1 files changed, 571 insertions, 0 deletions

diff --git a/lib/tevent/tevent_wrapper.c b/lib/tevent/tevent_wrapper.c
new file mode 100644
index 0000000..a0e915f
--- /dev/null
+++ b/lib/tevent/tevent_wrapper.c
@@ -0,0 +1,571 @@
+/*
+   Infrastructure for event context wrappers
+
+   Copyright (C) Stefan Metzmacher 2014
+
+     ** 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"
+#ifdef HAVE_PTHREAD
+#include "system/threads.h"
+#endif
+#define TEVENT_DEPRECATED 1
+#include "tevent.h"
+#include "tevent_internal.h"
+#include "tevent_util.h"
+
+static int tevent_wrapper_glue_context_init(struct tevent_context *ev)
+{
+	tevent_abort(ev, "tevent_wrapper_glue_context_init() called");
+	errno = ENOSYS;
+	return -1;
+}
+
+static struct tevent_fd *tevent_wrapper_glue_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 tevent_wrapper_glue *glue = ev->wrapper.glue;
+	struct tevent_fd *fde = NULL;
+
+	if (glue->destroyed) {
+		tevent_abort(ev, "add_fd wrapper use after free");
+		return NULL;
+	}
+
+	if (glue->main_ev == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	fde = _tevent_add_fd(glue->main_ev, mem_ctx, fd, flags,
+			     handler, private_data,
+			     handler_name, location);
+	if (fde == NULL) {
+		return NULL;
+	}
+
+	fde->wrapper = glue;
+
+	return fde;
+}
+
+static struct tevent_timer *tevent_wrapper_glue_add_timer(struct tevent_context *ev,
+							  TALLOC_CTX *mem_ctx,
+							  struct timeval next_event,
+							  tevent_timer_handler_t handler,
+							  void *private_data,
+							  const char *handler_name,
+							  const char *location)
+{
+	struct tevent_wrapper_glue *glue = ev->wrapper.glue;
+	struct tevent_timer *te = NULL;
+
+	if (glue->destroyed) {
+		tevent_abort(ev, "add_timer wrapper use after free");
+		return NULL;
+	}
+
+	if (glue->main_ev == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	te = _tevent_add_timer(glue->main_ev, mem_ctx, next_event,
+			       handler, private_data,
+			       handler_name, location);
+	if (te == NULL) {
+		return NULL;
+	}
+
+	te->wrapper = glue;
+
+	return te;
+}
+
+static void tevent_wrapper_glue_schedule_immediate(struct tevent_immediate *im,
+						   struct tevent_context *ev,
+						   tevent_immediate_handler_t handler,
+						   void *private_data,
+						   const char *handler_name,
+						   const char *location)
+{
+	struct tevent_wrapper_glue *glue = ev->wrapper.glue;
+
+	if (glue->destroyed) {
+		tevent_abort(ev, "scheduke_immediate wrapper use after free");
+		return;
+	}
+
+	if (glue->main_ev == NULL) {
+		tevent_abort(ev, location);
+		errno = EINVAL;
+		return;
+	}
+
+	_tevent_schedule_immediate(im, glue->main_ev,
+				   handler, private_data,
+				   handler_name, location);
+
+	im->wrapper = glue;
+
+	return;
+}
+
+static struct tevent_signal *tevent_wrapper_glue_add_signal(struct tevent_context *ev,
+							    TALLOC_CTX *mem_ctx,
+							    int signum, int sa_flags,
+							    tevent_signal_handler_t handler,
+							    void *private_data,
+							    const char *handler_name,
+							    const char *location)
+{
