Add SaveDataFile resizing

src/LibHac/IO/Save/AllocationTableStorage.cs

@@ -6,7 +6,7 @@ namespace LibHac.IO.Save
     {
         private IStorage BaseStorage { get; }
         private int BlockSize { get; }
-        private int InitialBlock { get; }
+        internal int InitialBlock { get; private set; }
         private AllocationTable Fat { get; }
 
         private long _length;
@@ -18,7 +18,7 @@ namespace LibHac.IO.Save
             Fat = table;
             InitialBlock = initialBlock;
 
-            _length = table.GetListLength(initialBlock) * blockSize;
+            _length = initialBlock == -1 ? 0 : table.GetListLength(initialBlock) * blockSize;
         }
 
         protected override void ReadImpl(Span<byte> destination, long offset)
@@ -81,5 +81,44 @@ namespace LibHac.IO.Save
         }
 
         public override long GetSize() => _length;
+
+        public override void SetSize(long size)
+        {
+            int oldBlockCount = (int)Util.DivideByRoundUp(_length, BlockSize);
+            int newBlockCount = (int)Util.DivideByRoundUp(size, BlockSize);
+
+            if (oldBlockCount == newBlockCount) return;
+
+            if (oldBlockCount == 0)
+            {
+                InitialBlock = Fat.Allocate(newBlockCount);
+                _length = newBlockCount * BlockSize;
+
+                return;
+            }
+
+            if (newBlockCount == 0)
+            {
+                Fat.Free(InitialBlock);
+
+                InitialBlock = -1;
+                _length = 0;
+
+                return;
+            }
+
+            if (newBlockCount > oldBlockCount)
+            {
+                int newBlocks = Fat.Allocate(newBlockCount - oldBlockCount);
+                Fat.Join(InitialBlock, newBlocks);
+            }
+            else
+            {
+                int oldBlocks = Fat.Trim(InitialBlock, newBlockCount);
+                Fat.Free(oldBlocks);
+            }
+
+            _length = newBlockCount * BlockSize;
+        }
     }
 }

src/LibHac/IO/Save/SaveDataFile.cs

@@ -1,18 +1,21 @@
 using System;
+using System.IO;
 
 namespace LibHac.IO.Save
 {
     public class SaveDataFile : FileBase
     {
         private AllocationTableStorage BaseStorage { get; }
-        private long Offset { get; }
+        private string Path { get; }
-        private long Size { get; }
+        private HierarchicalSaveFileTable FileTable { get; }
+        private long Size { get; set; }
 
-        public SaveDataFile(AllocationTableStorage baseStorage, long offset, long size, OpenMode mode)
+        public SaveDataFile(AllocationTableStorage baseStorage, string path, HierarchicalSaveFileTable fileTable, long size, OpenMode mode)
         {
             Mode = mode;
             BaseStorage = baseStorage;
-            Offset = offset;
+            Path = path;
+            FileTable = fileTable;
             Size = size;
         }
 
@@ -20,8 +23,7 @@ namespace LibHac.IO.Save
         {
             int toRead = ValidateReadParamsAndGetSize(destination, offset);
 
-            long storageOffset = Offset + offset;
+            BaseStorage.Read(destination.Slice(0, toRead), offset);
-            BaseStorage.Read(destination.Slice(0, toRead), storageOffset);
 
             return toRead;
         }
@@ -45,7 +47,22 @@ namespace LibHac.IO.Save
 
         public override void SetSize(long size)
         {
-            throw new NotImplementedException();
+            if (size < 0) throw new ArgumentOutOfRangeException(nameof(size));
+            if (Size == size) return;
+
+            BaseStorage.SetSize(size);
+
+            if (!FileTable.TryOpenFile(Path, out SaveFileInfo fileInfo))
+            {
+                throw new FileNotFoundException();
+            }
+
+            fileInfo.StartBlock = BaseStorage.InitialBlock;
+            fileInfo.Length = size;
+
+            FileTable.AddFile(Path, ref fileInfo);
+
+            Size = size;
         }
     }
 }

src/LibHac/IO/Save/SaveDataFileSystemCore.cs

@@ -86,14 +86,9 @@ namespace LibHac.IO.Save
                 throw new FileNotFoundException();
             }
 
-            if (file.StartBlock < 0)
-            {
-                return new NullFile();
-            }
-
             AllocationTableStorage storage = OpenFatStorage(file.StartBlock);
 
-            return new SaveDataFile(storage, 0, file.Length, mode);
+            return new SaveDataFile(storage, path, FileTable, file.Length, mode);
         }
 
         public void RenameDirectory(string srcPath, string dstPath)