win7下使用共享内存方式CreateFileMapping返回GetLastError总是0x5的问题解决

在普通应用程序中使用共享内存方式创建内存共享对象时，CreateFileMapping函数总是返回句柄为NULL，通过GetLastError得到返回错误码 0x5， 问题解决：

使用Local 代替Global, 问题解决，下面是使用实例：

TCHAR szName[] = TEXT("Local\\MyFileMappingObject");

TCHAR szName[] = TEXT("Global\\MyFileMappingObject");

原来 Global\\ 保证创建的对象是全局的，对权限要求比较高，而使用local可以保证服务对象仅对当前用户中的进程和线程可见。这就是总是返回权限失败问题的原因。

附一个使用实例：

// testsharemem.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

#include <Windows.h>
#include <stdio.h>
#include <conio.h>
#include <tchar.h>

#define BUF_SIZE 256
TCHAR szName[] = TEXT("Local\\MyFileMappingObject");
TCHAR szMsg[] = TEXT("Message from first process.");

int p1();
int p2();

int _tmain(int argc, _TCHAR* argv[])
{
if (argc == 1)
{
p1();
}
else
{
p2();
}
return 0;
}

int p1()
{
HANDLE hMapFile;
LPCTSTR pBuf;

hMapFile = CreateFileMapping(
INVALID_HANDLE_VALUE, // use paging file
NULL, // default security
PAGE_READWRITE, // read/write access
0, // maximum object size (high-order DWORD)
BUF_SIZE, // maximum object size (low-order DWORD)
szName); // name of mapping object

if (hMapFile == NULL)
{
_tprintf(TEXT("P1: Could not create file mapping object (%d).\n"),
GetLastError());
return 1;
}
else
{
_tprintf(TEXT("P1: create file mapping object hMapFile= (0x%x).\n", hMapFile));
}
pBuf = (LPTSTR)MapViewOfFile(hMapFile, // handle to map object
FILE_MAP_ALL_ACCESS, // read/write permission
0,
0,
BUF_SIZE);

if (pBuf == NULL)
{
_tprintf(TEXT("P1: Could not map view of file (%d).\n"),
GetLastError());

CloseHandle(hMapFile);

return 1;
}

CopyMemory((PVOID)pBuf, szMsg, (_tcslen(szMsg) * sizeof(TCHAR)));
_getch();

UnmapViewOfFile(pBuf);

CloseHandle(hMapFile);

return 0;
}

int p2()
{
HANDLE hMapFile;
LPCTSTR pBuf;

hMapFile = OpenFileMapping(
FILE_MAP_ALL_ACCESS, // read/write access
FALSE, // do not inherit the name
szName); // name of mapping object

if (hMapFile == NULL)
{
_tprintf(TEXT("P2: Could not open file mapping object (%d).\n"),
GetLastError());
return 1;
}

pBuf = (LPTSTR)MapViewOfFile(hMapFile, // handle to map object
FILE_MAP_ALL_ACCESS, // read/write permission
0,
0,
BUF_SIZE);

if (pBuf == NULL)
{
_tprintf(TEXT("P2: Could not map view of file (%d).\n"),
GetLastError());

CloseHandle(hMapFile);

return 1;
}

MessageBox(NULL, pBuf, TEXT("Process2"), MB_OK);

UnmapViewOfFile(pBuf);

CloseHandle(hMapFile);

return 0;
}