If there is no timeout defined on a socket, and the socket is closed while another thread is waiting in nn_recv(), it would be very helpful for me to get an error back directly. Similar to how nn_term() works.

thread_recv_block.c

#include "src/nn.h"
#include "src/reqrep.h"

#include "src/utils/err.c"
#include "src/utils/thread.c"
#include "src/utils/sleep.c"

#include <stddef.h>
#include <assert.h>
#include <stdlib.h>
#include <string.h>

int rep;

void worker (void *arg)
{
	int rc;
	int i;
	int timeo;
	char buf[3];

	rc = nn_recv(rep, buf, 3, 0);
}

int main(int argc, char *argv[])
{
	int rc;
	int req;
	int timeo;
	struct nn_thread thread;

	req = nn_socket(AF_SP, NN_REQ);
	assert(req != -1);
	rc = nn_connect(req, "inproc://thread_recv_close");
	assert(rc >= 0);

	rep = nn_socket(AF_SP, NN_REP);
	assert(rep != -1);
	rc = nn_bind(rep, "inproc://thread_recv_close");
	assert(rc >= 0);

	/*  Wait a bit till the worker thread blocks in nn_recv(). */
	nn_thread_init(&thread, worker, NULL);
	nn_sleep(100);

	/* Calling nn_term() before close will unblock the thread. */
	/* nn_term(); */

	rc = nn_close(req);
	assert(rc == 0);

	rc = nn_close(rep);
	assert(rc == 0);

	nn_thread_term(&thread);

	return 0;
}