Fix nullable implementation

Fixes #13

Author: lone7254

src/VmmSharpEx/Extensions/Input/VmmInputManager.cs

@@ -63,9 +63,7 @@ public VmmInputManager(Vmm vmm)
             _vmm = vmm;
             if (!_vmm.PidGetFromName("winlogon.exe", out _winLogonPid))
                 throw new VmmException("Failed to get winlogon.exe PID");
-            var pids = _vmm.PidGetAllFromName("csrss.exe");
-            if (pids is null || pids.Length == 0)
-                throw new VmmException("Failed to get csrss.exe PIDs");
+            var pids = _vmm.PidGetAllFromName("csrss.exe") ?? throw new InvalidOperationException("Failed to get csrss process");
             ulong gafAsyncKeyStateExport = 0;
 
             var exceptions = new List<Exception>();

src/VmmSharpEx/Extensions/VmmExtensions.cs

@@ -144,7 +144,7 @@ public static bool FixCr3(this Vmm vmm, string processName, uint pid)
             // Wait for progress to reach 100%
             while (true)
             {
-                var percentBytes = vmm.VfsRead(@"\misc\procinfo\progress_percent.txt", 4);
+                _ = vmm.VfsRead(@"\misc\procinfo\progress_percent.txt", out var percentBytes, 4);
                 if (percentBytes is not null &&
                     int.TryParse(Encoding.ASCII.GetString(percentBytes).Trim(), out int percent) &&
                     percent == 100)
@@ -154,8 +154,8 @@ public static bool FixCr3(this Vmm vmm, string processName, uint pid)
             }
 
             // VFS list and read DTBs
-            //var vfsEntries = vmm.VfsList(@"\misc\procinfo\");
-            var dtbRaw = vmm.VfsRead(@"\misc\procinfo\dtb.txt", 0x1000);
+            _ = vmm.VfsList(@"\misc\procinfo\");
+            _ = vmm.VfsRead(@"\misc\procinfo\dtb.txt", out var dtbRaw, 0x1000);
             if (dtbRaw is null)
                 return false;
 

src/VmmSharpEx/Internal/Vmmi.cs

@@ -1462,7 +1462,7 @@ public static unsafe partial bool VMMDLL_Log(
     [return: MarshalAs(UnmanagedType.Bool)]
     public static partial bool VMMDLL_LogCallback(
         IntPtr hVMM,
-        Vmm.VMMDLL_LOG_CALLBACK_PFN pfnCB);
+        Vmm.VMMDLL_LOG_CALLBACK_PFN? pfnCB);
 
     [LibraryImport("vmm.dll", EntryPoint = "VMMDLL_MemCallback")]
     [return: MarshalAs(UnmanagedType.Bool)]

src/VmmSharpEx/LeechCore.cs

@@ -35,15 +35,14 @@ namespace VmmSharpEx;
 /// </remarks>
 public sealed class LeechCore : IDisposable
 {
-    private readonly Vmm _parent;
+    private readonly Vmm? _parent;
     private IntPtr _handle;
 
     private LeechCore() { throw new NotImplementedException(); }
 
     private LeechCore(IntPtr hLC)
     {
         _handle = hLC;
-        _parent = null!;  // Required for nullable, but will be set in internal constructor
     }
 
     /// <summary>
@@ -152,7 +151,7 @@ public override string ToString()
                     configErrorInfo.fUserInputRequest = e.fUserInputRequest;
                     if (e.cwszUserText > 0)
                     {
-                        configErrorInfo.strUserText = Marshal.PtrToStringUni((IntPtr)(pLcErrorInfo.ToInt64() + cbERROR_INFO)) ?? "";
+                        configErrorInfo.strUserText = Marshal.PtrToStringUni((IntPtr)(pLcErrorInfo.ToInt64() + cbERROR_INFO));
                     }
                 }
 
