Add a path normalizer that behaves like the one in FS

src/LibHac/Common/PathBuilder.cs

@@ -0,0 +1,123 @@
+using System;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+using LibHac.Fs;
+using LibHac.FsSystem;
+
+namespace LibHac.Common
+{
+    [DebuggerDisplay("{ToString()}")]
+    internal ref struct PathBuilder
+    {
+        private Span<byte> _buffer;
+        private int _pos;
+
+        public int Length
+        {
+            get => _pos;
+            set
+            {
+                Debug.Assert(value >= 0);
+                Debug.Assert(value <= Capacity);
+                _pos = value;
+            }
+        }
+
+        public int Capacity => _buffer.Length - 1;
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public PathBuilder(Span<byte> buffer)
+        {
+            _buffer = buffer;
+            _pos = 0;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public Result Append(byte value)
+        {
+            int pos = _pos;
+            if (pos >= Capacity)
+            {
+                return ResultFs.TooLongPath.Log();
+            }
+
+            _buffer[pos] = value;
+            _pos = pos + 1;
+            return Result.Success;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public Result Append(ReadOnlySpan<byte> value)
+        {
+            int pos = _pos;
+            if (pos + value.Length >= Capacity)
+            {
+                return ResultFs.TooLongPath.Log();
+            }
+
+            value.CopyTo(_buffer.Slice(pos));
+            _pos = pos + value.Length;
+            return Result.Success;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public Result AppendWithPrecedingSeparator(byte value)
+        {
+            int pos = _pos;
+            if (pos + 1 >= Capacity)
+            {
+                // Append the separator if there's enough space
+                if (pos < Capacity)
+                {
+                    _buffer[pos] = (byte)'/';
+                    _pos = pos + 1;
+                }
+
+                return ResultFs.TooLongPath.Log();
+            }
+
+            _buffer[pos] = (byte)'/';
+            _buffer[pos + 1] = value;
+            _pos = pos + 2;
+            return Result.Success;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public Result RewindLevels(int count)
+        {
+            Debug.Assert(count > 0);
+
+            int separators = 0;
+            int pos = _pos - 1;
+
+            for (; pos >= 0; pos--)
+            {
+                if (PathTools.IsDirectorySeparator(_buffer[pos]))
+                {
+                    separators++;
+
+                    if (separators == count) break;
+                }
+            }
+
+            if (separators != count) return ResultFs.DirectoryUnobtainable.Log();
+
+            _pos = pos;
+            return Result.Success;
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Terminate()
+        {
+            if (_buffer.Length > _pos)
+            {
+                _buffer[_pos] = 0;
+            }
+        }
+
+        public override string ToString()
+        {
+            return StringUtils.Utf8ZToString(_buffer.Slice(0, Length));
+        }
+    }
+}

src/LibHac/Fs/FileBase.cs

@@ -41,7 +41,7 @@ namespace LibHac.Fs
             {
                 if (options.HasFlag(WriteOption.Flush))
                 {
-                    return Flush();
+                    return FlushImpl();
                 }
 
                 return Result.Success;
@@ -83,7 +83,7 @@ namespace LibHac.Fs
         {
             if (IsDisposed) return ResultFs.PreconditionViolation.Log();
 
-            return OperateRange(outBuffer, operationId, offset, size, inBuffer);
+            return OperateRangeImpl(outBuffer, operationId, offset, size, inBuffer);
         }
 
         public void Dispose()

src/LibHac/FsSystem/PathTools.cs

@@ -12,8 +12,8 @@ namespace LibHac.FsSystem
 {
     public static class PathTools
     {
-        public static readonly char DirectorySeparator = '/';
+        internal const char DirectorySeparator = '/';
-        public static readonly char MountSeparator = ':';
+        internal const char MountSeparator = ':';
         internal const int MountNameLength = 0xF;
 
