import uctypes # http://www.gnu.org/software/tar/manual/html_node/Standard.html TAR_HEADER = { "name": (uctypes.ARRAY | 0, uctypes.UINT8 | 100), "size": (uctypes.ARRAY | 124, uctypes.UINT8 | 11), } DIRTYPE = "dir" REGTYPE = "file" def roundup(val, align): return (val + align - 1) & ~(align - 1) class FileSection: def __init__(self, f, content_len, aligned_len): self.f = f self.content_len = content_len self.align = aligned_len - content_len def read(self, sz=65536): if self.content_len == 0: return b"" if sz > self.content_len: sz = self.content_len data = self.f.read(sz) sz = len(data) self.content_len -= sz return data def readinto(self, buf): if self.content_len == 0: return 0 if len(buf) > self.content_len: buf = memoryview(buf)[: self.content_len] sz = self.f.readinto(buf) self.content_len -= sz return sz def skip(self): sz = self.content_len + self.align if sz: buf = bytearray(16) while sz: s = min(sz, 16) self.f.readinto(buf, s) sz -= s class TarInfo: def __str__(self): return "TarInfo(%r, %s, %d)" % (self.name, self.type, self.size) class TarFile: def __init__(self, name=None, fileobj=None): if fileobj: self.f = fileobj else: self.f = open(name, "rb") self.subf = None def next(self): if self.subf: self.subf.skip() buf = self.f.read(512) if not buf: return None h = uctypes.struct(uctypes.addressof(buf), TAR_HEADER, uctypes.LITTLE_ENDIAN) # Empty block means end of archive if h.name[0] == 0: return None d = TarInfo() d.name = str(h.name, "utf-8").rstrip("\0") d.size = int(bytes(h.size), 8) d.type = [REGTYPE, DIRTYPE][d.name[-1] == "/"] self.subf = d.subf = FileSection(self.f, d.size, roundup(d.size, 512)) return d def __iter__(self): return self def __next__(self): v = self.next() if v is None: raise StopIteration return v def extractfile(self, tarinfo): return tarinfo.subf