Add directory mode. Add path normalizer with tests

src/LibHac/IO/CachedStorage.cs

@@ -136,7 +136,7 @@ namespace LibHac.IO
                 length = (int)Math.Min(Length - offset, length);
             }
 
-            BaseStorage.Read(block.Buffer, offset, length, 0);
+            BaseStorage.Read(block.Buffer.AsSpan(0, length), offset);
             block.Length = length;
             block.Index = index;
             block.Dirty = false;

src/LibHac/IO/IFileSystem.cs

@@ -1,4 +1,6 @@
-namespace LibHac.IO
+using System;
+
+namespace LibHac.IO
 {
     public interface IFileSystem
     {
@@ -7,11 +9,19 @@
         void CreateFile(string path, long size);
         void DeleteDirectory(string path);
         void DeleteFile(string path);
-        IDirectory OpenDirectory(string path);
+        IDirectory OpenDirectory(string path, OpenDirectoryMode mode);
         IFile OpenFile(string path);
         void RenameDirectory(string srcPath, string dstPath);
         void RenameFile(string srcPath, string dstPath);
         bool DirectoryExists(string path);
         bool FileExists(string path);
     }
+
+    [Flags]
+    public enum OpenDirectoryMode
+    {
+        Directories = 1,
+        Files = 2,
+        All = Directories | Files
+    }
 }

src/LibHac/IO/IFileSystemExtensions.cs

@@ -8,7 +8,7 @@ namespace LibHac.IO
     {
         public static void Extract(this IFileSystem fs, string outDir)
         {
-            var root = fs.OpenDirectory("/");
+            var root = fs.OpenDirectory("/", OpenDirectoryMode.All);
 
             foreach (var filename in root.EnumerateFiles())
             {
@@ -33,7 +33,7 @@ namespace LibHac.IO
             {
                 if (entry.Type == DirectoryEntryType.Directory)
                 {
-                    foreach(string a in EnumerateFiles(directory.ParentFileSystem.OpenDirectory(entry.Name)))
+                    foreach (string a in EnumerateFiles(directory.ParentFileSystem.OpenDirectory(entry.Name, OpenDirectoryMode.All)))
                     {
                         yield return a;
                     }

src/LibHac/IO/PathTools.cs

@@ -0,0 +1,102 @@
+using System;
+using System.IO;
+using System.Runtime.CompilerServices;
+
+namespace LibHac.IO
+{
+    public static class PathTools
+    {
+        public static readonly char DirectorySeparator = '/';
+
+        // Licensed to the .NET Foundation under one or more agreements.
+        // The .NET Foundation licenses this file to you under the MIT license.
+        // See the LICENSE file in the project root for more information.
+        public static string Normalize(string inPath)
+        {
+            ReadOnlySpan<char> path = inPath.AsSpan();
+
+            if (path.Length == 0) return DirectorySeparator.ToString();
+
+            if (path[0] != DirectorySeparator)
+            {
+                throw new InvalidDataException($"{nameof(path)} must begin with '{DirectorySeparator}'");
+            }
+
+            Span<char> initialBuffer = stackalloc char[0x200];
+            var sb = new ValueStringBuilder(initialBuffer);
+
+            for (int i = 0; i < path.Length; i++)
+            {
+                char c = path[i];
+
+                if (IsDirectorySeparator(c) && i + 1 < path.Length)
+                {
+                    // Skip this character if it's a directory separator and if the next character is, too,
+                    // e.g. "parent//child" => "parent/child"
+                    if (IsDirectorySeparator(path[i + 1])) continue;
+
+                    // Skip this character and the next if it's referring to the current directory,
+                    // e.g. "parent/./child" => "parent/child"
+                    if (IsCurrentDirectory(path, i))
+                    {
+                        i++;
+                        continue;
+                    }
+
+                    // Skip this character and the next two if it's referring to the parent directory,
+                    // e.g. "parent/child/../grandchild" => "parent/grandchild"
+                    if (IsParentDirectory(path, i))
+                    {
+                        // Unwind back to the last slash (and if there isn't one, clear out everything).
+                        for (int s = sb.Length - 1; s >= 0; s--)
+                        {
+                            if (IsDirectorySeparator(sb[s]))
+                            {
+                                sb.Length = s;
+                                break;
+                            }
+                        }
+
+                        i += 2;
+                        continue;
+                    }
+                }
+                sb.Append(c);
+            }
+
+            // If we haven't changed the source path, return the original
+            if (sb.Length == inPath.Length)
+            {
+                return inPath;
+            }
+
+            if (sb.Length == 0)
+            {
+                sb.Append(DirectorySeparator);
+            }
+
+            return sb.ToString();
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static bool IsDirectorySeparator(char c)
+        {
+            return c == DirectorySeparator;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static bool IsCurrentDirectory(ReadOnlySpan<char> path, int index)
+        {
+            return (index + 2 == path.Length || IsDirectorySeparator(path[index + 2])) &&
+                   path[index + 1] == '.';
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static bool IsParentDirectory(ReadOnlySpan<char> path, int index)
+        {
+            return index + 2 < path.Length &&
+                   (index + 3 == path.Length || IsDirectorySeparator(path[index + 3])) &&
+                   path[index + 1] == '.' && path[index + 2] == '.';
+        }
+    }
+}