@@ -513,18 +512,15 @@ public unsafe bool ExecuteCommand(LcCmd fOption, ReadOnlySpan<byte> dataIn, out
     /// Wraps native memory returned from a scatter read invocation.
     /// </summary>
     /// <remarks>
-    /// The underlying native scatter page buffers are released via <see cref="Lci.LcMemFree(void*)"/> when this handle
+    /// The underlying native scatter page buffers are released via <see cref="Lci.LcMemFree"/> when this handle
     /// is disposed.
     /// </remarks>
     public sealed class LcScatterHandle : IDisposable
     {
         private readonly PooledDictionary<ulong, ScatterData> _results;
         private IntPtr _mems;
 
-        private LcScatterHandle()
-        {
-            _results = new PooledDictionary<ulong, ScatterData>();
-        }
+        private LcScatterHandle() { throw new NotImplementedException(); }
 
         internal LcScatterHandle(PooledDictionary<ulong, ScatterData> results, IntPtr mems)
         {
@@ -652,7 +648,7 @@ public struct LcMemScatter
         /// A read-only view over the page contents pointed at by <see cref="pb"/>.
         /// </summary>
         /// <remarks>
-        /// DANGER: Do not access this memory after the memory is freed via <see cref="Lci.LcMemFree(void*)"/>.
+        /// DANGER: Do not access this memory after the memory is freed via <see cref="Lci.LcMemFree"/>.
         /// </remarks>
         public readonly unsafe ReadOnlySpan<byte> Data =>
             new ReadOnlySpan<byte>(pb.ToPointer(), checked((int)cb));

src/VmmSharpEx/Scatter/VmmScatter.cs

@@ -495,7 +495,7 @@ public void Clear(VmmFlags? flags = null, uint? pid = null)
         if (pid is uint p)
             _pid = p;
         _isPrepared = default;
-        Completed = null;
+        Completed = default;
         if (!Vmmi.VMMDLL_Scatter_Clear(_handle, _pid, _flags))
             throw new VmmException("Failed to clear VmmScatter Handle.");
     }

src/VmmSharpEx/Vmm.cs

@@ -284,7 +284,7 @@ public bool ConfigSet(VmmOption fOption, ulong qwValue)
     /// <param name="outputFile">If non-<see langword="null"/>, writes the memory map to disk at the specified output location.</param>
     /// <returns>Memory map ptr in string format.</returns>
     /// <exception cref="VmmException">Thrown if the memory map cannot be retrieved or applied.</exception>
-    public string? GetMemoryMap(
+    public string GetMemoryMap(
         bool applyMap = false,
         string? outputFile = null)
     {
@@ -684,12 +684,12 @@ public unsafe bool MemWriteSpan<T>(uint pid, ulong va, Span<T> span)
     /// </summary>
     /// <param name="pid">Process ID (PID) this operation will take place within.</param>
     /// <param name="va">Virtual address to translate from.</param>
-    /// <returns>Physical address if successful; otherwise 0 on failure.</returns>
+    /// <param name="pa">Translated physical address if successful, otherwise 0.</param>
+    /// <returns>True if successful, otherwise False.</returns>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public ulong MemVirt2Phys(uint pid, ulong va)
+    public bool MemVirt2Phys(uint pid, ulong va, out ulong pa)
     {
-        _ = Vmmi.VMMDLL_MemVirt2Phys(_handle, pid, va, out var pa);
-        return pa;
+        return Vmmi.VMMDLL_MemVirt2Phys(_handle, pid, va, out pa);
     }
 
     /// <summary>
@@ -865,56 +865,51 @@ public bool VfsList(string path, VfsContext ctx, VfsCallBack_AddFile callbackFil
     /// VFS list files and directories in a virtual file system path.
     /// </summary>
     /// <param name="path">Virtual path to enumerate.</param>
-    /// <returns>A list with file and directory entries on success; an empty list on failure.</returns>
-    public List<VfsEntry> VfsList(string path)
+    /// <returns>A list with file and directory entries on success; a null list on failure.</returns>
+    public List<VfsEntry>? VfsList(string path)
     {
         using var ctx = new VfsContext();
-        VfsList(path, ctx, VfsList_AddFileCB, VfsList_AddDirectoryCB);
+        if (!VfsList(path, ctx, VfsList_AddFileCB, VfsList_AddDirectoryCB))
+            return null;
         return ctx.Entries;
     }
 
