libusb/os/events_posix.c - third_party/libusb - Git at Google

 /*
  * libusb event abstraction on POSIX platforms
  *
  * Copyright © 2020 Chris Dickens <christopher.a.dickens@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #include "libusbi.h"

 #include <errno.h>
 #include <fcntl.h>
 #ifdef HAVE_EVENTFD
 #include <sys/eventfd.h>
 #endif
 #ifdef HAVE_TIMERFD
 #include <sys/timerfd.h>
 #endif
 #include <unistd.h>

 #ifdef HAVE_EVENTFD
 #define EVENT_READ_FD(e)	((e)->eventfd)
 #define EVENT_WRITE_FD(e)	((e)->eventfd)
 #else
 #define EVENT_READ_FD(e)	((e)->pipefd[0])
 #define EVENT_WRITE_FD(e)	((e)->pipefd[1])
 #endif

 #ifdef HAVE_NFDS_T
 typedef nfds_t usbi_nfds_t;
 #else
 typedef unsigned int usbi_nfds_t;
 #endif

 int usbi_create_event(usbi_event_t *event)
 {
 #ifdef HAVE_EVENTFD
 	event->eventfd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
 	if (event->eventfd == -1) {
 		usbi_err(NULL, "failed to create eventfd, errno=%d", errno);
 		return LIBUSB_ERROR_OTHER;
 	}

 	return 0;
 #else
 #if defined(HAVE_PIPE2)
 	int ret = pipe2(event->pipefd, O_CLOEXEC);
 #else
 	int ret = pipe(event->pipefd);
 #endif

 	if (ret != 0) {
 		usbi_err(NULL, "failed to create pipe, errno=%d", errno);
 		return LIBUSB_ERROR_OTHER;
 	}

 #if !defined(HAVE_PIPE2) && defined(FD_CLOEXEC)
 	ret = fcntl(event->pipefd[0], F_GETFD);
 	if (ret == -1) {
 		usbi_err(NULL, "failed to get pipe fd flags, errno=%d", errno);
 		goto err_close_pipe;
 	}
 	ret = fcntl(event->pipefd[0], F_SETFD, ret | FD_CLOEXEC);
 	if (ret == -1) {
 		usbi_err(NULL, "failed to set pipe fd flags, errno=%d", errno);
 		goto err_close_pipe;
 	}

 	ret = fcntl(event->pipefd[1], F_GETFD);
 	if (ret == -1) {
 		usbi_err(NULL, "failed to get pipe fd flags, errno=%d", errno);
 		goto err_close_pipe;
 	}
 	ret = fcntl(event->pipefd[1], F_SETFD, ret | FD_CLOEXEC);
 	if (ret == -1) {
 		usbi_err(NULL, "failed to set pipe fd flags, errno=%d", errno);
 		goto err_close_pipe;
 	}
 #endif

 	ret = fcntl(event->pipefd[1], F_GETFL);
 	if (ret == -1) {
 		usbi_err(NULL, "failed to get pipe fd status flags, errno=%d", errno);
 		goto err_close_pipe;
 	}
 	ret = fcntl(event->pipefd[1], F_SETFL, ret | O_NONBLOCK);
 	if (ret == -1) {
 		usbi_err(NULL, "failed to set pipe fd status flags, errno=%d", errno);
 		goto err_close_pipe;
 	}

 	return 0;

 err_close_pipe:
 	close(event->pipefd[1]);
 	close(event->pipefd[0]);
 	return LIBUSB_ERROR_OTHER;
 #endif
 }

 void usbi_destroy_event(usbi_event_t *event)
 {
 #ifdef HAVE_EVENTFD
 	if (close(event->eventfd) == -1)
 		usbi_warn(NULL, "failed to close eventfd, errno=%d", errno);
 #else
 	if (close(event->pipefd[1]) == -1)
 		usbi_warn(NULL, "failed to close pipe write end, errno=%d", errno);
 	if (close(event->pipefd[0]) == -1)
 		usbi_warn(NULL, "failed to close pipe read end, errno=%d", errno);
 #endif
 }