         // Todo: Remove
@@ -416,6 +416,12 @@ namespace LibHac.FsSystem
             return c == DirectorySeparator;
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        internal static bool IsDirectorySeparator(byte c)
+        {
+            return c == DirectorySeparator;
+        }
+
         public static Result GetMountName(string path, out string mountName)
         {
             Result rc = GetMountNameLength(path, out int length);
@@ -444,7 +450,7 @@ namespace LibHac.FsSystem
             }
 
             length = default;
-            return ResultFs.InvalidMountName;
+            return ResultFs.InvalidMountName.Log();
         }
 
         public static bool MatchesPattern(string searchPattern, string name, bool ignoreCase)
@@ -466,6 +472,200 @@ namespace LibHac.FsSystem
 
         private static bool IsValidMountNameChar(byte c) => IsValidMountNameChar((char)c);
 
+        private static Result GetPathRoot(out ReadOnlySpan<byte> afterRootPath, Span<byte> pathRootBuffer, out int outRootLength, ReadOnlySpan<byte> path)
+        {
+            outRootLength = 0;
+            afterRootPath = path;
+
+            if (path.Length == 0) return Result.Success;
+
+            int mountNameStart;
+            if (IsDirectorySeparator(path[0]))
+            {
+                mountNameStart = 1;
+            }
+            else
+            {
+                mountNameStart = 0;
+            }
+
+            int rootLength = 0;
+
+            for (int i = mountNameStart; i < mountNameStart + MountNameLength; i++)
+            {
+                if (i >= path.Length || path[i] == 0) break;
+
+                // Set the length to 0 if there's no mount name
+                if (IsDirectorySeparator(path[i]))
+                {
+                    outRootLength = 0;
+                    return Result.Success;
+                }
+
+                if (path[i] == MountSeparator)
+                {
+                    rootLength = i + 1;
+                    break;
+                }
+            }
+
+            if (mountNameStart >= rootLength - 1 || path[rootLength - 1] != MountSeparator)
+            {
+                return ResultFs.InvalidPathFormat.Log();
+            }
+
+            if (mountNameStart < rootLength)
+            {
+                for (int i = mountNameStart; i < rootLength; i++)
+                {
+                    if (path[i] == '.')
+                    {
+                        return ResultFs.InvalidCharacter.Log();
+                    }
+                }
+            }
+
+            if (!pathRootBuffer.IsEmpty)
+            {
+                if (rootLength > pathRootBuffer.Length)
+                {
+                    return ResultFs.TooLongPath.Log();
+                }
+
+                path.Slice(0, rootLength).CopyTo(pathRootBuffer);
+            }
+
+            afterRootPath = path.Slice(rootLength);
+            outRootLength = rootLength;
+            return Result.Success;
+        }
+
+        public static Result Normalize(Span<byte> outValue, out int outLength, ReadOnlySpan<byte> path, bool hasMountName)
+        {
+            outLength = 0;
+
+            int rootLength = 0;
+            ReadOnlySpan<byte> mainPath = path;
+
+            if (hasMountName)
+            {
+                Result pathRootRc = GetPathRoot(out mainPath, outValue, out rootLength, path);
+                if (pathRootRc.IsFailure()) return pathRootRc;
+            }
+
+            var sb = new PathBuilder(outValue.Slice(rootLength));
+
+            var state = NormalizeState.Initial;
+
+            for (int i = 0; i < mainPath.Length; i++)
+            {
+                Result rc = Result.Success;
+                byte c = mainPath[i];
+
+                // Read input strings as null-terminated
