Filetype Inference Library

1.2.0 · active · verified Sun Mar 29

Small and dependency-free Python package to infer file type and MIME type by checking the magic numbers signature of a file or buffer. It is a Python port from the 'filetype' Go package, offering a simple and friendly API for a wide range of file types. Currently at version 1.2.0, it is actively maintained with periodic updates.

Warnings

gotcha The `filetype.guess()` function returns `None` if it cannot determine the type of the given file or buffer. Always check for `None` before accessing `extension` or `mime` attributes.
Fix: Implement a check for `if kind is None:` or similar logic to handle unknown file types gracefully.
gotcha `filetype.guess()` will raise a `FileNotFoundError` if the provided file path does not exist. Ensure the file path is correct and the file is accessible.
Fix: Use `try-except FileNotFoundError` blocks to handle missing files, or verify file existence using `os.path.exists()` before calling `guess()`.
gotcha When guessing from a buffer, `filetype` typically only requires the first 261 bytes (maximum file header size) for accurate detection. Providing an insufficient number of bytes may lead to incorrect type inference or `None` being returned.
Fix: Ensure that the buffer passed to `filetype.guess()` contains at least the initial bytes of the file, ideally up to 261 bytes, for reliable type detection.

Install

pip install filetype Install stable version

Imports

filetype
```
import filetype
```

Quickstart

This quickstart demonstrates how to use `filetype.guess()` to infer the type of a file based on its path and from a bytes buffer. It creates a dummy JPEG file to showcase the functionality and then cleans it up. The library returns a `Kind` object with `extension` and `mime` attributes, or `None` if the type cannot be determined.

import filetype
import os

# Create a dummy JPEG file for demonstration
dummy_jpeg_path = 'dummy.jpg'
# A minimal JPEG header (first few bytes of a typical JPEG file)
# In a real scenario, you'd read from an actual file.
jpeg_magic_bytes = b'\xFF\xD8\xFF\xE0\x00\x10\x4A\x46\x49\x46\x00\x01'

try:
    with open(dummy_jpeg_path, 'wb') as f:
        f.write(jpeg_magic_bytes)

    # Guess the file type from the path
    kind = filetype.guess(dummy_jpeg_path)

    if kind is None:
        print('Cannot guess file type!')
    else:
        print(f'File extension: {kind.extension}')
        print(f'File MIME type: {kind.mime}')

    # You can also guess from a buffer/bytes object
    kind_from_buffer = filetype.guess(jpeg_magic_bytes)
    if kind_from_buffer:
        print(f'Buffer extension: {kind_from_buffer.extension}')
        print(f'Buffer MIME type: {kind_from_buffer.mime}')

finally:
    # Clean up the dummy file
    if os.path.exists(dummy_jpeg_path):
        os.remove(dummy_jpeg_path)

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