 void usbi_signal_event(usbi_event_t *event)
 {
 	uint64_t dummy = 1;
 	ssize_t r;

 	r = write(EVENT_WRITE_FD(event), &dummy, sizeof(dummy));
 	if (r != sizeof(dummy))
 		usbi_warn(NULL, "event write failed");
 }

 void usbi_clear_event(usbi_event_t *event)
 {
 	uint64_t dummy;
 	ssize_t r;

 	r = read(EVENT_READ_FD(event), &dummy, sizeof(dummy));
 	if (r != sizeof(dummy))
 		usbi_warn(NULL, "event read failed");
 }

 #ifdef HAVE_TIMERFD
 int usbi_create_timer(usbi_timer_t *timer)
 {
 	timer->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK | TFD_CLOEXEC);
 	if (timer->timerfd == -1) {
 		usbi_warn(NULL, "failed to create timerfd, errno=%d", errno);
 		return LIBUSB_ERROR_OTHER;
 	}

 	return 0;
 }

 void usbi_destroy_timer(usbi_timer_t *timer)
 {
 	if (close(timer->timerfd) == -1)
 		usbi_warn(NULL, "failed to close timerfd, errno=%d", errno);
 }

 int usbi_arm_timer(usbi_timer_t *timer, const struct timespec *timeout)
 {
 	const struct itimerspec it = { { 0, 0 }, { timeout->tv_sec, timeout->tv_nsec } };

 	if (timerfd_settime(timer->timerfd, TFD_TIMER_ABSTIME, &it, NULL) == -1) {
 		usbi_warn(NULL, "failed to arm timerfd, errno=%d", errno);
 		return LIBUSB_ERROR_OTHER;
 	}

 	return 0;
 }

 int usbi_disarm_timer(usbi_timer_t *timer)
 {
 	const struct itimerspec it = { { 0, 0 }, { 0, 0 } };

 	if (timerfd_settime(timer->timerfd, 0, &it, NULL) == -1) {
 		usbi_warn(NULL, "failed to disarm timerfd, errno=%d", errno);
 		return LIBUSB_ERROR_OTHER;
 	}

 	return 0;
 }
 #endif

 int usbi_alloc_event_data(struct libusb_context *ctx)
 {
 	struct usbi_event_source *ievent_source;
 	struct pollfd *fds;
 	size_t i = 0;

 	if (ctx->event_data) {
 		free(ctx->event_data);
 		ctx->event_data = NULL;
 	}

 	ctx->event_data_cnt = 0;
 	for_each_event_source(ctx, ievent_source)
 		ctx->event_data_cnt++;

 	fds = calloc(ctx->event_data_cnt, sizeof(*fds));
 	if (!fds)
 		return LIBUSB_ERROR_NO_MEM;

 	for_each_event_source(ctx, ievent_source) {
 		fds[i].fd = ievent_source->data.os_handle;
 		fds[i].events = ievent_source->data.poll_events;
 		i++;
 	}

 	ctx->event_data = fds;
 	return 0;
 }

 int usbi_wait_for_events(struct libusb_context *ctx,
 	struct usbi_reported_events *reported_events, int timeout_ms)
 {
 	struct pollfd *fds = ctx->event_data;
 	usbi_nfds_t nfds = (usbi_nfds_t)ctx->event_data_cnt;
 	int internal_fds, num_ready;

 	usbi_dbg(ctx, "poll() %u fds with timeout in %dms", (unsigned int)nfds, timeout_ms);
 	num_ready = poll(fds, nfds, timeout_ms);
 	usbi_dbg(ctx, "poll() returned %d", num_ready);
 	if (num_ready == 0) {
 		if (usbi_using_timer(ctx))
 			goto done;
 		return LIBUSB_ERROR_TIMEOUT;
 	} else if (num_ready == -1) {
 		if (errno == EINTR)
 			return LIBUSB_ERROR_INTERRUPTED;
 		usbi_err(ctx, "poll() failed, errno=%d", errno);
 		return LIBUSB_ERROR_IO;
 	}

