| Guido van Rossum | baf0603 | 1998-08-25 14:06:55 +0000 | [diff] [blame] | 1 | _orig_open = open |
| 2 | |
| 3 | class _BkFile: |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 4 | def __init__(self, file, mode, bufsize): |
| 5 | import os |
| 6 | self.__filename = file |
| 7 | self.__backup = file + '~' |
| 8 | try: |
| 9 | os.unlink(self.__backup) |
| Andrew Svetlov | 8b33dd8 | 2012-12-24 19:58:48 +0200 | [diff] [blame] | 10 | except OSError: |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 11 | pass |
| 12 | try: |
| 13 | os.rename(file, self.__backup) |
| Andrew Svetlov | 8b33dd8 | 2012-12-24 19:58:48 +0200 | [diff] [blame] | 14 | except OSError: |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 15 | self.__backup = None |
| 16 | self.__file = _orig_open(file, mode, bufsize) |
| 17 | self.closed = self.__file.closed |
| 18 | self.fileno = self.__file.fileno |
| 19 | self.flush = self.__file.flush |
| 20 | self.isatty = self.__file.isatty |
| 21 | self.mode = self.__file.mode |
| 22 | self.name = self.__file.name |
| 23 | self.read = self.__file.read |
| Guido van Rossum | 5397039 | 2007-06-12 00:28:30 +0000 | [diff] [blame] | 24 | try: |
| 25 | self.readinto = self.__file.readinto |
| 26 | except AttributeError: |
| 27 | pass |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 28 | self.readline = self.__file.readline |
| 29 | self.readlines = self.__file.readlines |
| 30 | self.seek = self.__file.seek |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 31 | self.tell = self.__file.tell |
| 32 | self.truncate = self.__file.truncate |
| 33 | self.write = self.__file.write |
| 34 | self.writelines = self.__file.writelines |
| Guido van Rossum | baf0603 | 1998-08-25 14:06:55 +0000 | [diff] [blame] | 35 | |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 36 | def close(self): |
| 37 | self.__file.close() |
| 38 | if self.__backup is None: |
| 39 | return |
| 40 | import filecmp |
| 41 | if filecmp.cmp(self.__backup, self.__filename, shallow = 0): |
| 42 | import os |
| 43 | os.unlink(self.__filename) |
| 44 | os.rename(self.__backup, self.__filename) |
| Guido van Rossum | baf0603 | 1998-08-25 14:06:55 +0000 | [diff] [blame] | 45 | |
| 46 | def open(file, mode = 'r', bufsize = -1): |
| Tim Peters | 182b5ac | 2004-07-18 06:16:08 +0000 | [diff] [blame] | 47 | if 'w' not in mode: |
| 48 | return _orig_open(file, mode, bufsize) |
| 49 | return _BkFile(file, mode, bufsize) |