dll: create.c: refactoring

build/VStudio/winfsp_dll.vcxproj

@@ -24,7 +24,6 @@
     <ClInclude Include="..\..\src\dll\library.h" />
   </ItemGroup>
   <ItemGroup>
-    <ClCompile Include="..\..\src\dll\access.c" />
     <ClCompile Include="..\..\src\dll\cleanup.c" />
     <ClCompile Include="..\..\src\dll\close.c" />
     <ClCompile Include="..\..\src\dll\create.c" />

build/VStudio/winfsp_dll.vcxproj.filters

@@ -43,9 +43,6 @@
     <ClCompile Include="..\..\src\dll\create.c">
       <Filter>Source</Filter>
     </ClCompile>
-    <ClCompile Include="..\..\src\dll\access.c">
-      <Filter>Source</Filter>
-    </ClCompile>
     <ClCompile Include="..\..\src\dll\path.c">
       <Filter>Source</Filter>
     </ClCompile>

inc/winfsp/winfsp.h

@@ -50,9 +50,6 @@ typedef VOID FSP_FILE_SYSTEM_DISPATCHER(FSP_FILE_SYSTEM *, FSP_FSCTL_TRANSACT_RE
 typedef NTSTATUS FSP_FILE_SYSTEM_OPERATION(FSP_FILE_SYSTEM *, FSP_FSCTL_TRANSACT_REQ *);
 typedef struct _FSP_FILE_SYSTEM_INTERFACE
 {
-    NTSTATUS (*AccessCheck)(FSP_FILE_SYSTEM *FileSystem,
-        FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN CheckParentDirectory, BOOLEAN AllowTraverseCheck,
-        DWORD DesiredAccess, PDWORD PGrantedAccess);
     NTSTATUS (*GetSecurity)(FSP_FILE_SYSTEM *FileSystem,
         PWSTR FileName, PDWORD PFileAttributes,
         PSECURITY_DESCRIPTOR SecurityDescriptor, SIZE_T *PSecurityDescriptorSize);
@@ -149,6 +146,24 @@ FSP_API NTSTATUS FspFileSystemSendResponseWithStatus(FSP_FILE_SYSTEM *FileSystem
 /*
  * File System Operations
  */
+FSP_API PGENERIC_MAPPING FspGetFileGenericMapping(VOID);
+FSP_API NTSTATUS FspAccessCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN CheckParentDirectory, BOOLEAN AllowTraverseCheck,
+    DWORD DesiredAccess, PDWORD PGrantedAccess);
+FSP_API NTSTATUS FspShareCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode);
+FSP_API NTSTATUS FspFileSystemPreCreateCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck, PDWORD PGrantedAccess);
+FSP_API VOID FspFileSystemPostCreateCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode);
+FSP_API NTSTATUS FspFileSystemPreOpenCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck, PDWORD PGrantedAccess);
+FSP_API NTSTATUS FspFileSystemPostOpenCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode);
+FSP_API NTSTATUS FspFileSystemPreOverwriteCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck, PDWORD PGrantedAccess);
+FSP_API NTSTATUS FspFileSystemPostOverwriteCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode);
 FSP_API NTSTATUS FspFileSystemOpCreate(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request);
 FSP_API NTSTATUS FspFileSystemOpCleanup(FSP_FILE_SYSTEM *FileSystem,
@@ -163,16 +178,6 @@ FSP_API NTSTATUS FspFileSystemSendCloseResponse(FSP_FILE_SYSTEM *FileSystem,
 FSP_API NTSTATUS FspFileSystemSendCleanupResponse(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request);
 
-/*
- * Access Checks
- */
-FSP_API PGENERIC_MAPPING FspGetFileGenericMapping(VOID);
-FSP_API NTSTATUS FspAccessCheck(FSP_FILE_SYSTEM *FileSystem,
-    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN CheckParentDirectory, BOOLEAN AllowTraverseCheck,
-    DWORD DesiredAccess, PDWORD PGrantedAccess);
-FSP_API NTSTATUS FspShareCheck(FSP_FILE_SYSTEM *FileSystem,
-    DWORD GrantedAccess, DWORD ShareAccess, FSP_FILE_NODE *FileNode);
-
 /*
  * Path Handling
  */