+                if (c == 0) break;
+
+                switch (state)
+                {
+                    case NormalizeState.Initial when IsDirectorySeparator(c):
+                        state = NormalizeState.Delimiter;
+                        break;
+
+                    case NormalizeState.Initial:
+                        return ResultFs.InvalidPathFormat.Log();
+
+                    case NormalizeState.Normal when IsDirectorySeparator(c):
+                        state = NormalizeState.Delimiter;
+                        break;
+
+                    case NormalizeState.Normal:
+                        rc = sb.Append(c);
+                        break;
+
+                    case NormalizeState.Delimiter when IsDirectorySeparator(c):
+                        break;
+
+                    case NormalizeState.Delimiter when c == '.':
+                        state = NormalizeState.Dot;
+                        rc = sb.AppendWithPrecedingSeparator(c);
+                        break;
+
+                    case NormalizeState.Delimiter:
+                        state = NormalizeState.Normal;
+                        rc = sb.AppendWithPrecedingSeparator(c);
+                        break;
+
+                    case NormalizeState.Dot when IsDirectorySeparator(c):
+                        state = NormalizeState.Delimiter;
+                        rc = sb.RewindLevels(1);
+                        break;
+
+                    case NormalizeState.Dot when c == '.':
+                        state = NormalizeState.DoubleDot;
+                        rc = sb.Append(c);
+                        break;
+
+                    case NormalizeState.Dot:
+                        state = NormalizeState.Normal;
+                        rc = sb.Append(c);
+                        break;
+
+                    case NormalizeState.DoubleDot when IsDirectorySeparator(c):
+                        state = NormalizeState.Delimiter;
+                        rc = sb.RewindLevels(2);
+                        break;
+
+                    case NormalizeState.DoubleDot:
+                        state = NormalizeState.Normal;
+                        break;
+                }
+
+                if (rc.IsFailure())
+                {
+                    if (rc == ResultFs.TooLongPath)
+                    {
+                        // Make sure pending delimiters are added to the string if possible
+                        if (state == NormalizeState.Delimiter)
+                        {
+                            sb.Append((byte)DirectorySeparator);
+                        }
+                    }
+
+                    outLength = sb.Length;
+                    sb.Terminate();
+                    return rc;
+                }
+            }
+
+            Result finalRc = Result.Success;
+
+            switch (state)
+            {
+                case NormalizeState.Dot:
+                    state = NormalizeState.Delimiter;
+                    finalRc = sb.RewindLevels(1);
+                    break;
+
+                case NormalizeState.DoubleDot:
+                    state = NormalizeState.Delimiter;
+                    finalRc = sb.RewindLevels(2);
+                    break;
+            }
+
+            // Add the pending delimiter if the path is empty
+            // or if the path has only a mount name with no trailing delimiter
+            if (state == NormalizeState.Delimiter && sb.Length == 0 ||
+                rootLength > 0 && sb.Length == 0)
+            {
+                finalRc = sb.Append((byte)'/');
+            }
+
+            outLength = sb.Length;
+            sb.Terminate();
+
+            return finalRc;
+        }
+
         private enum NormalizeState
         {
             Initial,

