/* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */ /* * Copyright 2000-2007 Niels Provos <provos@citi.umich.edu> * Copyright 2007-2012 Niels Provos and Nick Mathewson * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include "event2/event-config.h" #include "evconfig-private.h" #ifdef EVENT__HAVE_SELECT #ifdef __APPLE__ /* Apple wants us to define this if we might ever pass more than * FD_SETSIZE bits to select(). */ #define _DARWIN_UNLIMITED_SELECT #endif #include <sys/types.h> #ifdef EVENT__HAVE_SYS_TIME_H #include <sys/time.h> #endif #ifdef EVENT__HAVE_SYS_SELECT_H #include <sys/select.h> #endif #include <sys/queue.h> #include <signal.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <errno.h> #include "event-internal.h" #include "evsignal-internal.h" #include "event2/thread.h" #include "evthread-internal.h" #include "log-internal.h" #include "evmap-internal.h" #ifndef EVENT__HAVE_FD_MASK /* This type is mandatory, but Android doesn't define it. */ typedef unsigned long fd_mask; #endif #ifndef NFDBITS #define NFDBITS (sizeof(fd_mask)*8) #endif /* Divide positive x by y, rounding up. */ #define DIV_ROUNDUP(x, y) (((x)+((y)-1))/(y)) /* How many bytes to allocate for N fds? */ #define SELECT_ALLOC_SIZE(n) \ (DIV_ROUNDUP(n, NFDBITS) * sizeof(fd_mask)) struct selectop { int event_fds; /* Highest fd in fd set */ int event_fdsz; int resize_out_sets; fd_set *event_readset_in; fd_set *event_writeset_in; fd_set *event_readset_out; fd_set *event_writeset_out; }; static void *select_init(struct event_base *); static int select_add(struct event_base *, int, short old, short events, void*); static int select_del(struct event_base *, int, short old, short events, void*); static int select_dispatch(struct event_base *, struct timeval *); static void select_dealloc(struct event_base *); const struct eventop selectops = { "select", select_init, select_add, select_del, select_dispatch, select_dealloc, 1, /* need_reinit. */ EV_FEATURE_FDS, 0, }; static int select_resize(struct selectop *sop, int fdsz); static void select_free_selectop(struct selectop *sop); static void * select_init(struct event_base *base) { struct selectop *sop; if (!(sop = mm_calloc(1, sizeof(struct selectop)))) return (NULL); if (select_resize(sop, SELECT_ALLOC_SIZE(32 + 1))) { select_free_selectop(sop); return (NULL); } evsig_init_(base); evutil_weakrand_seed_(&base->weakrand_seed, 0); return (sop); } #ifdef CHECK_INVARIANTS static void check_selectop(struct selectop *sop) { /* nothing to be done here */ } #else #define check_selectop(sop) do { (void) sop; } while (0) #endif static int select_dispatch(struct event_base *base, struct timeval *tv) { int res=0, i, j, nfds; struct selectop *sop = base->evbase; check_selectop(sop); if (sop->resize_out_sets) { fd_set *readset_out=NULL, *writeset_out=NULL; size_t sz = sop->event_fdsz; if (!(readset_out = mm_realloc(sop->event_readset_out, sz))) return (-1); sop->event_readset_out = readset_out; if (!