传递从用户模式可变长度结构来内核模式

Question

我正在写虚拟磁盘驱动器，并有我有这样的定义的结构：

typedef struct _MOUNT_NEW_QUERY { 
    PWCHAR imagePath; 
    WCHAR letter; 
    PCHAR key; 
} MOUNT_NEW_QUERY, *PMOUNT_NEW_QUERY; 

所以我有几分动态大小的结构。

我该如何将它从用户模式传递给我的驱动程序？

Answer 1

分配内存连续块，足以同时容纳你的结构和“重点”和“路径”的数据 - 这样的事情：

/* we add + 1 for terminating NULLs to make life easy */ 
size_t keyLen = (strlen(key) + 1); 
size_t imgLen = (wcslen(imagePath) + 1) * sizeof(WCHAR); 

PMOUNT_NEW_QUERY pMNQ = malloc(sizeof(MOUNT_NEW_QUERY) + keyLen + imgLen); 

if(pMNQ != NULL) 
{  
    /* make imagePath point to the allocated buffer immediately after 
    * the MOUNT_NEW_QUERY portion 
    */ 
    pMNQ->imagePath = (PWCHAR)((PBYTE)pMNQ + sizeof(MOUNT_NEW_QUERY)); 

    /* make the key point to the allocated buffer immediately after 
    * the imagePath portion (including a NULL WCHAR terminator) 
    */ 
    pMNQ->key = (PCHAR)((PBYTE)pMNQ + sizeof(MOUNT_NEW_QUERY) + imgLen); 

    /* populate the data here appropriately, typically with strcpy 
    * and wcscpy, and then send the IOCTL 
    */ 
    fun(pMNQ); 
} 

当你调用IOCTL您的驱动程序，通总计缓冲区的大小，而不仅仅是MOUNT_NEW_QUERY结构的大小。