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Format scatterhash.py

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TKE
2020-12-18 10:06:10 +01:00
parent 175e780248
commit c32e4bf314
1 changed files with 11 additions and 14 deletions
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scatterhash.py
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@@ -17,30 +17,27 @@ def even_select(N, M):
q, r = divmod(N, M) q, r = divmod(N, M)
indices = [q*i + min(i, r) for i in range(M)] indices = [q*i + min(i, r) for i in range(M)]
cut[indices] = False cut[indices] = False
return cut return cut
def get_offsets(blocksize, blockcount,blocks_to_hash): def get_offsets(blocksize, blockcount,blocks_to_hash):
selection=even_select(blockcount,blocks_to_hash) selection = even_select(blockcount,blocks_to_hash)
for i in range(0,blockcount): for i in range(0,blockcount):
if selection[i]==0: if selection[i] == 0:
offset=int(blocksize*i) offset = int(blocksize*i)
yield offset yield offset
def get_hash(file,hashalgo,spread): def get_hash(file,hashalgo,spread):
h=hashlib.new(hashalgo) h=hashlib.new(hashalgo)
filesize=os.path.getsize(file.name) filesize = os.path.getsize(file.name)
blocksize=h.block_size*65535 blocksize = h.block_size*65535
blockcount=math.ceil(filesize/blocksize) blockcount = math.ceil(filesize/blocksize)
blocks_to_hash=math.ceil(blockcount*spread/100) blocks_to_hash = math.ceil(blockcount*spread/100)
if filesize>blocksize: if filesize>blocksize:
for of in get_offsets(blocksize,blockcount,blocks_to_hash): for of in get_offsets(blocksize,blockcount,blocks_to_hash):
infile.seek(of) infile.seek(of)
h.update(file.read(blocksize)) h.update(file.read(blocksize))
else: else:
h.update(file.read(blocksize)) h.update(file.read(blocksize))
result="{};{};{};{};{}".format(h.hexdigest(),spread,filesize,hashalgo,file.name) result="{};{};{};{};{}".format(h.hexdigest(),spread,filesize,hashalgo,file.name)
return result return result
@@ -48,10 +45,10 @@ parser = argparse.ArgumentParser(description='Sparsly hash large files. Only a g
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('-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('-c', action="store",dest="hashalgo",nargs='?',default="md5",help='select an hashalgorithm (default=md5)') 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='+') parser.add_argument('file', type=argparse.FileType('rb'), nargs='+')
args=parser.parse_args() args = parser.parse_args()
hashalgo=args.hashalgo hashalgo = args.hashalgo
spread=args.spread spread = args.spread
for infile in args.file: for infile in args.file:
hashvalue=get_hash(infile,hashalgo,spread) hashvalue = get_hash(infile,hashalgo,spread)
print(hashvalue) print(hashvalue)