src/dll/access.c

@@ -1,213 +0,0 @@
-/**
- * @file dll/access.c
- *
- * @copyright 2015 Bill Zissimopoulos
- */
-
-#include <dll/library.h>
-
-static GENERIC_MAPPING FspFileGenericMapping =
-{
-    .GenericRead = FILE_GENERIC_READ,
-    .GenericWrite = FILE_GENERIC_WRITE,
-    .GenericExecute = FILE_GENERIC_EXECUTE,
-    .GenericAll = FILE_ALL_ACCESS,
-};
-
-FSP_API PGENERIC_MAPPING FspGetFileGenericMapping(VOID)
-{
-    return &FspFileGenericMapping;
-}
-
-static NTSTATUS FspGetSecurity(FSP_FILE_SYSTEM *FileSystem,
-    PWSTR FileName, PDWORD PFileAttributes,
-    PSECURITY_DESCRIPTOR *PSecurityDescriptor, SIZE_T *PSecurityDescriptorSize)
-{
-    for (;;)
-    {
-        NTSTATUS Result = FileSystem->Interface->GetSecurity(FileSystem,
-            FileName, PFileAttributes, *PSecurityDescriptor, PSecurityDescriptorSize);
-        if (STATUS_BUFFER_OVERFLOW != Result)
-            return Result;
-
-        MemFree(*PSecurityDescriptor);
-        *PSecurityDescriptor = MemAlloc(*PSecurityDescriptorSize);
-        if (0 == *PSecurityDescriptor)
-            return STATUS_INSUFFICIENT_RESOURCES;
-    }
-}
-
-FSP_API NTSTATUS FspAccessCheck(FSP_FILE_SYSTEM *FileSystem,
-    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN CheckParentDirectory, BOOLEAN AllowTraverseCheck,
-    DWORD DesiredAccess, PDWORD PGrantedAccess)
-{
-    if (0 != FileSystem->Interface->AccessCheck)
-        return FileSystem->Interface->AccessCheck(FileSystem,
-            Request, CheckParentDirectory, AllowTraverseCheck, DesiredAccess, PGrantedAccess);
-
-    if (0 == FileSystem->Interface->GetSecurity)
-    {
-        *PGrantedAccess = DesiredAccess;
-        return STATUS_SUCCESS;
-    }
-
-    NTSTATUS Result;
-    PWSTR Parent, Suffix;
-    DWORD FileAttributes;
-    PSECURITY_DESCRIPTOR SecurityDescriptor = 0;
-    SIZE_T SecurityDescriptorSize;
-    DWORD PrivilegeSetLength;
-    BOOL AccessStatus;
-
-    *PGrantedAccess = 0;
-
-    if (CheckParentDirectory)
-        FspPathSuffix((PWSTR)Request->Buffer, &Parent, &Suffix);
-
-    SecurityDescriptorSize = 1024;
-    SecurityDescriptor = MemAlloc(SecurityDescriptorSize);
-    if (0 == SecurityDescriptor)
-    {
-        Result = STATUS_INSUFFICIENT_RESOURCES;
-        goto exit;
-    }
-
-    if (AllowTraverseCheck && !Request->Req.Create.HasTraversePrivilege)
-    {
-        PWSTR Path = (PWSTR)Request->Buffer, Prefix;
-        DWORD TraverseAccess;
-
-        for (;;)
-        {
-            FspPathPrefix(Path, &Prefix, &Path);
-            if (L'\0' == Path[0])
-            {
-                FspPathCombine((PWSTR)Request->Buffer, Path);
-                break;
-            }
-
-            Prefix = L'\0' == Prefix[0] ? L"\\" : (PWSTR)Request->Buffer;
-            Result = FspGetSecurity(FileSystem, Prefix, 0,
-                &SecurityDescriptor, &SecurityDescriptorSize);
-
-            FspPathCombine((PWSTR)Request->Buffer, Path);
-
-            if (!NT_SUCCESS(Result))
-            {
-                if (STATUS_OBJECT_NAME_NOT_FOUND == Result)
-                    Result = STATUS_OBJECT_PATH_NOT_FOUND;
-                goto exit;
-            }
-
-            if (AccessCheck(SecurityDescriptor, (HANDLE)Request->Req.Create.AccessToken, FILE_TRAVERSE,
-                &FspFileGenericMapping, 0, &PrivilegeSetLength, &TraverseAccess, &AccessStatus))
-                Result = AccessStatus ? STATUS_SUCCESS : STATUS_ACCESS_DENIED;
-            else
-                Result = FspNtStatusFromWin32(GetLastError());
-
-            if (!NT_SUCCESS(Result))
-                goto exit;
-        }
-    }
-
-    Result = FspGetSecurity(FileSystem, (PWSTR)Request->Buffer, &FileAttributes,
-        &SecurityDescriptor, &SecurityDescriptorSize);
-    if (!NT_SUCCESS(Result))
-        goto exit;
-
-    if (CheckParentDirectory)
-    {
