Add a game_state argument to decode_ui()

Some games would like a way to check that the parameters in the encoded
UI string are consistent with the game parameters.  Since this might
depend on the current state of the game (this being what changed_state()
is for), implement this by adding a game_state parameter to decode_ui().
Nothing currently uses it, though Guess usefully could.

blackbox.c

@@ -511,7 +511,8 @@ static char *encode_ui(const game_ui *ui)
     return dupstr(buf);
 }
 
-static void decode_ui(game_ui *ui, const char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding,
+                      const game_state *state)
 {
     sscanf(encoding, "E%d", &ui->errors);
 }

devel.but

@@ -890,14 +890,17 @@ this function it can just set the pointer to \cw{NULL}.
 
 \S{backend-decode-ui} \cw{decode_ui()}
 
-\c void (*decode_ui)(game_ui *ui, const char *encoding);
+\c void (*decode_ui)(game_ui *ui, const char *encoding,
+\c                   const game_state *state);
 
 This function parses a string previously output by \cw{encode_ui()},
 and writes the decoded data back into the freshly-created \c{game_ui}
 structure provided.  If the string is invalid, the function should do
 the best it can, which might just mean not changing the \c{game_ui}
 structure at all.  This might happen if a save file is corrupted, or
-simply from a newer version that encodes more \c{game_ui} data.
+simply from a newer version that encodes more \c{game_ui} data.  The
+current \c{game_state} is provided in case the function needs to
+refer to it for validation.
 
 Like \cw{encode_ui()}, \cw{decode_ui()} is optional.  If a back-end
 doesn't need this function it can just set the pointer to \cw{NULL}.

guess.c

@@ -452,7 +452,8 @@ static char *encode_ui(const game_ui *ui)
     return sresize(ret, p - ret, char);
 }
 
-static void decode_ui(game_ui *ui, const char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding,
+                      const game_state *state)
 {
     int i;
     const char *p = encoding;

inertia.c

@@ -1527,7 +1527,8 @@ static char *encode_ui(const game_ui *ui)
     return dupstr(buf);
 }
 
-static void decode_ui(game_ui *ui, const char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding,
+                      const game_state *state)
 {
     int p = 0;
     sscanf(encoding, "D%d%n", &ui->deaths, &p);

midend.c

@@ -2542,7 +2542,8 @@ static const char *midend_deserialise_internal(
 
     data.ui = me->ourgame->new_ui(data.states[0].state);
     if (data.uistr && me->ourgame->decode_ui)
-        me->ourgame->decode_ui(data.ui, data.uistr);
+        me->ourgame->decode_ui(data.ui, data.uistr,
+                               data.states[data.statepos-1].state);
 
     /*
      * Run the externally provided check function, and abort if it

mines.c

@@ -2413,7 +2413,8 @@ static char *encode_ui(const game_ui *ui)
     return dupstr(buf);
 }
 
-static void decode_ui(game_ui *ui, const char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding,
+                      const game_state *state)
 {
     int p= 0;
     sscanf(encoding, "D%d%n", &ui->deaths, &p);

net.c

@@ -2041,7 +2041,8 @@ static char *encode_ui(const game_ui *ui)
     return dupstr(buf);
 }
 
-static void decode_ui(game_ui *ui, const char *encoding)
+static void decode_ui(game_ui *ui, const char *encoding,
+                      const game_state *state)
 {
     sscanf(encoding, "O%d,%d;C%d,%d",
 	   &ui->org_x, &ui->org_y, &ui->cx, &ui->cy);

puzzles.h

@@ -664,7 +664,8 @@ struct game {
     game_ui *(*new_ui)(const game_state *state);
     void (*free_ui)(game_ui *ui);
     char *(*encode_ui)(const game_ui *ui);
-    void (*decode_ui)(game_ui *ui, const char *encoding);
+    void (*decode_ui)(game_ui *ui, const char *encoding,
+                      const game_state *state);
     key_label *(*request_keys)(const game_params *params, int *nkeys);
     void (*changed_state)(game_ui *ui, const game_state *oldstate,
                           const game_state *newstate);