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contrib/dhcpcd/src/eloop.c

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/* SPDX-License-Identifier: BSD-2-Clause */
/*
* eloop - portable event based main loop.
* Copyright (c) 2006-2021 Roy Marples <roy@marples.name>
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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 <sys/time.h>
#include <assert.h>
#include <errno.h>
#include <limits.h>
#include <poll.h>
#include <stdbool.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/* config.h should define HAVE_PPOLL, etc. */
#if defined(HAVE_CONFIG_H) && !defined(NO_CONFIG_H)
#include "config.h"
#endif
#if defined(HAVE_PPOLL)
#elif defined(HAVE_POLLTS)
#define ppoll pollts
#elif !defined(HAVE_PSELECT)
#pragma message("Compiling eloop with pselect(2) support.")
#define HAVE_PSELECT
#define ppoll eloop_ppoll
#endif
#include "eloop.h"
#ifndef UNUSED
#define UNUSED(a) (void)((a))
#endif
#ifndef __unused
#ifdef __GNUC__
#define __unused __attribute__((__unused__))
#else
#define __unused
#endif
#endif
#ifdef HAVE_PSELECT
#include <sys/select.h>
#endif
/* Our structures require TAILQ macros, which really every libc should
* ship as they are useful beyond belief.
* Sadly some libc's don't have sys/queue.h and some that do don't have
* the TAILQ_FOREACH macro. For those that don't, the application using
* this implementation will need to ship a working queue.h somewhere.
* If we don't have sys/queue.h found in config.h, then
* allow QUEUE_H to override loading queue.h in the current directory. */
#ifndef TAILQ_FOREACH
#ifdef HAVE_SYS_QUEUE_H
#include <sys/queue.h>
#elif defined(QUEUE_H)
#define __QUEUE_HEADER(x) #x
#define _QUEUE_HEADER(x) __QUEUE_HEADER(x)
#include _QUEUE_HEADER(QUEUE_H)
#else
#include "queue.h"
#endif
#endif
#ifdef ELOOP_DEBUG
#include <stdio.h>
#endif
/*
* Allow a backlog of signals.
* If you use many eloops in the same process, they should all
* use the same signal handler or have the signal handler unset.
* Otherwise the signal might not behave as expected.
*/
#define ELOOP_NSIGNALS 5
/*
* time_t is a signed integer of an unspecified size.
* To adjust for time_t wrapping, we need to work the maximum signed
* value and use that as a maximum.
*/
#ifndef TIME_MAX
#define TIME_MAX ((1ULL << (sizeof(time_t) * NBBY - 1)) - 1)
#endif
/* The unsigned maximum is then simple - multiply by two and add one. */
#ifndef UTIME_MAX
#define UTIME_MAX (TIME_MAX * 2) + 1
#endif
struct eloop_event {
TAILQ_ENTRY(eloop_event) next;
int fd;
void (*read_cb)(void *);
void *read_cb_arg;
void (*write_cb)(void *);
void *write_cb_arg;
struct pollfd *pollfd;
};
struct eloop_timeout {
TAILQ_ENTRY(eloop_timeout) next;
unsigned int seconds;
unsigned int nseconds;
void (*callback)(void *);
void *arg;
int queue;
};
struct eloop {
TAILQ_HEAD (event_head, eloop_event) events;
size_t nevents;
struct event_head free_events;
bool events_need_setup;
struct timespec now;
TAILQ_HEAD (timeout_head, eloop_timeout) timeouts;
struct timeout_head free_timeouts;
const int *signals;
size_t signals_len;
void (*signal_cb)(int, void *);
void *signal_cb_ctx;
struct pollfd *fds;
size_t nfds;
int exitnow;
int exitcode;
};
#ifdef HAVE_REALLOCARRAY
#define eloop_realloca reallocarray
#else
/* Handy routing to check for potential overflow.
