ustrzncpy (3) - Linux Manuals
ustrzncpy: Copies a string into another one, specifying size. Allegro game programming library.
NAMEustrzncpy - Copies a string into another one, specifying size. Allegro game programming library.
char *ustrzncpy(char *dest, int size, const char *src, int n);
DESCRIPTIONThis function is like ustrzcpy() except that no more than `n' characters from `src' are copied into `dest'. If `src' is shorter than `n' characters, null characters are appended to `dest' as padding until `n' characters have been written. In any case, `dest' is guaranteed to be null-terminated.
Note that, even for empty strings, your destination string must have at least enough bytes to store the terminating null character of the string, and your parameter `size' must reflect this. Otherwise, the debug version of Allegro will abort at an assertion, and the release version of Allegro will overrun the destination buffer.