scanf
POSIX specification:
http://www.opengroup.org/onlinepubs/9699919799/functions/scanf.html
Gnulib module: stdio, nonblocking
Portability problems fixed by Gnulib module stdio, together with module nonblocking:
errno being set to EINVAL instead of EAGAIN on
some platforms:
mingw, MSVC 9.
Portability problems not fixed by Gnulib:
feof would return nonzero. However, on some systems this
function attempts to read from the underlying file descriptor even if
the stream's end-of-file indicator is set. These systems include
glibc and default Solaris.
errno
upon failure.
hh, ll, j,
t, z size specifiers.