* reallocarray(3) and reallocarr(3) are not portable. */
#define SQRT_SIZE_MAX (((size_t)1) << (sizeof(size_t) * CHAR_BIT / 2))
static void *
eloop_realloca(void *ptr, size_t n, size_t size)
{
if ((n | size) >= SQRT_SIZE_MAX && n > SIZE_MAX / size) {
errno = EOVERFLOW;
return NULL;
}
return realloc(ptr, n * size);
}
#endif
#ifdef HAVE_PSELECT
/* Wrapper around pselect, to imitate the ppoll call. */
static int
eloop_ppoll(struct pollfd * fds, nfds_t nfds,
const struct timespec *ts, const sigset_t *sigmask)
{
fd_set read_fds, write_fds;
nfds_t n;
int maxfd, r;
FD_ZERO(&read_fds);
FD_ZERO(&write_fds);
maxfd = 0;
for (n = 0; n < nfds; n++) {
if (fds[n].events & POLLIN) {
FD_SET(fds[n].fd, &read_fds);
if (fds[n].fd > maxfd)
maxfd = fds[n].fd;
}
if (fds[n].events & POLLOUT) {
FD_SET(fds[n].fd, &write_fds);
if (fds[n].fd > maxfd)
maxfd = fds[n].fd;
}
}
r = pselect(maxfd + 1, &read_fds, &write_fds, NULL, ts, sigmask);
if (r > 0) {
for (n = 0; n < nfds; n++) {
fds[n].revents =
FD_ISSET(fds[n].fd, &read_fds) ? POLLIN : 0;
if (FD_ISSET(fds[n].fd, &write_fds))
fds[n].revents |= POLLOUT;
}
}
return r;
}
#endif
unsigned long long
eloop_timespec_diff(const struct timespec *tsp, const struct timespec *usp,
unsigned int *nsp)
{
unsigned long long tsecs, usecs, secs;
long nsecs;
if (tsp->tv_sec < 0) /* time wreapped */
tsecs = UTIME_MAX - (unsigned long long)(-tsp->tv_sec);
else
tsecs = (unsigned long long)tsp->tv_sec;
if (usp->tv_sec < 0) /* time wrapped */
usecs = UTIME_MAX - (unsigned long long)(-usp->tv_sec);
else
usecs = (unsigned long long)usp->tv_sec;
if (usecs > tsecs) /* time wrapped */
secs = (UTIME_MAX - usecs) + tsecs;
else
secs = tsecs - usecs;
nsecs = tsp->tv_nsec - usp->tv_nsec;
if (nsecs < 0) {
if (secs == 0)
nsecs = 0;
else {
secs--;
nsecs += NSEC_PER_SEC;
}
}
if (nsp != NULL)
*nsp = (unsigned int)nsecs;
return secs;
}
static void
eloop_reduce_timers(struct eloop *eloop)
{
struct timespec now;
unsigned long long secs;
unsigned int nsecs;
struct eloop_timeout *t;
clock_gettime(CLOCK_MONOTONIC, &now);
secs = eloop_timespec_diff(&now, &eloop->now, &nsecs);
TAILQ_FOREACH(t, &eloop->timeouts, next) {
if (secs > t->seconds) {
t->seconds = 0;
t->nseconds = 0;
} else {
t->seconds -= (unsigned int)secs;
if (nsecs > t->nseconds) {
if (t->seconds == 0)
t->nseconds = 0;
else {
t->seconds--;
t->nseconds = NSEC_PER_SEC
- (nsecs - t->nseconds);
}
} else
t->nseconds -= nsecs;
}
}
eloop->now = now;
}
static void
eloop_event_setup_fds(struct eloop *eloop)
{
struct eloop_event *e, *ne;
struct pollfd *pfd;
pfd = eloop->fds;
TAILQ_FOREACH_SAFE(e, &eloop->events, next, ne) {
if (e->fd == -1) {
TAILQ_REMOVE(&eloop->events, e, next);
TAILQ_INSERT_TAIL(&eloop->free_events, e, next);
continue;
