bson_strndup()
Synopsis
char *
bson_strndup (const char *str,
              size_t      n_bytes);Parameters
| str | A string to copy. | 
| n_bytes | A size_t. | 
Description
Allocates a new string and copies up to n_bytes from str into it. A trailing \0 is always set.
Returns
A newly allocated string that should be freed with bson_free().