tevent: Add a poll backend

1 files changed, 306 insertions, 0 deletions

diff --git a/lib/tevent/tevent_poll.c b/lib/tevent/tevent_poll.c
new file mode 100644
index 00000000000..c1331940723
--- /dev/null
+++ b/lib/tevent/tevent_poll.c
@@ -0,0 +1,306 @@
+/*
+   Unix SMB/CIFS implementation.
+   main select loop and event handling
+   Copyright (C) Andrew Tridgell	2003-2005
+   Copyright (C) Stefan Metzmacher	2005-2009
+
+     ** NOTE! The following LGPL license applies to the tevent
+     ** library. This does NOT imply that all of Samba is released
+     ** under the LGPL
+
+   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 3 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "replace.h"
+#include "system/filesys.h"
+#include "system/select.h"
+#include "tevent.h"
+#include "tevent_util.h"
+#include "tevent_internal.h"
+
+struct poll_event_context {
+	/*
+	 * These two arrays are maintained together.
+	 */
+	struct pollfd *fds;
+	struct tevent_fd **fd_events;
+	int num_fds;
+
+	/* information for exiting from the event loop */
+	int exit_code;
+};
+
+/*
+  create a select_event_context structure.
+*/
+static int poll_event_context_init(struct tevent_context *ev)
+{
+	struct poll_event_context *poll_ev;
+
+	poll_ev = talloc_zero(ev, struct poll_event_context);
+	if (poll_ev == NULL) {
+		return -1;
+	}
+	ev->additional_data = poll_ev;
+	return 0;
+}
+
+/*
+  destroy an fd_event
+*/
+static int poll_event_fd_destructor(struct tevent_fd *fde)
+{
+	struct tevent_context *ev = fde->event_ctx;
+	struct poll_event_context *poll_ev = NULL;
+	struct tevent_fd *moved_fde;
+	int del_idx;
+
+	if (ev == NULL) {
+		goto done;
+	}
+
+	poll_ev = talloc_get_type_abort(
+		ev->additional_data, struct poll_event_context);
+
+	/*
+	 * Assume a void * can carry enough bits to hold num_fds.
+	 */
+	del_idx = (int)(fde->additional_data);
+
+	moved_fde = poll_ev->fd_events[poll_ev->num_fds-1];
+	poll_ev->fd_events[del_idx] = moved_fde;
+	poll_ev->fds[del_idx] = poll_ev->fds[poll_ev->num_fds-1];
+	moved_fde->additional_data = (void *)del_idx;
+
+	poll_ev->num_fds -= 1;
+done:
+	return tevent_common_fd_destructor(fde);
+}
+
+/*
+  add a fd based event
+  return NULL on failure (memory allocation error)
+*/
+static struct tevent_fd *poll_event_add_fd(struct tevent_context *ev,
+					   TALLOC_CTX *mem_ctx,
+					   int fd, uint16_t flags,
+					   tevent_fd_handler_t handler,
+					   void *private_data,
+					   const char *handler_name,
+					   const char *location)
+{
+	struct poll_event_context *poll_ev = talloc_get_type_abort(
+		ev->additional_data, struct poll_event_context);
+	struct pollfd *pfd;
+	struct tevent_fd *fde;
+
+	fde = tevent_common_add_fd(ev, mem_ctx, fd, flags,
+				   handler, private_data,
+				   handler_name, location);
+	if (fde == NULL) {
+		return NULL;
+	}
+
+	/* we allocate 16 slots to avoid a lot of reallocations */
+	if (talloc_array_length(poll_ev->fds) == poll_ev->num_fds) {
+		struct pollfd *tmp_fds;
+		struct tevent_fd **tmp_fd_events;
+		tmp_fds = talloc_realloc(
+			poll_ev, poll_ev->fds, struct pollfd,
+			poll_ev->num_fds + 16);
+		if (tmp_fds == NULL) {
+			TALLOC_FREE(fde);
+			return NULL;
+		}
+		poll_ev->fds = tmp_fds;
+
+		tmp_fd_events = talloc_realloc(
+			poll_ev, poll_ev->fd_events, struct tevent_fd *,
+			poll_ev->num_fds + 16);
+		if (tmp_fd_events == NULL) {
+			TALLOC_FREE(fde);
+			return NULL;
+		}
+		poll_ev->fd_events = tmp_fd_events;
+	}
+
+	pfd = &poll_ev->fds[poll_ev->num_fds];
+
+	pfd->fd = fd;
+
+	pfd->events = 0;
+	pfd->revents = 0;
+
+	if (flags & TEVENT_FD_READ) {
+		pfd->events |= (POLLIN|POLLHUP);
+	}
+	if (flags & TEVENT_FD_WRITE) {
+		pfd->events |= (POLLOUT);
+	}
+
+	/*
+	 * Assume a void * can carry enough bits to hold num_fds.
