binhex.py 文件源码

def _fill(self, wtd):
        self.pre_buffer = self.pre_buffer + self.ifp.read(wtd + 4)
        if self.ifp.eof:
            self.post_buffer = self.post_buffer + \
                binascii.rledecode_hqx(self.pre_buffer)
            self.pre_buffer = b''
            return

        #
        # Obfuscated code ahead. We have to take care that we don't
        # end up with an orphaned RUNCHAR later on. So, we keep a couple
        # of bytes in the buffer, depending on what the end of
        # the buffer looks like:
        # '\220\0\220' - Keep 3 bytes: repeated \220 (escaped as \220\0)
        # '?\220' - Keep 2 bytes: repeated something-else
        # '\220\0' - Escaped \220: Keep 2 bytes.
        # '?\220?' - Complete repeat sequence: decode all
        # otherwise: keep 1 byte.
        #
        mark = len(self.pre_buffer)
        if self.pre_buffer[-3:] == RUNCHAR + b'\0' + RUNCHAR:
            mark = mark - 3
        elif self.pre_buffer[-1:] == RUNCHAR:
            mark = mark - 2
        elif self.pre_buffer[-2:] == RUNCHAR + b'\0':
            mark = mark - 2
        elif self.pre_buffer[-2:-1] == RUNCHAR:
            pass # Decode all
        else:
            mark = mark - 1

        self.post_buffer = self.post_buffer + \
            binascii.rledecode_hqx(self.pre_buffer[:mark])
        self.pre_buffer = self.pre_buffer[mark:]