Summary of Kernel-Mode Safe String Functions

Article
12/15/2021

The following table summarizes the safe string functions that are available to kernel-mode drivers, and it indicates the C/C++ language runtime library functions that they replace. If a function's name contains Cb, the function treats strings as byte-counted. If a function's name contains Cch, the function treats strings as character-counted.

Functions	Purpose	Replaces
RtlStringCbCat RtlStringCbCatEx RtlStringCchCat RtlStringCchCatEx RtlUnicodeStringCat RtlUnicodeStringCatEx RtlUnicodeStringCatString RtlUnicodeStringCatStringEx RtlUnicodeStringCbCatStringN RtlUnicodeStringCbCatStringNEx RtlUnicodeStringCchCatStringN RtlUnicodeStringCchCatStringNEx	Concatenate two strings.	strcat wcscat
RtlStringCbCatN RtlStringCbCatNEx RtlStringCchCatN RtlStringCchCatNEx RtlUnicodeStringCbCatN RtlUnicodeStringCbCatNEx RtlUnicodeStringCchCatN RtlUnicodeStringCchCatNEx	Concatenate two byte-counted strings, while limiting the size of the appended string.	strncat wcsncat
RtlStringCbCopy RtlStringCbCopyEx RtlStringCbCopyUnicodeString RtlStringCbCopyUnicodeStringEx RtlStringCchCopy RtlStringCchCopyEx RtlStringCchCopyUnicodeString RtlStringCchCopyUnicodeStringEx RtlUnicodeStringCopy RtlUnicodeStringCopyEx RtlUnicodeStringCopyString RtlUnicodeStringCopyStringEx	Copy a string into a buffer.	strcpy wcscpy
RtlStringCbCopyN RtlStringCbCopyNEx RtlStringCchCopyN RtlStringCchCopyNEx RtlUnicodeStringCbCopyN RtlUnicodeStringCbCopyNEx RtlUnicodeStringCchCopyN RtlUnicodeStringCchCopyNEx RtlUnicodeStringCbCopyStringN RtlUnicodeStringCbCopyStringNEx RtlUnicodeStringCchCopyStringN RtlUnicodeStringCchCopyStringNEx	Copy a string into a buffer, while limiting the size of the copied string.	strncpy wcsncpy
RtlStringCbLength RtlStringCchLength RtlUnalignedStringCbLength RtlUnalignedStringCchLength	Determine the length of a supplied string.	strlen wcslen
RtlStringCbPrintf RtlStringCbPrintfEx RtlStringCchPrintf RtlStringCchPrintfEx RtlUnicodeStringPrintf RtlUnicodeStringPrintfEx	Create a formatted text string that is based on a format string and a set of additional function arguments.	sprintf swprintf _snprintf _snwprintf
RtlStringCbVPrintf RtlStringCbVPrintfEx RtlStringCchVPrintf RtlStringCchVPrintfEx RtlUnicodeStringVPrintf RtlUnicodeStringVPrintfEx	Create a formatted text string that is based on a format string and one additional function argument.	vsprintf vswprintf _vsnprintf _vsnwprintf
RtlUnicodeStringInit RtlUnicodeStringInitEx RtlUnicodeStringValidate RtlUnicodeStringValidateEx	Initialize or validate a UNICODE_STRING structure.	None