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RtlUnicodeStringCbCatN function (ntstrsafe.h)

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The RtlUnicodeStringCbCatN function concatenates two strings that are contained in UNICODE_STRING structures while limiting the size of the copied string.

Syntax

NTSTRSAFEDDI RtlUnicodeStringCbCatN(
  [in, out] PUNICODE_STRING  DestinationString,
  [in]      PCUNICODE_STRING SourceString,
  [in]      size_t           cbToAppend
);

Parameters

[in, out] DestinationString

A pointer to a UNICODE_STRING structure. This structure includes a buffer that, on input, contains a destination string to which the source string will be concatenated. On output, this buffer is the destination buffer that contains the entire resultant string. The source string is added to the end of the destination string. The maximum number of bytes in the structure's string buffer is NTSTRSAFE_UNICODE_STRING_MAX_CCH * sizeof(WCHAR).

[in] SourceString

A pointer to a UNICODE_STRING structure. This structure includes a buffer that contains the source string. This string will be added to the end of the destination string. The maximum number of bytes in the structure's string buffer is NTSTRSAFE_UNICODE_STRING_MAX_CCH * sizeof(WCHAR).

[in] cbToAppend

The maximum number of bytes to append to the string that the DestinationString parameter describes.

Return value

RtlUnicodeStringCbCatN returns one of the following NTSTATUS values.

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

RtlUnicodeStringCbCatN 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.
  • The cbToAppend parameter's value is greater than NTSTRSAFE_UNICODE_STRING_MAX_CCH * sizeof(WCHAR).
For information about how to test NTSTATUS values, see Using NTSTATUS Values.

Remarks

The RtlUnicodeStringCbCatN 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 value (that is, with zero).

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

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

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

Requirements

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

RtlUnicodeStringCbCatNEx

RtlUnicodeStringCchCatN

UNICODE_STRING