82 lines
2.2 KiB
Python
82 lines
2.2 KiB
Python
#!/usr/bin/python3
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import struct
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class Cpio(object):
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def __init__(self, buf):
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self.buf = buf
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self.off = 0
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def __iter__(self):
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return self
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def next(self):
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f = CpioFile(self.off, self.buf)
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if f.fin():
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raise StopIteration
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self.off = self.off + f.length()
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return f
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class CpioFile(object):
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def __init__(self, off, buf):
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self.off = off
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self.buf = buf
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if (off & 3):
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raise Exception("invalid offset %d" % off)
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fmt = "6s8s8s8s8s8s8s8s8s8s8s8s8s8s"
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off = self.off + struct.calcsize(fmt)
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fields = struct.unpack(fmt, buf[self.off:off])
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if fields[0] != "070701":
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raise Exception("invalid cpio header %s" % self.c_magic)
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names = ("c_ino", "c_mode", "c_uid", "c_gid",
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"c_nlink", "c_mtime", "c_filesize",
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"c_devmajor", "c_devminor", "c_rdevmajor",
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"c_rdevminor", "c_namesize", "c_check")
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for (n, v) in zip(names, fields[1:]):
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setattr(self, n, int(v, 16))
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nlen = self.c_namesize - 1
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self.name = struct.unpack('%ds' % nlen, buf[off:off + nlen])[0]
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off = off + nlen + 1
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if (off & 3):
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off = off + 4 - (off & 3) # padding
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self.payloadstart = off
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def fin(self):
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return self.name == 'TRAILER!!!'
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def __str__(self):
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return "[%s %d]" % (self.name, self.c_filesize)
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def header(self):
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return self.buf[self.payloadstart:self.payloadstart + self.c_filesize]
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def length(self):
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len = self.payloadstart - self.off + self.c_filesize
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if (self.c_filesize & 3):
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len = len + 4 - (self.c_filesize & 3)
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return len
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if __name__ == '__main__':
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from optparse import OptionParser
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parser = OptionParser()
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parser.add_option("--debug", action="store_true", help="debug output")
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parser.add_option("--verbose", action="store_true", help="verbose")
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(options, args) = parser.parse_args()
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for fn in args:
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fh = open(fn, 'rb')
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cpio = Cpio(fh.read())
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for i in cpio:
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print(i)
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ofh = open(i.name, 'wb')
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ofh.write(i.header())
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ofh.close()
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