Add fs_Host shims

src/LibHac/Common/U8StringBuilder.cs

@@ -12,6 +12,7 @@ namespace LibHac.Common
         private int _length;
 
         public bool Overflowed { get; private set; }
+        public int Length => _length;
         public int Capacity => _buffer.Length - NullTerminatorLength;
 
         public U8StringBuilder(Span<byte> buffer)

src/LibHac/Fs/CommonMountNames.cs

@@ -4,6 +4,8 @@ namespace LibHac.Fs
 {
     internal static class CommonMountNames
     {
+        public const char ReservedMountNamePrefixCharacter = '@';
+
         public static readonly U8String GameCardFileSystemMountName = new U8String("@Gc");
         public static readonly U8String ContentStorageSystemMountName = new U8String("@SystemContent");
         public static readonly U8String ContentStorageUserMountName = new U8String("@UserContent");

src/LibHac/Fs/FileSystemClient.AccessLog.cs

@@ -150,6 +150,30 @@ namespace LibHac.Fs
             OutputAccessLogImpl(result, startTime, endTime, handle.GetId(), message, caller);
         }
 
+        internal void OutputAccessLogUnlessResultSuccess(Result result, TimeSpan startTime, TimeSpan endTime, string message, [CallerMemberName] string caller = "")
+        {
+            if (result.IsFailure())
+            {
+                OutputAccessLogImpl(result, startTime, endTime, 0, message, caller);
+            }
+        }
+
+        internal void OutputAccessLogUnlessResultSuccess(Result result, TimeSpan startTime, TimeSpan endTime, FileHandle handle, string message, [CallerMemberName] string caller = "")
+        {
+            if (result.IsFailure())
+            {
+                OutputAccessLogImpl(result, startTime, endTime, handle.GetId(), message, caller);
+            }
+        }
+
+        internal void OutputAccessLogUnlessResultSuccess(Result result, TimeSpan startTime, TimeSpan endTime, DirectoryHandle handle, string message, [CallerMemberName] string caller = "")
+        {
+            if (result.IsFailure())
+            {
+                OutputAccessLogImpl(result, startTime, endTime, handle.GetId(), message, caller);
+            }
+        }
+
         internal void OutputAccessLogImpl(Result result, TimeSpan startTime, TimeSpan endTime, int handleId,
             string message, [CallerMemberName] string caller = "")
         {
@@ -208,6 +232,27 @@ namespace LibHac.Fs
 
             return rc;
         }
+
+        public Result RunOperationWithAccessLogOnFailure(AccessLogTarget logTarget, Func<Result> operation,
+            Func<string> textGenerator, [CallerMemberName] string caller = "")
+        {
+            Result rc;
+
+            if (IsEnabledAccessLog(logTarget))
+            {
+                TimeSpan startTime = Time.GetCurrent();
+                rc = operation();
+                TimeSpan endTime = Time.GetCurrent();
+
+                OutputAccessLogUnlessResultSuccess(rc, startTime, endTime, textGenerator(), caller);
+            }
+            else
+            {
+                rc = operation();
+            }
+
+            return rc;
+        }
     }
 
     [Flags]

src/LibHac/Fs/FsEnums.cs

@@ -187,4 +187,10 @@ namespace LibHac.Fs
         Nand = 1,
         SdCard = 2
     }
+
+    public enum MountHostOption
+    {
+        None = 0,
+        PseudoCaseSensitive = 1
+    }
 }

src/LibHac/Fs/MountHelpers.cs

@@ -1,4 +1,5 @@
 using LibHac.Common;
+using static LibHac.Fs.CommonMountNames;
 
 namespace LibHac.Fs
 {
@@ -23,6 +24,11 @@ namespace LibHac.Fs
             return Result.Success;
         }
 
