The strncpy() function shall copy not more than n bytes (bytes
that follow a null byte are not copied) from the array pointed to by s2
to the array pointed to by s1. If copying takes place between objects
that overlap, the behavior is undefined.
If the array pointed to by s2 is a string that is shorter than n
bytes, null bytes shall be appended to the copy in the array pointed to by
s1, until n bytes in all are written.
Character movement is performed differently in different implementations. Thus,
overlapping moves may yield surprises.
If there is no null byte in the first n bytes of the array pointed to by
s2, the result is not null-terminated.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html