/* * File: xcompat.c * Version: 3.0 * Last modified on Sat Oct  1 11:28:05 1994 by eroberts * ----------------------------------------------------- * This implementation and the corresponding interface simulate the * operation of any BSD4.2 calls that are required by the graphics * package but that are not defined in the local system.  See the * interface for details.  Note that this file generates no code * unless one of the conditions is set. */#ifdef HasPoll#include <stdio.h>#include <stdlib.h>#include <poll.h>#include <sys/time.h>#include <sys/types.h>#include "xcompat.h"/* Private function prototypes */static void SigAlarmHandler();/* * Function: SimulateSelect * ------------------------ * This function simulates the BSD select call by mapping it onto * the poll system call implemented under System V. */int SimulateSelect(int width,                   fd_set *readfds,                   fd_set *writefds,                   fd_set *exceptfds,                   struct timeval *tvp){    struct pollfd fds[FOPEN_MAX];    int i, fd, nfds;    short events;    int timeout, nready;    nfds = 0;    if (tvp == NULL) {        timeout = 0;    } else {        timeout = tvp->tv_sec * 1000 + (tvp->tv_usec + 500) / 1000;    }    for (fd = 0; fd < width; fd++) {        events = 0;        if (readfds && FD_ISSET(fd, readfds)) {            events |= POLLIN;            FD_CLR(fd, readfds);        }        if (writefds && FD_ISSET(fd, writefds)) {            events |= POLLOUT;            FD_CLR(fd, writefds);        }        if (exceptfds && FD_ISSET(fd, exceptfds)) {            events |= POLLIN | POLLOUT;            FD_CLR(fd, exceptfds);        }        if (events != 0) {            fds[nfds].fd = fd;            fds[nfds].events = events;            fds[nfds].revents = 0;            nfds++;        }    }    nready = poll(fds, nfds, timeout);    if (nready <= 0) return (nready);    for (i = 0; i < nfds; i++) {        if (fds[i].revents & (POLLIN | POLLPRI | POLLHUP)) {            FD_SET(fds[i].fd, readfds);        }        if (fds[i].revents & POLLOUT) {            FD_SET(fds[i].fd, writefds);        }        if (fds[i].revents & (POLLERR | POLLNVAL)) {            FD_SET(fds[i].fd, exceptfds);        }    }    return (nready);}#endif