     /// <summary>
     /// VFS read data from a virtual file.
     /// </summary>
     /// <param name="fileName">The file name/path within the VFS.</param>
-    /// <param name="ntStatus">Receives the NTSTATUS value of the operation (success = 0).</param>
+    /// <param name="data">The data read from the operation on success; otherwise null.</param>
     /// <param name="size">The maximum number of bytes to read. 0 = default = 16MB.</param>
     /// <param name="offset">Optional offset within the file to start reading at.</param>
-    /// <returns>The data read on success. Zero-length data on failure. NB! Data read may be shorter than <paramref name="size"/>.</returns>
-    public unsafe byte[] VfsRead(string fileName, out uint ntStatus, uint size = 0, ulong offset = 0)
+    /// <returns>The NTSTATUS value of the operation (success = 0).</returns>
+    public unsafe uint VfsRead(string fileName, out byte[]? data, uint size = 0, ulong offset = 0)
     {
         uint cbRead = 0;
         if (size == 0)
         {
             size = 0x01000000; // 16MB
         }
 
-        var data = new byte[size];
-        fixed (byte* pb = data)
+        var dataLocal = new byte[size];
+        fixed (byte* pb = dataLocal)
         {
-            ntStatus = Vmmi.VMMDLL_VfsRead(_handle, fileName.Replace('/', '\\'), pb, size, out cbRead, offset);
-            var pbData = new byte[cbRead];
-            if (cbRead > 0)
+            uint ret = Vmmi.VMMDLL_VfsRead(_handle, fileName.Replace('/', '\\'), pb, size, out cbRead, offset);
+            if (ret == 0) // STATUS_SUCCESS
+            {
+                if (cbRead < size)
+                {
+                    Array.Resize(ref dataLocal, (int)cbRead);
+                }
+                data = dataLocal;
+            }
+            else
             {
-                data.AsSpan(0, pbData.Length).CopyTo(pbData);
+                data = null;
             }
-
-            return pbData;
+            return ret;
         }
     }
 
-    /// <summary>
-    /// VFS read data from a virtual file.
-    /// </summary>
-    /// <param name="fileName">The file name/path within the VFS.</param>
-    /// <param name="size">The maximum number of bytes to read. 0 = default = 16MB.</param>
-    /// <param name="offset">Optional offset within the file to start reading at.</param>
-    /// <returns>The data read on success. Zero-length data on failure. NB! Data read may be shorter than <paramref name="size"/>.</returns>
-    public byte[] VfsRead(string fileName, uint size = 0, ulong offset = 0)
-    {
-        return VfsRead(fileName, out _, size, offset);
-    }
-
     /// <summary>
     /// VFS write data to a virtual file.
     /// </summary>
@@ -989,7 +984,7 @@ public bool PidGetFromName(string sProcName, out uint pdwPID)
     /// Get all process IDs (PIDs) for a given process name.
     /// </summary>
     /// <param name="sProcName">Name of the process to look up.</param>
-    /// <returns>Array of PIDs that match; null array if no matches.</returns>
+    /// <returns>Array of PIDs that match, or null if failed.</returns>
     public uint[]? PidGetAllFromName(string sProcName)
     {
         var pids = new List<uint>();
@@ -1005,7 +1000,8 @@ public bool PidGetFromName(string sProcName, out uint pdwPID)
                 pids.Add(procInfo[i].dwPID);
             }
         }
-        return pids.ToArray();
+        return pids.Count > 0 ?
+            pids.ToArray() : null;
     }
 
