20、Windows API 进程间通信，邮槽(Mailslot)

通过mailslot进程间通信
**************************************/
/* 头文件 */
#include < windows.h >
#include < stdio.h >
/* 全局变量 */
HANDLE hSlot;
LPTSTR lpszSlotName = TEXT( " \\\\.\\mailslot\\sample_mailslot " );
LPTSTR Message = TEXT( " Message for mailslot in primary domain. " );

/* ************************************
* void main()
* 功能 进程间mailslot通信客户端
************************************* */
void main()
{
DWORD cbMessage, cMessage, cbRead;
BOOL fResult;
LPTSTR lpszBuffer;
TCHAR achID[ 80 ];
DWORD cAllMessages;
HANDLE hEvent;
OVERLAPPED ov;

cbMessage = cMessage = cbRead = 0 ;

hSlot = CreateMailslot(
lpszSlotName, // mailslot 名
0 , // 不限制消息大小
MAILSLOT_WAIT_FOREVER, // 无超时
(LPSECURITY_ATTRIBUTES) NULL);

if (hSlot == INVALID_HANDLE_VALUE)
{
printf( " CreateMailslot failed with %d\n " , GetLastError());
return ;
}
else printf( " Mailslot created successfully.\n " );

while ( 1 )
{
// 获取mailslot信息
fResult = GetMailslotInfo(hSlot, // mailslot 句柄
(LPDWORD) NULL, // 无最大消息限制
& cbMessage, // 下一条消息的大小
& cMessage, // 消息的数量
(LPDWORD) NULL); // 无时限

if ( ! fResult)
{
printf( " GetMailslotInfo failed with %d.\n " , GetLastError());
return ;
}

if (cbMessage == MAILSLOT_NO_MESSAGE)
{
// 没有消息，过一段时间再去读
Sleep( 20000 );
continue ;
}

cAllMessages = cMessage;

while (cMessage != 0 ) // 获取全部消息，有可能不只一条
{
// 提示信息
wsprintf((LPTSTR) achID,
" \nMessage #%d of %d\n " ,
cAllMessages - cMessage + 1 ,
cAllMessages);

// 分配空间
lpszBuffer = (LPTSTR) HeapAlloc(GetProcessHeap(),HEAP_ZERO_MEMORY,
lstrlen((LPTSTR) achID) * sizeof (TCHAR) + cbMessage);
if ( NULL == lpszBuffer )
{
return ;
}
// 读取消息
fResult = ReadFile(hSlot, // mailslot句柄
lpszBuffer, // 缓存
cbMessage, // 消息的长度
& cbRead, // 实际读取的长度
NULL);

if ( ! fResult)
{
printf( " ReadFile failed with %d.\n " , GetLastError());
GlobalFree((HGLOBAL) lpszBuffer);
return ;
}

// 处理信息，显示
lstrcat(lpszBuffer, (LPTSTR) achID);
printf( " Contents of the mailslot: %s\n " , lpszBuffer);

HeapFree(GetProcessHeap(), 0 ,lpszBuffer);
// 计算剩余的消息数
fResult = GetMailslotInfo(hSlot,
(LPDWORD) NULL,
& cbMessage,
& cMessage,
(LPDWORD) NULL);

if ( ! fResult)
{
printf( " GetMailslotInfo failed (%d)\n " , GetLastError());
return ;
}
}
}
return ;
}

通过mailslot进程间通信
**************************************/
/* 头文件 */
#include < windows.h >
#include < stdio.h >
/* 全局变量 */
HANDLE hSlot;
LPTSTR lpszSlotName = TEXT( " \\\\.\\mailslot\\sample_mailslot " ); // mailslot名
LPTSTR lpszMessage = TEXT( " Test Message for mailslot " ); // 通信的内容

/* ************************************
* void main()
* 功能 进程间mailslot通信客户端
************************************* */
void main()
{
BOOL fResult;
HANDLE hFile;
DWORD cbWritten;

DWORD cbMessage;
// 打开mailslot
hFile = CreateFile(lpszSlotName,
GENERIC_WRITE, // 可写
FILE_SHARE_READ,
(LPSECURITY_ATTRIBUTES) NULL,
OPEN_EXISTING, // 打开一个已经存在的mailslot，应该由服务端已经创建
FILE_ATTRIBUTE_NORMAL,
(HANDLE) NULL);

if (hFile == INVALID_HANDLE_VALUE)
{
printf( " CreateFile failed with %d.\n " , GetLastError());
return ;
}
// 向mailslot写入
fResult = WriteFile(hFile,
lpszMessage,
(DWORD) (lstrlen(lpszMessage) + 1 ) * sizeof (TCHAR),
& cbWritten,
(LPOVERLAPPED) NULL);

if ( ! fResult)
{
printf( " WriteFile failed with %d.\n " , GetLastError());
return ;
}
// 结束
printf( " Slot written to successfully.\n " );
CloseHandle(hFile);
return ;
}