95 lines
2.4 KiB
Python
95 lines
2.4 KiB
Python
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import uctypes
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# http://www.gnu.org/software/tar/manual/html_node/Standard.html
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TAR_HEADER = {
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"name": (uctypes.ARRAY | 0, uctypes.UINT8 | 100),
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"size": (uctypes.ARRAY | 124, uctypes.UINT8 | 12),
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}
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DIRTYPE = "dir"
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REGTYPE = "file"
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def roundup(val, align):
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return (val + align - 1) & ~(align - 1)
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class FileSection:
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def __init__(self, f, content_len, aligned_len):
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self.f = f
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self.content_len = content_len
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self.align = aligned_len - content_len
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def read(self, sz=65536):
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if self.content_len == 0:
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return b""
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if sz > self.content_len:
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sz = self.content_len
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data = self.f.read(sz)
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sz = len(data)
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self.content_len -= sz
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return data
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def readinto(self, buf):
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if self.content_len == 0:
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return 0
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if len(buf) > self.content_len:
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buf = memoryview(buf)[:self.content_len]
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sz = self.f.readinto(buf)
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self.content_len -= sz
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return sz
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def skip(self):
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sz = self.content_len + self.align
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if sz:
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buf = bytearray(16)
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while sz:
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s = min(sz, 16)
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self.f.readinto(buf, s)
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sz -= s
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class TarInfo:
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def __str__(self):
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return "TarInfo(%r, %s, %d)" % (self.name, self.type, self.size)
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class TarFile:
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def __init__(self, name=None, fileobj=None):
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if fileobj:
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self.f = fileobj
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else:
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self.f = open(name, "rb")
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self.subf = None
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def next(self):
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if self.subf:
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self.subf.skip()
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buf = self.f.read(512)
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if not buf:
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return None
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h = uctypes.struct(uctypes.addressof(buf), TAR_HEADER, uctypes.LITTLE_ENDIAN)
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# Empty block means end of archive
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if h.name[0] == 0:
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return None
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d = TarInfo()
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d.name = str(h.name, "utf-8").rstrip()
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d.size = int(bytes(h.size).rstrip(), 8)
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d.type = [REGTYPE, DIRTYPE][d.name[-1] == "/"]
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self.subf = d.subf = FileSection(self.f, d.size, roundup(d.size, 512))
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return d
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def __iter__(self):
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return self
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def __next__(self):
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v = self.next()
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if v is None:
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raise StopIteration
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return v
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def extractfile(self, tarinfo):
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return tarinfo.subf
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