+	struct tevent_wrapper_glue *glue = ev->wrapper.glue;
+	struct tevent_signal *se = NULL;
+
+	if (glue->destroyed) {
+		tevent_abort(ev, "add_signal wrapper use after free");
+		return NULL;
+	}
+
+	if (glue->main_ev == NULL) {
+		errno = EINVAL;
+		return NULL;
+	}
+
+	se = _tevent_add_signal(glue->main_ev, mem_ctx,
+				signum, sa_flags,
+				handler, private_data,
+				handler_name, location);
+	if (se == NULL) {
+		return NULL;
+	}
+
+	se->wrapper = glue;
+
+	return se;
+}
+
+static int tevent_wrapper_glue_loop_once(struct tevent_context *ev, const char *location)
+{
+	tevent_abort(ev, "tevent_wrapper_glue_loop_once() called");
+	errno = ENOSYS;
+	return -1;
+}
+
+static int tevent_wrapper_glue_loop_wait(struct tevent_context *ev, const char *location)
+{
+	tevent_abort(ev, "tevent_wrapper_glue_loop_wait() called");
+	errno = ENOSYS;
+	return -1;
+}
+
+static const struct tevent_ops tevent_wrapper_glue_ops = {
+	.context_init		= tevent_wrapper_glue_context_init,
+	.add_fd			= tevent_wrapper_glue_add_fd,
+	.set_fd_close_fn	= tevent_common_fd_set_close_fn,
+	.get_fd_flags		= tevent_common_fd_get_flags,
+	.set_fd_flags		= tevent_common_fd_set_flags,
+	.add_timer		= tevent_wrapper_glue_add_timer,
+	.schedule_immediate	= tevent_wrapper_glue_schedule_immediate,
+	.add_signal		= tevent_wrapper_glue_add_signal,
+	.loop_once		= tevent_wrapper_glue_loop_once,
+	.loop_wait		= tevent_wrapper_glue_loop_wait,
+};
+
+static int tevent_wrapper_context_destructor(struct tevent_context *wrap_ev)
+{
+	struct tevent_wrapper_glue *glue = wrap_ev->wrapper.glue;
+	struct tevent_context *main_ev = NULL;
+	struct tevent_fd *fd = NULL, *fn = NULL;
+	struct tevent_timer *te = NULL, *tn = NULL;
+	struct tevent_immediate *ie = NULL, *in = NULL;
+	struct tevent_signal *se = NULL, *sn = NULL;
+#ifdef HAVE_PTHREAD
+	struct tevent_threaded_context *tctx = NULL, *tctxn = NULL;
+#endif
+
+	if (glue == NULL) {
+		tevent_abort(wrap_ev,
+			"tevent_wrapper_context_destructor() active on main");
+		/* static checker support, return below is never reached */
+		return -1;
+	}
+
+	if (glue->destroyed && glue->busy) {
+		tevent_common_check_double_free(wrap_ev,
+			"tevent_context wrapper double free");
+	}
+	glue->destroyed = true;
+
+	if (glue->busy) {
+		return -1;
+	}
+
+	main_ev = glue->main_ev;
+	if (main_ev == NULL) {
+		return 0;
+	}
+
+	tevent_debug(wrap_ev, TEVENT_DEBUG_TRACE,
+		     "Destroying wrapper context %p \"%s\"\n",
+		     wrap_ev, talloc_get_name(glue->private_state));
+
+	glue->main_ev = NULL;
+	DLIST_REMOVE(main_ev->wrapper.list, glue);
+
+#ifdef HAVE_PTHREAD
+	for (tctx = main_ev->threaded_contexts; tctx != NULL; tctx = tctxn) {
+		int ret;
+
+		tctxn = tctx->next;
+
+		if (tctx->event_ctx != glue->wrap_ev) {
+			continue;
+		}
+
+		ret = pthread_mutex_lock(&tctx->event_ctx_mutex);
+		if (ret != 0) {
+			abort();
+		}
+
+		/*
+		 * Indicate to the thread that the tevent_context is
+		 * gone. The counterpart of this is in
+		 * _tevent_threaded_schedule_immediate, there we read
+		 * this under the threaded_context's mutex.
