RtlStringCbCatNExA function (ntstrsafe.h)

The RtlStringCbCatNExW and RtlStringCbCatNExA functions concatenate two byte-counted strings while limiting the size of the appended string.

Syntax

NTSTRSAFEDDI RtlStringCbCatNExA(
  [in, out, optional] NTSTRSAFE_PSTR pszDest,
  [in]                size_t         cbDest,
  [in, optional]      STRSAFE_PCNZCH pszSrc,
                      size_t         cbToAppend,
  [out, optional]     NTSTRSAFE_PSTR *ppszDestEnd,
  [out, optional]     size_t         *pcbRemaining,
  [in]                DWORD          dwFlags
);

Parameters

[in, out, optional] pszDest

A pointer to a buffer which, on input, contains a null-terminated string to which pszSrc will be concatenated. On output, this is the destination buffer that contains the entire resultant string. The string at pszSrc, up to cbMaxAppend bytes, is added to the end of the string at pszDest, and terminated with a null character. The pszDest pointer can be NULL, but only if STRSAFE_IGNORE_NULLS is set in dwFlags.

[in] cbDest

The size of the destination buffer, in bytes. The buffer must be large enough to include both strings and the terminating null character.

For Unicode strings, the maximum number of bytes is NTSTRSAFE_MAX_CCH * sizeof(WCHAR)

For ANSI strings, the maximum number of bytes is NTSTRSAFE_MAX_CCH * sizeof(char)

If pszDest is NULL, cbDest must be zero.

[in, optional] pszSrc

A pointer to a null-terminated string. This string will be concatenated to the end of the string that is contained in the buffer at pszDest. The pszSrc pointer can be NULL, but only if STRSAFE_IGNORE_NULLS is set in dwFlags.

cbToAppend

The maximum number of bytes to append to pszDest.

[out, optional] ppszDestEnd

If the caller supplies a non-NULL address pointer, then after the concatenation operation completes, the function loads that address with a pointer to the destination buffer's resulting NULL string terminator.

[out, optional] pcbRemaining

If the caller supplies a non-NULL address pointer, the function loads the address with the number of unused bytes that are in the buffer pointed to by pszDest, including bytes used for the terminating null character.

[in] dwFlags

One or more flags and, optionally, a fill byte. The flags are defined as follows:

Return value

The function returns one of the NTSTATUS values that are listed in the following table. For information about how to test NTSTATUS values, see Using NTSTATUS Values.

Remarks

RtlStringCbCatNExW and RtlStringCbCatNExA should be used instead of the following functions:

• strncat
• wcsncat

The size, in bytes, of the destination buffer is provided to RtlStringCbCatNExW and RtlStringCbCatNExA to ensure that they do not write past the end of the buffer.

RtlStringCbCatNEx adds to the functionality of RtlStringCbCatN by returning a pointer to the end of the destination string as well as the number of bytes left unused in that string. Flags can be passed to the function for additional control.

Use RtlStringCbCatNExW to handle Unicode strings and RtlStringCbCatNExA to handle ANSI strings. The form you use depends on your data, as shown in the following table.

If pszSrc and pszDest point to overlapping strings, the behavior of the function is undefined.

Neither pszSrc nor pszDest can be NULL unless the STRSAFE_IGNORE_NULLS flag is set, in which case either or both can be NULL. If pszDest is NULL, pszSrc must either be NULL or point to an empty string.

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

Requirements

See also

• RtlStringCbCatEx
• RtlStringCbCatN
• RtlStringCchCatNEx