+        public static bool IsReservedMountName(U8Span name)
+        {
+            return (uint)name.Length > 0 && name[0] == ReservedMountNamePrefixCharacter;
+        }
+
         // ReSharper disable once UnusedParameter.Local
         private static bool CheckMountNameImpl(U8Span name)
         {

src/LibHac/Fs/Shim/Host.cs

@@ -0,0 +1,304 @@
+using System;
+using System.Diagnostics;
+using System.Runtime.CompilerServices;
+using LibHac.Common;
+using LibHac.FsService;
+using LibHac.FsSystem;
+using static LibHac.Fs.CommonMountNames;
+
+namespace LibHac.Fs.Shim
+{
+    public static class Host
+    {
+        private static ReadOnlySpan<byte> HostRootFileSystemPath => new[]
+            {(byte) '@', (byte) 'H', (byte) 'o', (byte) 's', (byte) 't', (byte) ':', (byte) '/'};
+
+        private const int HostRootFileSystemPathLength = 8;
+
+        private class HostCommonMountNameGenerator : ICommonMountNameGenerator
+        {
+            private FsPath _path;
+
+            public HostCommonMountNameGenerator(U8Span path)
+            {
+                StringUtils.Copy(_path.Str, path);
+
+                int pathLength = StringUtils.GetLength(_path.Str);
+                if (pathLength != 0 && _path.Str[pathLength - 1] == StringTraits.DirectorySeparator)
+                {
+                    _path.Str[pathLength - 1] = StringTraits.NullTerminator;
+                }
+            }
+
+            public Result GenerateCommonMountName(Span<byte> nameBuffer)
+            {
+                int requiredNameBufferSize = StringUtils.GetLength(_path.Str, FsPath.MaxLength) + HostRootFileSystemPathLength;
+
+                if (nameBuffer.Length < requiredNameBufferSize)
+                    return ResultFs.TooLongPath.Log();
+
+                int size = new U8StringBuilder(nameBuffer).Append(HostRootFileSystemPath).Append(_path.Str).Length;
+                Debug.Assert(size == requiredNameBufferSize - 1);
+
+                return Result.Success;
+            }
+        }
+
+        private class HostRootCommonMountNameGenerator : ICommonMountNameGenerator
+        {
+            public Result GenerateCommonMountName(Span<byte> nameBuffer)
+            {
+                const int requiredNameBufferSize = HostRootFileSystemPathLength;
+
+                Debug.Assert(nameBuffer.Length >= requiredNameBufferSize);
+
+                int size = StringUtils.Copy(nameBuffer, HostRootFileSystemPath);
+                Debug.Assert(size == requiredNameBufferSize - 1);
+
+                return Result.Success;
+            }
+        }
+
+        public static Result MountHostRoot(this FileSystemClient fs)
+        {
+            IFileSystem hostFileSystem = default;
+            var path = new FsPath();
+            path.Str[0] = 0;
+
+            static string LogMessageGenerator() => $", name: \"{HostRootFileSystemMountName.ToString()}\"";
+
+            Result OpenHostFs() => OpenHostFileSystemImpl(fs, out hostFileSystem, ref path, MountHostOption.None);
+
+            Result MountHostFs() => fs.Register(HostRootFileSystemMountName, hostFileSystem,
+                new HostRootCommonMountNameGenerator());
+
+            // Open the host file system
+            Result result =
+                fs.RunOperationWithAccessLogOnFailure(AccessLogTarget.Application, OpenHostFs, LogMessageGenerator);
+            if (result.IsFailure()) return result;
+
+            // Mount the host file system
+            result = fs.RunOperationWithAccessLog(AccessLogTarget.Application, MountHostFs, LogMessageGenerator);
+            if (result.IsFailure()) return result;
+
+            if (fs.IsEnabledAccessLog(AccessLogTarget.Application))
+                fs.EnableFileSystemAccessorAccessLog(HostRootFileSystemMountName);
+
+            return Result.Success;
+        }
+
+        public static Result MountHostRoot(this FileSystemClient fs, MountHostOption option)
+        {
+            IFileSystem hostFileSystem = default;
+            var path = new FsPath();
+            path.Str[0] = 0;
+
+            string LogMessageGenerator() =>
+                $", name: \"{HostRootFileSystemMountName.ToString()}, mount_host_option: {option}\"";
+
+            Result OpenHostFs() => OpenHostFileSystemImpl(fs, out hostFileSystem, ref path, option);
+
+            Result MountHostFs() => fs.Register(HostRootFileSystemMountName, hostFileSystem,
+                new HostRootCommonMountNameGenerator());
+
+            // Open the host file system
+            Result result =
+                fs.RunOperationWithAccessLogOnFailure(AccessLogTarget.Application, OpenHostFs, LogMessageGenerator);
+            if (result.IsFailure()) return result;
+
+            // Mount the host file system
+            result = fs.RunOperationWithAccessLog(AccessLogTarget.Application, MountHostFs, LogMessageGenerator);
+            if (result.IsFailure()) return result;
+
+            if (fs.IsEnabledAccessLog(AccessLogTarget.Application))
+                fs.EnableFileSystemAccessorAccessLog(HostRootFileSystemMountName);
+
+            return Result.Success;
+        }
+
+        public static void UnmountHostRoot(this FileSystemClient fs)
+        {
+            fs.Unmount(HostRootFileSystemMountName);
+        }
+
+        public static Result MountHost(this FileSystemClient fs, U8Span mountName, U8Span path)
+        {
+            return MountHostImpl(fs, mountName, path, null);
+        }
+
+        public static Result MountHost(this FileSystemClient fs, U8Span mountName, U8Span path, MountHostOption option)
+        {
+            return MountHostImpl(fs, mountName, path, option);
+        }
+
+        private static Result MountHostImpl(this FileSystemClient fs, U8Span mountName, U8Span path,
+            MountHostOption? optionalOption, [CallerMemberName] string caller = "")
+        {
+            Result rc;
+            ICommonMountNameGenerator nameGenerator;
