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/* $OpenBSD: poll.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_POLL

#include <sys/types.h>
#ifdef EVENT__HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <sys/queue.h>
#include <poll.h>
#include <signal.h>
#include <limits.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 "log-internal.h"
#include "evmap-internal.h"
#include "event2/thread.h"
#include "evthread-internal.h"
#include "time-internal.h"

struct pollidx {
int idxplus1;
};

struct pollop {
int event_count; /* Highest number alloc */
int nfds; /* Highest number used */
int realloc_copy; /* True iff we must realloc
* event_set_copy */
struct pollfd *event_set;
struct pollfd *event_set_copy;
};

static void *poll_init(struct event_base *);
static int poll_add(struct event_base *, int, short old, short events, void *idx);
static int poll_del(struct event_base *, int, short old, short events, void *idx);
static int poll_dispatch(struct event_base *, struct timeval *);
static void poll_dealloc(struct event_base *);

const struct eventop pollops = {
"poll",
poll_init,
poll_add,
poll_del,
poll_dispatch,
poll_dealloc,
0, /* doesn't need_reinit */
EV_FEATURE_FDS,
sizeof(struct pollidx),
};

static void *
poll_init(struct event_base *base)
{
struct pollop *pollop;

if (!(pollop = mm_calloc(1, sizeof(struct pollop))))
return (NULL);

evsig_init_(base);

evutil_weakrand_seed_(&base->weakrand_seed, 0);

return (pollop);
}

#ifdef CHECK_INVARIANTS
static void
poll_check_ok(struct pollop *pop)
{
int i, idx;
struct event *ev;

for (i = 0; i < pop->fd_count; ++i) {
idx = pop->idxplus1_by_fd[i]-1;
if (idx < 0)
continue;
EVUTIL_ASSERT(pop->event_set[idx].fd == i);
}
for (i = 0; i < pop->nfds; ++i) {
struct pollfd *pfd = &pop->event_set[i];
EVUTIL_ASSERT(pop->idxplus1_by_fd[pfd->fd] == i+1);
}
}
#else
#define poll_check_ok(pop)
#endif

static int
poll_dispatch(struct event_base *base, struct timeval *tv)
{
int res, i, j, nfds;
long msec = -1;
struct pollop *pop = base->evbase;
struct pollfd *event_set;

poll_check_ok(pop);

nfds = pop->nfds;

#ifndef EVENT__DISABLE_THREAD_SUPPORT
if (base->th_base_lock) {
/* If we're using this backend in a multithreaded setting,
* then we need to work on a copy of event_set, so that we can
* let other threads modify the main event_set while we're
* polling. If we're not multithreaded, then we'll skip the
* copy step here to save memory and time. */
if (pop->realloc_copy) {
struct pollfd *tmp = mm_realloc(pop->event_set_copy,
pop->event_count * sizeof(struct pollfd));
if (tmp == NULL) {
event_warn("realloc");
return -1;
}
pop->event_set_copy = tmp;
pop->realloc_copy = 0;
}
memcpy(pop->event_set_copy, pop->event_set,
sizeof(struct pollfd)*nfds);
event_set = pop->event_set_copy;
} else {
event_set = pop->event_set;
}
#else
event_set = pop->event_set;
#endif

if (tv != NULL) {
msec = evutil_tv_to_msec_(tv);
if (msec < 0 || msec > INT_MAX)
msec = INT_MAX;
}

EVBASE_RELEASE_LOCK(base, th_base_lock);

res = poll(event_set, nfds, msec);

EVBASE_ACQUIRE_LOCK(base, th_base_lock);

if (res == -1) {
if (errno != EINTR) {
event_warn("poll");
return (-1);
}

return (0);
}

event_debug(("%s: poll reports %d", __func__, res));

if (res == 0 || nfds == 0)
return (0);

i = evutil_weakrand_range_(&base->weakrand_seed, nfds);
for (j = 0; j < nfds; j++) {
int what;
if (++i == nfds)
i = 0;
what = event_set[i].revents;
if (!what)
continue;

res = 0;

/* If the file gets closed notify */
if (what & (POLLHUP|POLLERR))
what |= POLLIN|POLLOUT;
if (what & POLLIN)
res |= EV_READ;
if (what & POLLOUT)
res |= EV_WRITE;
if (res == 0)
continue;

evmap_io_active_(base, event_set[i].fd, res);
}

return (0);
}

static int
poll_add(struct event_base *base, int fd, short old, short events, void *idx_)
{
struct pollop *pop = base->evbase;
struct pollfd *pfd = NULL;
struct pollidx *idx = idx_;
int i;

EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
if (!(events & (EV_READ|EV_WRITE)))
return (0);

poll_check_ok(pop);
if (pop->nfds + 1 >= pop->event_count) {
struct pollfd *tmp_event_set;
int tmp_event_count;

if (pop->event_count < 32)
tmp_event_count = 32;
else
tmp_event_count = pop->event_count * 2;

/* We need more file descriptors */
tmp_event_set = mm_realloc(pop->event_set,
tmp_event_count * sizeof(struct pollfd));
if (tmp_event_set == NULL) {
event_warn("realloc");
return (-1);
}
pop->event_set = tmp_event_set;

pop->event_count = tmp_event_count;
pop->realloc_copy = 1;
}

i = idx->idxplus1 - 1;

if (i >= 0) {
pfd = &pop->event_set[i];
} else {
i = pop->nfds++;
pfd = &pop->event_set[i];
pfd->events = 0;
pfd->fd = fd;
idx->idxplus1 = i + 1;
}

pfd->revents = 0;
if (events & EV_WRITE)
pfd->events |= POLLOUT;
if (events & EV_READ)
pfd->events |= POLLIN;
poll_check_ok(pop);

return (0);
}

/*
* Nothing to be done here.
*/

static int
poll_del(struct event_base *base, int fd, short old, short events, void *idx_)
{
struct pollop *pop = base->evbase;
struct pollfd *pfd = NULL;
struct pollidx *idx = idx_;
int i;

EVUTIL_ASSERT((events & EV_SIGNAL) == 0);
if (!(events & (EV_READ|EV_WRITE)))
return (0);

poll_check_ok(pop);
i = idx->idxplus1 - 1;
if (i < 0)
return (-1);

/* Do we still want to read or write? */
pfd = &pop->event_set[i];
if (events & EV_READ)
pfd->events &= ~POLLIN;
if (events & EV_WRITE)
pfd->events &= ~POLLOUT;
poll_check_ok(pop);
if (pfd->events)
/* Another event cares about that fd. */
return (0);

/* Okay, so we aren't interested in that fd anymore. */
idx->idxplus1 = 0;

--pop->nfds;
if (i != pop->nfds) {
/*
* Shift the last pollfd down into the now-unoccupied
* position.
*/
memcpy(&pop->event_set[i], &pop->event_set[pop->nfds],
sizeof(struct pollfd));
idx = evmap_io_get_fdinfo_(&base->io, pop->event_set[i].fd);
EVUTIL_ASSERT(idx);
EVUTIL_ASSERT(idx->idxplus1 == pop->nfds + 1);
idx->idxplus1 = i + 1;
}

poll_check_ok(pop);
return (0);
}

static void
poll_dealloc(struct event_base *base)
{
struct pollop *pop = base->evbase;

evsig_dealloc_(base);
if (pop->event_set)
mm_free(pop->event_set);
if (pop->event_set_copy)
mm_free(pop->event_set_copy);

memset(pop, 0, sizeof(struct pollop));
mm_free(pop);
}

#endif /* EVENT__HAVE_POLL */
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