48 lines
1.6 KiB
Python
48 lines
1.6 KiB
Python
import io
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import os
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class CappedBufferedReader(io.BufferedReader):
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def __init__(self, raw, buffer_size=io.DEFAULT_BUFFER_SIZE, capped_size=None):
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super().__init__(raw, buffer_size)
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self.capped_size = capped_size
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def read(self, size=None):
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if self.capped_size is not None:
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if size is None or size < 0 or size > self.capped_size:
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size = self.capped_size
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self.capped_size -= size
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return super().read(size)
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def seek(self, offset, whence=os.SEEK_SET):
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if self.capped_size is not None:
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if offset == 0 and whence == os.SEEK_END:
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if self.capped_size < 0:
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offset = 0
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else:
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real_end = super().seek(0, os.SEEK_END)
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if self.capped_size > real_end:
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offset = real_end
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else:
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offset = self.capped_size
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self.capped_size -= offset
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whence = os.SEEK_SET
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elif whence == os.SEEK_SET:
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current_pos = self.tell()
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if current_pos > offset:
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self.capped_size += current_pos - offset
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return super().seek(offset, whence)
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@property
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def name(self):
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try:
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return self._name
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except AttributeError:
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return super().name
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@name.setter
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def name(self, new_name):
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self._name = new_name
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def bopen(file, capped_size):
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return CappedBufferedReader(open(file, 'rb', buffering=0), capped_size=capped_size)
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