}
#ifdef ELOOP_DEBUG
fprintf(stderr, "%s(%d) fd=%d, rcb=%p, wcb=%p\n",
__func__, getpid(), e->fd, e->read_cb, e->write_cb);
#endif
e->pollfd = pfd;
pfd->fd = e->fd;
pfd->events = 0;
if (e->read_cb != NULL)
pfd->events |= POLLIN;
if (e->write_cb != NULL)
pfd->events |= POLLOUT;
pfd->revents = 0;
pfd++;
}
eloop->events_need_setup = false;
}
size_t
eloop_event_count(const struct eloop *eloop)
{
return eloop->nevents;
}
int
eloop_event_add_rw(struct eloop *eloop, int fd,
void (*read_cb)(void *), void *read_cb_arg,
void (*write_cb)(void *), void *write_cb_arg)
{
struct eloop_event *e;
struct pollfd *pfd;
assert(eloop != NULL);
assert(read_cb != NULL || write_cb != NULL);
if (fd == -1) {
errno = EINVAL;
return -1;
}
TAILQ_FOREACH(e, &eloop->events, next) {
if (e->fd == fd)
break;
}
if (e == NULL) {
if (eloop->nevents + 1 > eloop->nfds) {
pfd = eloop_realloca(eloop->fds, eloop->nevents + 1,
sizeof(*pfd));
if (pfd == NULL)
return -1;
eloop->fds = pfd;
eloop->nfds++;
}
e = TAILQ_FIRST(&eloop->free_events);
if (e != NULL)
TAILQ_REMOVE(&eloop->free_events, e, next);
else {
e = malloc(sizeof(*e));
if (e == NULL)
return -1;
}
TAILQ_INSERT_HEAD(&eloop->events, e, next);
eloop->nevents++;
e->fd = fd;
e->read_cb = read_cb;
e->read_cb_arg = read_cb_arg;
e->write_cb = write_cb;
e->write_cb_arg = write_cb_arg;
goto setup;
}
if (read_cb) {
e->read_cb = read_cb;
e->read_cb_arg = read_cb_arg;
}
if (write_cb) {
e->write_cb = write_cb;
e->write_cb_arg = write_cb_arg;
}
setup:
e->pollfd = NULL;
eloop->events_need_setup = true;
return 0;
}
int
eloop_event_add(struct eloop *eloop, int fd,
void (*read_cb)(void *), void *read_cb_arg)
{
return eloop_event_add_rw(eloop, fd, read_cb, read_cb_arg, NULL, NULL);
}
int
eloop_event_add_w(struct eloop *eloop, int fd,
void (*write_cb)(void *), void *write_cb_arg)
{
return eloop_event_add_rw(eloop, fd, NULL,NULL, write_cb, write_cb_arg);
}
int
eloop_event_delete_write(struct eloop *eloop, int fd, int write_only)
{
struct eloop_event *e;
assert(eloop != NULL);
if (fd == -1) {
errno = EINVAL;
return -1;
}
TAILQ_FOREACH(e, &eloop->events, next) {
if (e->fd == fd)
break;
}
if (e == NULL) {
errno = ENOENT;
return -1;
}
if (write_only) {
if (e->read_cb == NULL)
goto remove;
e->write_cb = NULL;
e->write_cb_arg = NULL;
if (e->pollfd != NULL) {
e->pollfd->events &= ~POLLOUT;
e->pollfd->revents &= ~POLLOUT;
}
return 1;
}
remove:
e->fd = -1;
eloop->nevents--;
eloop->events_need_setup = true;
return 1;
}
/*
* This implementation should cope with UINT_MAX seconds on a system
* where time_t is INT32_MAX. It should also cope with the monotonic timer
* wrapping, although this is highly unlikely.
* unsigned int should match or be greater than any on wire specified timeout.