src/LibHac/IO/RomFsDirectory.cs

@@ -7,8 +7,9 @@ namespace LibHac.IO
         public IFileSystem ParentFileSystem { get; }
 
         private RomfsDir Directory { get; }
+        private OpenDirectoryMode Mode { get; }
 
-        public RomFsDirectory(RomFsFileSystem fs, string path)
+        public RomFsDirectory(RomFsFileSystem fs, string path, OpenDirectoryMode mode)
         {
             if (!fs.DirectoryDict.TryGetValue(path, out RomfsDir dir))
             {
@@ -17,6 +18,7 @@ namespace LibHac.IO
 
             ParentFileSystem = fs;
             Directory = dir;
+            Mode = mode;
         }
 
         public DirectoryEntry[] Read()
@@ -26,22 +28,29 @@ namespace LibHac.IO
             var entries = new DirectoryEntry[count];
             int index = 0;
 
-            var dirEntry = Directory.FirstChild;
-
-            while (dirEntry != null)
+            if (Mode.HasFlag(OpenDirectoryMode.Directories))
             {
-                entries[index] = new DirectoryEntry(dirEntry.FullPath, DirectoryEntryType.Directory, 0);
-                dirEntry = dirEntry.NextSibling;
-                index++;
+                RomfsDir dirEntry = Directory.FirstChild;
+
+                while (dirEntry != null)
+                {
+                    entries[index] = new DirectoryEntry(dirEntry.FullPath, DirectoryEntryType.Directory, 0);
+                    dirEntry = dirEntry.NextSibling;
+                    index++;
+                }
             }
 
-            RomfsFile fileEntry = Directory.FirstFile;
-
-            while (fileEntry != null)
+            if (Mode.HasFlag(OpenDirectoryMode.Files))
             {
-                entries[index] = new DirectoryEntry(fileEntry.FullPath, DirectoryEntryType.File, fileEntry.DataLength);
-                fileEntry = fileEntry.NextSibling;
-                index++;
+                RomfsFile fileEntry = Directory.FirstFile;
+
+                while (fileEntry != null)
+                {
+                    entries[index] =
+                        new DirectoryEntry(fileEntry.FullPath, DirectoryEntryType.File, fileEntry.DataLength);
+                    fileEntry = fileEntry.NextSibling;
+                    index++;
+                }
             }
 
             return entries;
@@ -50,20 +59,27 @@ namespace LibHac.IO
         public int GetEntryCount()
         {
             int count = 0;
-            RomfsDir dirEntry = Directory.FirstChild;
 
-            while (dirEntry != null)
+            if (Mode.HasFlag(OpenDirectoryMode.Directories))
             {
-                count++;
-                dirEntry = dirEntry.NextSibling;
+                RomfsDir dirEntry = Directory.FirstChild;
+
+                while (dirEntry != null)
+                {
+                    count++;
+                    dirEntry = dirEntry.NextSibling;
+                }
             }
 
-            RomfsFile fileEntry = Directory.FirstFile;
-
-            while (fileEntry != null)
+            if (Mode.HasFlag(OpenDirectoryMode.Files))
             {
-                count++;
-                fileEntry = fileEntry.NextSibling;
+                RomfsFile fileEntry = Directory.FirstFile;
+
+                while (fileEntry != null)
+                {
+                    count++;
+                    fileEntry = fileEntry.NextSibling;
+                }
             }
 
             return count;

src/LibHac/IO/RomFsFile.cs

@@ -39,7 +39,7 @@ namespace LibHac.IO
 
         public long SetSize()
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
     }
 }

src/LibHac/IO/RomFsFileSystem.cs

@@ -86,32 +86,32 @@ namespace LibHac.IO
 
         public void Commit()
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
         public void CreateDirectory(string path)
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
         public void CreateFile(string path, long size)
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
         public void DeleteDirectory(string path)
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
         public void DeleteFile(string path)
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
-        public IDirectory OpenDirectory(string path)
+        public IDirectory OpenDirectory(string path, OpenDirectoryMode mode)
         {
-            return new RomFsDirectory(this, path);
+            return new RomFsDirectory(this, path, mode);
         }
 
