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/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
using System;
using System.IO;
using System.IO.MemoryMappedFiles;
using System.Text;
namespace Tunnel
{
public class Ringlogger
{
private readonly MemoryMappedViewAccessor _viewAccessor;
public Ringlogger(string filename)
{
var file = File.Open(filename, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
var mmap = MemoryMappedFile.CreateFromFile(file, null, 0, MemoryMappedFileAccess.Read, HandleInheritability.None, false);
_viewAccessor = mmap.CreateViewAccessor(0, 8 + 2048 * (512 + 8), MemoryMappedFileAccess.Read);
if (_viewAccessor.ReadUInt32(0) != 0xbadbabe)
throw new InvalidDataException("The provided file is missing the magic number.");
}
public void WriteTo(TextWriter writer)
{
var start = _viewAccessor.ReadUInt32(4);
for (var i = 0; i < 2048; ++i)
{
var lineOffset = 8 + (8 + 512) * ((i + start) % 2048);
var timeNs = _viewAccessor.ReadInt64(lineOffset);
if (timeNs == 0)
continue;
var textBytes = new byte[512];
_viewAccessor.ReadArray<byte>(lineOffset + 8, textBytes, 0, textBytes.Length);
var nullByte = Array.IndexOf<byte>(textBytes, 0);
if (nullByte <= 0)
continue;
var text = Encoding.UTF8.GetString(textBytes, 0, nullByte);
var time = DateTimeOffset.FromUnixTimeMilliseconds(timeNs / 1000000).ToString("yyyy'-'MM'-'dd HH':'mm':'ss'.'ffffff");
writer.WriteLine(String.Format("{0}: {1}", time, text));
}
}
}
}
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