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/* dnsmasq is Copyright (c) 2000-2020 Simon Kelley
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 dated June, 1991, or
(at your option) version 3 dated 29 June, 2007.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "dnsmasq.h"
/* Wrapper for poll(). Allocates and extends array of struct pollfds,
keeps them in fd order so that we can set and test conditions on
fd using a simple but efficient binary chop. */
/* poll_reset()
poll_listen(fd, event)
.
.
poll_listen(fd, event);
hits = do_poll(timeout);
if (poll_check(fd, event)
.
.
if (poll_check(fd, event)
.
.
event is OR of POLLIN, POLLOUT, POLLERR, etc
*/
static struct pollfd *pollfds = NULL;
static nfds_t nfds, arrsize = 0;
/* Binary search. Returns either the pollfd with fd, or
if the fd doesn't match, or return equals nfds, the entry
to the left of which a new record should be inserted. */
static nfds_t fd_search(int fd)
{
nfds_t left, right, mid;
if ((right = nfds) == 0)
return 0;
left = 0;
while (1)
{
if (right == left + 1)
return (pollfds[left].fd >= fd) ? left : right;
mid = (left + right)/2;
if (pollfds[mid].fd > fd)
right = mid;
else
left = mid;
}
}
void poll_reset(void)
{
nfds = 0;
}
int do_poll(int timeout)
{
return poll(pollfds, nfds, timeout);
}
int poll_check(int fd, short event)
{
nfds_t i = fd_search(fd);
if (i < nfds && pollfds[i].fd == fd)
return pollfds[i].revents & event;
return 0;
}
void poll_listen(int fd, short event)
{
nfds_t i = fd_search(fd);
if (i < nfds && pollfds[i].fd == fd)
pollfds[i].events |= event;
else
{
if (arrsize != nfds)
memmove(&pollfds[i+1], &pollfds[i], (nfds - i) * sizeof(struct pollfd));
else
{
/* Array too small, extend. */
struct pollfd *new;
arrsize = (arrsize == 0) ? 64 : arrsize * 2;
if (!(new = whine_malloc(arrsize * sizeof(struct pollfd))))
return;
if (pollfds)
{
memcpy(new, pollfds, i * sizeof(struct pollfd));
memcpy(&new[i+1], &pollfds[i], (nfds - i) * sizeof(struct pollfd));
free(pollfds);
}
pollfds = new;
}
pollfds[i].fd = fd;
pollfds[i].events = event;
nfds++;
}
}
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