         public IFile OpenFile(string path)
@@ -131,17 +131,17 @@ namespace LibHac.IO
 
         public void RenameDirectory(string srcPath, string dstPath)
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
         public void RenameFile(string srcPath, string dstPath)
         {
-            throw new NotImplementedException();
+            throw new NotSupportedException();
         }
 
         public bool DirectoryExists(string path)
         {
-            throw new NotImplementedException();
+            return DirectoryDict.ContainsKey(path);
         }
 
         public bool FileExists(string path)

src/LibHac/IO/ValueStringBuilder.cs

@@ -0,0 +1,271 @@
+using System;
+using System.Buffers;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace LibHac.IO
+{
+    internal ref struct ValueStringBuilder
+    {
+        private char[] _arrayToReturnToPool;
+        private Span<char> _chars;
+        private int _pos;
+
+        public ValueStringBuilder(Span<char> initialBuffer)
+        {
+            _arrayToReturnToPool = null;
+            _chars = initialBuffer;
+            _pos = 0;
+        }
+
+        public ValueStringBuilder(int initialCapacity)
+        {
+            _arrayToReturnToPool = ArrayPool<char>.Shared.Rent(initialCapacity);
+            _chars = _arrayToReturnToPool;
+            _pos = 0;
+        }
+
+        public int Length
+        {
+            get => _pos;
+            set
+            {
+                Debug.Assert(value >= 0);
+                Debug.Assert(value <= _chars.Length);
+                _pos = value;
+            }
+        }
+
+        public int Capacity => _chars.Length;
+
+        public void EnsureCapacity(int capacity)
+        {
+            if (capacity > _chars.Length)
+                Grow(capacity - _chars.Length);
+        }
+
+        /// <summary>
+        /// Get a pinnable reference to the builder.
+        /// Does not ensure there is a null char after <see cref="Length"/>
+        /// This overload is pattern matched in the C# 7.3+ compiler so you can omit
+        /// the explicit method call, and write eg "fixed (char* c = builder)"
+        /// </summary>
+        public ref char GetPinnableReference()
+        {
+            return ref MemoryMarshal.GetReference(_chars);
+        }
+
+        /// <summary>
+        /// Get a pinnable reference to the builder.
+        /// </summary>
+        /// <param name="terminate">Ensures that the builder has a null char after <see cref="Length"/></param>
+        public ref char GetPinnableReference(bool terminate)
+        {
+            if (terminate)
+            {
+                EnsureCapacity(Length + 1);
+                _chars[Length] = '\0';
+            }
+            return ref MemoryMarshal.GetReference(_chars);
+        }
+
+        public ref char this[int index]
+        {
+            get
+            {
+                Debug.Assert(index < _pos);
+                return ref _chars[index];
+            }
+        }
+
+        public override string ToString()
+        {
+            var s = _chars.Slice(0, _pos).ToString();
+            Dispose();
+            return s;
+        }
+
+        /// <summary>Returns the underlying storage of the builder.</summary>
+        public Span<char> RawChars => _chars;
+
+        /// <summary>
+        /// Returns a span around the contents of the builder.
+        /// </summary>
+        /// <param name="terminate">Ensures that the builder has a null char after <see cref="Length"/></param>
+        public ReadOnlySpan<char> AsSpan(bool terminate)
+        {
+            if (terminate)
+            {
+                EnsureCapacity(Length + 1);
+                _chars[Length] = '\0';
+            }
+            return _chars.Slice(0, _pos);
+        }
+
+        public ReadOnlySpan<char> AsSpan() => _chars.Slice(0, _pos);
+        public ReadOnlySpan<char> AsSpan(int start) => _chars.Slice(start, _pos - start);
+        public ReadOnlySpan<char> AsSpan(int start, int length) => _chars.Slice(start, length);
+
+        public bool TryCopyTo(Span<char> destination, out int charsWritten)
+        {
+            if (_chars.Slice(0, _pos).TryCopyTo(destination))
+            {
+                charsWritten = _pos;
+                Dispose();
+                return true;
+            }
+            else
+            {
+                charsWritten = 0;
+                Dispose();
+                return false;
+            }
+        }
+
+        public void Insert(int index, char value, int count)
+        {
+            if (_pos > _chars.Length - count)
+            {
+                Grow(count);
+            }
+
+            int remaining = _pos - index;
+            _chars.Slice(index, remaining).CopyTo(_chars.Slice(index + count));
+            _chars.Slice(index, count).Fill(value);
+            _pos += count;
+        }
+
+        public void Insert(int index, string s)
+        {
+            int count = s.Length;
+
+            if (_pos > (_chars.Length - count))
+            {
+                Grow(count);
+            }
+
+            int remaining = _pos - index;
+            _chars.Slice(index, remaining).CopyTo(_chars.Slice(index + count));
+            s.AsSpan().CopyTo(_chars.Slice(index));
+            _pos += count;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Append(char c)
+        {
+            int pos = _pos;
+            if ((uint)pos < (uint)_chars.Length)
+            {
+                _chars[pos] = c;
+                _pos = pos + 1;
+            }
+            else
+            {
+                GrowAndAppend(c);
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Append(string s)
+        {
+            int pos = _pos;
+            if (s.Length == 1 && (uint)pos < (uint)_chars.Length) // very common case, e.g. appending strings from NumberFormatInfo like separators, percent symbols, etc.
+            {
+                _chars[pos] = s[0];
+                _pos = pos + 1;
+            }
+            else
+            {
+                AppendSlow(s);
+            }
+        }
+
+        private void AppendSlow(string s)
+        {
+            int pos = _pos;
+            if (pos > _chars.Length - s.Length)
+            {
+                Grow(s.Length);
+            }
+
+            s.AsSpan().CopyTo(_chars.Slice(pos));
+            _pos += s.Length;
+        }
+
+        public void Append(char c, int count)
+        {
+            if (_pos > _chars.Length - count)
+            {
+                Grow(count);
+            }
+
+            Span<char> dst = _chars.Slice(_pos, count);
+            for (int i = 0; i < dst.Length; i++)
+            {
+                dst[i] = c;
+            }
+            _pos += count;
+        }
+
+        public void Append(ReadOnlySpan<char> value)
+        {
+            int pos = _pos;
+            if (pos > _chars.Length - value.Length)
+            {
+                Grow(value.Length);
+            }
+
+            value.CopyTo(_chars.Slice(_pos));
+            _pos += value.Length;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public Span<char> AppendSpan(int length)
+        {
+            int origPos = _pos;
+            if (origPos > _chars.Length - length)
+            {
+                Grow(length);
+            }
+
+            _pos = origPos + length;
+            return _chars.Slice(origPos, length);
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private void GrowAndAppend(char c)
+        {
+            Grow(1);
+            Append(c);
+        }
+
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private void Grow(int requiredAdditionalCapacity)
+        {
+            Debug.Assert(requiredAdditionalCapacity > 0);
+
+            char[] poolArray = ArrayPool<char>.Shared.Rent(Math.Max(_pos + requiredAdditionalCapacity, _chars.Length * 2));
+
+            _chars.CopyTo(poolArray);
+
+            char[] toReturn = _arrayToReturnToPool;
+            _chars = _arrayToReturnToPool = poolArray;
+            if (toReturn != null)
+            {
+                ArrayPool<char>.Shared.Return(toReturn);
+            }
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Dispose()
+        {
+            char[] toReturn = _arrayToReturnToPool;
+            this = default; // for safety, to avoid using pooled array if this instance is erroneously appended to again
+            if (toReturn != null)
+            {
+                ArrayPool<char>.Shared.Return(toReturn);
+            }
+        }
+    }
+}