     /// <summary>
@@ -1729,7 +1725,7 @@ public unsafe bool Map_GetHeap(uint pid, out HeapMap result)
     /// Get the user-mode path of the process image.
     /// </summary>
     /// <param name="pid">Process ID (PID) for this operation.</param>
-    /// <returns>A string path on success; otherwise null.</returns>
+    /// <returns>A string path on success; otherwise a null string.</returns>
     public string? GetProcessPathUser(uint pid)
     {
         return GetProcessInformationString(pid, VMMDLL_PROCESS_INFORMATION_OPT_STRING_PATH_USER_IMAGE);
@@ -1739,7 +1735,7 @@ public unsafe bool Map_GetHeap(uint pid, out HeapMap result)
     /// Get the kernel-mode path of the process image.
     /// </summary>
     /// <param name="pid">Process ID (PID) for this operation.</param>
-    /// <returns>A string path on success; otherwise null.</returns>
+    /// <returns>A string path on success; otherwise a null string.</returns>
     public string? GetProcessPathKernel(uint pid)
     {
         return GetProcessInformationString(pid, VMMDLL_PROCESS_INFORMATION_OPT_STRING_PATH_KERNEL);
@@ -1749,7 +1745,7 @@ public unsafe bool Map_GetHeap(uint pid, out HeapMap result)
     /// Get the process command line.
     /// </summary>
     /// <param name="pid">Process ID (PID) for this operation.</param>
-    /// <returns>The command line string on success; otherwise null.</returns>
+    /// <returns>The command line string on success; otherwise a null string.</returns>
     public string? GetProcessCmdline(uint pid)
     {
         return GetProcessInformationString(pid, VMMDLL_PROCESS_INFORMATION_OPT_STRING_CMDLINE);
@@ -1760,18 +1756,24 @@ public unsafe bool Map_GetHeap(uint pid, out HeapMap result)
     /// </summary>
     /// <param name="pid">Process ID (PID) for this operation.</param>
     /// <param name="fOptionString">A VMMDLL_PROCESS_INFORMATION_OPT_* flag indicating which string to fetch.</param>
-    /// <returns>The string value on success; otherwise null.</returns>
+    /// <returns>The string value on success; otherwise a null string.</returns>
     public unsafe string? GetProcessInformationString(uint pid, uint fOptionString)
     {
         var pb = Vmmi.VMMDLL_ProcessGetInformationString(_handle, pid, fOptionString);
-        if (pb == null)
+        try
         {
-            return null;
-        }
+            if (pb is null)
+            {
+                return null;
+            }
 
-        var s = Marshal.PtrToStringAnsi((IntPtr)pb);
-        Vmmi.VMMDLL_MemFree(pb);
-        return s;
+            var s = Marshal.PtrToStringAnsi((IntPtr)pb);
+            return s;
+        }
+        finally
+        {
+            Vmmi.VMMDLL_MemFree(pb);
+        }
     }
 
     /// <summary>
@@ -2285,8 +2287,8 @@ public struct ThreadEntry
         public ulong vaStackLimitUser;
         public ulong vaStackBaseKernel;
         public ulong vaStackLimitKernel;
-        public ulong vaImpersonationToken;
         public ulong vaTrapFrame;
+        public ulong vaImpersonationToken;
         public ulong vaRIP;
         public ulong vaRSP;
         public ulong qwAffinity;
@@ -2793,6 +2795,7 @@ public struct PfnEntry
         public uint dwPfn;
         public PfnType tp;
         public PfnTypeExtended tpExtended;
+        public ulong va;
         public ulong vaPte;
         public ulong OriginalPte;
         public uint dwPID;
@@ -3240,7 +3243,7 @@ public struct PfnEntry
         uint cbPfns;
         var cbMAP = Marshal.SizeOf<Vmmi.VMMDLL_MAP_PFN>();
         var cbENTRY = Marshal.SizeOf<Vmmi.VMMDLL_MAP_PFNENTRY>();
-        if (pfns.Length == 0)
+        if (pfns.IsEmpty)
         {
             return null;
         }
@@ -3283,7 +3286,7 @@ public struct PfnEntry
                     };
                     if (e.tp == PfnType.Active && !e.fPrototype)
                     {
-                        e.vaPte = n.va;
+                        e.va = n.va;
                         e.dwPID = n.dwPfnPte[0];
                     }
 