*/
static int
eloop_q_timeout_add(struct eloop *eloop, int queue,
unsigned int seconds, unsigned int nseconds,
void (*callback)(void *), void *arg)
{
struct eloop_timeout *t, *tt = NULL;
assert(eloop != NULL);
assert(callback != NULL);
assert(nseconds <= NSEC_PER_SEC);
/* Remove existing timeout if present. */
TAILQ_FOREACH(t, &eloop->timeouts, next) {
if (t->callback == callback && t->arg == arg) {
TAILQ_REMOVE(&eloop->timeouts, t, next);
break;
}
}
if (t == NULL) {
/* No existing, so allocate or grab one from the free pool. */
if ((t = TAILQ_FIRST(&eloop->free_timeouts))) {
TAILQ_REMOVE(&eloop->free_timeouts, t, next);
} else {
if ((t = malloc(sizeof(*t))) == NULL)
return -1;
}
}
eloop_reduce_timers(eloop);
t->seconds = seconds;
t->nseconds = nseconds;
t->callback = callback;
t->arg = arg;
t->queue = queue;
/* The timeout list should be in chronological order,
* soonest first. */
TAILQ_FOREACH(tt, &eloop->timeouts, next) {
if (t->seconds < tt->seconds ||
(t->seconds == tt->seconds && t->nseconds < tt->nseconds))
{
TAILQ_INSERT_BEFORE(tt, t, next);
return 0;
}
}
TAILQ_INSERT_TAIL(&eloop->timeouts, t, next);
return 0;
}
int
eloop_q_timeout_add_tv(struct eloop *eloop, int queue,
const struct timespec *when, void (*callback)(void *), void *arg)
{
if (when->tv_sec < 0 || (unsigned long)when->tv_sec > UINT_MAX) {
errno = EINVAL;
return -1;
}
if (when->tv_nsec < 0 || when->tv_nsec > NSEC_PER_SEC) {
errno = EINVAL;
return -1;
}
return eloop_q_timeout_add(eloop, queue,
(unsigned int)when->tv_sec, (unsigned int)when->tv_sec,
callback, arg);
}
int
eloop_q_timeout_add_sec(struct eloop *eloop, int queue, unsigned int seconds,
void (*callback)(void *), void *arg)
{
return eloop_q_timeout_add(eloop, queue, seconds, 0, callback, arg);
}
int
eloop_q_timeout_add_msec(struct eloop *eloop, int queue, unsigned long when,
void (*callback)(void *), void *arg)
{
unsigned long seconds, nseconds;
seconds = when / MSEC_PER_SEC;
if (seconds > UINT_MAX) {
errno = EINVAL;
return -1;
}
nseconds = (when % MSEC_PER_SEC) * NSEC_PER_MSEC;
return eloop_q_timeout_add(eloop, queue,
(unsigned int)seconds, (unsigned int)nseconds, callback, arg);
}
int
eloop_q_timeout_delete(struct eloop *eloop, int queue,
void (*callback)(void *), void *arg)
{
struct eloop_timeout *t, *tt;
int n;
assert(eloop != NULL);
n = 0;
TAILQ_FOREACH_SAFE(t, &eloop->timeouts, next, tt) {
if ((queue == 0 || t->queue == queue) &&
t->arg == arg &&
(!callback || t->callback == callback))
{
TAILQ_REMOVE(&eloop->timeouts, t, next);
TAILQ_INSERT_TAIL(&eloop->free_timeouts, t, next);
n++;
}
}
return n;
}
void
eloop_exit(struct eloop *eloop, int code)
{
assert(eloop != NULL);
eloop->exitcode = code;
eloop->exitnow = 1;
}
void
eloop_enter(struct eloop *eloop)
{
eloop->exitnow = 0;
}
void
eloop_signal_set_cb(struct eloop *eloop,
const int *signals, size_t signals_len,
void (*signal_cb)(int, void *), void *signal_cb_ctx)
{
assert(eloop != NULL);
eloop->signals = signals;
eloop->signals_len = signals_len;
eloop->signal_cb = signal_cb;
eloop->signal_cb_ctx = signal_cb_ctx;
}
static volatile int _eloop_sig[ELOOP_NSIGNALS];
static volatile size_t _eloop_nsig;
static void
eloop_signal3(int sig, __unused siginfo_t *siginfo, __unused void *arg)
{
if (_eloop_nsig == __arraycount(_eloop_sig)) {