+		 */
+
+		tctx->event_ctx = NULL;
+
+		ret = pthread_mutex_unlock(&tctx->event_ctx_mutex);
+		if (ret != 0) {
+			abort();
+		}
+
+		DLIST_REMOVE(main_ev->threaded_contexts, tctx);
+	}
+#endif
+
+	for (fd = main_ev->fd_events; fd; fd = fn) {
+		fn = fd->next;
+
+		if (fd->wrapper != glue) {
+			continue;
+		}
+
+		tevent_fd_set_flags(fd, 0);
+
+		fd->wrapper = NULL;
+		fd->event_ctx = NULL;
+		DLIST_REMOVE(main_ev->fd_events, fd);
+	}
+
+	for (te = main_ev->timer_events; te; te = tn) {
+		tn = te->next;
+
+		if (te->wrapper != glue) {
+			continue;
+		}
+
+		te->wrapper = NULL;
+		te->event_ctx = NULL;
+
+		if (main_ev->last_zero_timer == te) {
+			main_ev->last_zero_timer = DLIST_PREV(te);
+		}
+		DLIST_REMOVE(main_ev->timer_events, te);
+	}
+
+	for (ie = main_ev->immediate_events; ie; ie = in) {
+		in = ie->next;
+
+		if (ie->wrapper != glue) {
+			continue;
+		}
+
+		ie->wrapper = NULL;
+		ie->event_ctx = NULL;
+		ie->cancel_fn = NULL;
+		DLIST_REMOVE(main_ev->immediate_events, ie);
+	}
+
+	for (se = main_ev->signal_events; se; se = sn) {
+		sn = se->next;
+
+		if (se->wrapper != glue) {
+			continue;
+		}
+
+		se->wrapper = NULL;
+		tevent_cleanup_pending_signal_handlers(se);
+	}
+
+	return 0;
+}
+
+struct tevent_context *_tevent_context_wrapper_create(struct tevent_context *main_ev,
+						TALLOC_CTX *mem_ctx,
+						const struct tevent_wrapper_ops *ops,
+						void *pstate,
+						size_t psize,
+						const char *type,
+						const char *location)
+{
+	void **ppstate = (void **)pstate;
+	struct tevent_context *ev = NULL;
+
+	if (main_ev->wrapper.glue != NULL) {
+		/*
+		 * stacking of wrappers is not supported
+		 */
+		tevent_debug(main_ev->wrapper.glue->main_ev, TEVENT_DEBUG_FATAL,
+			     "%s: %s() stacking not allowed\n",
+			     __func__, location);
+		errno = EINVAL;
+		return NULL;
+	}
+
+	if (main_ev->nesting.allowed) {
+		/*
+		 * wrappers conflict with nesting
+		 */
+		tevent_debug(main_ev, TEVENT_DEBUG_FATAL,
+			     "%s: %s() conflicts with nesting\n",
+			     __func__, location);
+		errno = EINVAL;
+		return NULL;
+	}
+
+	ev = talloc_zero(mem_ctx, struct tevent_context);
+	if (ev == NULL) {
+		return NULL;
+	}
+	ev->ops = &tevent_wrapper_glue_ops;
+
+	ev->wrapper.glue = talloc_zero(ev, struct tevent_wrapper_glue);
+	if (ev->wrapper.glue == NULL) {
+		talloc_free(ev);
+		return NULL;
+	}
+
+	talloc_set_destructor(ev, tevent_wrapper_context_destructor);
+
+	ev->wrapper.glue->wrap_ev = ev;
+	ev->wrapper.glue->main_ev = main_ev;
+	ev->wrapper.glue->ops = ops;
+	ev->wrapper.glue->private_state = talloc_zero_size(ev->wrapper.glue, psize);
+	if (ev->wrapper.glue->private_state == NULL) {
+		talloc_free(ev);
+		return NULL;
+	}
+	talloc_set_name_const(ev->wrapper.glue->private_state, type);
+
+	DLIST_ADD_END(main_ev->wrapper.list, ev->wrapper.glue);
+
+	*ppstate = ev->wrapper.glue->private_state;
+	return ev;
+}
+
+bool tevent_context_is_wrapper(struct tevent_context *ev)
+{
+	if (ev->wrapper.glue != NULL) {
+		return true;
+	}
+
+	return false;
+}
+
+_PRIVATE_
+struct tevent_context *tevent_wrapper_main_ev(struct tevent_context *ev)
+{
+	if (ev == NULL) {
+		return NULL;
+	}
+
+	if (ev->wrapper.glue == NULL) {
+		return ev;
+	}
+
+	return ev->wrapper.glue->main_ev;
+}
+
+/*
+ * 32 stack elements should be more than enough
+ *
+ * e.g. Samba uses just 8 elements for [un]become_{root,user}()
+ */
+#define TEVENT_WRAPPER_STACK_SIZE 32
+
+static struct tevent_wrapper_stack {
+	const void *ev_ptr;
+	const struct tevent_wrapper_glue *wrapper;
+} wrapper_stack[TEVENT_WRAPPER_STACK_SIZE];
+
+static size_t wrapper_stack_idx;
+
+_PRIVATE_
+void tevent_wrapper_push_use_internal(struct tevent_context *ev,
+				      struct tevent_wrapper_glue *wrapper)
+{
+	/*
+	 * ev and wrapper need to belong together!
+	 * It's also fine to only have a raw ev
+	 * without a wrapper.