 	/* fds[0] is always the internal signalling event */
 	if (fds[0].revents) {
 		reported_events->event_triggered = 1;
 		num_ready--;
 	} else {
 		reported_events->event_triggered = 0;
 	}

 #ifdef HAVE_OS_TIMER
 	/* on timer configurations, fds[1] is the timer */
 	if (usbi_using_timer(ctx) && fds[1].revents) {
 		reported_events->timer_triggered = 1;
 		num_ready--;
 	} else {
 		reported_events->timer_triggered = 0;
 	}
 #endif

 	if (!num_ready)
 		goto done;

 	/* the backend will never need to attempt to handle events on the
 	 * library's internal file descriptors, so we determine how many are
 	 * in use internally for this context and skip these when passing any
 	 * remaining pollfds to the backend. */
 	internal_fds = usbi_using_timer(ctx) ? 2 : 1;
 	fds += internal_fds;
 	nfds -= internal_fds;

 	usbi_mutex_lock(&ctx->event_data_lock);
 	if (ctx->event_flags & USBI_EVENT_EVENT_SOURCES_MODIFIED) {
 		struct usbi_event_source *ievent_source;

 		for_each_removed_event_source(ctx, ievent_source) {
 			usbi_nfds_t n;

 			for (n = 0; n < nfds; n++) {
 				if (ievent_source->data.os_handle != fds[n].fd)
 					continue;
 				if (!fds[n].revents)
 					continue;
 				/* pollfd was removed between the creation of the fds array and
 				 * here. remove triggered revent as it is no longer relevant. */
 				usbi_dbg(ctx, "fd %d was removed, ignoring raised events", fds[n].fd);
 				fds[n].revents = 0;
 				num_ready--;
 				break;
 			}
 		}
 	}
 	usbi_mutex_unlock(&ctx->event_data_lock);

 	if (num_ready) {
 		assert(num_ready > 0);
 		reported_events->event_data = fds;
 		reported_events->event_data_count = (unsigned int)nfds;
 	}

 done:
 	reported_events->num_ready = num_ready;
 	return LIBUSB_SUCCESS;
 }
	/*
	* libusb event abstraction on POSIX platforms
	*
	* Copyright © 2020 Chris Dickens <christopher.a.dickens@gmail.com>
	*
	* This library is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* This library 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
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with this library; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include "libusbi.h"

	#include <errno.h>
	#include <fcntl.h>
	#ifdef HAVE_EVENTFD
	#include <sys/eventfd.h>
	#endif
	#ifdef HAVE_TIMERFD
	#include <sys/timerfd.h>
	#endif
	#include <unistd.h>

	#ifdef HAVE_EVENTFD
	#define EVENT_READ_FD(e) ((e)->eventfd)
	#define EVENT_WRITE_FD(e) ((e)->eventfd)
	#else
	#define EVENT_READ_FD(e) ((e)->pipefd[0])
	#define EVENT_WRITE_FD(e) ((e)->pipefd[1])
	#endif

	#ifdef HAVE_NFDS_T
	typedef nfds_t usbi_nfds_t;
	#else
	typedef unsigned int usbi_nfds_t;
	#endif

	int usbi_create_event(usbi_event_t *event)
	{
	#ifdef HAVE_EVENTFD
	event->eventfd = eventfd(0, EFD_NONBLOCK \| EFD_CLOEXEC);
	if (event->eventfd == -1) {
	usbi_err(NULL, "failed to create eventfd, errno=%d", errno);
	return LIBUSB_ERROR_OTHER;
	}

	return 0;
	#else
	#if defined(HAVE_PIPE2)
	int ret = pipe2(event->pipefd, O_CLOEXEC);
	#else
	int ret = pipe(event->pipefd);
	#endif

	if (ret != 0) {
	usbi_err(NULL, "failed to create pipe, errno=%d", errno);
	return LIBUSB_ERROR_OTHER;
	}

