RtlUnicodeStringCopyString function (ntstrsafe.h)

The RtlUnicodeStringCopyString function copies a string into a UNICODE_STRING structure.


NTSTRSAFEDDI RtlUnicodeStringCopyString(
  [out] PUNICODE_STRING  DestinationString,


[out] DestinationString

A pointer to a UNICODE_STRING structure that receives the copied string. The string that the pszSrc parameter points to (excluding the terminating null) is copied into the buffer that the DestinationString parameter's UNICODE_STRING structure points to. The maximum number of bytes in the string is NTSTRSAFE_UNICODE_STRING_MAX_CCH * sizeof(WCHAR).

[in] pszSrc

A pointer to a null-terminated string. This string will be copied into the buffer that the DestinationString parameter's UNICODE_STRING structure points to.

Return value

RtlUnicodeStringCopyString returns one of the following NTSTATUS values.

Return code Description
This success status means that source data was present and the string was copied without truncation.
This warning status means that the copy operation did not complete because of insufficient buffer space. The destination buffer contains a truncated, null-terminated version of the intended result.
This error status means that the function received an invalid input parameter. For more information, see the following list.

RtlUnicodeStringCopyString returns the STATUS_INVALID_PARAMETER value when one of the following occurs:

  • The contents of the UNICODE_STRING structure are invalid.
  • The destination buffer is already full.
  • A buffer pointer is NULL.
  • The destination buffer's length is zero, but a nonzero length source string is present.
For information about how to test NTSTATUS values, see Using NTSTATUS Values.


The RtlUnicodeStringCopyString function uses the destination buffer's size to ensure that the concatenation operation does not write past the end of the buffer. The function does not terminate the resultant string with a null character.

If the source and destination strings overlap, the behavior of the function is undefined.

The pszSrc and DestinationString pointers cannot be NULL. If you need to handle NULL pointer values, use the RtlUnicodeStringCopyStringEx function.

For more information about the safe string functions, see Using Safe String Functions.


Requirement Value
Minimum supported client Available in Windows XP with Service Pack 1 (SP1) and later versions of Windows.
Target Platform Desktop
Header ntstrsafe.h (include Ntstrsafe.h)
Library Ntstrsafe.lib
IRQL Any if strings being manipulated are always resident in memory, otherwise PASSIVE_LEVEL

See also