42 lines
1.8 KiB
Python
42 lines
1.8 KiB
Python
import os
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def ReadFileRangeFromEnd(FilePath, StartLineFromEnd, EndLineFromEnd, BufferSize=1024 * 10, ReturnType=str):
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if StartLineFromEnd < 1 or EndLineFromEnd < 1:
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raise ValueError("Line number must be greater than 0")
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if StartLineFromEnd > EndLineFromEnd:
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raise ValueError("StartLineFromEnd must be less than or equal to EndLineFromEnd")
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LineCount = EndLineFromEnd
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BufferSize = BufferSize * LineCount
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with open(FilePath, 'rb') as FileObj:
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FileObj.seek(0, 2)
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FileSize = FileObj.tell()
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BufferSize = min(BufferSize, FileSize)
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Lines = []
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CurrentPosition = FileSize
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FoundLines = 0
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while CurrentPosition > 0 and FoundLines < LineCount:
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ReadPosition = max(0, CurrentPosition - BufferSize)
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ChunkSize = CurrentPosition - ReadPosition
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FileObj.seek(ReadPosition)
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Chunk = FileObj.read(ChunkSize)
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ChunkLines = Chunk.splitlines()
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ChunkLines = ChunkLines[::-1]
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for Line in ChunkLines:
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if FoundLines < LineCount:
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Lines.append(Line)
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FoundLines += 1
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else:
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break
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CurrentPosition = ReadPosition
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Lines = Lines[::-1]
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StartIndex = max(0, len(Lines) - EndLineFromEnd)
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EndIndex = len(Lines) - StartLineFromEnd + 1
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ResultLines = Lines[StartIndex:EndIndex]
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R = [Line.decode('utf-8', errors='ignore') for Line in ResultLines]
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if ReturnType == str: return '\n'.join(R)
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elif ReturnType == list: return R
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else: raise ValueError("Return Type Error")
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TempDir = os.getenv("temp")
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LogFile = os.path.join(TempDir, "T.log")
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ResultLines = ReadFileRangeFromEnd(LogFile, 1, 300) |