import os import string import random import mmap import sys DATATYPES = dict( ascii_letters=string.ascii_letters.encode(), ascii_lowercase=string.ascii_lowercase.encode(), ascii_uppercase=string.ascii_uppercase.encode(), digits=string.digits.encode(), hexdigits=string.hexdigits.encode(), octdigits=string.octdigits.encode(), punctuation=string.punctuation.encode(), whitespace=string.whitespace.encode(), ascii=string.printable.encode(), bytes=bytes(range(256)) ) class TransformGenerator: """ Perform a byte-by-byte transform another generator - that is, for each input byte, the transformation must produce one output byte. gen: A generator to wrap transform: A function (offset, data) -> transformed """ def __init__(self, gen, transform): self.gen = gen self.transform = transform def __len__(self): return len(self.gen) def __getitem__(self, x): d = self.gen.__getitem__(x) if isinstance(x, slice): return self.transform(x.start, d) return self.transform(x, d) def __repr__(self): return "'transform(%s)'" % self.gen def rand_byte(chars): """ Return a random character as byte from a charset. """ # bytearray has consistent behaviour on both Python 2 and 3 # while bytes does not return bytes([random.choice(chars)]) class RandomGenerator: def __init__(self, dtype, length): self.dtype = dtype self.length = length def __len__(self): return self.length def __getitem__(self, x): chars = DATATYPES[self.dtype] if isinstance(x, slice): return b"".join(rand_byte(chars) for _ in range(*x.indices(min(self.length, sys.maxsize)))) return rand_byte(chars) def __repr__(self): return "%s random from %s" % (self.length, self.dtype) class FileGenerator: def __init__(self, path): self.path = path def __len__(self): return os.path.getsize(self.path) def __getitem__(self, x): with open(self.path, mode="rb") as f: if isinstance(x, slice): with mmap.mmap(f.fileno(), 0, access=mmap.ACCESS_READ) as mapped: return mapped.__getitem__(x) else: f.seek(x) return f.read(1) def __repr__(self): return "<%s" % self.path