-        if (0 == (FileAttributes && FILE_ATTRIBUTE_DIRECTORY))
-            return STATUS_NOT_A_DIRECTORY;
-    }
-    else
-    {
-        if ((Request->Req.Create.CreateOptions & FILE_DIRECTORY_FILE) &&
-            0 == (FileAttributes && FILE_ATTRIBUTE_DIRECTORY))
-            return STATUS_NOT_A_DIRECTORY;
-        if ((Request->Req.Create.CreateOptions & FILE_NON_DIRECTORY_FILE) &&
-            0 != (FileAttributes && FILE_ATTRIBUTE_DIRECTORY))
-            return STATUS_NOT_A_DIRECTORY;
-    }
-
-    if (0 != (FileAttributes && FILE_ATTRIBUTE_READONLY))
-    {
-        if (DesiredAccess &
-            (FILE_WRITE_DATA | FILE_APPEND_DATA | FILE_ADD_SUBDIRECTORY | FILE_DELETE_CHILD))
-        {
-            Result = STATUS_ACCESS_DENIED;
-            goto exit;
-        }
-        if (Request->Req.Create.CreateOptions & FILE_DELETE_ON_CLOSE)
-        {
-            Result = STATUS_CANNOT_DELETE;
-            goto exit;
-        }
-    }
-
-    if (AccessCheck(SecurityDescriptor, (HANDLE)Request->Req.Create.AccessToken, DesiredAccess,
-        &FspFileGenericMapping, 0, &PrivilegeSetLength, PGrantedAccess, &AccessStatus))
-        Result = AccessStatus ? STATUS_SUCCESS : STATUS_ACCESS_DENIED;
-    else
-        Result = FspNtStatusFromWin32(GetLastError());
-
-exit:
-    MemFree(SecurityDescriptor);
-
-    if (CheckParentDirectory)
-        FspPathCombine((PWSTR)Request->Buffer, Suffix);
-
-    return Result;
-}
-
-FSP_API NTSTATUS FspShareCheck(FSP_FILE_SYSTEM *FileSystem,
-    DWORD GrantedAccess, DWORD ShareAccess, FSP_FILE_NODE *FileNode)
-{
-    BOOLEAN ReadAccess, WriteAccess, DeleteAccess;
-    BOOLEAN SharedRead, SharedWrite, SharedDelete;
-    ULONG OpenCount;
-
-    ReadAccess = 0 != (GrantedAccess & (FILE_READ_DATA | FILE_EXECUTE));
-    WriteAccess = 0 != (GrantedAccess & (FILE_WRITE_DATA | FILE_APPEND_DATA));
-    DeleteAccess = 0 != (GrantedAccess & DELETE);
-
-    if (ReadAccess || WriteAccess || DeleteAccess)
-    {
-        SharedRead = 0 != (ShareAccess & FILE_SHARE_READ);
-        SharedWrite = 0 != (ShareAccess & FILE_SHARE_WRITE);
-        SharedDelete = 0 != (ShareAccess & FILE_SHARE_DELETE);
-
-        OpenCount = FileNode->ShareAccess.OpenCount;
-
-        /*
-         * IF ReadAccess AND there are already some exclusive readers
-         * OR WriteAccess AND there are already some exclusive writers
-         * OR DeleteAccess AND there are already some exclusive deleters
-         * OR exclusive read requested AND there are already some readers
-         * OR exclusive write requested AND there are already some writers
-         * OR exclusive delete requested AND there are already some deleters
-         */
-        if (ReadAccess && (FileNode->ShareAccess.SharedRead < OpenCount))
-            return STATUS_SHARING_VIOLATION;
-        if (WriteAccess && (FileNode->ShareAccess.SharedWrite < OpenCount))
-            return STATUS_SHARING_VIOLATION;
-        if (DeleteAccess && (FileNode->ShareAccess.SharedDelete < OpenCount))
-            return STATUS_SHARING_VIOLATION;
-        if (!SharedRead && 0 != FileNode->ShareAccess.Readers)
-            return STATUS_SHARING_VIOLATION;
-        if (!SharedWrite && 0 != FileNode->ShareAccess.Writers)
-            return STATUS_SHARING_VIOLATION;
-        if (!SharedDelete && 0 != FileNode->ShareAccess.Deleters)
-            return STATUS_SHARING_VIOLATION;
-
-        FileNode->ShareAccess.OpenCount++;
-        FileNode->ShareAccess.Readers += ReadAccess;
-        FileNode->ShareAccess.Writers += WriteAccess;
-        FileNode->ShareAccess.Deleters += DeleteAccess;
-        FileNode->ShareAccess.SharedRead += SharedRead;
-        FileNode->ShareAccess.SharedWrite += SharedWrite;
-        FileNode->ShareAccess.SharedDelete += SharedDelete;
-    }
-
-    return STATUS_SUCCESS;
-}

