Yes, they do!
In other words, your wrappers are exactly equivalent to those built-ins; except that they are in C and thus vastly more efficient; and well tried and tested thus more likely to be correct.
As for that; there is a huge difference between quoting the manual and understanding what it says.
The *ONLY REASON* print and readline are said to "not work with select", is because they will block if they receive a partial message, thus preventing the code from getting back to the select. IE. They do exactly what your wrappers do; except they're more likely correct.