《Windows驱动开发技术详解》部分代码请教
代码如下：[code=Assembly][/code]
NTSTATUS HelloDDKDispatchRoutin(IN PDEVICE_OBJECT pDevObj,
IN PIRP pIrp)
{
KdPrint(("Enter HelloDDKDispatchRoutin\n"));
PIO_STACK_LOCATION stack = IoGetCurrentIrpStackLocation(pIrp);
//建立一个字符串数组与IRP类型对应起来
static char* irpname[] =
{
"IRP_MJ_CREATE",
"IRP_MJ_CREATE_NAMED_PIPE",
"IRP_MJ_CLOSE",
"IRP_MJ_READ",
"IRP_MJ_WRITE",
"IRP_MJ_QUERY_INFORMATION",
"IRP_MJ_SET_INFORMATION",
"IRP_MJ_QUERY_EA",
"IRP_MJ_SET_EA",
"IRP_MJ_FLUSH_BUFFERS",
"IRP_MJ_QUERY_VOLUME_INFORMATION",
"IRP_MJ_SET_VOLUME_INFORMATION",
"IRP_MJ_DIRECTORY_CONTROL",
"IRP_MJ_FILE_SYSTEM_CONTROL",
"IRP_MJ_DEVICE_CONTROL",
"IRP_MJ_INTERNAL_DEVICE_CONTROL",
"IRP_MJ_SHUTDOWN",
"IRP_MJ_LOCK_CONTROL",
"IRP_MJ_CLEANUP",
"IRP_MJ_CREATE_MAILSLOT",
"IRP_MJ_QUERY_SECURITY",
"IRP_MJ_SET_SECURITY",
"IRP_MJ_POWER",
"IRP_MJ_SYSTEM_CONTROL",
"IRP_MJ_DEVICE_CHANGE",
"IRP_MJ_QUERY_QUOTA",
"IRP_MJ_SET_QUOTA",
"IRP_MJ_PNP",
};
UCHAR type = stack->MajorFunction;
if (type >= arraysize(irpname))//计算数组元素个数
KdPrint((" - Unknown IRP, major type %X\n", type));
else
KdPrint(("\t%s\n", irpname[type]));
//对一般IRP的简单操作，后面会介绍对IRP更复杂的操作
NTSTATUS status = STATUS_SUCCESS;
// 完成IRP
pIrp->IoStatus.Status = status;
pIrp->IoStatus.Information = 0;// bytes xfered
IoCompleteRequest( pIrp, IO_NO_INCREMENT );
KdPrint(("Leave HelloDDKDispatchRoutin\n"));
return status;
}
小弟对
UCHAR type = stack->MajorFunction;
if (type >= arraysize(irpname))//计算数组元素个数
KdPrint((" - Unknown IRP, major type %X\n", type));
else
KdPrint(("\t%s\n", irpname[type]));
这部分代码理解不清楚，不知道怎么会根据type就出来了KdPrint(("\t%s\n", irpname[type]));
谢谢
[解决办法]
type是UCHAR类型，在C里边当作1字节非负整数使用，因此可以作为数组下标。
[解决办法]
这个字符串数组和MajorFunction里的是一一对应的！！！！！！！
看下ntddk.h头文件就知道了！！！！！！！！！
[解决办法]
ntddk.h头文件中没有，要看wdm.h头文件中。
[解决办法]
stack->MajorFunction 返回IRP的主功能号，如IRP_MJ_CREATE。
事实上IRP_MJ_CREATE是一个宏嘛，定义为0x00，正好对应字符串数组的下标。你可以看wdm.h的定义，你会发现数组的IRP功能号和字符串都是一一对应的：
[code=C]
#define IRP_MJ_CREATE 0x00
#define IRP_MJ_CREATE_NAMED_PIPE 0x01
#define IRP_MJ_CLOSE 0x02
#define IRP_MJ_READ 0x03
#define IRP_MJ_WRITE 0x04
#define IRP_MJ_QUERY_INFORMATION 0x05
#define IRP_MJ_SET_INFORMATION 0x06
#define IRP_MJ_QUERY_EA 0x07
#define IRP_MJ_SET_EA 0x08
#define IRP_MJ_FLUSH_BUFFERS 0x09
#define IRP_MJ_QUERY_VOLUME_INFORMATION 0x0a
#define IRP_MJ_SET_VOLUME_INFORMATION 0x0b
#define IRP_MJ_DIRECTORY_CONTROL 0x0c
#define IRP_MJ_FILE_SYSTEM_CONTROL 0x0d
#define IRP_MJ_DEVICE_CONTROL 0x0e
#define IRP_MJ_INTERNAL_DEVICE_CONTROL 0x0f
#define IRP_MJ_SHUTDOWN 0x10
#define IRP_MJ_LOCK_CONTROL 0x11
#define IRP_MJ_CLEANUP 0x12
#define IRP_MJ_CREATE_MAILSLOT 0x13
#define IRP_MJ_QUERY_SECURITY 0x14
#define IRP_MJ_SET_SECURITY 0x15
#define IRP_MJ_POWER 0x16
#define IRP_MJ_SYSTEM_CONTROL 0x17
#define IRP_MJ_DEVICE_CHANGE 0x18
#define IRP_MJ_QUERY_QUOTA 0x19
#define IRP_MJ_SET_QUOTA 0x1a
#define IRP_MJ_PNP 0x1b
#define IRP_MJ_PNP_POWER IRP_MJ_PNP // Obsolete....
#define IRP_MJ_MAXIMUM_FUNCTION 0x1b
[/code]