src/dll/create.c

@@ -6,19 +6,221 @@
 
 #include <dll/library.h>
 
-static inline
+static GENERIC_MAPPING FspFileGenericMapping =
-BOOLEAN FspIsRootDirectory(PWSTR FileName)
 {
-    for (PWSTR Pointer = FileName; *Pointer; Pointer++)
+    .GenericRead = FILE_GENERIC_READ,
-        if (L'\\' != *Pointer)
+    .GenericWrite = FILE_GENERIC_WRITE,
-            return FALSE;
+    .GenericExecute = FILE_GENERIC_EXECUTE,
-    return TRUE;
+    .GenericAll = FILE_ALL_ACCESS,
+};
+
+FSP_API PGENERIC_MAPPING FspGetFileGenericMapping(VOID)
+{
+    return &FspFileGenericMapping;
 }
 
-static inline
+static NTSTATUS FspGetSecurity(FSP_FILE_SYSTEM *FileSystem,
-NTSTATUS FspCreateCheck(FSP_FILE_SYSTEM *FileSystem,
+    PWSTR FileName, PDWORD PFileAttributes,
-    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck,
+    PSECURITY_DESCRIPTOR *PSecurityDescriptor, SIZE_T *PSecurityDescriptorSize)
-    PDWORD PGrantedAccess)
+{
+    for (;;)
+    {
+        NTSTATUS Result = FileSystem->Interface->GetSecurity(FileSystem,
+            FileName, PFileAttributes, *PSecurityDescriptor, PSecurityDescriptorSize);
+        if (STATUS_BUFFER_OVERFLOW != Result)
+            return Result;
+
+        MemFree(*PSecurityDescriptor);
+        *PSecurityDescriptor = MemAlloc(*PSecurityDescriptorSize);
+        if (0 == *PSecurityDescriptor)
+            return STATUS_INSUFFICIENT_RESOURCES;
+    }
+}
+
+FSP_API NTSTATUS FspAccessCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN CheckParentDirectory, BOOLEAN AllowTraverseCheck,
+    DWORD DesiredAccess, PDWORD PGrantedAccess)
+{
+    if (0 == FileSystem->Interface->GetSecurity)
+    {
+        *PGrantedAccess = DesiredAccess;
+        return STATUS_SUCCESS;
+    }
+
+    NTSTATUS Result;
+    PWSTR Parent, Suffix, Prefix, Remain;
+    DWORD FileAttributes;
+    PSECURITY_DESCRIPTOR SecurityDescriptor = 0;
+    SIZE_T SecurityDescriptorSize;
+    DWORD PrivilegeSetLength;
+    DWORD TraverseAccess;
+    BOOL AccessStatus;
+
+    *PGrantedAccess = 0;
+
+    if (CheckParentDirectory)
+        FspPathSuffix((PWSTR)Request->Buffer, &Parent, &Suffix);
+
+    SecurityDescriptorSize = 1024;
+    SecurityDescriptor = MemAlloc(SecurityDescriptorSize);
+    if (0 == SecurityDescriptor)
+    {
+        Result = STATUS_INSUFFICIENT_RESOURCES;
+        goto exit;
+    }
+
+    if (AllowTraverseCheck && !Request->Req.Create.HasTraversePrivilege)
+    {
+        Remain = (PWSTR)Request->Buffer;
+        for (;;)
+        {
+            FspPathPrefix(Remain, &Prefix, &Remain);
+            if (L'\0' == Remain[0])
+            {
+                FspPathCombine((PWSTR)Request->Buffer, Remain);
+                break;
+            }
+
+            Prefix = L'\0' == Prefix[0] ? L"\\" : (PWSTR)Request->Buffer;
+            Result = FspGetSecurity(FileSystem, Prefix, 0,
+                &SecurityDescriptor, &SecurityDescriptorSize);
+
+            FspPathCombine((PWSTR)Request->Buffer, Remain);
+
+            if (!NT_SUCCESS(Result))
+            {
+                if (STATUS_OBJECT_NAME_NOT_FOUND == Result)
+                    Result = STATUS_OBJECT_PATH_NOT_FOUND;
+                goto exit;
+            }
+
+            if (AccessCheck(SecurityDescriptor, (HANDLE)Request->Req.Create.AccessToken, FILE_TRAVERSE,
+                &FspFileGenericMapping, 0, &PrivilegeSetLength, &TraverseAccess, &AccessStatus))
+                Result = AccessStatus ? STATUS_SUCCESS : STATUS_ACCESS_DENIED;
+            else
+                Result = FspNtStatusFromWin32(GetLastError());
+
+            if (!NT_SUCCESS(Result))
+                goto exit;
+        }
+    }
+
+    Result = FspGetSecurity(FileSystem, (PWSTR)Request->Buffer, &FileAttributes,
+        &SecurityDescriptor, &SecurityDescriptorSize);
+    if (!NT_SUCCESS(Result))
+        goto exit;
+
+    if (AccessCheck(SecurityDescriptor, (HANDLE)Request->Req.Create.AccessToken, DesiredAccess,
+        &FspFileGenericMapping, 0, &PrivilegeSetLength, PGrantedAccess, &AccessStatus))
