+static struct blocker *blockers;
+
+#ifdef HAVE_EPOLL
+
+/*
+ * Support for epoll. Optimally, different I/O loops should be split
+ * into different files for greater clarity, but I'll save that fun
+ * for another day.
+ *
+ * Scroll down to #else for the normal select loop.
+ */
+
+#include <sys/epoll.h>
+
+struct blocker {
+ struct blocker *n, *p, *n2, *p2;
+ int fd, reg;
+ int ev;
+ time_t to;
+ struct muth *th;
+};
+
+static int epfd = -1, fdln = 0;
+static struct blocker **fdlist;
+
+static int regfd(struct blocker *bl)
+{
+ struct blocker *o;
+ struct epoll_event evd;
+
+ evd.events = 0;
+ if(bl->ev & EV_READ)
+ evd.events |= EPOLLIN;
+ if(bl->ev & EV_WRITE)
+ evd.events |= EPOLLOUT;
+ evd.data.fd = bl->fd;
+ if(bl->fd >= fdln) {
+ if(fdlist) {
+ fdlist = srealloc(fdlist, sizeof(*fdlist) * (bl->fd + 1));
+ memset(fdlist + fdln, 0, sizeof(*fdlist) * (bl->fd + 1 - fdln));
+ fdln = bl->fd + 1;
+ } else {
+ fdlist = szmalloc(sizeof(*fdlist) * (fdln = (bl->fd + 1)));
+ }
+ }
+ if(fdlist[bl->fd] == NULL) {
+ if(epoll_ctl(epfd, EPOLL_CTL_ADD, bl->fd, &evd)) {
+ /* XXX?! Whatever to do, really? */
+ flog(LOG_ERR, "epoll_add on fd %i: %s", bl->fd, strerror(errno));
+ return(-1);
+ }
+ } else {
+ for(o = fdlist[bl->fd]; o; o = o->n2) {
+ if(o->ev & EV_READ)
+ evd.events |= EPOLLIN;
+ if(o->ev & EV_WRITE)
+ evd.events |= EPOLLOUT;
+ }
+ if(epoll_ctl(epfd, EPOLL_CTL_MOD, bl->fd, &evd)) {
+ /* XXX?! Whatever to do, really? */
+ flog(LOG_ERR, "epoll_mod on fd %i: %s", bl->fd, strerror(errno));
+ return(-1);
+ }
+ }
+ bl->n2 = fdlist[bl->fd];
+ bl->p2 = NULL;
+ if(fdlist[bl->fd] != NULL)
+ fdlist[bl->fd]->p2 = bl;
+ fdlist[bl->fd] = bl;
+ bl->reg = 1;
+ return(0);
+}
+
+static void remfd(struct blocker *bl)
+{
+ struct blocker *o;
+ struct epoll_event evd;
+
+ if(!bl->reg)
+ return;
+ if(bl->n2)
+ bl->n2->p2 = bl->p2;
+ if(bl->p2)
+ bl->p2->n2 = bl->n2;
+ if(bl == fdlist[bl->fd])
+ fdlist[bl->fd] = bl->n2;
+ if(fdlist[bl->fd] == NULL) {
+ if(epoll_ctl(epfd, EPOLL_CTL_DEL, bl->fd, NULL))
+ flog(LOG_ERR, "epoll_del on fd %i: %s", bl->fd, strerror(errno));
+ } else {
+ evd.events = 0;
+ evd.data.fd = bl->fd;
+ for(o = fdlist[bl->fd]; o; o = o->n2) {
+ if(o->ev & EV_READ)
+ evd.events |= EPOLLIN;
+ if(o->ev & EV_WRITE)
+ evd.events |= EPOLLOUT;
+ }
+ if(epoll_ctl(epfd, EPOLL_CTL_MOD, bl->fd, &evd)) {
+ /* XXX?! Whatever to do, really? */
+ flog(LOG_ERR, "epoll_mod on fd %i: %s", bl->fd, strerror(errno));
+ }
+ }
+}
+
+int block(int fd, int ev, time_t to)
+{
+ struct blocker *bl;
+ int rv;
+
+ omalloc(bl);
+ bl->fd = fd;
+ bl->ev = ev;
+ if(to > 0)
+ bl->to = time(NULL) + to;
+ bl->th = current;
+ if((epfd >= 0) && regfd(bl)) {
+ free(bl);
+ return(-1);
+ }
+ bl->n = blockers;
+ if(blockers)
+ blockers->p = bl;
+ blockers = bl;
+ rv = yield();
+ if(bl->n)
+ bl->n->p = bl->p;
+ if(bl->p)
+ bl->p->n = bl->n;
+ if(bl == blockers)
+ blockers = bl->n;
+ remfd(bl);
+ free(bl);
+ return(rv);
+}
+
+void ioloop(void)
+{
+ struct blocker *bl, *nbl;
+ struct epoll_event evr[16];
+ int i, fd, nev, ev;
+ time_t now, timeout;
+
+ epfd = epoll_create(128);
+ for(bl = blockers; bl; bl = nbl) {
+ nbl = bl->n;
+ if(regfd(bl))
+ resume(bl->th, -1);
+ }
+ while(blockers != NULL) {
+ timeout = 0;
+ for(bl = blockers; bl; bl = bl->n) {
+ if((bl->to != 0) && ((timeout == 0) || (timeout > bl->to)))
+ timeout = bl->to;
+ }
+ now = time(NULL);
+ nev = epoll_wait(epfd, evr, sizeof(evr) / sizeof(*evr), timeout?((timeout - now) * 1000):-1);
+ if(nev < 0) {
+ if(errno != EINTR) {
+ flog(LOG_CRIT, "ioloop: select errored out: %s", strerror(errno));
+ /* To avoid CPU hogging in case it's bad, which it
+ * probably is. */
+ sleep(1);
+ }
+ continue;
+ }
+ now = time(NULL);
+ for(i = 0; i < nev; i++) {
+ fd = evr[i].data.fd;
+ ev = 0;
+ if(evr[i].events & EPOLLIN)
+ ev |= EV_READ;
+ if(evr[i].events & EPOLLOUT)
+ ev |= EV_WRITE;
+ if(evr[i].events & ~(EPOLLIN | EPOLLOUT))
+ ev = -1;
+ for(bl = fdlist[fd]; bl; bl = nbl) {
+ nbl = bl->n2;
+ if((ev < 0) || (ev & bl->ev))
+ resume(bl->th, ev);
+ else if((bl->to != 0) && (bl->to <= now))
+ resume(bl->th, 0);
+ }
+ }
+ }
+ close(epfd);
+ epfd = -1;
+}
+
+#else
+