libdill: Structured Concurrency for C


term_attach - creates TERM protocol on top of underlying socket


#include <libdill.h>

int term_attach(
    int s,
    const void* buf,
    size_t len,
    int64_t deadline);


TERM is a protocol that implements clean terminal handshake between peers. When creating the protocol instance user specifies the terminal message to use. When closing the protocol, terminal messages are exchanged between peers in both directions. After the protocol shuts down the peers agree on their position in the message stream.

This function instantiates TERM protocol on top of the underlying protocol.

s: Handle of the underlying socket. It must be a message protocol.

buf: The terminal message.

len: Size of the terminal message, in bytes.

deadline: A point in time when the operation should time out, in milliseconds. Use the now function to get your current point in time. 0 means immediate timeout, i.e., perform the operation if possible or return without blocking if not. -1 means no deadline, i.e., the call will block forever if the operation cannot be performed.

The socket can be cleanly shut down using term_detach function.

This function is not available if libdill is compiled with --disable-sockets option.


In case of success the function returns newly created socket handle. In case of error it returns -1 and sets errno to one of the values below.



s = term_attach(s, "STOP", 4);
/* Send terminal message to the peer. */
term_done(s, -1);
/* Process remaining inbound messages. */
while(1) {
    char buf[256];
    ssize_t sz = mrecv(s, buf, sizeof(buf), -1);
    /* Check whether terminal message was received from the peer. */
    if(sz < 0 && errno == EPIPE) break;
    frobnicate(buff, sz);
s = term_detach(s);


hclose(3) mrecv(3) mrecvl(3) msend(3) msendl(3) now(3) term_attach_mem(3) term_detach(3) term_done(3)