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bpo-45150: add a simple file_digest helper #28252

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bpo-45150: add a simple file_digest helper #28252

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23 changes: 22 additions & 1 deletion Lib/hashlib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,8 @@
algorithms_available = set(__always_supported)

__all__ = __always_supported + ('new', 'algorithms_guaranteed',
'algorithms_available', 'pbkdf2_hmac')
'algorithms_available', 'pbkdf2_hmac',
'file_digest')


__builtin_constructor_cache = {}
Expand Down Expand Up @@ -254,6 +255,22 @@ def prf(msg, inner=inner, outer=outer):
pass


def file_digest(filepath, digest=None, chunk_size=4096, hex=True):
"""Returns a digest of a file.
"""
if digest is None:
from _sha256 import sha256
digest = sha256

hash = digest()
with open(filepath, "rb") as f:
for chunk in iter(lambda: f.read(chunk_size), b""):
hash.update(chunk)
if hex:
return hash.hexdigest()
return hash.digest()


for __func_name in __always_supported:
# try them all, some may not work due to the OpenSSL
# version not supporting that algorithm.
Expand All @@ -263,6 +280,10 @@ def prf(msg, inner=inner, outer=outer):
import logging
logging.exception('code for hash %s was not found.', __func_name)

if __name__ == '__main__':
import sys

print(file_digest(sys.argv[1]))

# Cleanup locals()
del __always_supported, __func_name, __get_hash
Expand Down