| 1 | _orig_open = open
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| 2 |
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| 3 | class _BkFile:
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| 4 | def __init__(self, file, mode, bufsize):
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| 5 | import os
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| 6 | self.__filename = file
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| 7 | self.__backup = file + '~'
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| 8 | try:
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| 9 | os.unlink(self.__backup)
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| 10 | except os.error:
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| 11 | pass
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| 12 | try:
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| 13 | os.rename(file, self.__backup)
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| 14 | except os.error:
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| 15 | self.__backup = None
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| 16 | self.__file = _orig_open(file, mode, bufsize)
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| 17 | self.closed = self.__file.closed
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| 18 | self.fileno = self.__file.fileno
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| 19 | self.flush = self.__file.flush
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| 20 | self.isatty = self.__file.isatty
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| 21 | self.mode = self.__file.mode
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| 22 | self.name = self.__file.name
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| 23 | self.read = self.__file.read
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| 24 | self.readinto = self.__file.readinto
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| 25 | self.readline = self.__file.readline
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| 26 | self.readlines = self.__file.readlines
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| 27 | self.seek = self.__file.seek
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| 28 | self.softspace = self.__file.softspace
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| 29 | self.tell = self.__file.tell
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| 30 | self.truncate = self.__file.truncate
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| 31 | self.write = self.__file.write
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| 32 | self.writelines = self.__file.writelines
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| 33 |
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| 34 | def close(self):
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| 35 | self.__file.close()
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| 36 | if self.__backup is None:
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| 37 | return
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| 38 | import filecmp
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| 39 | if filecmp.cmp(self.__backup, self.__filename, shallow = 0):
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| 40 | import os
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| 41 | os.unlink(self.__filename)
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| 42 | os.rename(self.__backup, self.__filename)
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| 43 |
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| 44 | def open(file, mode = 'r', bufsize = -1):
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| 45 | if 'w' not in mode:
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| 46 | return _orig_open(file, mode, bufsize)
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| 47 | return _BkFile(file, mode, bufsize)
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