#include "stdafx.h"

#include <windows.h>

#include <iostream>

using namespace std;

#define PAGE_SIZE 0x1000

void Sub_1(); //ReadFile 异步操作

void Sub_2(); //ReadFileEx

DWORD WINAPI Sub_1ThreadProcedure(LPVOID ParameterData);

DWORD WINAPI Sub_2ThreadProcedure(LPVOID ParameterData);

OVERLAPPED __Overlapped = { 0 };

char __BufferData[4] = {0};

int main()

{

Sub_1();

//Sub_2();

}

void Sub_1()

{

BOOL IsOk = FALSE;

DWORD ReturnLength = 0;

HANDLE FileHandle = CreateFile(L"ReadMe.txt", GENERIC_ALL, FILE_SHARE_READ | FILE_SHARE_WRITE,

NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL);//FILE_FLAG_OVERLAPPED很重要在异步

//有FILE_FLAG_OVERLAPPED系统就已经默认OverLapped了如果要同步必须删除

if (FileHandle == INVALID_HANDLE_VALUE)

{

int LastError = GetLastError();

goto Exit;

}

__Overlapped.hEvent = CreateEvent(NULL, FALSE, FALSE, NULL); //绝对要创建 IRP那里看

if (__BufferData == NULL)

{

goto Exit;

}

IsOk = ReadFile(FileHandle, __BufferData, 4, &ReturnLength, &__Overlapped); //这里是通知IO要进行异步__Overlapped

//接下来返回到线程，所以有Wait那一步，线程才会去执行 线程和当前进程无关

if (IsOk == FALSE)

{

int LastError = GetLastError();

if (LastError == ERROR_IO_PENDING)

{

printf("ERROR_IO_PENDING\r\n");

}

}

HANDLE ThreadHandle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)Sub_1ThreadProcedure,

(LPVOID)FileHandle, 0, NULL);

WaitForSingleObject(ThreadHandle, INFINITE);

Exit:

if (FileHandle != NULL)

{

CloseHandle(FileHandle);

FileHandle = NULL;

}

printf("\r\n");

return;

}

DWORD WINAPI Sub_1ThreadProcedure(LPVOID ParameterData)

{

HANDLE FileHandle = (HANDLE)ParameterData;

BOOL IsOk = FALSE;

DWORD ReturnLength = 0;

while (1)

{

IsOk = WaitForSingleObject(__Overlapped.hEvent, INFINITE);

IsOk -= WAIT_OBJECT_0;

if (IsOk == 0)

{

IsOk = GetOverlappedResult(FileHandle, &__Overlapped, &ReturnLength, INFINITE);//ReturnLength读了多少字节

if (IsOk==TRUE)

{

int i = 0;

for (i = 0; i < ReturnLength; i++)

{

printf("%c", __BufferData[i]);

}

__Overlapped.Offset += ReturnLength;//这里是每次读写的起始位置，所以要加下去

ReadFile(FileHandle, &__BufferData, 4, &ReturnLength, &__Overlapped);

}

else

{

//数据完毕

break;

}

}

else

{

return 0;

}

}

return 0;

}

void Sub_2()

{

BOOL IsOk = FALSE;

HANDLE FileHandle = CreateFile(L"ReadMe.txt", GENERIC_ALL, FILE_SHARE_READ | FILE_SHARE_WRITE,

NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED, NULL);

if (FileHandle == INVALID_HANDLE_VALUE)

{

int LastError = GetLastError();

goto Exit;

}

//__Overlapped.hEvent = CreateEvent(NULL, FALSE, FALSE, NULL); //绝对不能提供该事件

HANDLE ThreadHandle = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)Sub_2ThreadProcedure,

(LPVOID)FileHandle, 0, NULL);

if (__BufferData == NULL)

{

goto Exit;

}

IsOk = ReadFileEx(FileHandle, __BufferData, 4, &__Overlapped, NULL);

if (IsOk == FALSE)

{

int LastError = GetLastError();

if (LastError == ERROR_IO_PENDING)

{

//成功

}

}

WaitForSingleObject(ThreadHandle, INFINITE);

Exit:

if (FileHandle != NULL)

{

CloseHandle(FileHandle);

FileHandle = NULL;

}

printf("\r\n");

return;

}

DWORD WINAPI Sub_2ThreadProcedure(LPVOID ParameterData)

{

HANDLE FileHandle = (HANDLE)ParameterData;

DWORD ReturnLength = 0;

BOOL IsOk = FALSE;

while (1)

{

/*如果函数调用返回FALSE则可以用GetLastError来得到错误，如果返回成功则可以通过

lpNumberOfBytesTransferred参数来确定当前有多少数据已经被读或写。lpOverlapped

参数必须与调用ReadFile或WriteFile时使用同一个数据区。最后一个参数bWait表明是

否等待异步操作结束时才返回，如果设置为TRUE就可以等待文件读写完成时返回，

否则就会马上返回，利用这个特点可以利用它来等待异步文件操作的结束

（就如同等待事件变为有信号状态一样起到相同的作用）。

*/

IsOk = GetOverlappedResult(FileHandle, &__Overlapped, &ReturnLength, TRUE);

//IsOk = WaitForSingleObject(__Overlapped.hEvent, INFINITE); //?? 绝对不能这样做

if (IsOk == TRUE)

{

int i = 0;

for (i = 0; i < ReturnLength; i++)

{

printf("%c", __BufferData[i]);

}

__Overlapped.Offset += ReturnLength;

ReadFileEx(FileHandle, &__BufferData, 4, &__Overlapped, NULL);

}

else

{

return 0;

}

}

return 0;

}