pathlib import Path
>>> paths = [str(path) for path in Path("samples").rglob("*.png")]
>>> pygfried.identify_many(paths, workers=4)
{'siegfried': '1.11.2', ...}
>>> pygfried.identify_dir("samples", recursive=True, workers=4)
{'siegfried': '1.11.2', ...}

The workers argument controls Go-side concurrency. The default is 1, which is the most conservative setting. For directories or large path lists, higher values can be much faster because pygfried avoids repeated Python-to-Go calls and identifies multiple files in parallel. A good starting point is the number of CPU cores available to your process, then measure with your own files.

By default identify_dir skips symlinks. Use follow_symlinks=True to identify file symlinks and descend symlinked directories; directory cycles are skipped, and repeated links to the same directory are scanned once.

Limitations

Go libraries can clash

This project uses Go's -buildmode=c-shared to provide its Python extension. Loading multiple Go-based shared libraries in the same process is unsupported and may result in panics or crashes due to conflicts between separate Go runtimes.

This limitation should only affect you if you're using pygfried together with another Python library that also uses a Go extension (built with the same c-shared mechanism) in the same process. If you're just using pygfried on its own, you don't need to worry - everything should work as expected.

Credits

pygfried is powered by the original siegfried project, which is distributed under the Apache License, Version 2.0. All core file format identification logic and signatures are provided by siegfried. We gratefully acknowledge the work of the siegfried project and its contributors.