关于内存映射文件的不解
以下是微软提供的两个进程通过映射文件访问的例子,我的不解是第二个进程调用UnmapViewOfFile(pBuf)的话,是不是第一个进程
MapViewOfFile的内存也被释放了。2.如果第一个进程UnmapViewOfFile(pBuf)了,内存映射文件的内容是不是清除了,是不是第二个进程就无法访问内存映射文件了或者访问到,但是获得内存内容为空了。
谢谢。小弟愚昧,请达人指教
第一个
#include <windows.h>
#include <stdio.h>
#include <conio.h>
#define BUF_SIZE 256
TCHAR szName[]=TEXT("MyFileMappingObject");
TCHAR szMsg[]=TEXT("Message from first process");
void main()
{
HANDLE hMapFile;
LPCTSTR pBuf;
hMapFile = CreateFileMapping(
INVALID_HANDLE_VALUE, // use paging file
NULL, // default security
PAGE_READWRITE, // read/write access
0, // max. object size
BUF_SIZE, // buffer size
szName); // name of mapping object
if (hMapFile == NULL || hMapFile == INVALID_HANDLE_VALUE)
{
printf("Could not create file mapping object (%d).\n",
GetLastError());
return;
}
pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object
FILE_MAP_ALL_ACCESS, // read/write permission
0,
0,
BUF_SIZE);
if (pBuf == NULL)
{
printf("Could not map view of file (%d).\n",
GetLastError());
return;
}
CopyMemory((PVOID)pBuf, szMsg, strlen(szMsg));
getch();
UnmapViewOfFile(pBuf);
CloseHandle(hMapFile);
}
/////////////////////////////////////////////
第二个
#include <windows.h>
#include <stdio.h>
#include <conio.h>
#include <windows.h>
#define BUF_SIZE 256
TCHAR szName[]=TEXT("MyFileMappingObject");
void main()
{
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)
{
printf("Could not open file mapping object (%d).\n",
GetLastError());
return;
}
pBuf = MapViewOfFile(hMapFile, // handle to mapping object
FILE_MAP_ALL_ACCESS, // read/write permission
0,
0,
BUF_SIZE);
if (pBuf == NULL)
{
printf("Could not map view of file (%d).\n",
GetLastError());
return;
}
MessageBox(NULL, pBuf, TEXT("Process2"), MB_OK);
UnmapViewOfFile(pBuf);
CloseHandle(hMapFile);
}