+
+            string logMessage = null;
+            var option = MountHostOption.None;
+
+            // Set the mount option if it was specified
+            if (optionalOption.HasValue)
+            {
+                option = optionalOption.Value;
+            }
+
+            if (fs.IsEnabledAccessLog(AccessLogTarget.Application))
+            {
+                if (optionalOption.HasValue)
+                {
+                    logMessage = $", name: \"{mountName.ToString()}\", mount_host_option: {option}";
+                }
+                else
+                {
+                    logMessage = $", name: \"{mountName.ToString()}\"";
+                }
+
+                TimeSpan startTime = fs.Time.GetCurrent();
+                rc = PreMountHost(out nameGenerator, mountName, path);
+                TimeSpan endTime = fs.Time.GetCurrent();
+
+                fs.OutputAccessLogUnlessResultSuccess(rc, startTime, endTime, logMessage, caller);
+            }
+            else
+            {
+                rc = PreMountHost(out nameGenerator, mountName, path);
+            }
+
+            if (rc.IsFailure()) return rc;
+
+            IFileSystem hostFileSystem;
+
+            if (fs.IsEnabledAccessLog(AccessLogTarget.Application))
+            {
+                TimeSpan startTime = fs.Time.GetCurrent();
+                rc = OpenHostFileSystem(fs, out hostFileSystem, mountName, path, option);
+                TimeSpan endTime = fs.Time.GetCurrent();
+
+                fs.OutputAccessLogUnlessResultSuccess(rc, startTime, endTime, logMessage, caller);
+            }
+            else
+            {
+                rc = OpenHostFileSystem(fs, out hostFileSystem, mountName, path, option);
+            }
+
+            if (rc.IsFailure()) return rc;
+
+            if (fs.IsEnabledAccessLog(AccessLogTarget.Application))
+            {
+                TimeSpan startTime = fs.Time.GetCurrent();
+                rc = fs.Register(mountName, hostFileSystem, nameGenerator);
+                TimeSpan endTime = fs.Time.GetCurrent();
+
+                fs.OutputAccessLog(rc, startTime, endTime, logMessage, caller);
+            }
+            else
+            {
+                rc = fs.Register(mountName, hostFileSystem, nameGenerator);
+            }
+
+            if (rc.IsFailure()) return rc;
+
+            if (fs.IsEnabledAccessLog(AccessLogTarget.Application))
+            {
+                fs.EnableFileSystemAccessorAccessLog(mountName);
+            }
+
+            return Result.Success;
+        }
+
+        private static Result PreMountHost(out ICommonMountNameGenerator nameGenerator, U8Span mountName, U8Span path)
+        {
+            nameGenerator = default;
+
+            Result rc = MountHelpers.CheckMountName(mountName);
+            if (rc.IsFailure()) return rc;
+
+            if (path.IsNull())
+                return ResultFs.NullptrArgument.Log();
+
+            nameGenerator = new HostCommonMountNameGenerator(path);
+            return Result.Success;
+        }
+
+        private static Result OpenHostFileSystem(FileSystemClient fs, out IFileSystem fileSystem, U8Span mountName,
+            U8Span path, MountHostOption option)
+        {
+            fileSystem = default;
+
+            if (mountName.IsNull())
+                return ResultFs.NullptrArgument.Log();
+
+            if (path.IsNull())
+                return ResultFs.NullptrArgument.Log();
+
+            if (PathUtility.IsWindowsDrive(mountName))
+                return ResultFs.InvalidMountName.Log();
+
+            if (MountHelpers.IsReservedMountName(mountName))
+                return ResultFs.InvalidMountName.Log();
+
+            bool needsTrailingSeparator = false;
+            int pathLength = StringUtils.GetLength(path, PathTools.MaxPathLength + 1);
+
+            if (pathLength != 0 && PathTool.IsSeparator(path[pathLength - 1]))
+            {
+                needsTrailingSeparator = true;
+                pathLength++;
+            }
+
+            if (pathLength + 1 > PathTools.MaxPathLength)
+                return ResultFs.TooLongPath.Log();
+
+            FsPath fullPath;
+            unsafe { _ = &fullPath; } // workaround for CS0165
+
+            var sb = new U8StringBuilder(fullPath.Str);
+            sb.Append(StringTraits.DirectorySeparator).Append(path);
+
+            if (needsTrailingSeparator)
+            {
+                sb.Append(StringTraits.DirectorySeparator);
+            }
+
+            if (sb.Overflowed)
+                return ResultFs.TooLongPath.Log();
+
+            // If the input path begins with "//", change any leading '/' characters to '\'
+            if (PathTool.IsSeparator(fullPath.Str[1]) && PathTool.IsSeparator(fullPath.Str[2]))
+            {
+                for (int i = 1; PathTool.IsSeparator(fullPath.Str[i]); i++)
+                {
+                    fullPath.Str[i] = StringTraits.AltDirectorySeparator;
+                }
+            }
+
+            return OpenHostFileSystemImpl(fs, out fileSystem, ref fullPath, option);
+        }
+
+        private static Result OpenHostFileSystemImpl(FileSystemClient fs, out IFileSystem fileSystem, ref FsPath path, MountHostOption option)
+        {
+            fileSystem = default;
+
+            IFileSystemProxy fsProxy = fs.GetFileSystemProxyServiceObject();
+            IFileSystem hostFs;
+
+            if (option == MountHostOption.None)
+            {
+                Result rc = fsProxy.OpenHostFileSystem(out hostFs, ref path);
+                if (rc.IsFailure()) return rc;
+            }
+            else
+            {
+                Result rc = fsProxy.OpenHostFileSystemWithOption(out hostFs, ref path, option);
+                if (rc.IsFailure()) return rc;
+            }
+
+            fileSystem = hostFs;
+            return Result.Success;
+        }
+    }
+}

