I'm really sorry if my question is a duplicate, but I didn't find useful infos in the site.
I'm using non blocking sockets and a select(). How can I detect if a client closed the connection on non-blocking socket? I saw that a read() returns -1 with errno = EWOULDBLOCK when no datas are available to be read and also when a connection is closed.
How can I discriminate above cases?
When the peer has closed the connection:
select() will return the socket as readable.recv() or read() on the socket will return zero.I saw that a read() returns -1 with errno = EWOULDBLOCK when no datas are available to be read
Correct, but the connection isn't closed.
and also when a connection is closed.
No you didn't. That's not correct. It returns zero.
How can I discriminate above cases?
They aren't the same, and they don't manifest themselves in the same way.
When the peer had closed the connection for a specific socket, a call to read() on this socket would return 0. This behaviour is independent from the socket's blocking state.
From man 2 read (italics by me):
RETURN VALUE
On success, the number of bytes read is returned (zero indicates end of file)