	#if !defined(HAVE_PIPE2) && defined(FD_CLOEXEC)
	ret = fcntl(event->pipefd[0], F_GETFD);
	if (ret == -1) {
	usbi_err(NULL, "failed to get pipe fd flags, errno=%d", errno);
	goto err_close_pipe;
	}
	ret = fcntl(event->pipefd[0], F_SETFD, ret \| FD_CLOEXEC);
	if (ret == -1) {
	usbi_err(NULL, "failed to set pipe fd flags, errno=%d", errno);
	goto err_close_pipe;
	}

	ret = fcntl(event->pipefd[1], F_GETFD);
	if (ret == -1) {
	usbi_err(NULL, "failed to get pipe fd flags, errno=%d", errno);
	goto err_close_pipe;
	}
	ret = fcntl(event->pipefd[1], F_SETFD, ret \| FD_CLOEXEC);
	if (ret == -1) {
	usbi_err(NULL, "failed to set pipe fd flags, errno=%d", errno);
	goto err_close_pipe;
	}
	#endif

	ret = fcntl(event->pipefd[1], F_GETFL);
	if (ret == -1) {
	usbi_err(NULL, "failed to get pipe fd status flags, errno=%d", errno);
	goto err_close_pipe;
	}
	ret = fcntl(event->pipefd[1], F_SETFL, ret \| O_NONBLOCK);
	if (ret == -1) {
	usbi_err(NULL, "failed to set pipe fd status flags, errno=%d", errno);
	goto err_close_pipe;
	}

	return 0;

	err_close_pipe:
	close(event->pipefd[1]);
	close(event->pipefd[0]);
	return LIBUSB_ERROR_OTHER;
	#endif
	}

	void usbi_destroy_event(usbi_event_t *event)
	{
	#ifdef HAVE_EVENTFD
	if (close(event->eventfd) == -1)
	usbi_warn(NULL, "failed to close eventfd, errno=%d", errno);
	#else
	if (close(event->pipefd[1]) == -1)
	usbi_warn(NULL, "failed to close pipe write end, errno=%d", errno);
	if (close(event->pipefd[0]) == -1)
	usbi_warn(NULL, "failed to close pipe read end, errno=%d", errno);
	#endif
	}

	void usbi_signal_event(usbi_event_t *event)
	{
	uint64_t dummy = 1;
	ssize_t r;

	r = write(EVENT_WRITE_FD(event), &dummy, sizeof(dummy));
	if (r != sizeof(dummy))
	usbi_warn(NULL, "event write failed");
	}

	void usbi_clear_event(usbi_event_t *event)
	{
	uint64_t dummy;
	ssize_t r;

	r = read(EVENT_READ_FD(event), &dummy, sizeof(dummy));
	if (r != sizeof(dummy))
	usbi_warn(NULL, "event read failed");
	}

	#ifdef HAVE_TIMERFD
	int usbi_create_timer(usbi_timer_t *timer)
	{
	timer->timerfd = timerfd_create(CLOCK_MONOTONIC, TFD_NONBLOCK \| TFD_CLOEXEC);
	if (timer->timerfd == -1) {
	usbi_warn(NULL, "failed to create timerfd, errno=%d", errno);
	return LIBUSB_ERROR_OTHER;
	}

	return 0;
	}

	void usbi_destroy_timer(usbi_timer_t *timer)
	{
	if (close(timer->timerfd) == -1)
	usbi_warn(NULL, "failed to close timerfd, errno=%d", errno);
	}

	int usbi_arm_timer(usbi_timer_t timer, const struct timespec timeout)
	{
	const struct itimerspec it = { { 0, 0 }, { timeout->tv_sec, timeout->tv_nsec } };

	if (timerfd_settime(timer->timerfd, TFD_TIMER_ABSTIME, &it, NULL) == -1) {
	usbi_warn(NULL, "failed to arm timerfd, errno=%d", errno);
	return LIBUSB_ERROR_OTHER;
	}

	return 0;
	}

	int usbi_disarm_timer(usbi_timer_t *timer)
	{
	const struct itimerspec it = { { 0, 0 }, { 0, 0 } };