src/LibHac/FsService/FileSystemProxy.cs

@@ -42,7 +42,7 @@ namespace LibHac.FsService
 
             var normalizer = new PathNormalizer(path, GetPathNormalizerOptions(path));
             if (normalizer.Result.IsFailure()) return normalizer.Result;
-            
+
             // ReSharper disable once ConditionIsAlwaysTrueOrFalse
             return FsProxyCore.OpenFileSystem(out fileSystem, normalizer.Path, type, canMountSystemDataPrivate, titleId);
         }
@@ -682,7 +682,12 @@ namespace LibHac.FsService
             throw new NotImplementedException();
         }
 
-        public Result OpenHostFileSystem(out IFileSystem fileSystem, ref FsPath subPath)
+        public Result OpenHostFileSystemWithOption(out IFileSystem fileSystem, ref FsPath path, MountHostOption option)
+        {
+            throw new NotImplementedException();
+        }
+
+        public Result OpenHostFileSystem(out IFileSystem fileSystem, ref FsPath path)
         {
             throw new NotImplementedException();
         }

src/LibHac/FsService/IFileSystemProxy.cs

@@ -17,7 +17,8 @@ namespace LibHac.FsService
         Result OpenBisFileSystem(out IFileSystem fileSystem, ref FsPath rootPath, BisPartitionId partitionId);
         Result OpenBisStorage(out IStorage storage, BisPartitionId partitionId);
         Result InvalidateBisCache();
-        Result OpenHostFileSystem(out IFileSystem fileSystem, ref FsPath subPath);
+        Result OpenHostFileSystemWithOption(out IFileSystem fileSystem, ref FsPath path, MountHostOption option);
+        Result OpenHostFileSystem(out IFileSystem fileSystem, ref FsPath path);
         Result OpenSdCardFileSystem(out IFileSystem fileSystem);
         Result FormatSdCardFileSystem();
         Result DeleteSaveDataFileSystem(ulong saveDataId);