refactor the file reading part

2021-07-02 02:17:59 +08:00
parent 4345885cc9
commit 7ab2cda120
7 changed files with 175 additions and 159 deletions
--- a/AssetStudio/FileReader.cs
+++ b/AssetStudio/FileReader.cs
@@ -0,0 +1,98 @@
+using System.IO;
+using System.Linq;
+
+namespace AssetStudio
+{
+    public class FileReader : EndianBinaryReader
+    {
+        public string FullPath;
+        public string FileName;
+        public FileType FileType;
+
+        public FileReader(string path) : this(path, File.Open(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite)) { }
+
+        public FileReader(string path, Stream stream) : base(stream, EndianType.BigEndian)
+        {
+            FullPath = Path.GetFullPath(path);
+            FileName = Path.GetFileName(path);
+            CheckFileType();
+        }
+
+        private void CheckFileType()
+        {
+            var signature = this.ReadStringToNull(20);
+            Position = 0;
+            switch (signature)
+            {
+                case "UnityWeb":
+                case "UnityRaw":
+                case "UnityArchive":
+                case "UnityFS":
+                    FileType = FileType.BundleFile;
+                    break;
+                case "UnityWebData1.0":
+                    FileType = FileType.WebFile;
+                    break;
+                default:
+                    var magic = ReadBytes(2);
+                    Position = 0;
+                    if (WebFile.gzipMagic.SequenceEqual(magic))
+                    {
+                        FileType = FileType.WebFile;
+                    }
+                    Position = 0x20;
+                    magic = ReadBytes(6);
+                    Position = 0;
+                    if (WebFile.brotliMagic.SequenceEqual(magic))
+                    {
+                        FileType = FileType.WebFile;
+                    }
+                    if (IsSerializedFile())
+                    {
+                        FileType = FileType.AssetsFile;
+                    }
+                    else
+                    {
+                        FileType = FileType.ResourceFile;
+                    }
+                    break;
+            }
+        }
+
+        private bool IsSerializedFile()
+        {
+            var fileSize = BaseStream.Length;
+            if (fileSize < 20)
+            {
+                return false;
+            }
+            var m_MetadataSize = ReadUInt32();
+            long m_FileSize = ReadUInt32();
+            var m_Version = ReadUInt32();
+            long m_DataOffset = ReadUInt32();
+            var m_Endianess = ReadByte();
+            var m_Reserved = ReadBytes(3);
+            if (m_Version >= 22)
+            {
+                if (fileSize < 48)
+                {
+                    Position = 0;
+                    return false;
+                }
+                m_MetadataSize = ReadUInt32();
+                m_FileSize = ReadInt64();
+                m_DataOffset = ReadInt64();
+            }
+            Position = 0;
+            if (m_FileSize != fileSize)
+            {
+                return false;
+            }
+            if (m_DataOffset > fileSize)
+            {
+                return false;
+            }
+            return true;
+        }
+    }
+}