From: Simon Marchi <simon.marchi@efficios.com>
Date: Thu, 28 Nov 2019 22:51:01 +0000 (-0500)
Subject: actions: introduce function typedef for creating actions from buffer
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=869a3c2d29b8c75cc3b30f76ebd38c9a8b239018

actions: introduce function typedef for creating actions from buffer

The only existing action type, LTTNG_ACTION_TYPE_NOTIFY, does not
require deserializing additional data (on top of the action type field),
so lttng_action_create_from_buffer handles it in a trivial way.
Upcoming patches will introduce new action types which will need to
deserialize some additional data.  This patch prepares
lttng_action_create_from_buffer for that by making it call an
action-specific function for deserializing this additional data.  The
changes are inspired by what lttng_condition_create_from_buffer does.

No functional changes intended.

Change-Id: I469a67b744aa2cf7a45d7d970f1bbee6a994a2a9
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/include/lttng/action/action-internal.h b/include/lttng/action/action-internal.h
index 787e9087a..d08024a03 100644
--- a/include/lttng/action/action-internal.h
+++ b/include/lttng/action/action-internal.h
@@ -19,6 +19,9 @@ typedef bool (*action_validate_cb)(struct lttng_action *action);
 typedef void (*action_destroy_cb)(struct lttng_action *action);
 typedef int (*action_serialize_cb)(struct lttng_action *action,
 		struct lttng_dynamic_buffer *buf);
+typedef ssize_t (*action_create_from_buffer_cb)(
+		const struct lttng_buffer_view *view,
+		struct lttng_action **action);
 
 struct lttng_action {
 	enum lttng_action_type type;
diff --git a/include/lttng/action/notify-internal.h b/include/lttng/action/notify-internal.h
index e6cb174ce..a9d50612d 100644
--- a/include/lttng/action/notify-internal.h
+++ b/include/lttng/action/notify-internal.h
@@ -15,4 +15,9 @@ struct lttng_action_notify {
 	struct lttng_action parent;
 };
 
+LTTNG_HIDDEN
+ssize_t lttng_action_notify_create_from_buffer(
+		const struct lttng_buffer_view *view,
+		struct lttng_action **action);
+
 #endif /* LTTNG_ACTION_NOTIFY_INTERNAL_H */
diff --git a/src/common/actions/action.c b/src/common/actions/action.c
index dc72d37b4..982ca45ff 100644
--- a/src/common/actions/action.c
+++ b/src/common/actions/action.c
@@ -78,34 +78,48 @@ end:
 
 LTTNG_HIDDEN
 ssize_t lttng_action_create_from_buffer(const struct lttng_buffer_view *view,
-		struct lttng_action **_action)
+		struct lttng_action **action)
 {
-	ssize_t ret, action_size = sizeof(struct lttng_action_comm);
-	struct lttng_action *action;
+	ssize_t consumed_len, specific_action_consumed_len;
 	const struct lttng_action_comm *action_comm;
+	action_create_from_buffer_cb create_from_buffer_cb;
+	struct lttng_buffer_view specific_action_view;
 
-	if (!view || !_action) {
-		ret = -1;
+	if (!view || !action) {
+		consumed_len = -1;
 		goto end;
 	}
 
 	action_comm = (const struct lttng_action_comm *) view->data;
+
 	DBG("Deserializing action from buffer");
 	switch (action_comm->action_type) {
 	case LTTNG_ACTION_TYPE_NOTIFY:
-		action = lttng_action_notify_create();
+		create_from_buffer_cb = lttng_action_notify_create_from_buffer;
 		break;
 	default:
-		ret = -1;
+		consumed_len = -1;
 		goto end;
 	}
 
-	if (!action) {
-		ret = -1;
+	/* Create buffer view for the action-type-specific data. */
+	specific_action_view = lttng_buffer_view_from_view(view,
+			sizeof(struct lttng_action_comm),
+			view->size - sizeof(struct lttng_action_comm));
+
+	specific_action_consumed_len =
+			create_from_buffer_cb(&specific_action_view, action);
+	if (specific_action_consumed_len < 0) {
+		ERR("Failed to create specific action from buffer.");
+		consumed_len = -1;
 		goto end;
 	}
-	ret = action_size;
-	*_action = action;
+
+	assert(*action);
+
+	consumed_len = sizeof(struct lttng_action_comm) +
+		       specific_action_consumed_len;
+
 end:
-	return ret;
+	return consumed_len;
 }
diff --git a/src/common/actions/notify.c b/src/common/actions/notify.c
index 00d1a0ef4..9d005b823 100644
--- a/src/common/actions/notify.c
+++ b/src/common/actions/notify.c
@@ -38,3 +38,20 @@ struct lttng_action *lttng_action_notify_create(void)
 end:
 	return &notify->parent;
 }
+
+ssize_t lttng_action_notify_create_from_buffer(
+		const struct lttng_buffer_view *view,
+		struct lttng_action **action)
+{
+	ssize_t consumed_length;
+
+	*action = lttng_action_notify_create();
+	if (!*action) {
+		consumed_length = -1;
+		goto end;
+	}
+
+	consumed_length = 0;
+end:
+	return consumed_length;
+}