	if (timerfd_settime(timer->timerfd, 0, &it, NULL) == -1) {
	usbi_warn(NULL, "failed to disarm timerfd, errno=%d", errno);
	return LIBUSB_ERROR_OTHER;
	}

	return 0;
	}
	#endif

	int usbi_alloc_event_data(struct libusb_context *ctx)
	{
	struct usbi_event_source *ievent_source;
	struct pollfd *fds;
	size_t i = 0;

	if (ctx->event_data) {
	free(ctx->event_data);
	ctx->event_data = NULL;
	}

	ctx->event_data_cnt = 0;
	for_each_event_source(ctx, ievent_source)
	ctx->event_data_cnt++;

	fds = calloc(ctx->event_data_cnt, sizeof(*fds));
	if (!fds)
	return LIBUSB_ERROR_NO_MEM;

	for_each_event_source(ctx, ievent_source) {
	fds[i].fd = ievent_source->data.os_handle;
	fds[i].events = ievent_source->data.poll_events;
	i++;
	}

	ctx->event_data = fds;
	return 0;
	}

	int usbi_wait_for_events(struct libusb_context *ctx,
	struct usbi_reported_events *reported_events, int timeout_ms)
	{
	struct pollfd *fds = ctx->event_data;
	usbi_nfds_t nfds = (usbi_nfds_t)ctx->event_data_cnt;
	int internal_fds, num_ready;

	usbi_dbg(ctx, "poll() %u fds with timeout in %dms", (unsigned int)nfds, timeout_ms);
	num_ready = poll(fds, nfds, timeout_ms);
	usbi_dbg(ctx, "poll() returned %d", num_ready);
	if (num_ready == 0) {
	if (usbi_using_timer(ctx))
	goto done;
	return LIBUSB_ERROR_TIMEOUT;
	} else if (num_ready == -1) {
	if (errno == EINTR)
	return LIBUSB_ERROR_INTERRUPTED;
	usbi_err(ctx, "poll() failed, errno=%d", errno);
	return LIBUSB_ERROR_IO;
	}

	/* fds[0] is always the internal signalling event */
	if (fds[0].revents) {
	reported_events->event_triggered = 1;
	num_ready--;
	} else {
	reported_events->event_triggered = 0;
	}

	#ifdef HAVE_OS_TIMER
	/* on timer configurations, fds[1] is the timer */
	if (usbi_using_timer(ctx) && fds[1].revents) {
	reported_events->timer_triggered = 1;
	num_ready--;
	} else {
	reported_events->timer_triggered = 0;
	}
	#endif

	if (!num_ready)
	goto done;

	/* the backend will never need to attempt to handle events on the
	* library's internal file descriptors, so we determine how many are
	* in use internally for this context and skip these when passing any
	* remaining pollfds to the backend. */
	internal_fds = usbi_using_timer(ctx) ? 2 : 1;
	fds += internal_fds;
	nfds -= internal_fds;

	usbi_mutex_lock(&ctx->event_data_lock);
	if (ctx->event_flags & USBI_EVENT_EVENT_SOURCES_MODIFIED) {
	struct usbi_event_source *ievent_source;

	for_each_removed_event_source(ctx, ievent_source) {
	usbi_nfds_t n;

	for (n = 0; n < nfds; n++) {
	if (ievent_source->data.os_handle != fds[n].fd)
	continue;
	if (!fds[n].revents)
	continue;
	/* pollfd was removed between the creation of the fds array and
	* here. remove triggered revent as it is no longer relevant. */
	usbi_dbg(ctx, "fd %d was removed, ignoring raised events", fds[n].fd);
	fds[n].revents = 0;
	num_ready--;
	break;
	}
	}
	}
	usbi_mutex_unlock(&ctx->event_data_lock);

	if (num_ready) {
	assert(num_ready > 0);
	reported_events->event_data = fds;
	reported_events->event_data_count = (unsigned int)nfds;
	}

	done:
	reported_events->num_ready = num_ready;
	return LIBUSB_SUCCESS;
	}