c/string/wide/wcsncat

@1@ Appends at most wide characters from the wide string pointed to by, stopping if the null terminator is copied, to the end of the character string pointed to by. The wide character replaces the null terminator at the end of. The null terminator is always appended in the end (so the maximum number of wide characters the function may write is ). @@ The behavior is undefined if the destination array is not large enough for the contents of both and  and the terminating null wide character. @@ The behavior is undefined if the strings overlap. @2@ Same as, except that this function may clobber the remainder of the destination array (from the last wide character written to ) and that the following errors are detected at runtime and call the currently installed constraint handler function:
 * or is a null pointer
 * or is zero or greater than
 * there is no null wide character in the first wide characters of
 * truncation would occur: or the length of, whichever is less, exceeds the space available between the null terminator of  and.
 * overlap would occur between the source and the destination strings

Return value
@1@ returns a copy of @2@ returns zero on success, returns non-zero on error. Also, on error, writes to  (unless  is a null pointer or  is zero or greater than ).