|
| 1 | +import uctypes |
| 2 | + |
| 3 | +# http://www.gnu.org/software/tar/manual/html_node/Standard.html |
| 4 | +TAR_HEADER = { |
| 5 | + "name": (uctypes.ARRAY | 0, uctypes.UINT8 | 100), |
| 6 | + "size": (uctypes.ARRAY | 124, uctypes.UINT8 | 12), |
| 7 | +} |
| 8 | + |
| 9 | +DIRTYPE = "dir" |
| 10 | +REGTYPE = "file" |
| 11 | + |
| 12 | +def roundup(val, align): |
| 13 | + return (val + align - 1) & ~(align - 1) |
| 14 | + |
| 15 | +def skip(f, size): |
| 16 | + assert size % 512 == 0 |
| 17 | + buf = bytearray(512) |
| 18 | + while size: |
| 19 | + size -= f.readinto(buf) |
| 20 | + |
| 21 | +class FileSection: |
| 22 | + |
| 23 | + def __init__(self, f, content_len, aligned_len): |
| 24 | + self.f = f |
| 25 | + self.content_len = content_len |
| 26 | + self.align = aligned_len - content_len |
| 27 | + |
| 28 | + def read(self, sz=65536): |
| 29 | + if self.content_len == 0: |
| 30 | + return b"" |
| 31 | + if sz > self.content_len: |
| 32 | + sz = self.content_len |
| 33 | + data = self.f.read(sz) |
| 34 | + sz = len(data) |
| 35 | + self.content_len -= sz |
| 36 | + return data |
| 37 | + |
| 38 | + def skip(self): |
| 39 | + self.f.read(self.content_len + self.align) |
| 40 | + |
| 41 | +class TarInfo: |
| 42 | + |
| 43 | + def __str__(self): |
| 44 | + return "TarInfo(%r, %s, %d)" % (self.name, self.type, self.size) |
| 45 | + |
| 46 | +class TarFile: |
| 47 | + |
| 48 | + def __init__(self, name): |
| 49 | + self.f = open(name, "rb") |
| 50 | + self.subf = None |
| 51 | + |
| 52 | + def next(self): |
| 53 | + if self.subf: |
| 54 | + self.subf.skip() |
| 55 | + buf = self.f.read(512) |
| 56 | + if not buf: |
| 57 | + return None |
| 58 | + |
| 59 | + h = uctypes.struct(TAR_HEADER, uctypes.addressof(buf), uctypes.LITTLE_ENDIAN) |
| 60 | + |
| 61 | + # Empty block means end of archive |
| 62 | + if h.name[0] == 0: |
| 63 | + return None |
| 64 | + |
| 65 | + d = TarInfo() |
| 66 | + d.name = str(h.name, "utf-8").rstrip() |
| 67 | + d.size = int(bytes(h.size).rstrip(), 8) |
| 68 | + d.type = [REGTYPE, DIRTYPE][d.name[-1] == "/"] |
| 69 | + self.subf = d.subf = FileSection(self.f, d.size, roundup(d.size, 512)) |
| 70 | + return d |
| 71 | + |
| 72 | + def __iter__(self): |
| 73 | + return self |
| 74 | + |
| 75 | + def __next__(self): |
| 76 | + v = self.next() |
| 77 | + if v is None: |
| 78 | + raise StopIteration |
| 79 | + return v |
| 80 | + |
| 81 | + def extractfile(self, tarinfo): |
| 82 | + return tarinfo.subf |
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