+        Result = AccessStatus ? STATUS_SUCCESS : STATUS_ACCESS_DENIED;
+    else
+        Result = FspNtStatusFromWin32(GetLastError());
+    if (!NT_SUCCESS(Result))
+        goto exit;
+
+    if (CheckParentDirectory)
+    {
+        if (0 == (FileAttributes & FILE_ATTRIBUTE_DIRECTORY))
+        {
+            Result = STATUS_NOT_A_DIRECTORY;
+            goto exit;
+        }
+    }
+    else
+    {
+        if ((Request->Req.Create.CreateOptions & FILE_DIRECTORY_FILE) &&
+            0 == (FileAttributes & FILE_ATTRIBUTE_DIRECTORY))
+        {
+            Result = STATUS_NOT_A_DIRECTORY;
+            goto exit;
+        }
+        if ((Request->Req.Create.CreateOptions & FILE_NON_DIRECTORY_FILE) &&
+            0 != (FileAttributes & FILE_ATTRIBUTE_DIRECTORY))
+        {
+            Result = STATUS_FILE_IS_A_DIRECTORY;
+            goto exit;
+        }
+    }
+
+    if (0 != (FileAttributes & FILE_ATTRIBUTE_READONLY))
+    {
+        if (DesiredAccess &
+            (FILE_WRITE_DATA | FILE_APPEND_DATA | FILE_ADD_SUBDIRECTORY | FILE_DELETE_CHILD))
+        {
+            Result = STATUS_ACCESS_DENIED;
+            goto exit;
+        }
+        if (Request->Req.Create.CreateOptions & FILE_DELETE_ON_CLOSE)
+        {
+            Result = STATUS_CANNOT_DELETE;
+            goto exit;
+        }
+    }
+
+exit:
+    MemFree(SecurityDescriptor);
+
+    if (CheckParentDirectory)
+        FspPathCombine((PWSTR)Request->Buffer, Suffix);
+
+    return Result;
+}
+
+FSP_API NTSTATUS FspShareCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode)
+{
+    DWORD ShareAccess = Request->Req.Create.ShareAccess;
+    BOOLEAN ReadAccess, WriteAccess, DeleteAccess;
+    BOOLEAN SharedRead, SharedWrite, SharedDelete;
+    ULONG OpenCount;
+
+    ReadAccess = 0 != (GrantedAccess & (FILE_READ_DATA | FILE_EXECUTE));
+    WriteAccess = 0 != (GrantedAccess & (FILE_WRITE_DATA | FILE_APPEND_DATA));
+    DeleteAccess = 0 != (GrantedAccess & DELETE);
+
+    if (ReadAccess || WriteAccess || DeleteAccess)
+    {
+        SharedRead = 0 != (ShareAccess & FILE_SHARE_READ);
+        SharedWrite = 0 != (ShareAccess & FILE_SHARE_WRITE);
+        SharedDelete = 0 != (ShareAccess & FILE_SHARE_DELETE);
+
+        OpenCount = FileNode->ShareAccess.OpenCount;
+
+        /*
+         * IF ReadAccess AND there are already some exclusive readers
+         * OR WriteAccess AND there are already some exclusive writers
+         * OR DeleteAccess AND there are already some exclusive deleters
+         * OR exclusive read requested AND there are already some readers
+         * OR exclusive write requested AND there are already some writers
+         * OR exclusive delete requested AND there are already some deleters
+         */
+        if (ReadAccess && (FileNode->ShareAccess.SharedRead < OpenCount))
+            return STATUS_SHARING_VIOLATION;
+        if (WriteAccess && (FileNode->ShareAccess.SharedWrite < OpenCount))
+            return STATUS_SHARING_VIOLATION;
+        if (DeleteAccess && (FileNode->ShareAccess.SharedDelete < OpenCount))
+            return STATUS_SHARING_VIOLATION;
+        if (!SharedRead && 0 != FileNode->ShareAccess.Readers)
+            return STATUS_SHARING_VIOLATION;
+        if (!SharedWrite && 0 != FileNode->ShareAccess.Writers)
+            return STATUS_SHARING_VIOLATION;
+        if (!SharedDelete && 0 != FileNode->ShareAccess.Deleters)
+            return STATUS_SHARING_VIOLATION;
+
+        FileNode->ShareAccess.OpenCount++;
+        FileNode->ShareAccess.Readers += ReadAccess;
+        FileNode->ShareAccess.Writers += WriteAccess;
+        FileNode->ShareAccess.Deleters += DeleteAccess;
+        FileNode->ShareAccess.SharedRead += SharedRead;
+        FileNode->ShareAccess.SharedWrite += SharedWrite;
+        FileNode->ShareAccess.SharedDelete += SharedDelete;
+    }
+
+    return STATUS_SUCCESS;
+}
+
+FSP_API NTSTATUS FspFileSystemPreCreateCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck, PDWORD PGrantedAccess)
 {
     NTSTATUS Result;
 
