Windows Kernel-Mode Safe String Library
One of the major problems in software security is related to the vulnerability of working with strings. To provide greater security, Windows provides a safe string library.
Safe string library routines are prefixed with the letters "Rtl"; for a list of all safe string library routines for the kernel, see Safe String Functions for Unicode and ANSI Characters and Safe String Functions for UNICODE_STRING Structures.
For more information about using safe strings, see Using Safe String Functions.
Note that there is also a separate run-time library for general C programming in the kernel that has string functionality as well. For more information about the run-time library (RTL), see Windows Kernel-Mode Run-Time Library. Note that even though both libraries are prefixed with "Rtl" they are not the same library.