应用程序访问驱动的问题

e3e4shine

应用程序访问驱动的问题 [复制链接]

大家好,请问SetProcPermissions 和MapPtrToProcess这两个函数是干什么的,是不是SetProcPermissions 和MapPtrToProcessr 的作用是一样的呢?

hjwahjl

SetProcPermissions():

This function sets the internal permissions bitmask for the current thread, thereby enabling access to the address space of another process.

MapPtrToProcess();

The handle for hProc is obtained using GetCurrentProcess or GetCallerProcess.

Note that OEM* functions typically do not call this function. This kernel function is primarily provided for use by device drivers; however, any application can call this function.

If the pointer is already mapped, MapPtrToProcess returns the original pointer if the application calling the function has the access necessary to dereference that pointer; otherwise, NULL is returned. If the pointer is unmapped, MapPtrToProcess first maps the pointer and then returns the mapped pointer, if the application calling the function can access it; otherwise, NULL is returned. This function should be called to map pointers that are passed to a protected server library where the pointer is not a parameter directly, but it is, rather, obtained from a structure and must be adjusted for the address space.

For example, to pass the pointer pPointer to another process, first make the following call.

pPointer_retval = MapPtrToProcess(pPointer, GetCurrentProcess());
Then pPointer_retval can be passed within calls to the other process.

mhw1216

也不大懂!

lyzj3210

驱动程序和应用程序之间传递数据时何时调用MapPtrToProcess？
因为设备管理器负责加载驱动程序DLL，这意味着当应用程序调用驱动程序接口函数的时候，WINCE内核会将调用驱动程序接口函数的线程转移到设备管理器的进程空间然后执行具体的驱动程序代码，应用程序和设备管理器处于两个进程空间，这就造成设备管理器无法访问应用程序传递的指针（虚拟地址），所以当我们在应用程序中传递指针给流驱动程序接口函数时，WINCE内核从中作了一个地址映射，例如ReadFile、WriteFile、DeviceIoControl函数的参数凡是指针都经过了映射才传递给驱动程序，所以很多驱动程序开发者并不了解其中的奥秘就可以编程了。但是如果参数是一个指向一个结构体的指针，而结构体里包括一个或多个指针，那么WINCE内核并不负责映射，所以就需要开发者在驱动程序接口函数中调用API函数MapPtrToProcess来映射地址。例如：pPointer_retval = MapPtrToProcess(pPointer, GetCallerProcess());