Initial commit

srcs/RobotNet10/RobotApp/Communication/CartographerSharp/IO/ProtoStreamReader.cs

@@ -0,0 +1,158 @@
+/*
+ * Copyright 2016 The Cartographer Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.IO.Compression;
+using System.Text;
+using System.Text.Json;
+
+namespace CartographerSharp.IO;
+
+/// <summary>
+/// A reader of the format produced by ProtoStreamWriter.
+/// </summary>
+public class ProtoStreamReader : IProtoStreamReader, IDisposable
+{
+    // First eight bytes to identify our proto stream format.
+    private const ulong Magic = 0x7b1d1f7b5bf501db;
+
+
+    private static readonly JsonSerializerOptions JsonOptions = new()
+    {
+        PropertyNameCaseInsensitive = true
+    };
+
+    private readonly FileStream _fileStream;
+    private bool _disposed;
+    private bool _magicRead;
+
+    public ProtoStreamReader(string filename)
+    {
+        if (string.IsNullOrEmpty(filename))
+            throw new ArgumentException("Filename cannot be null or empty", nameof(filename));
+
+        if (!File.Exists(filename))
+            throw new FileNotFoundException($"File not found: {filename}", filename);
+
+        _fileStream = new FileStream(filename, FileMode.Open, FileAccess.Read, FileShare.Read);
+        ReadMagic();
+    }
+
+    private void ReadMagic()
+    {
+        ulong magic = ReadSizeAsLittleEndian();
+        if (magic != Magic)
+        {
+            throw new InvalidDataException($"Invalid proto stream format. Expected magic: 0x{Magic:X16}, got: 0x{magic:X16}");
+        }
+        _magicRead = true;
+    }
+
+    private ulong ReadSizeAsLittleEndian()
+    {
+        ulong size = 0;
+        for (int i = 0; i < 8; i++)
+        {
+            int byteValue = _fileStream.ReadByte();
+            if (byteValue == -1)
+                throw new EndOfStreamException("Unexpected end of stream while reading size");
+            
+            size >>= 8;
+            size += (ulong)byteValue << 56;
+        }
+        return size;
+    }
+
+    private bool Read(out string decompressedData)
+    {
+        decompressedData = string.Empty;
+
+        if (!_magicRead)
+        {
+            ReadMagic();
+        }
+
+        if (_fileStream.Position >= _fileStream.Length)
+        {
+            return false; // EOF
+        }
+
+        // Read compressed size
+        ulong compressedSize = ReadSizeAsLittleEndian();
+        
+        if (compressedSize == 0 || compressedSize > int.MaxValue)
+        {
+            return false;
+        }
+
+        // Read compressed data
+        byte[] compressedBytes = new byte[compressedSize];
+        int bytesRead = _fileStream.Read(compressedBytes, 0, (int)compressedSize);
+        
+        if (bytesRead != (int)compressedSize)
+        {
+            return false;
+        }
+
+        // Decompress using GZip
+        using var memoryStream = new MemoryStream(compressedBytes);
+        using var gzipStream = new GZipStream(memoryStream, CompressionMode.Decompress);
+        using var reader = new StreamReader(gzipStream, Encoding.UTF8);
+
+        decompressedData = reader.ReadToEnd();
+
+        return true;
+    }
+
+    /// <summary>
+    /// Deserializes compressed proto from the pb stream.
+    /// </summary>
+    public bool ReadProto<T>(out T? proto)
+    {
+        proto = default;
+
+        if (!Read(out string decompressedData))
+        {
+            return false;
+        }
+
+        try
+        {
+            proto = JsonSerializer.Deserialize<T>(decompressedData, JsonOptions);
+            return proto != null && !EqualityComparer<T>.Default.Equals(proto, default);
+        }
+        catch (JsonException)
+        {
+            proto = default;
+            return false;
+        }
+    }
+
+    /// <summary>
+    /// 'End-of-file' marker for the pb stream.
+    /// </summary>
+    public bool Eof => _fileStream.Position >= _fileStream.Length;
+
+    public void Dispose()
+    {
+        if (!_disposed)
+        {
+            _fileStream?.Dispose();
+            _disposed = true;
+        }
+
+        GC.SuppressFinalize(this);
+    }
+}