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# R overlay -- roverlay package, digest
# -*- coding: utf-8 -*-
# Copyright (C) 2012 André Erdmann <dywi@mailerd.de>
# Distributed under the terms of the GNU General Public License;
# either version 2 of the License, or (at your option) any later version.
"""provides digest related utility functions (e.g. md5sum_file())"""
__all__ = [
'digest_compare', 'digest_comparator',
'digest_supported', 'dodigest_file',
'multihash', 'multihash_file',
'md5sum_file', 'sha1_file', 'sha256_file', 'sha512_file',
'whirlpool_file',
]
DEFAULT_BLOCKSIZE=16384
import hashlib
_HASH_CREATE_MAP = {
'md5' : hashlib.md5,
'sha1' : hashlib.sha1,
'sha256' : hashlib.sha256,
'sha512' : hashlib.sha512,
}
def hashlib_wrap ( name ):
"""Creates a wrapper that uses hashlib.new(<name>) for the given name.
arguments:
* name -- hash name, e.g. whirlpool
"""
def wrapped ( *args, **kwargs ):
return hashlib.new ( name, *args, **kwargs )
# --- end of wrapped (...) ---
h = hashlib.new
wrapped.__dict__.update ( h.__dict__ )
wrapped.__name__ = name
wrapped.__doc__ = h.__doc__
del h
return wrapped
# --- end of hashlib_wrap (...) ---
def hashlib_supports ( name ):
"""Returns True if the given hash type is supported, else False.
arguments:
* name --
"""
if name in getattr ( hashlib, 'algorithms_available', () ):
# python 2's hashlib has no algorithms_available attribute
return True
else:
ret = False
try:
hashlib.new ( name )
except ValueError:
pass
else:
ret = True
return ret
# --- end of hashlib_supports (...) ---
if hashlib_supports ( 'whirlpool' ):
_HASH_CREATE_MAP ['whirlpool'] = hashlib_wrap ( "whirlpool" )
else:
import portage.util.whirlpool
_HASH_CREATE_MAP ['whirlpool'] = portage.util.whirlpool.new
# -- end of imports / HASH_CREATE_MAP
def _generic_obj_hash (
hashobj, fh, binary_digest=False, blocksize=DEFAULT_BLOCKSIZE
):
block = fh.read ( blocksize )
while block:
hashobj.update ( block )
block = fh.read ( blocksize )
return hashobj.digest() if binary_digest else hashobj.hexdigest()
# --- end of _hashsum_generic (...) ---
def _generic_file_obj_hash (
hashobj, filepath, binary_digest=False, blocksize=DEFAULT_BLOCKSIZE
):
ret = None
with open ( filepath, 'rb' ) as fh:
ret = _generic_obj_hash ( hashobj, fh, binary_digest, blocksize )
return ret
# --- end of _generic_file_obj_hash (...) ---
def multihash (
fh, hashlist, binary_digest=False, blocksize=DEFAULT_BLOCKSIZE
):
"""Calculates multiple digests for an already openened file and returns the
resulting hashes as dict.
arguments:
* fh -- file handle
* hashlist -- iterable with hash names (e.g. md5)
* binary_digest -- whether the hashes should be binary or not
* blocksize -- block size for reading
"""
hashobj_dict = {
h: _HASH_CREATE_MAP[h]() for h in hashlist
}
block = fh.read ( blocksize )
while block:
for hashobj in hashobj_dict.values():
hashobj.update ( block )
block = fh.read ( blocksize )
if binary_digest:
return { h: hashobj.digest() for h, hashobj in hashobj_dict.items() }
else:
return { h: hashobj.hexdigest() for h, hashobj in hashobj_dict.items() }
# --- end of multihash (...) ---
def multihash_file ( filepath, digest_types, **kwargs ):
"""Calculates multiple digests for the given file path.
Returns an empty dict if digest_types is empty.
arguments:
* filepath --
* digest_types --
* **kwargs -- passed to multihash()
"""
if digest_types:
hashdict = None
with open ( filepath, mode='rb' ) as fh:
hashdict = multihash ( fh, digest_types, **kwargs )
return hashdict
else:
return dict()
# --- end of multihash_file (...) ---
def md5sum_file ( filepath, **kw ):
"""Returns the md5 sum for a file."""
return _generic_file_obj_hash ( hashlib.md5(), filepath, **kw )
# --- end of md5sum_file (...) ---
def sha1_file ( filepath, **kw ):
return _generic_obj_hash ( hashlib.sha1(), filepath, **kw )
# --- end of sha1_file (...) ---
def sha256_file ( filepath, **kw ):
return _generic_obj_hash ( hashlib.sha256(), filepath, **kw )
# --- end of sha256_file (...) ---
def sha512_file ( filepath, **kw ):
return _generic_obj_hash ( hashlib.sha512(), filepath, **kw )
# --- end of sha512_file (...) ---
def whirlpool_file ( filepath, **kw ):
return _generic_obj_hash (
portage.util.whirlpool.new(), filepath, **kw
)
# --- end of whirlpool_file (...) ---
def digest_supported ( digest_type ):
"""Returns True if the given digest type is supported, else False."""
return digest_type in _HASH_CREATE_MAP
# --- digest_supported (...) ---
def dodigest_file ( _file, digest_type, **kwargs ):
return _generic_file_obj_hash (
hashobj = _HASH_CREATE_MAP [digest_type](),
filepath = _file,
**kwargs
)
# --- end of dodigest_file (...) ---
def digest_compare ( digest, digest_type, filepath, **kwargs ):
return digest == dodigest_file ( filepath, digest_type, **kwargs )
# --- end of digest_compare (...) ---
# digest_comparator :: digest_type -> digest -> ( filepath, ... ) -> bool
digest_comparator = (
lambda digest_type : (
lambda digest : (
lambda filepath, *args, **kwargs : digest_compare (
digest, digest_type, *args, **kwargs
)
)
)
)
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