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/* $OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */

/*
* Copyright 2000-2003 Niels Provos <provos@citi.umich.edu>
* All rights reserved.
*
* 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.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/types.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <sys/_time.h>
#endif
#include <sys/queue.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#ifdef CHECK_INVARIANTS
#include <assert.h>
#endif

#include "event.h"
#include "event-internal.h"
#include "evsignal.h"
#include "log.h"

struct pollop {
int event_count; /* Highest number alloc */
int nfds; /* Size of event_* */
int fd_count; /* Size of idxplus1_by_fd */
struct pollfd *event_set;
struct event **event_r_back;
struct event **event_w_back;
int *idxplus1_by_fd; /* Index into event_set by fd; we add 1 so
* that 0 (which is easy to memset) can mean
* "no entry." */
};

static void *poll_init (struct event_base *);
static int poll_add (void *, struct event *);
static int poll_del (void *, struct event *);
static int poll_dispatch (struct event_base *, void *, struct timeval *);
static void poll_dealloc (struct event_base *, void *);

const struct eventop pollops = {
"poll",
poll_init,
poll_add,
poll_del,
poll_dispatch,
poll_dealloc,
    0
};

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

/* Disable poll when this environment variable is set */
if (getenv("EVENT_NOPOLL"))
return (NULL);

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

evsignal_init(base);

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;
assert(pop->event_set[idx].fd == i);
if (pop->event_set[idx].events & POLLIN) {
ev = pop->event_r_back[idx];
assert(ev);
assert(ev->ev_events & EV_READ);
assert(ev->ev_fd == i);
}
if (pop->event_set[idx].events & POLLOUT) {
ev = pop->event_w_back[idx];
assert(ev);
assert(ev->ev_events & EV_WRITE);
assert(ev->ev_fd == i);
}
}
for (i = 0; i < pop->nfds; ++i) {
struct pollfd *pfd = &pop->event_set[i];
assert(pop->idxplus1_by_fd[pfd->fd] == i+1);
}
}
#else
#define poll_check_ok(pop)
#endif

static int
poll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
{
int res, i, msec = -1, nfds;
struct pollop *pop = arg;

poll_check_ok(pop);

if (tv != NULL)
msec = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;

nfds = pop->nfds;
res = poll(pop->event_set, nfds, msec);

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

evsignal_process(base);
return (0);
} else if (base->sig.evsignal_caught) {
evsignal_process(base);
}

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

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

for (i = 0; i < nfds; i++) {
int what = pop->event_set[i].revents;
struct event *r_ev = NULL, *w_ev = NULL;
if (!what)
continue;

res = 0;

/* If the file gets closed notify */
if (what & (POLLHUP|POLLERR))
what |= POLLIN|POLLOUT;
if (what & POLLIN) {
res |= EV_READ;
r_ev = pop->event_r_back[i];
}
if (what & POLLOUT) {
res |= EV_WRITE;
w_ev = pop->event_w_back[i];
}
if (res == 0)
continue;

if (r_ev && (res & r_ev->ev_events)) {
event_active(r_ev, res & r_ev->ev_events, 1);
}
if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
event_active(w_ev, res & w_ev->ev_events, 1);
}
}

return (0);
}

static int
poll_add(void *arg, struct event *ev)
{
struct pollop *pop = arg;
struct pollfd *pfd = NULL;
int i;

if (ev->ev_events & EV_SIGNAL)
return (evsignal_add(ev));
if (!(ev->ev_events & (EV_READ|EV_WRITE)))
return (0);

poll_check_ok(pop);
if (pop->nfds + 1 >= pop->event_count) {
struct pollfd *tmp_event_set;
struct event **tmp_event_r_back;
struct event **tmp_event_w_back;
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 = 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;

tmp_event_r_back = realloc(pop->event_r_back,
tmp_event_count * sizeof(struct event *));
if (tmp_event_r_back == NULL) {
/* event_set overallocated; that's okay. */
event_warn("realloc");
return (-1);
}
pop->event_r_back = tmp_event_r_back;

tmp_event_w_back = realloc(pop->event_w_back,
tmp_event_count * sizeof(struct event *));
if (tmp_event_w_back == NULL) {
/* event_set and event_r_back overallocated; that's
* okay. */
event_warn("realloc");
return (-1);
}
pop->event_w_back = tmp_event_w_back;

pop->event_count = tmp_event_count;
}
if (ev->ev_fd >= pop->fd_count) {
int *tmp_idxplus1_by_fd;
int new_count;
if (pop->fd_count < 32)
new_count = 32;
else
new_count = pop->fd_count * 2;
while (new_count <= ev->ev_fd)
new_count *= 2;
tmp_idxplus1_by_fd =
realloc(pop->idxplus1_by_fd, new_count * sizeof(int));
if (tmp_idxplus1_by_fd == NULL) {
event_warn("realloc");
return (-1);
}
pop->idxplus1_by_fd = tmp_idxplus1_by_fd;
memset(pop->idxplus1_by_fd + pop->fd_count,
0, sizeof(int)*(new_count - pop->fd_count));
pop->fd_count = new_count;
}

i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
if (i >= 0) {
pfd = &pop->event_set[i];
} else {
i = pop->nfds++;
pfd = &pop->event_set[i];
pfd->events = 0;
pfd->fd = ev->ev_fd;
pop->event_w_back[i] = pop->event_r_back[i] = NULL;
pop->idxplus1_by_fd[ev->ev_fd] = i + 1;
}

pfd->revents = 0;
if (ev->ev_events & EV_WRITE) {
pfd->events |= POLLOUT;
pop->event_w_back[i] = ev;
}
if (ev->ev_events & EV_READ) {
pfd->events |= POLLIN;
pop->event_r_back[i] = ev;
}
poll_check_ok(pop);

return (0);
}

/*
* Nothing to be done here.
*/

static int
poll_del(void *arg, struct event *ev)
{
struct pollop *pop = arg;
struct pollfd *pfd = NULL;
int i;

if (ev->ev_events & EV_SIGNAL)
return (evsignal_del(ev));

if (!(ev->ev_events & (EV_READ|EV_WRITE)))
return (0);

poll_check_ok(pop);
i = pop->idxplus1_by_fd[ev->ev_fd] - 1;
if (i < 0)
return (-1);

/* Do we still want to read or write? */
pfd = &pop->event_set[i];
if (ev->ev_events & EV_READ) {
pfd->events &= ~POLLIN;
pop->event_r_back[i] = NULL;
}
if (ev->ev_events & EV_WRITE) {
pfd->events &= ~POLLOUT;
pop->event_w_back[i] = NULL;
}
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. */
pop->idxplus1_by_fd[ev->ev_fd] = 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));
pop->event_r_back[i] = pop->event_r_back[pop->nfds];
pop->event_w_back[i] = pop->event_w_back[pop->nfds];
pop->idxplus1_by_fd[pop->event_set[i].fd] = i + 1;
}

poll_check_ok(pop);
return (0);
}

static void
poll_dealloc(struct event_base *base, void *arg)
{
struct pollop *pop = arg;

evsignal_dealloc(base);
if (pop->event_set)
free(pop->event_set);
if (pop->event_r_back)
free(pop->event_r_back);
if (pop->event_w_back)
free(pop->event_w_back);
if (pop->idxplus1_by_fd)
free(pop->idxplus1_by_fd);

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