tests/LibHac.Tests/PathToolsTests.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using LibHac.Common;
+using LibHac.Fs;
 using LibHac.FsSystem;
 using Xunit;
 
@@ -169,5 +171,109 @@ namespace LibHac.Tests
 
             return paths.Select(x => new object[] { x }).ToArray();
         }
+
+        public static object[][] NormalizedPathTestItemsU8NoMountName =
+        {
+            new object[] {"/", "/", Result.Success},
+            new object[] {"/.", "/", Result.Success},
+            new object[] {"/..", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"/abc", "/abc", Result.Success},
+            new object[] {"/a/..", "/", Result.Success},
+            new object[] {"/a/b/c", "/a/b/c", Result.Success},
+            new object[] {"/a/b/../c", "/a/c", Result.Success},
+            new object[] {"/a/b/c/..", "/a/b", Result.Success},
+            new object[] {"/a/b/c/.", "/a/b/c", Result.Success},
+            new object[] {"/a/../../..", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"/a/../../../a/b/c", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"//a/b//.//c", "/a/b/c", Result.Success},
+            new object[] {"/../a/b/c/.", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"/./aaa/bbb/ccc/.", "/aaa/bbb/ccc", Result.Success},
+
+            new object[] {"/a/b/c/", "/a/b/c", Result.Success},
+            new object[] {"/aa/./bb/../cc/", "/aa/cc", Result.Success},
+            new object[] {"/./b/../c/", "/c", Result.Success},
+            new object[] {"/a/../../../", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"//a/b//.//c/", "/a/b/c", Result.Success},
+            new object[] {"/tmp/../", "/", Result.Success},
+            new object[] {"abc", "", ResultFs.InvalidPathFormat}
+        };
+
+        public static object[][] NormalizedPathTestItemsU8MountName =
+        {
+            new object[] {"mount:/a/b/../c", "mount:/a/c", Result.Success},
+            new object[] {"a:/a/b/c", "a:/a/b/c", Result.Success},
+            new object[] {"mount:/a/b/../c", "mount:/a/c", Result.Success},
+            new object[] {"mount:", "mount:/", Result.Success},
+            new object[] {"abc:/a/../../../a/b/c", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"abc:/./b/../c/", "abc:/c", Result.Success},
+            new object[] {"abc:/.", "abc:/", Result.Success},
+            new object[] {"abc:/..", "", ResultFs.DirectoryUnobtainable},
+            new object[] {"abc:/", "abc:/", Result.Success},
+            new object[] {"abc://a/b//.//c", "abc:/a/b/c", Result.Success},
+            new object[] {"abc:/././/././a/b//.//c", "abc:/a/b/c", Result.Success},
+            new object[] {"mount:/d./aa", "mount:/d./aa", Result.Success},
+            new object[] {"mount:/d/..", "mount:/", Result.Success}
+        };
+
+        [Theory]
+        [MemberData(nameof(NormalizedPathTestItemsU8NoMountName))]
+        public static void NormalizePathU8NoMountName(string path, string expected, Result expectedResult)
+        {
+            U8String u8Path = path.ToU8String();
+            Span<byte> buffer = stackalloc byte[0x301];
+
+            Result rc = PathTools.Normalize(buffer, out _, u8Path, false);
+
+            string actual = StringUtils.Utf8ZToString(buffer);
+
+            Assert.Equal(expectedResult, rc);
+            if (expectedResult == Result.Success)
+            {
+                Assert.Equal(expected, actual);
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(NormalizedPathTestItemsU8MountName))]
+        public static void NormalizePathU8MountName(string path, string expected, Result expectedResult)
+        {
+            U8String u8Path = path.ToU8String();
+            Span<byte> buffer = stackalloc byte[0x301];
+
+            Result rc = PathTools.Normalize(buffer, out _, u8Path, true);
+
+            string actual = StringUtils.Utf8ZToString(buffer);
+
+            Assert.Equal(expectedResult, rc);
+            if (expectedResult == Result.Success)
+            {
+                Assert.Equal(expected, actual);
+            }
+        }
+
+        public static object[][] NormalizedPathTestItemsU8TooShort =
+        {
+            new object[] {"/a/b/c", "", 0},
+            new object[] {"/a/b/c", "/a/", 4},
+            new object[] {"/a/b/c", "/a/b", 5},
+            new object[] {"/a/b/c", "/a/b/", 6}
+        };
+
+        [Theory]
+        [MemberData(nameof(NormalizedPathTestItemsU8TooShort))]
+        public static void NormalizePathU8TooShortDest(string path, string expected, int destSize)
+        {
+            U8String u8Path = path.ToU8String();
+
+            Span<byte> buffer = stackalloc byte[destSize];
+
+            Result rc = PathTools.Normalize(buffer, out int normalizedLength, u8Path, false);
+
+            string actual = StringUtils.Utf8ZToString(buffer);
+
+            Assert.Equal(ResultFs.TooLongPath, rc);
+            Assert.Equal(Math.Max(0, destSize - 1), normalizedLength);
+            Assert.Equal(expected, actual);
+        }
     }
 }