开发常识 | 彻底理清 CreateFile 读写权限与共享模式的关系

NTSTATUS IoCheckShareAccess(
  IN ACCESS_MASK DesiredAccess,
  IN ULONG DesiredShareAccess,
  IN OUT PFILE_OBJECT FileObject,
  IN OUT PSHARE_ACCESS ShareAccess,
  IN BOOLEAN Update
)
{
  PAGED_CODE();
  
  // 获取本次调用时，指定的 读/写/删除 访问权限标志
  FileObject->ReadAccess = (BOOLEAN) ((DesiredAccess & (FILE_EXECUTE | FILE_READ_DATA)) != 0);
  FileObject->WriteAccess = (BOOLEAN) ((DesiredAccess & (FILE_WRITE_DATA | FILE_APPEND_DATA)) != 0);
  FileObject->DeleteAccess = (BOOLEAN) ((DesiredAccess & DELETE) != 0);
  
  if (FileObject->ReadAccess || FileObject->WriteAccess || FileObject->DeleteAccess)
  {      
    // 获取本次调用时，指定的 读/写/删除 共享模式标志
    FileObject->SharedRead = (BOOLEAN) ((DesiredShareAccess & FILE_SHARE_READ) != 0);
    FileObject->SharedWrite = (BOOLEAN) ((DesiredShareAccess & FILE_SHARE_WRITE) != 0);
    FileObject->SharedDelete = (BOOLEAN) ((DesiredShareAccess & FILE_SHARE_DELETE) != 0);
  
    if (FileObject->Flags & FO_FILE_OBJECT_HAS_EXTENSION)
    {
      PIOP_FILE_OBJECT_EXTENSION  fileObjectExtension =(PIOP_FILE_OBJECT_EXTENSION)(FileObject + 1);
      if (fileObjectExtension->FileObjectExtensionFlags & FO_EXTENSION_IGNORE_SHARE_ACCESS_CHECK)
        return STATUS_SUCCESS;
    }
  
    ULONG ocount = ShareAccess->OpenCount;
  
    if ( // 本次调用时 DesiredAccess 包含了读/写/删除标志，并且
         // 在之前的调用中，DesiredShareAccess 缺少对应的读/写/删除标志（ShareXXX < ocount）
         (FileObject->ReadAccess && (ShareAccess->SharedRead < ocount))
      || (FileObject->WriteAccess && (ShareAccess->SharedWrite < ocount))
      || (FileObject->DeleteAccess && (ShareAccess->SharedDelete < ocount))
         // 之前的调用中 DesiredAccess 包含了读/写/删除标志，并且
         // 本次调用时 DesiredShareAccess 缺少对应读/写/删除标志 
      || ((ShareAccess->Readers != 0) && !FileObject->SharedRead)
      || ((ShareAccess->Writers != 0) && !FileObject->SharedWrite)
      || ((ShareAccess->Deleters != 0) && !FileObject->SharedDelete)
    )
    {
      return STATUS_SHARING_VIOLATION;
    }
    else if (Update)
    {
      ShareAccess->OpenCount++; // 每次权限检查通过后，打开计数 +1
      
      // 本次调用时 DesiredAccess 包含了读/写/删除标志，对应的计数 +1
      ShareAccess->Readers += FileObject->ReadAccess;
      ShareAccess->Writers += FileObject->WriteAccess;
      ShareAccess->Deleters += FileObject->DeleteAccess;
      
      // 本次调用时 DesiredShareAccess 包含了读/写/删除标志，对应的计数 +1
      ShareAccess->SharedRead += FileObject->SharedRead;
      ShareAccess->SharedWrite += FileObject->SharedWrite;
      ShareAccess->SharedDelete += FileObject->SharedDelete;
    }
  }
  return STATUS_SUCCESS;
}

using System;
using System.Collections.Generic;
using System.CommandLine;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CreateFile
{
    class Program
    {
        // ref https://learn.microsoft.com/en-us/dotnet/standard/commandline/define-commands
        static Command SetupCommandHandler()
        {
            var filePathOption = new Option<string>(name: "--path", getDefaultValue: () => "test.txt", description: "file path");
            filePathOption.AddAlias("-f");
            filePathOption.AddAlias("-p");

            var fileModeOption = new Option<string>(name: "--mode", getDefaultValue: () => "Open", description: "file mode")
                .FromAmong("CreateNew", "Create", "Open", "OpenOrCreate", "Truncate", "Append");
            fileModeOption.AddAlias("-m");

            var fileShareOption = new Option<string>("--share", "file share") { IsRequired = true }
                .FromAmong("None", "Read", "Write", "ReadWrite", "Delete", "Inheritable");
            fileShareOption.AddAlias("-s");

            var fileAccessOption = new Option<string>("--access", "file access") { IsRequired = true }
                .FromAmong("Read", "Write", "ReadWrite");
            fileAccessOption.AddAlias("-a");

            var autoQuitOption = new Option<bool>(name: "--autoquit", getDefaultValue: () => false, description: "auto quit");
            autoQuitOption.AddAlias("-q");

            var command = new RootCommand();
            command.Add(filePathOption);
            command.Add(fileModeOption);
            command.Add(fileShareOption);
            command.Add(fileAccessOption);
            command.Add(autoQuitOption);

            command.SetHandler((filePath, fileMode, fileShare, fileAccess, autoQuit) =>
            {
                OpenFileAndWait(filePath, fileMode, fileShare, fileAccess, autoQuit);
            }, filePathOption, fileModeOption, fileShareOption, fileAccessOption, autoQuitOption);

            return command;
        }

        static void Main(string[] args)
        {
            var command = SetupCommandHandler();
            command.Invoke(args);
        }

        static void OpenFileAndWait(string strFilePath, string strFileMode, string strFileShare, string strFileAccess, bool autoQuit)
        {
            FileStream stream = null;
            try
            {
                var fileMode = (FileMode)System.Enum.Parse(typeof(FileMode), strFileMode);
                var fileShare = (FileShare)System.Enum.Parse(typeof(FileShare), strFileShare);
                var fileAccess = (FileAccess)System.Enum.Parse(typeof(FileAccess), strFileAccess);

                System.Console.WriteLine(string.Format("[{0}] file:{1}, mode: {2}, share: {3}, access: {4}!"
                  , System.DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"), strFilePath, strFileMode, strFileShare, strFileAccess));

                stream = File.Open(strFilePath, fileMode, fileAccess, fileShare);
            }
            catch (Exception ex)
            {
                System.Console.WriteLine(string.Format("opening file [{0}] failed with {1}!", strFilePath, ex));
            }

            if (!autoQuit)
            {
                System.Console.WriteLine("press any key to continue...");
                System.Console.ReadKey();
            }

            if (stream != null)
            {
                stream.Dispose();
            }
        }
    }
}

:: read-readwrite-write-none.bat
CreateFileBatchCaller.bat %~n0%

:: CreateFileBatchCaller.bat
@echo off
cd /d %~dp0

setlocal enabledelayedexpansion

set AccessParams=%1%
set AccessParams=%AccessParams:read=Read%
set AccessParams=%AccessParams:write=Write%
set AccessParams=%AccessParams:none=None%

For /f "tokens=1-4 delims=_/. " %%i In ("%AccessParams%") do (
    set Access1=%%i
    set SharedAccess1=%%j
    set Access2=%%k
    set SharedAccess2=%%l
)

start CreateFile -f test.txt -a %Access1% -s %SharedAccess1%

:: will this success?
timeout /T 1
start CreateFile -f test.txt -a %Access2% -s %SharedAccess2%