tests/LibHac.Tests/PathToolsTests.cs

@@ -0,0 +1,45 @@
+using System.IO;
+using LibHac.IO;
+using Xunit;
+
+namespace LibHac.Tests
+{
+    public class PathToolsTests
+    {
+        public static object[][] NormalizedPathTestItems =
+        {
+            new object[] {"", "/"},
+            new object[] {"/", "/"},
+            new object[] {"/.", "/"},
+            new object[] {"/a/b/c", "/a/b/c"},
+            new object[] {"/a/b/../c", "/a/c"},
+            new object[] {"/a/b/c/..", "/a/b"},
+            new object[] {"/a/b/c/.", "/a/b/c"},
+            new object[] {"/a/../../..", "/"},
+            new object[] {"/a/../../../a/b/c", "/a/b/c"},
+            new object[] {"//a/b//.//c", "/a/b/c"},
+
+
+            new object[] {"/a/b/c/", "/a/b/c/"},
+            new object[] {"/a/./b/../c/", "/a/c/"},
+            new object[] {"/a/../../../", "/"},
+            new object[] {"//a/b//.//c/", "/a/b/c/"},
+            new object[] {@"/tmp/../", @"/"},
+        };
+
+        [Theory]
+        [MemberData(nameof(NormalizedPathTestItems))]
+        public static void NormalizePath(string path, string expected)
+        {
+            string actual = PathTools.Normalize(path);
+
+            Assert.Equal(expected, actual);
+        }
+
+        [Fact]
+        public static void NormalizeThrowsOnInvalidStartChar()
+        {
+            Assert.Throws<InvalidDataException>(() => PathTools.Normalize(@"c:\a\b\c"));
+        }
+    }
+}