+	 */
+	fde->additional_data = (void *)poll_ev->num_fds;
+	poll_ev->fd_events[poll_ev->num_fds] = fde;
+
+	poll_ev->num_fds += 1;
+
+	talloc_set_destructor(fde, poll_event_fd_destructor);
+
+	return fde;
+}
+
+/*
+  set the fd event flags
+*/
+static void poll_event_set_fd_flags(struct tevent_fd *fde, uint16_t flags)
+{
+	struct poll_event_context *poll_ev = talloc_get_type_abort(
+		fde->event_ctx->additional_data, struct poll_event_context);
+	int idx;
+	uint16_t pollflags = 0;
+
+	if (flags & TEVENT_FD_READ) {
+		pollflags |= (POLLIN|POLLHUP);
+	}
+	if (flags & TEVENT_FD_WRITE) {
+		pollflags |= (POLLOUT);
+	}
+
+	idx = (int)(fde->additional_data);
+	poll_ev->fds[idx].events = pollflags;
+
+	fde->flags = flags;
+}
+
+/*
+  event loop handling using select()
+*/
+static int poll_event_loop_poll(struct tevent_context *ev,
+				struct timeval *tvalp)
+{
+	struct poll_event_context *poll_ev = talloc_get_type_abort(
+		ev->additional_data, struct poll_event_context);
+	struct tevent_fd *fde;
+	int pollrtn;
+	int timeout = -1;
+
+	if (ev->signal_events && tevent_common_check_signal(ev)) {
+		return 0;
+	}
+
+	if (tvalp != NULL) {
+		timeout = tvalp->tv_sec * 1000;
+		timeout += (tvalp->tv_usec + 999) / 1000;
+	}
+
+	pollrtn = poll(poll_ev->fds, poll_ev->num_fds, timeout);
+
+	if (pollrtn == -1 && errno == EINTR && ev->signal_events) {
+		tevent_common_check_signal(ev);
+		return 0;
+	}
+
+	if (pollrtn == -1 && errno == EBADF) {
+		/* the socket is dead! this should never
+		   happen as the socket should have first been
+		   made readable and that should have removed
+		   the event, so this must be a bug. This is a
+		   fatal error. */
+		tevent_debug(ev, TEVENT_DEBUG_FATAL,
+			     "ERROR: EBADF on poll_event_loop_once\n");
+		poll_ev->exit_code = EBADF;
+		return -1;
+	}
+
+	if (pollrtn == 0 && tvalp) {
+		/* we don't care about a possible delay here */
+		tevent_common_loop_timer_delay(ev);
+		return 0;
+	}
+
+	if (pollrtn > 0) {
+		/* at least one file descriptor is ready - check
+		   which ones and call the handler, being careful to allow
+		   the handler to remove itself when called */
+		for (fde = ev->fd_events; fde; fde = fde->next) {
+			struct pollfd *pfd;
+			int pfd_idx;
+			uint16_t flags = 0;
+
+			pfd_idx = (int)(fde->additional_data);
+
+			pfd = &poll_ev->fds[pfd_idx];
+
+			if (pfd->revents & (POLLIN|POLLHUP|POLLERR)) {
+				flags |= TEVENT_FD_READ;
+			}
+			if (pfd->revents & POLLOUT) {
+				flags |= TEVENT_FD_WRITE;
+			}
+			if (flags != 0) {
+				fde->handler(ev, fde, flags,
+					     fde->private_data);
+				break;
+			}
+		}
+	}
+
+	return 0;
+}
+
+/*
+  do a single event loop using the events defined in ev
+*/
+static int poll_event_loop_once(struct tevent_context *ev,
+				const char *location)
+{
+	struct timeval tval;
+
+	if (ev->signal_events &&
+	    tevent_common_check_signal(ev)) {
+		return 0;
+	}
+
+	if (ev->immediate_events &&
+	    tevent_common_loop_immediate(ev)) {
+		return 0;
+	}
+
+	tval = tevent_common_loop_timer_delay(ev);
+	if (tevent_timeval_is_zero(&tval)) {
+		return 0;
+	}
+
+	return poll_event_loop_poll(ev, &tval);
+}
+
+static const struct tevent_ops poll_event_ops = {
+	.context_init		= poll_event_context_init,
+	.add_fd			= poll_event_add_fd,
+	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
+	.get_fd_flags		= tevent_common_fd_get_flags,
+	.set_fd_flags		= poll_event_set_fd_flags,
+	.add_timer		= tevent_common_add_timer,
+	.schedule_immediate	= tevent_common_schedule_immediate,
+	.add_signal		= tevent_common_add_signal,
+	.loop_once		= poll_event_loop_once,
+	.loop_wait		= tevent_common_loop_wait,
+};
+
+_PRIVATE_ bool tevent_poll_init(void)
+{
+	return tevent_register_backend("poll", &poll_event_ops);
+}