(writeset_out = mm_realloc(sop->event_writeset_out, sz))) { /* We don't free readset_out here, since it was * already successfully reallocated. The next time * we call select_dispatch, the realloc will be a * no-op. */ return (-1); } sop->event_writeset_out = writeset_out; sop->resize_out_sets = 0; } memcpy(sop->event_readset_out, sop->event_readset_in, sop->event_fdsz); memcpy(sop->event_writeset_out, sop->event_writeset_in, sop->event_fdsz); nfds = sop->event_fds+1; EVBASE_RELEASE_LOCK(base, th_base_lock); res = select(nfds, sop->event_readset_out, sop->event_writeset_out, NULL, tv); EVBASE_ACQUIRE_LOCK(base, th_base_lock); check_selectop(sop); if (res == -1) { if (errno != EINTR) { event_warn("select"); return (-1); } return (0); } event_debug(("%s: select reports %d", __func__, res)); check_selectop(sop); i = evutil_weakrand_range_(&base->weakrand_seed, nfds); for (j = 0; j < nfds; ++j) { if (++i >= nfds) i = 0; res = 0; if (FD_ISSET(i, sop->event_readset_out)) res |= EV_READ; if (FD_ISSET(i, sop->event_writeset_out)) res |= EV_WRITE; if (res == 0) continue; evmap_io_active_(base, i, res); } check_selectop(sop); return (0); } static int select_resize(struct selectop *sop, int fdsz) { fd_set *readset_in = NULL; fd_set *writeset_in = NULL; if (sop->event_readset_in) check_selectop(sop); if ((readset_in = mm_realloc(sop->event_readset_in, fdsz)) == NULL) goto error; sop->event_readset_in = readset_in; if ((writeset_in = mm_realloc(sop->event_writeset_in, fdsz)) == NULL) { /* Note that this will leave event_readset_in expanded. * That's okay; we wouldn't want to free it, since that would * change the semantics of select_resize from "expand the * readset_in and writeset_in, or return -1" to "expand the * *set_in members, or trash them and return -1." */ goto error; } sop->event_writeset_in = writeset_in; sop->resize_out_sets = 1; memset((char *)sop->event_readset_in + sop->event_fdsz, 0, fdsz - sop->event_fdsz); memset((char *)sop->event_writeset_in + sop->event_fdsz, 0, fdsz - sop->event_fdsz); sop->event_fdsz = fdsz; check_selectop(sop); return (0); error: event_warn("malloc"); return (-1); } static int select_add(struct event_base *base, int fd, short old, short events, void *p) { struct selectop *sop = base->evbase; (void) p; EVUTIL_ASSERT((events & EV_SIGNAL) == 0); check_selectop(sop); /* * Keep track of the highest fd, so that we can calculate the size * of the fd_sets for select(2) */ if (sop->event_fds < fd) { int fdsz = sop->event_fdsz; if (fdsz < (int)sizeof(fd_mask)) fdsz = (int)sizeof(fd_mask); /* In theory we should worry about overflow here. In * reality, though, the highest fd on a unixy system will * not overflow here. XXXX */ while (fdsz < (int) SELECT_ALLOC_SIZE(fd + 1)) fdsz *= 2; if (fdsz != sop->event_fdsz) { if (select_resize(sop, fdsz)) { check_selectop(sop); return (-1); } } sop->event_fds = fd; } if (events & EV_READ) FD_SET(fd, sop->event_readset_in); if (events & EV_WRITE) FD_SET(fd, sop->event_writeset_in); check_selectop(sop); return (0); } /* * Nothing to be done here. */ static int select_del(struct event_base *base, int fd, short old, short events, void *p) { struct selectop *sop = base->evbase; (void)p; EVUTIL_ASSERT((events & EV_SIGNAL) == 0); check_selectop(sop); if (sop->event_fds < fd) { check_selectop(sop); return (0); } if (events & EV_READ) FD_CLR(fd, sop->event_readset_in); if (events & EV_WRITE) FD_CLR(fd, sop->event_writeset_in); check_selectop(sop); return (0); } static void select_free_selectop(struct selectop *sop) { if (sop->event_readset_in) mm_free(sop->event_readset_in); if (sop->event_writeset_in) mm_free(sop->event_writeset_in); if (sop->event_readset_out) mm_free(sop->event_readset_out); if (sop->event_writeset_out) mm_free(sop->event_writeset_out); memset(sop, 0, sizeof(struct selectop)); mm_free(sop); } static void select_dealloc(struct event_base *base) { evsig_dealloc_(base); select_free_selectop(base->evbase); } #endif /* EVENT__HAVE_SELECT */