/* Create two loopback address sockets connected to each other, shutdown the first socket for writing, and then test the poll bits on the first socket. */ #include "udp.h" int main(void) { int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); if ( fd < 0 ) err(1, "first socket"); struct sockaddr_in sin; memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_addr.s_addr = htobe32(INADDR_LOOPBACK); sin.sin_port = htobe16(0); if ( bind(fd, (const struct sockaddr*) &sin, sizeof(sin)) < 0 ) err(1, "first bind"); struct sockaddr_in local; socklen_t locallen = sizeof(local); if ( getsockname(fd, (struct sockaddr*) &local, &locallen) < 0 ) err(1, "first getsockname"); int fd2 = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); if ( fd2 < 0 ) err(1, "second socket"); if ( bind(fd2, (const struct sockaddr*) &sin, sizeof(sin)) < 0 ) err(1, "second bind"); struct sockaddr_in local2; socklen_t locallen2 = sizeof(local2); if ( getsockname(fd2, (struct sockaddr*) &local2, &locallen2) < 0 ) err(1, "second getsockname"); if ( connect(fd, (const struct sockaddr*) &local2, locallen2) < 0 ) err(1, "first connect"); if ( connect(fd2, (const struct sockaddr*) &local, locallen) < 0 ) err(1, "second connect"); if ( shutdown(fd, SHUT_WR) < 0 ) err(1, "shutdown"); struct pollfd pfd; memset(&pfd, 0, sizeof(pfd)); pfd.fd = fd; pfd.events = POLLIN | POLLOUT; int num_events = poll(&pfd, 1, 0); if ( num_events < 0 ) err(1, "poll"); if ( num_events == 0 ) errx(1, "poll returned 0"); printf("0"); if ( pfd.revents & POLLIN ) printf(" | POLLIN"); if ( pfd.revents & POLLPRI ) printf(" | POLLPRI"); if ( pfd.revents & POLLOUT ) printf(" | POLLOUT"); #if defined(POLLRDHUP) && POLLRDHUP != POLLHUP if ( pfd.revents & POLLRDHUP ) printf(" | POLLRDHUP"); #endif if ( pfd.revents & POLLERR ) printf(" | POLLERR"); if ( pfd.revents & POLLHUP ) printf(" | POLLHUP"); #if POLLRDNORM != POLLIN if ( pfd.revents & POLLRDNORM ) printf(" | POLLRDNORM"); #endif #if POLLRDBAND != POLLPRI if ( pfd.revents & POLLRDBAND ) printf(" | POLLRDBAND"); #endif #if POLLWRNORM != POLLOUT if ( pfd.revents & POLLWRNORM ) printf(" | POLLWRNORM"); #endif #if POLLWRBAND != POLLOUT if ( pfd.revents & POLLWRBAND ) printf(" | POLLWRBAND"); #endif putchar('\n'); return 0; }