在windows下通过代码弹出U盘

 #include <windows.h>
#include <dbt.h>
#include <stdio.h>
#include <math.h>


   #define LOCK_TIMEOUT        10000       // 10 Seconds
   #define LOCK_RETRIES        20
/***************
Function： UninstallUsb
Description： 根据盘符将usb设备弹出
Parameters：
discId 要弹出的盘符
Returns：
-1 失败
0 成功
***************/
static int UninstallUsb(char *discId)
{
DWORD accessMode = GENERIC_WRITE | GENERIC_READ;
DWORD shareMode = FILE_SHARE_READ | FILE_SHARE_WRITE;
HANDLE hDevice;
long bResult = 0;
DWORD retu = 0;
DWORD dwError;
DWORD dwBytesReturned;
DWORD dwSleepAmount;
int nTryCount;
char szDriv[10];


if(discId == NULL){
return 0;
}
dwSleepAmount = LOCK_TIMEOUT/LOCK_RETRIES;
sprintf(szDriv,"\\\\.\\%s:",discId);
hDevice = CreateFile(szDriv,accessMode,shareMode,NULL,OPEN_EXISTING,0,NULL);
if(hDevice == INVALID_HANDLE_VALUE){
printf("uninstallusb createfile failed error:%d\n",GetLastError());
return -1;
}
#if 0
//此循环是用于锁定要弹出的U盘设备，如果U盘在使用，则循环等待
// Do this in a loop until a timeout period has expired
for(nTryCount = 0;nTryCount < LOCK_RETRIES;nTryCount++){
if(DeviceIoControl(hDevice,FSCTL_LOCK_VOLUME,NULL,0,NULL,0,&dwBytesReturned,NULL)){
break;
}
}
//卸载U盘卷，不论是否在使用
dwBytesReturned = 0;
if(!DeviceIoControl(hDevice,FSCTL_DISMOUNT_VOLUME,NULL,0,NULL,0,&dwBytesReturned,NULL)){
printf("deviceIoConrol FSCTL_DISMOUNT_VOLUME failed\n");
}
#endif
dwBytesReturned = 0;
PREVENT_MEDIA_REMOVAL PMRBuffer;
PMRBuffer.PreventMediaRemoval = FALSE;
if(!DeviceIoControl(hDevice,IOCTL_STORAGE_MEDIA_REMOVAL,&PMRBuffer,sizeof(PREVENT_MEDIA_REMOVAL),NULL,0,&dwBytesReturned,NULL)){
printf("DeviceIoControl IOCTL_STORAGE_MEDIA_REMOVAL failed:%d\n",GetLastError());
}
bResult = DeviceIoControl(hDevice,IOCTL_STORAGE_EJECT_MEDIA,NULL,0,NULL,0,&retu,NULL);
if(!bResult){
CloseHandle(hDevice);
printf("uninstallusb DeviceIoControl failed error:%d\n",GetLastError());
return -1;
}
CloseHandle(hDevice);
return 0;
}

int main()
{
    UninstallUsb("H");
    return 0;
}