@@ -33,17 +235,73 @@ NTSTATUS FspCreateCheck(FSP_FILE_SYSTEM *FileSystem,
     return Result;
 }
 
+FSP_API VOID FspFileSystemPostCreateCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode)
+{
+    memset(&FileNode->Flags, 0, sizeof FileNode->Flags);
+    memset(&FileNode->ShareAccess, 0, sizeof FileNode->ShareAccess);
+
+    FspShareCheck(FileSystem, Request, GrantedAccess, FileNode);
+}
+
+FSP_API NTSTATUS FspFileSystemPreOpenCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck, PDWORD PGrantedAccess)
+{
+    return FspAccessCheck(FileSystem, Request, FALSE, AllowTraverseCheck,
+        Request->Req.Create.DesiredAccess, PGrantedAccess);
+}
+
+FSP_API NTSTATUS FspFileSystemPostOpenCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode)
+{
+    return FspShareCheck(FileSystem, Request, GrantedAccess, FileNode);
+}
+
+FSP_API NTSTATUS FspFileSystemPreOverwriteCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN AllowTraverseCheck, PDWORD PGrantedAccess)
+{
+    NTSTATUS Result;
+    BOOLEAN Supersede = FILE_SUPERSEDE == ((Request->Req.Create.CreateOptions >> 24) & 0xff);
+
+    Result = FspAccessCheck(FileSystem, Request, FALSE, AllowTraverseCheck,
+        Request->Req.Create.DesiredAccess | (Supersede ? DELETE : FILE_WRITE_DATA),
+        PGrantedAccess);
+    if (NT_SUCCESS(Result))
+    {
+        if (0 == (Request->Req.Create.DesiredAccess & MAXIMUM_ALLOWED))
+            *PGrantedAccess &= Supersede ?
+                (~DELETE | (Request->Req.Create.DesiredAccess & DELETE)) :
+                (~FILE_WRITE_DATA | (Request->Req.Create.DesiredAccess & FILE_WRITE_DATA));
+    }
+
+    return Result;
+}
+
+FSP_API NTSTATUS FspFileSystemPostOverwriteCheck(FSP_FILE_SYSTEM *FileSystem,
+    FSP_FSCTL_TRANSACT_REQ *Request, DWORD GrantedAccess, FSP_FILE_NODE *FileNode)
+{
+    return FspShareCheck(FileSystem, Request, GrantedAccess, FileNode);
+}
+
+static BOOLEAN FspIsRootDirectory(PWSTR FileName)
+{
+    for (PWSTR Pointer = FileName; *Pointer; Pointer++)
+        if (L'\\' != *Pointer)
+            return FALSE;
+    return TRUE;
+}
+
 static NTSTATUS FspFileSystemOpCreate_FileCreate(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request)
 {
-    if (FspIsRootDirectory((PWSTR)Request->Buffer))
-        return STATUS_ACCESS_DENIED;
-
     NTSTATUS Result;
     DWORD GrantedAccess;
     FSP_FILE_NODE *FileNode;
 
-    Result = FspCreateCheck(FileSystem, Request, TRUE, &GrantedAccess);
+    if (FspIsRootDirectory((PWSTR)Request->Buffer))
+        return STATUS_ACCESS_DENIED;
+
+    Result = FspFileSystemPreCreateCheck(FileSystem, Request, TRUE, &GrantedAccess);
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
@@ -51,10 +309,7 @@ static NTSTATUS FspFileSystemOpCreate_FileCreate(FSP_FILE_SYSTEM *FileSystem,
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-    memset(&FileNode->Flags, 0, sizeof FileNode->Flags);
+    FspFileSystemPostCreateCheck(FileSystem, Request, GrantedAccess, FileNode);
-    memset(&FileNode->ShareAccess, 0, sizeof FileNode->ShareAccess);
-
-    FspShareCheck(FileSystem, GrantedAccess, Request->Req.Create.ShareAccess, FileNode);
 
     return FspFileSystemSendCreateResponse(FileSystem, Request,
         FILE_CREATED, FileNode, GrantedAccess);
@@ -67,8 +322,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOpen(FSP_FILE_SYSTEM *FileSystem,
     DWORD GrantedAccess;
     FSP_FILE_NODE *FileNode;
 
-    Result = FspAccessCheck(FileSystem, Request, FALSE, TRUE,
+    Result = FspFileSystemPreOpenCheck(FileSystem, Request, TRUE, &GrantedAccess);
-        Request->Req.Create.DesiredAccess, &GrantedAccess);
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
@@ -76,7 +330,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOpen(FSP_FILE_SYSTEM *FileSystem,
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-    Result = FspShareCheck(FileSystem, GrantedAccess, Request->Req.Create.ShareAccess, FileNode);
+    Result = FspFileSystemPostOpenCheck(FileSystem, Request, GrantedAccess, FileNode);
     if (!NT_SUCCESS(Result))
     {
         if (0 != FileSystem->Interface->Close)
@@ -96,8 +350,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOpenIf(FSP_FILE_SYSTEM *FileSystem,
     FSP_FILE_NODE *FileNode;
     BOOLEAN Create = FALSE;
 
-    Result = FspAccessCheck(FileSystem, Request, FALSE, TRUE,
+    Result = FspFileSystemPreOpenCheck(FileSystem, Request, TRUE, &GrantedAccess);
-        Request->Req.Create.DesiredAccess, &GrantedAccess);
     if (!NT_SUCCESS(Result))
     {
         if (STATUS_OBJECT_NAME_NOT_FOUND != Result)
@@ -114,6 +367,16 @@ static NTSTATUS FspFileSystemOpCreate_FileOpenIf(FSP_FILE_SYSTEM *FileSystem,
                 return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
             Create = TRUE;
         }
+        else
+        {
+            Result = FspFileSystemPostOpenCheck(FileSystem, Request, GrantedAccess, FileNode);
+            if (!NT_SUCCESS(Result))
+            {
+                if (0 != FileSystem->Interface->Close)
+                    FileSystem->Interface->Close(FileSystem, Request, FileNode);
+                return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
+            }
+        }
     }
 
     if (Create)
@@ -121,7 +384,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOpenIf(FSP_FILE_SYSTEM *FileSystem,
         if (FspIsRootDirectory((PWSTR)Request->Buffer))
             return STATUS_ACCESS_DENIED;
 
