60 lines
2.2 KiB
Python
Executable File
60 lines
2.2 KiB
Python
Executable File
#!/usr/bin/python3
|
|
import sys
|
|
import hashlib
|
|
import os
|
|
import numpy as np
|
|
import math
|
|
import argparse
|
|
|
|
def even_select(N, M):
|
|
if M > N/2:
|
|
cut = np.zeros(N, dtype=int)
|
|
q, r = divmod(N, N-M)
|
|
indices = [q*i + min(i, r) for i in range(N-M)]
|
|
cut[indices] = True
|
|
else:
|
|
cut = np.ones(N, dtype=int)
|
|
q, r = divmod(N, M)
|
|
indices = [q*i + min(i, r) for i in range(M)]
|
|
cut[indices] = False
|
|
return cut
|
|
|
|
def get_offsets(blocksize, blockcount,blocks_to_hash):
|
|
selection = even_select(blockcount,blocks_to_hash)
|
|
for i in range(0,blockcount):
|
|
if selection[i] == 0:
|
|
offset = int(blocksize*i)
|
|
yield offset
|
|
|
|
def get_hash(file,hashalgo,spread,maxsize):
|
|
h=hashlib.new(hashalgo)
|
|
filesize = os.path.getsize(file.name)
|
|
blocksize = h.block_size*65535
|
|
blockcount = math.ceil(filesize/blocksize)
|
|
blocks_to_hash = math.ceil(blockcount*spread/100)
|
|
if (blocks_to_hash * blocksize) > maxsize:
|
|
blocks_to_hash = math.ceil(maxsize/blocksize)
|
|
if filesize>blocksize:
|
|
for of in get_offsets(blocksize,blockcount,blocks_to_hash):
|
|
infile.seek(of)
|
|
h.update(file.read(blocksize))
|
|
else:
|
|
h.update(file.read(blocksize))
|
|
result="{};{};{};{};{}".format(h.hexdigest(),blocks_to_hash,filesize,hashalgo,file.name)
|
|
return result
|
|
|
|
parser = argparse.ArgumentParser(description='Sparsly hash large files. Only a given percentage of the file is actualy hashed.')
|
|
|
|
parser.add_argument('-p',metavar='N', action="store",dest="spread",type=int, nargs='?',default=10,help='percentage of file to hash. 0 < N < 100 (default=10)')
|
|
parser.add_argument('-s',metavar='N', action="store",dest="size",type=int, nargs='?',default=10,help='maximum amount of data per file in MB')
|
|
parser.add_argument('-c', action="store",dest="hashalgo",nargs='?',default="md5",help='select an hashalgorithm (default=md5)')
|
|
parser.add_argument('file', type=argparse.FileType('rb'), nargs='+')
|
|
args = parser.parse_args()
|
|
|
|
hashalgo = args.hashalgo
|
|
spread = args.spread
|
|
maxsize = args.size * 1024 * 1024
|
|
for infile in args.file:
|
|
hashvalue = get_hash(infile,hashalgo,spread,maxsize)
|
|
print(hashvalue)
|