From e6d0756c2827550205cf03a105217ec9a5865c16 Mon Sep 17 00:00:00 2001
From: Marko Lindqvist <cazfi74@gmail.com>
Date: Thu, 5 Jan 2023 05:25:20 +0200
Subject: [PATCH 33/33] Sanity check diplstate max_state

See osdn #44732

Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>
---
 server/diplhand.c           | 15 +++++++++++++++
 server/diplhand.h           |  4 ++++
 server/sanitycheck.c        |  2 ++
 server/savegame/savegame2.c |  7 +++++++
 server/savegame/savegame3.c |  9 ++++++++-
 5 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/server/diplhand.c b/server/diplhand.c
index 1bdd560f56..a194678964 100644
--- a/server/diplhand.c
+++ b/server/diplhand.c
@@ -104,6 +104,21 @@ static enum diplstate_type dst_closest(enum diplstate_type a,
   }
 }
 
+/**********************************************************************//**
+  Return closest diplstate dst has had, with extra sanity checking
+  (i.e. may return state other than the recorder max_state)
+**************************************************************************/
+enum diplstate_type valid_dst_closest(struct player_diplstate *dst)
+{
+  if (dst_closest(dst->type, dst->max_state) == dst->max_state) {
+    /* Sane max_state */
+    return dst->max_state;
+  }
+
+  /* max_state illegally lower than current. Return current as max_state */
+  return dst->type;
+}
+
 /**********************************************************************//**
   Set diplstate between two players.
 **************************************************************************/
diff --git a/server/diplhand.h b/server/diplhand.h
index 21bfa8e55d..2876df9b2b 100644
--- a/server/diplhand.h
+++ b/server/diplhand.h
@@ -13,8 +13,10 @@
 #ifndef FC__DIPLHAND_H
 #define FC__DIPLHAND_H
 
+/* common */
 #include "fc_types.h"
 
+/* server */
 #include "hand_gen.h"
 
 struct Treaty;
@@ -31,4 +33,6 @@ void set_diplstate_type(struct player_diplstate *state1,
                         struct player_diplstate *state2,
                         enum diplstate_type type);
 
+enum diplstate_type valid_dst_closest(struct player_diplstate *dst);
+
 #endif  /* FC__DIPLHAND_H */
diff --git a/server/sanitycheck.c b/server/sanitycheck.c
index 11c88a8b24..66e561edad 100644
--- a/server/sanitycheck.c
+++ b/server/sanitycheck.c
@@ -36,6 +36,7 @@
 /* server */
 #include "citytools.h"
 #include "cityturn.h"           /* city_repair_size() */
+#include "diplhand.h"           /* valid_dst_closest() */
 #include "maphand.h"
 #include "plrhand.h"
 #include "srv_main.h"
@@ -543,6 +544,7 @@ static void check_players(const char *file, const char *function, int line)
       state2 = player_diplstate_get(pplayer2, pplayer);
       SANITY_CHECK(state1->type == state2->type);
       SANITY_CHECK(state1->max_state == state2->max_state);
+      SANITY_CHECK(valid_dst_closest(state1) == state1->max_state);
       if (state1->type == DS_CEASEFIRE
           || state1->type == DS_ARMISTICE) {
         SANITY_CHECK(state1->turns_left == state2->turns_left);
diff --git a/server/savegame/savegame2.c b/server/savegame/savegame2.c
index 0581c750ed..e9e02122e9 100644
--- a/server/savegame/savegame2.c
+++ b/server/savegame/savegame2.c
@@ -2953,6 +2953,13 @@ static void sg_load_player_main(struct loaddata *loading,
     }
 #endif
 
+    if (valid_dst_closest(ds) != ds->max_state) {
+      sg_regr(03020000,
+              "Player%d: closest diplstate to player %d less than current. "
+              "Updated.", plrno, i);
+      ds->max_state = ds->type;
+    }
+
     ds->first_contact_turn =
       secfile_lookup_int_default(loading->file, 0,
                                  "%s.first_contact_turn", buf);
diff --git a/server/savegame/savegame3.c b/server/savegame/savegame3.c
index 0b22efe58f..7e79a2ca02 100644
--- a/server/savegame/savegame3.c
+++ b/server/savegame/savegame3.c
@@ -4090,7 +4090,7 @@ static void sg_load_player_main(struct loaddata *loading,
     struct player_diplstate *ds = player_diplstate_get(plr, pplayer);
     i = player_index(pplayer);
 
-    /* load diplomatic status */
+    /* Load diplomatic status */
     fc_snprintf(buf, sizeof(buf), "player%d.diplstate%d", plrno, i);
 
     ds->type =
@@ -4110,6 +4110,13 @@ static void sg_load_player_main(struct loaddata *loading,
     }
 #endif
 
+    if (valid_dst_closest(ds) != ds->max_state) {
+      sg_regr(03020000,
+              "Player%d: closest diplstate to player %d less than current. "
+              "Updated.", plrno, i);
+      ds->max_state = ds->type;
+    }
+
     ds->first_contact_turn =
       secfile_lookup_int_default(loading->file, 0,
                                  "%s.first_contact_turn", buf);
-- 
2.39.0