+	 */
+	if (unlikely(ev->wrapper.glue != wrapper)) {
+		tevent_abort(ev, "tevent_wrapper_push_use_internal() invalid arguments");
+		return;
+	}
+
+	if (wrapper != NULL) {
+		if (unlikely(wrapper->busy)) {
+			tevent_abort(ev, "wrapper already busy!");
+			return;
+		}
+		wrapper->busy = true;
+	}
+
+	if (unlikely(wrapper_stack_idx >= TEVENT_WRAPPER_STACK_SIZE)) {
+		tevent_abort(ev, "TEVENT_WRAPPER_STACK_SIZE overflow");
+		return;
+	}
+
+	wrapper_stack[wrapper_stack_idx] = (struct tevent_wrapper_stack) {
+		.ev_ptr = ev,
+		.wrapper = wrapper,
+	};
+	wrapper_stack_idx++;
+}
+
+_PRIVATE_
+void tevent_wrapper_pop_use_internal(const struct tevent_context *__ev_ptr,
+				     struct tevent_wrapper_glue *wrapper)
+{
+	struct tevent_context *main_ev = NULL;
+
+	/*
+	 * Note that __ev_ptr might a a stale pointer and should not
+	 * be touched, we just compare the pointer value in order
+	 * to enforce the stack order.
+	 */
+
+	if (wrapper != NULL) {
+		main_ev = wrapper->main_ev;
+	}
+
+	if (unlikely(wrapper_stack_idx == 0)) {
+		tevent_abort(main_ev, "tevent_wrapper stack already empty");
+		return;
+	}
+	wrapper_stack_idx--;
+
+	if (wrapper != NULL) {
+		wrapper->busy = false;
+	}
+
+	if (wrapper_stack[wrapper_stack_idx].ev_ptr != __ev_ptr) {
+		tevent_abort(main_ev, "tevent_wrapper_pop_use mismatch ev!");
+		return;
+	}
+	if (wrapper_stack[wrapper_stack_idx].wrapper != wrapper) {
+		tevent_abort(main_ev, "tevent_wrapper_pop_use mismatch wrap!");
+		return;
+	}
+
+	if (wrapper == NULL) {
+		return;
+	}
+
+	if (wrapper->destroyed) {
+		/*
+		 * Notice that we can't use TALLOC_FREE()
+		 * here because wrapper is a talloc child
+		 * of wrapper->wrap_ev.
+		 */
+		talloc_free(wrapper->wrap_ev);
+	}
+}
+
+bool _tevent_context_push_use(struct tevent_context *ev,
+			      const char *location)
+{
+	bool ok;
+
+	if (ev->wrapper.glue == NULL) {
+		tevent_wrapper_push_use_internal(ev, NULL);
+		return true;
+	}
+
+	if (ev->wrapper.glue->main_ev == NULL) {
+		return false;
+	}
+
+	tevent_wrapper_push_use_internal(ev, ev->wrapper.glue);
+	ok = ev->wrapper.glue->ops->before_use(ev->wrapper.glue->wrap_ev,
+					       ev->wrapper.glue->private_state,
+					       ev->wrapper.glue->main_ev,
+					       location);
+	if (!ok) {
+		tevent_wrapper_pop_use_internal(ev, ev->wrapper.glue);
+		return false;
+	}
+
+	return true;
+}
+
+void _tevent_context_pop_use(struct tevent_context *ev,
+			     const char *location)
+{
+	tevent_wrapper_pop_use_internal(ev, ev->wrapper.glue);
+
+	if (ev->wrapper.glue == NULL) {
+		return;
+	}
+
+	if (ev->wrapper.glue->main_ev == NULL) {
+		return;
+	}
+
+	ev->wrapper.glue->ops->after_use(ev->wrapper.glue->wrap_ev,
+					 ev->wrapper.glue->private_state,
+					 ev->wrapper.glue->main_ev,
+					 location);
+}
+
+bool tevent_context_same_loop(struct tevent_context *ev1,
+			      struct tevent_context *ev2)
+{
+	struct tevent_context *main_ev1 = tevent_wrapper_main_ev(ev1);
+	struct tevent_context *main_ev2 = tevent_wrapper_main_ev(ev2);
+
+	if (main_ev1 == NULL) {
+		return false;
+	}
+
+	if (main_ev1 == main_ev2) {
+		return true;
+	}
+
+	return false;
+}