关于RtlInitUnicodeString感想

2021-11-24 02:06:00

`01`	`VOID` `RtlInitUnicodeString (OUT PUNICODE_STRING DestinationString,IN` `PCWSTR` `SourceString OPTIONAL)`

02 {

`03`	`SIZE_T` `Length;`

`04`	`DestinationString->MaximumLength = 0;`

`05`	`DestinationString->Length = 0;`

`06`	`DestinationString->Buffer = (PWSTR)SourceString;`

`07`	`if` `(ARGUMENT_PRESENT(SourceString))`

08 {

`09`	`Length = wcslen(SourceString) *` `sizeof(WCHAR);`

`10`	`ASSERT(Length < MAX_USTRING);`

`11`	`if(Length >= MAX_USTRING)`

12 {

`13`	`Length = MAX_USTRING -` `sizeof(UNICODE_NULL);`

14 }

`15`	`DestinationString->Length = (USHORT)Length;`

`16`	`DestinationString->MaximumLength = (USHORT)(Length +` `sizeof(UNICODE_NULL));`

17 }

18 return;

19 }

20

`21`	`NTSTATUS RtlInitUnicodeStringEx ( OUT PUNICODE_STRING DestinationString,IN` `PCWSTR` `SourceString OPTIONAL)`

22 {

`23`	`SIZE_T` `Length;`

`24`	`DestinationString->Length = 0;`

`25`	`DestinationString->MaximumLength = 0;`

`26`	`DestinationString->Buffer = (PWSTR)SourceString;`

`27`	`if` `(ARGUMENT_PRESENT(SourceString))`

28 {

`29`	`Length = wcslen(SourceString);`

`30`	`// We are actually limited to 32765 characters since we want to store a meaningful MaximumLength also.`

`31`	`if` `(Length > (UNICODE_STRING_MAX_CHARS - 1))`

32 {

`33`	`return` `STATUS_NAME_TOO_LONG;`

34 }

`35`	`Length *=` `sizeof(WCHAR);`

`36`	`DestinationString->Length = (USHORT)Length;`

`37`	`DestinationString->MaximumLength = (USHORT)(Length +` `sizeof(WCHAR));`

38 }

`39`	`return` `STATUS_SUCCESS;`

40 }

从以上代码可见，这2个函数会将传入的字符串指针直接赋值给结构体，这样的话，如果传入的是栈字符串，那么UNICODE_STIRNG只能在当前域内使用，不能存储到其他生命周期更长的地方，否则栈恢复以后读取到不正确的数据，
然而传入一个全局字符串是可以的，例如：

UNICODE_STRING str1;
void func()
{
WCHAR buf[]=L"lich";
RtlInitUnicodeString(&str1,buf);
}
这是错误写法

https://www.0xaa55.com/forum.php?mod=viewthread&tid=1371&extra=page%3D6

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