@@ -3304,11 +3307,11 @@ public struct PfnEntry
     /// </summary>
     /// <param name="pid">Process ID (PID) whose module the symbols belong to.</param>
     /// <param name="vaModuleBase">Module base address.</param>
-    /// <param name="szModuleName">Receives the module name if successful.</param>
+    /// <param name="szModuleName">Receives the module name if successful, otherwise null.</param>
     /// <returns><see langword="true"/> if the PDB was loaded successfully; otherwise <see langword="false"/>.</returns>
-    public unsafe bool PdbLoad(uint pid, ulong vaModuleBase, out string szModuleName)
+    public unsafe bool PdbLoad(uint pid, ulong vaModuleBase, out string? szModuleName)
     {
-        szModuleName = "";
+        szModuleName = null;
         var data = new byte[260];
         fixed (byte* pb = data)
         {
@@ -3330,12 +3333,12 @@ public unsafe bool PdbLoad(uint pid, ulong vaModuleBase, out string szModuleName
     /// </summary>
     /// <param name="szModule">Module name.</param>
     /// <param name="cbSymbolAddressOrOffset">Symbol address or module-relative offset.</param>
-    /// <param name="szSymbolName">Receives the symbol name.</param>
+    /// <param name="szSymbolName">Receives the symbol name if succesful, otherwise null.</param>
     /// <param name="pdwSymbolDisplacement">Receives the displacement from the symbol.</param>
     /// <returns><see langword="true"/> on success; otherwise <see langword="false"/>.</returns>
-    public unsafe bool PdbSymbolName(string szModule, ulong cbSymbolAddressOrOffset, out string szSymbolName, out uint pdwSymbolDisplacement)
+    public unsafe bool PdbSymbolName(string szModule, ulong cbSymbolAddressOrOffset, out string? szSymbolName, out uint pdwSymbolDisplacement)
     {
-        szSymbolName = "";
+        szSymbolName = null;
         pdwSymbolDisplacement = 0;
         var data = new byte[260];
         fixed (byte* pb = data)
@@ -3452,7 +3455,7 @@ public delegate void VMMDLL_LOG_CALLBACK_PFN(
     /// </summary>
     /// <param name="pfnCB">The callback function to register, or <see langword="null"/> to unregister an existing callback.</param>
     /// <returns><see langword="true"/> if the callback was successfully registered/unregistered, otherwise <see langword="false"/>.</returns>
-    public bool LogCallback(VMMDLL_LOG_CALLBACK_PFN pfnCB)
+    public bool LogCallback(VMMDLL_LOG_CALLBACK_PFN? pfnCB)
     {
         return Vmmi.VMMDLL_LogCallback(_handle, pfnCB);
     }

src/VmmSharpEx_Benchmarks/ScatterBenchmarks.cs

@@ -18,7 +18,7 @@ public void SetupScatter()
             if (!_vmm.PidGetFromName("explorer.exe", out _pid))
                 throw new InvalidOperationException("Failed to setup VMM");
             var vads = _vmm.Map_GetVad(_pid);
-            if (vads is null)
+            if (vads.Length == 0)
                 throw new InvalidOperationException("Failed to setup VMM");
             var vas = new List<ulong>();
             foreach (var vad in vads)

src/VmmSharpEx_Tests/Manual/VmmSharpEx_VfsTests.cs

@@ -40,7 +40,7 @@ public void TestVfsList()
     public void TestVfsRead()
     {
         const string file = "LICENSE.txt";
-        var data = _vmm.VfsRead($"/{file}");
+        _ = _vmm.VfsRead($"/{file}", out var data);
         Assert.NotNull(data);
         Assert.NotEmpty(data);
         _output.WriteLine(Encoding.UTF8.GetString(data));