Python module and CLI for hashing of file system directories.
Project description
dirhash
A lightweight python module and tool for computing the hash of any directory based on its files' structure and content.
- Supports any hashing algorithm of Python's built-in
hashlib
module .gitignore
style "wildmatch" patterns for expressive filtering of files to include/exclude.- Multiprocessing for up to 6x speed-up
Installation
git clone git@github.com:andhus/dirhash.git
pip install dirhash/
Usage
Python module:
from dirhash import dirhash
dirpath = 'path/to/directory'
dir_md5 = dirhash(dirpath, 'md5')
filtered_sha1 = dirhash(dirpath, 'sha1', ignore=['.*', '.*/', '*.pyc'])
pyfiles_sha3_512 = dirhash(dirpath, 'sha3_512', match=['*.py'])
CLI:
dirhash path/to/directory -a md5
dirhash path/to/directory -a sha1 -i ".* .*/ *.pyc"
dirhash path/to/directory -a sha3_512 -m "*.py"
Why?
If you (or your application) need to verify the integrity of a set of files as well as their name and location, you might find this useful. Use-cases range from verification of your image classification dataset (before spending GPU-$$$ on training your fancy Deep Learning model) to validation of generated files in regression-testing.
There isn't really a standard way of doing this. There are plenty of recipes out
there (see e.g. these SO-questions for linux
and python)
but I couldn't find one that is properly tested (there are some gotcha:s to cover!)
and documented with a compelling user interface. dirhash
was created with this as
the goal.
checksumdir is another python module/tool with similar intent (that inspired this project) but it lacks much of the functionality offered here (most notably including file names/structure in the hash) and lacks tests.
Performance
The python hashlib
implementation of common hashing algorithms are highly
optimised. dirhash
mainly parses the file tree, pipes data to hashlib
and
combines the output. Reasonable measures have been taken to minimize the overhead
and for common use-cases, the majority of time is spent reading data from disk
and executing hashlib
code.
The main effort to boost performance is support for multiprocessing, where the reading and hashing is parallelized over individual files.
As a reference, let's compare the performance of the dirhash
CLI
with the shell command:
find path/to/folder -type f -print0 | sort -z | xargs -0 md5 | md5
which is the top answer for the SO-question: Linux: compute a single hash for a given folder & contents? Results for two test cases are shown below. Both have 1 GiB of random data: in "flat_1k_1MB", split into 1k files (1 MiB each) in a flat structure, and in "nested_32k_32kB", into 32k files (32 KiB each) spread over the 256 leaf directories in a binary tree of depth 8.
Implementation | Test Case | Time (s) | Speed up |
---|---|---|---|
shell reference | flat_1k_1MB | 2.29 | -> 1.0 |
dirhash |
flat_1k_1MB | 1.67 | 1.36 |
dirhash (8 workers) |
flat_1k_1MB | 0.48 | 4.73 |
shell reference | nested_32k_32kB | 6.82 | -> 1.0 |
dirhash |
nested_32k_32kB | 3.43 | 2.00 |
dirhash (8 workers) |
nested_32k_32kB | 1.14 | 6.00 |
The benchmark was run a MacBook Pro (2018), further details and source code here.
Documentation
Please refer to dirhash -h
and the python source code.
Project details
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