-        Result = FspCreateCheck(FileSystem, Request, FALSE, &GrantedAccess);
+        Result = FspFileSystemPreCreateCheck(FileSystem, Request, FALSE, &GrantedAccess);
         if (!NT_SUCCESS(Result))
             return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
@@ -129,16 +392,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOpenIf(FSP_FILE_SYSTEM *FileSystem,
         if (!NT_SUCCESS(Result))
             return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-        memset(&FileNode->Flags, 0, sizeof FileNode->Flags);
+        FspFileSystemPostCreateCheck(FileSystem, Request, GrantedAccess, FileNode);
-        memset(&FileNode->ShareAccess, 0, sizeof FileNode->ShareAccess);
-    }
-
-    Result = FspShareCheck(FileSystem, GrantedAccess, Request->Req.Create.ShareAccess, FileNode);
-    if (!NT_SUCCESS(Result))
-    {
-        if (0 != FileSystem->Interface->Close)
-            FileSystem->Interface->Close(FileSystem, Request, FileNode);
-        return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
     }
 
     return FspFileSystemSendCreateResponse(FileSystem, Request,
@@ -146,31 +400,25 @@ static NTSTATUS FspFileSystemOpCreate_FileOpenIf(FSP_FILE_SYSTEM *FileSystem,
 }
 
 static NTSTATUS FspFileSystemOpCreate_FileOverwrite(FSP_FILE_SYSTEM *FileSystem,
-    FSP_FSCTL_TRANSACT_REQ *Request, BOOLEAN Supersede)
+    FSP_FSCTL_TRANSACT_REQ *Request)
 {
-    if (FspIsRootDirectory((PWSTR)Request->Buffer))
-        return STATUS_ACCESS_DENIED;
-
     NTSTATUS Result;
     DWORD GrantedAccess;
     FSP_FILE_NODE *FileNode;
+    BOOLEAN Supersede = FILE_SUPERSEDE == ((Request->Req.Create.CreateOptions >> 24) & 0xff);
 
-    Result = FspAccessCheck(FileSystem, Request, FALSE, TRUE,
+    if (FspIsRootDirectory((PWSTR)Request->Buffer))
-        Request->Req.Create.DesiredAccess | (Supersede ? DELETE : FILE_WRITE_DATA),
+        return STATUS_ACCESS_DENIED;
-        &GrantedAccess);
+
+    Result = FspFileSystemPreOverwriteCheck(FileSystem, Request, TRUE, &GrantedAccess);
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-    if (0 == (Request->Req.Create.DesiredAccess & MAXIMUM_ALLOWED))
-        GrantedAccess &= Supersede ?
-            (~DELETE | (Request->Req.Create.DesiredAccess & DELETE)) :
-            (~FILE_WRITE_DATA | (Request->Req.Create.DesiredAccess & FILE_WRITE_DATA));
-
     Result = FileSystem->Interface->Open(FileSystem, Request, &FileNode);
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-    Result = FspShareCheck(FileSystem, GrantedAccess, Request->Req.Create.ShareAccess, FileNode);
+    Result = FspFileSystemPostOverwriteCheck(FileSystem, Request, GrantedAccess, FileNode);
     if (!NT_SUCCESS(Result))
     {
         if (0 != FileSystem->Interface->Close)
@@ -193,28 +441,21 @@ static NTSTATUS FspFileSystemOpCreate_FileOverwrite(FSP_FILE_SYSTEM *FileSystem,
 static NTSTATUS FspFileSystemOpCreate_FileOverwriteIf(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request)
 {
-    if (FspIsRootDirectory((PWSTR)Request->Buffer))
-        return STATUS_ACCESS_DENIED;
-
     NTSTATUS Result;
     DWORD GrantedAccess;
     FSP_FILE_NODE *FileNode;
     BOOLEAN Create = FALSE;
 
-    Result = FspAccessCheck(FileSystem, Request, FALSE, TRUE,
+    if (FspIsRootDirectory((PWSTR)Request->Buffer))
-        Request->Req.Create.DesiredAccess | FILE_WRITE_DATA,
+        return STATUS_ACCESS_DENIED;
-        &GrantedAccess);
+
+    Result = FspFileSystemPreOverwriteCheck(FileSystem, Request, TRUE, &GrantedAccess);
     if (!NT_SUCCESS(Result))
     {
         if (STATUS_OBJECT_NAME_NOT_FOUND != Result)
             return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
         Create = TRUE;
     }
-    else
-    {
-        if (0 == (Request->Req.Create.DesiredAccess & MAXIMUM_ALLOWED))
-            GrantedAccess &= ~FILE_WRITE_DATA | (Request->Req.Create.DesiredAccess & FILE_WRITE_DATA);
-    }
 
