From db774798fad6bda2c85d9b5251c42944c378878d Mon Sep 17 00:00:00 2001
From: Lorenz Meier <lm@inf.ethz.ch>
Date: Fri, 21 Oct 2016 13:54:44 +0200
Subject: [PATCH] Dataman: Store sizes of all containers and reset file if any
 of them changes.

---
 src/modules/dataman/dataman.c | 28 ++++++++++++++++++++++++++++
 src/modules/dataman/dataman.h | 15 ++++++++++++---
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/src/modules/dataman/dataman.c b/src/modules/dataman/dataman.c
index 6af444d880..cba88d478f 100644
--- a/src/modules/dataman/dataman.c
+++ b/src/modules/dataman/dataman.c
@@ -956,7 +956,26 @@ task_main(int argc, char *argv[])
 			}
 
 #else
+			// Read the mission state and check the hash
+			struct dataman_compat_s compat_state;
+			int ret = dm_read(DM_KEY_COMPAT, 0, &compat_state, sizeof(compat_state));
+
+			bool incompat = true;
+
+			if (ret == sizeof(compat_state)) {
+
+				if (compat_state.key == DM_COMPAT_KEY) {
+					incompat = false;
+				}
+
+			}
+
 			close(g_task_fd);
+
+			if (incompat) {
+				unlink(k_data_manager_device_path);
+			}
+
 #endif
 
 		}
@@ -977,6 +996,15 @@ task_main(int argc, char *argv[])
 			return -1;
 		}
 
+		/* Write current compat info */
+		struct dataman_compat_s compat_state;
+		compat_state.key = DM_COMPAT_KEY;
+		int ret = dm_write(DM_KEY_COMPAT, 0, DM_PERSIST_POWER_ON_RESET, &compat_state, sizeof(compat_state));
+
+		if (ret != sizeof(compat_state)) {
+			PX4_ERR("Failed writing compat.");
+		}
+
 		fsync(g_task_fd);
 	}
 
diff --git a/src/modules/dataman/dataman.h b/src/modules/dataman/dataman.h
index 337cdddef1..d5f9e90543 100644
--- a/src/modules/dataman/dataman.h
+++ b/src/modules/dataman/dataman.h
@@ -39,6 +39,7 @@
 #ifndef _DATAMANAGER_H
 #define _DATAMANAGER_H
 
+#include <string.h>
 #include <navigator/navigation.h>
 #include <uORB/topics/mission.h>
 #include <uORB/topics/fence.h>
@@ -56,6 +57,7 @@ typedef enum {
 	DM_KEY_WAYPOINTS_OFFBOARD_1,	/* (alernate between 0 and 1) */
 	DM_KEY_WAYPOINTS_ONBOARD,	/* Mission way point coordinates generated onboard */
 	DM_KEY_MISSION_STATE,		/* Persistent mission state */
+	DM_KEY_COMPAT,
 	DM_KEY_NUM_KEYS			/* Total number of item types defined */
 } dm_item_t;
 
@@ -103,14 +105,21 @@ typedef enum {
 	DM_INIT_REASON_VOLATILE			/* Data does not survive reset */
 } dm_reset_reason;
 
+struct dataman_compat_s {
+	uint32_t key;
+};
+
+#define DM_COMPAT_KEY ((sizeof(struct mission_item_s) << 24) + (sizeof(struct mission_s) << 16) + (sizeof(struct fence_vertex_s) << 8) + sizeof(struct dataman_compat_s))
+
 /** Maximum size in bytes of a single item instance is
  * defined by adding the structure type to the union below
  */
 
 typedef union dataman_max_size_t {
-	struct mission_item_s    mission_item;
-	struct mission_s	      mission;
-	struct fence_vertex_s    vertex;
+	struct mission_item_s		mission_item;
+	struct mission_s			mission;
+	struct fence_vertex_s		vertex;
+	struct dataman_compat_s		compat;
 } dataman_max_size_t;