内存映射文件

内存映射文件 (windows许多方法用此来在进程间传送数据）
1.CreateFile
2.CreateFileMapping //对含有SEC_LARGE_PAGES标志时用户必须具有启用内存锁定页面用户权限，否则会失败
3.MapViewOfFile
4. //FlushViewOfFile //确保所做的修改已经被写入到磁盘中，如果最初是FILE_MAP_COPY,将修改页交换文件中的文件数据副本，如果是这样的话ummapviewoffile后数据丢失。可以再做个PAGE_READWRITE视图，再MoveMemory从前一视图拷到这个视图。
5.UnmapViewOfFile
6.CloseHandle(hMap);CloseHandle(hFile); //先后顺序无关，MapViewOfFile副作用是增加hFile引用计数。

对多个进程共享同一个文件映射对象来说，所有进程使用的文件映射对象的名称必须完全相同。

CreateFileMapping传入INVALID_HANDLE_VALUE时映射页交换文件，不再映射磁盘文件。

#include <Windows.h>#include <string>#include <iostream>using namespace std;bool FileReverse(const wchar_t* pcFileName){BOOL bIsUnicode = false;HANDLE hFile = CreateFileW(pcFileName,GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);if( hFile == INVALID_HANDLE_VALUE )//here must check, because createfilemapping can accept INVALID_HANDLE_VALUE, and different map view {cout<<"CreateFileW fail"<<endl;return false;}DWORD dwFileSize = GetFileSize(hFile,NULL);HANDLE hMap = CreateFileMappingW(hFile,NULL,PAGE_READWRITE,0,dwFileSize*sizeof(wchar_t),NULL);if( hMap == NULL ){cout<<"CreateFileMappingW fail"<<endl;CloseHandle(hFile);return false;}PVOID pvFile = MapViewOfFile(hMap,FILE_MAP_WRITE,0,0,0);if( pvFile == NULL ){cout<<"MapViewOfFile fail"<<endl;CloseHandle(hMap);CloseHandle(hFile);return false;}int iUnicodeTestFlag = -1;bIsUnicode = IsTextUnicode(pvFile,dwFileSize,&iUnicodeTestFlag);if(!bIsUnicode){char *pchar = (char*)pvFile;pchar[dwFileSize/sizeof(char)] = '\0';_strrev(pchar);pchar = strstr(pchar,"\n\r");//find first \r\nwhile( pchar != NULL ){*pchar++ = '\r';*pchar++ = '\n';pchar = strstr(pchar,"\n\r");}}else{wchar_t *pwchar = (wchar_t*)pvFile;pwchar[dwFileSize/sizeof(wchar_t)] = L'\0';if((iUnicodeTestFlag & IS_TEXT_UNICODE_SIGNATURE) != 0){pwchar++;}_wcsrev(pwchar);pwchar = wcsstr(pwchar,L"\n\r");//find first \r\nwhile( pwchar != NULL ){*pwchar++ = L'\r';*pwchar++ = L'\n';pwchar = wcsstr(pwchar,L"\n\r");}}UnmapViewOfFile(pvFile);CloseHandle(hMap);//delete manuly append '\0'SetFilePointer(hFile,dwFileSize,NULL,FILE_BEGIN);SetEndOfFile(hFile);CloseHandle(hFile);return true;}void wmain(){FileReverse(L"testu.txt");}