Add LayeredFileSystem

build/_build.csproj.DotSettings

@@ -1,4 +1,4 @@
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src/LibHac/IO/LayeredFileSystem.cs

@@ -0,0 +1,89 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace LibHac.IO
+{
+    public class LayeredFileSystem : IFileSystem
+    {
+        private List<IFileSystem> Sources { get; } = new List<IFileSystem>();
+
+        public LayeredFileSystem(IList<IFileSystem> sourceFileSystems)
+        {
+            Sources.AddRange(sourceFileSystems);
+        }
+
+        public IDirectory OpenDirectory(string path, OpenDirectoryMode mode)
+        {
+            path = PathTools.Normalize(path);
+
+            var dirs = new List<IDirectory>();
+
+            foreach (IFileSystem fs in Sources)
+            {
+                if (fs.DirectoryExists(path))
+                {
+                    dirs.Add(fs.OpenDirectory(path, mode));
+                }
+            }
+
+            var dir = new LayeredFileSystemDirectory(this, dirs, path, mode);
+
+            return dir;
+        }
+
+        public IFile OpenFile(string path, OpenMode mode)
+        {
+            path = PathTools.Normalize(path);
+
+            foreach (IFileSystem fs in Sources)
+            {
+                if (fs.FileExists(path))
+                {
+                    return fs.OpenFile(path, mode);
+                }
+            }
+
+            throw new FileNotFoundException();
+        }
+
+        public bool DirectoryExists(string path)
+        {
+            path = PathTools.Normalize(path);
+
+            foreach (IFileSystem fs in Sources)
+            {
+                if (fs.DirectoryExists(path))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        public bool FileExists(string path)
+        {
+            path = PathTools.Normalize(path);
+
+            foreach (IFileSystem fs in Sources)
+            {
+                if (fs.FileExists(path))
+                {
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        public void Commit() { }
+
+        public void CreateDirectory(string path) => throw new NotSupportedException();
+        public void CreateFile(string path, long size) => throw new NotSupportedException();
+        public void DeleteDirectory(string path) => throw new NotSupportedException();
+        public void DeleteFile(string path) => throw new NotSupportedException();
+        public void RenameDirectory(string srcPath, string dstPath) => throw new NotSupportedException();
+        public void RenameFile(string srcPath, string dstPath) => throw new NotSupportedException();
+    }
+}

src/LibHac/IO/LayeredFileSystemDirectory.cs

@@ -0,0 +1,44 @@
+using System.Collections.Generic;
+using System.Linq;
+
+namespace LibHac.IO
+{
+    public class LayeredFileSystemDirectory : IDirectory
+    {
+        public IFileSystem ParentFileSystem { get; }
+
+        public string FullPath { get; }
+        public OpenDirectoryMode Mode { get; }
+
+        private List<IDirectory> Sources { get; }
+
+        public LayeredFileSystemDirectory(IFileSystem fs, List<IDirectory> sources, string path, OpenDirectoryMode mode)
+        {
+            ParentFileSystem = fs;
+            Sources = sources;
+            FullPath = path;
+            Mode = mode;
+        }
+
+        public IEnumerable<DirectoryEntry> Read()
+        {
+            var returnedFiles = new HashSet<string>();
+
+            foreach (IDirectory source in Sources)
+            {
+                foreach (DirectoryEntry entry in source.Read())
+                {
+                    if (returnedFiles.Contains(entry.FullPath)) continue;
+
+                    returnedFiles.Add(entry.FullPath);
+                    yield return entry;
+                }
+            }
+        }
+
+        public int GetEntryCount()
+        {
+            return Read().Count();
+        }
+    }
+}