#ifdef ELOOP_DEBUG
fprintf(stderr, "%s: signal storm, discarding signal %d\n",
__func__, sig);
#endif
return;
}
_eloop_sig[_eloop_nsig++] = sig;
}
int
eloop_signal_mask(struct eloop *eloop, sigset_t *oldset)
{
sigset_t newset;
size_t i;
struct sigaction sa = {
.sa_sigaction = eloop_signal3,
.sa_flags = SA_SIGINFO,
};
assert(eloop != NULL);
sigemptyset(&newset);
for (i = 0; i < eloop->signals_len; i++)
sigaddset(&newset, eloop->signals[i]);
if (sigprocmask(SIG_SETMASK, &newset, oldset) == -1)
return -1;
sigemptyset(&sa.sa_mask);
for (i = 0; i < eloop->signals_len; i++) {
if (sigaction(eloop->signals[i], &sa, NULL) == -1)
return -1;
}
return 0;
}
struct eloop *
eloop_new(void)
{
struct eloop *eloop;
eloop = calloc(1, sizeof(*eloop));
if (eloop == NULL)
return NULL;
/* Check we have a working monotonic clock. */
if (clock_gettime(CLOCK_MONOTONIC, &eloop->now) == -1) {
free(eloop);
return NULL;
}
TAILQ_INIT(&eloop->events);
TAILQ_INIT(&eloop->free_events);
TAILQ_INIT(&eloop->timeouts);
TAILQ_INIT(&eloop->free_timeouts);
eloop->exitcode = EXIT_FAILURE;
return eloop;
}
void
eloop_clear(struct eloop *eloop)
{
struct eloop_event *e;
struct eloop_timeout *t;
if (eloop == NULL)
return;
eloop->nevents = 0;
eloop->signals = NULL;
eloop->signals_len = 0;
while ((e = TAILQ_FIRST(&eloop->events))) {
TAILQ_REMOVE(&eloop->events, e, next);
free(e);
}
while ((e = TAILQ_FIRST(&eloop->free_events))) {
TAILQ_REMOVE(&eloop->free_events, e, next);
free(e);
}
while ((t = TAILQ_FIRST(&eloop->timeouts))) {
TAILQ_REMOVE(&eloop->timeouts, t, next);
free(t);
}
while ((t = TAILQ_FIRST(&eloop->free_timeouts))) {
TAILQ_REMOVE(&eloop->free_timeouts, t, next);
free(t);
}
free(eloop->fds);
eloop->fds = NULL;
eloop->nfds = 0;
}
void
eloop_free(struct eloop *eloop)
{
eloop_clear(eloop);
free(eloop);
}
int
eloop_start(struct eloop *eloop, sigset_t *signals)
{
int n;
struct eloop_event *e;
struct eloop_timeout *t;
struct timespec ts, *tsp;
assert(eloop != NULL);
for (;;) {
if (eloop->exitnow)
break;
if (_eloop_nsig != 0) {
n = _eloop_sig[--_eloop_nsig];
if (eloop->signal_cb != NULL)
eloop->signal_cb(n, eloop->signal_cb_ctx);
continue;
}
t = TAILQ_FIRST(&eloop->timeouts);
if (t == NULL && eloop->nevents == 0)
break;
if (t != NULL)
eloop_reduce_timers(eloop);
if (t != NULL && t->seconds == 0 && t->nseconds == 0) {
TAILQ_REMOVE(&eloop->timeouts, t, next);
t->callback(t->arg);
TAILQ_INSERT_TAIL(&eloop->free_timeouts, t, next);
continue;
}
if (t != NULL) {
if (t->seconds > INT_MAX) {
ts.tv_sec = (time_t)INT_MAX;
ts.tv_nsec = 0;
} else {
ts.tv_sec = (time_t)t->seconds;
ts.tv_nsec = (long)t->nseconds;
}
tsp = &ts;
} else
tsp = NULL;
if (eloop->events_need_setup)
eloop_event_setup_fds(eloop);
n = ppoll(eloop->fds, (nfds_t)eloop->nevents, tsp, signals);
if (n == -1) {
if (errno == EINTR)
continue;
return -errno;
}
if (n == 0)
continue;
TAILQ_FOREACH(e, &eloop->events, next) {
/* Skip freshly added events */
if (e->pollfd == NULL)
continue;
if (e->pollfd->revents)
n--;
if (e->fd != -1 && e->pollfd->revents & POLLOUT) {
if (e->write_cb != NULL)
e->write_cb(e->write_cb_arg);
}
if (e->fd != -1 &&
e->pollfd != NULL && e->pollfd->revents)
{
if (e->read_cb != NULL)
e->read_cb(e->read_cb_arg);
}
if (n == 0)
break;
}
}
return eloop->exitcode;
}