select (GNU Gnulib)

Gnulib module: select

Portability problems fixed by Gnulib:

On Windows platforms (excluding Cygwin), select can only be called on descriptors created by the socket function, not on regular file descriptors.
On Windows platforms (excluding Cygwin), error codes from this function are not placed in errno, and WSAGetLastError must be used instead.
On some platforms, this function fails to detect invalid fds with EBADF, but only if they lie beyond the current maximum open fd: FreeBSD 8.2.

Portability problems not fixed by Gnulib:

When you call select with a timeout, some implementations modify the timeout parameter so that upon return from the function, it contains the amount of time not slept. Other implementations leave the timeout parameter unmodified.
Under Windows, when passing a pipe, Gnulib’s select replacement might return 0 even before the timeout has passed. Programs using it with pipes can thus busy wait.
On Linux, when some file descriptor refers to a regular file, select may fail, setting errno to EBADF.