     if (!Create)
     {
@@ -225,11 +466,29 @@ static NTSTATUS FspFileSystemOpCreate_FileOverwriteIf(FSP_FILE_SYSTEM *FileSyste
                 return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
             Create = TRUE;
         }
+        else
+        {
+            Result = FspFileSystemPostOverwriteCheck(FileSystem, Request, GrantedAccess, FileNode);
+            if (!NT_SUCCESS(Result))
+            {
+                if (0 != FileSystem->Interface->Close)
+                    FileSystem->Interface->Close(FileSystem, Request, FileNode);
+                return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
+            }
+
+            Result = FileSystem->Interface->Overwrite(FileSystem, Request, FALSE, FileNode);
+            if (!NT_SUCCESS(Result))
+            {
+                if (0 != FileSystem->Interface->Close)
+                    FileSystem->Interface->Close(FileSystem, Request, FileNode);
+                return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
+            }
+        }
     }
 
     if (Create)
     {
-        Result = FspCreateCheck(FileSystem, Request, FALSE, &GrantedAccess);
+        Result = FspFileSystemPreCreateCheck(FileSystem, Request, FALSE, &GrantedAccess);
         if (!NT_SUCCESS(Result))
             return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
@@ -237,27 +496,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOverwriteIf(FSP_FILE_SYSTEM *FileSyste
         if (!NT_SUCCESS(Result))
             return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-        memset(&FileNode->Flags, 0, sizeof FileNode->Flags);
+        FspFileSystemPostCreateCheck(FileSystem, Request, GrantedAccess, FileNode);
-        memset(&FileNode->ShareAccess, 0, sizeof FileNode->ShareAccess);
-    }
-
-    Result = FspShareCheck(FileSystem, GrantedAccess, Request->Req.Create.ShareAccess, FileNode);
-    if (!NT_SUCCESS(Result))
-    {
-        if (0 != FileSystem->Interface->Close)
-            FileSystem->Interface->Close(FileSystem, Request, FileNode);
-        return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
-    }
-
-    if (!Create)
-    {
-        Result = FileSystem->Interface->Overwrite(FileSystem, Request, FALSE, FileNode);
-        if (!NT_SUCCESS(Result))
-        {
-            if (0 != FileSystem->Interface->Close)
-                FileSystem->Interface->Close(FileSystem, Request, FileNode);
-            return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
-        }
     }
 
     return FspFileSystemSendCreateResponse(FileSystem, Request,
@@ -267,15 +506,15 @@ static NTSTATUS FspFileSystemOpCreate_FileOverwriteIf(FSP_FILE_SYSTEM *FileSyste
 static NTSTATUS FspFileSystemOpCreate_FileOpenTargetDirectory(FSP_FILE_SYSTEM *FileSystem,
     FSP_FSCTL_TRANSACT_REQ *Request)
 {
-    if (FspIsRootDirectory((PWSTR)Request->Buffer))
-        return STATUS_ACCESS_DENIED;
-
     NTSTATUS Result;
     PWSTR Parent, Suffix;
     DWORD GrantedAccess;
     FSP_FILE_NODE *FileNode;
     UINT_PTR Information;
 
+    if (FspIsRootDirectory((PWSTR)Request->Buffer))
+        return STATUS_ACCESS_DENIED;
+
     Result = FspAccessCheck(FileSystem, Request, TRUE, TRUE,
         Request->Req.Create.DesiredAccess, &GrantedAccess);
     if (!NT_SUCCESS(Result))
@@ -287,7 +526,7 @@ static NTSTATUS FspFileSystemOpCreate_FileOpenTargetDirectory(FSP_FILE_SYSTEM *F
     if (!NT_SUCCESS(Result))
         return FspFileSystemSendResponseWithStatus(FileSystem, Request, Result);
 
-    Result = FspShareCheck(FileSystem, GrantedAccess, Request->Req.Create.ShareAccess, FileNode);
+    Result = FspFileSystemPostOpenCheck(FileSystem, Request, GrantedAccess, FileNode);
     if (!NT_SUCCESS(Result))
     {
         if (0 != FileSystem->Interface->Close)
@@ -326,9 +565,9 @@ FSP_API NTSTATUS FspFileSystemOpCreate(FSP_FILE_SYSTEM *FileSystem,
     case FILE_OPEN_IF:
         return FspFileSystemOpCreate_FileOpenIf(FileSystem, Request);
     case FILE_OVERWRITE:
-        return FspFileSystemOpCreate_FileOverwrite(FileSystem, Request, FALSE);
+        return FspFileSystemOpCreate_FileOverwrite(FileSystem, Request);
     case FILE_SUPERSEDE:
-        return FspFileSystemOpCreate_FileOverwrite(FileSystem, Request, TRUE);
+        return FspFileSystemOpCreate_FileOverwrite(FileSystem, Request);
     case FILE_OVERWRITE_IF:
         return FspFileSystemOpCreate_FileOverwriteIf(FileSystem, Request);
     default: