Undo Save State currently seems to be working almost as intended

(missing OSD messages). Undo Load State isn't working yet.

command.c

@@ -1578,27 +1578,6 @@ static void command_event_save_state(const char *path,
       char *s, size_t len)
 {
    settings_t *settings = config_get_ptr();
-   char buf[PATH_MAX_LENGTH] = {0};
-
-#if 0
-   /* if a save state already exists rename it to .last before saving 
-    * so it can be recovered */
-   if (path_file_exists(path))
-   {
-      strlcpy(buf, path, sizeof(buf));
-      snprintf(buf, sizeof(buf), "%s", path);
-      path_remove_extension(buf);
-      snprintf(buf, sizeof(buf), "%s.last", buf);
-
-      if (!content_rename_state(path, buf))
-      {
-         snprintf(s, len, "%s \"%s\".",
-               msg_hash_to_str(MSG_FAILED_TO_SAVE_UNDO),
-               path);
-         return;
-      }
-   }
-#endif
 
    if (!content_save_state(path))
    {
@@ -1616,6 +1595,16 @@ static void command_event_save_state(const char *path,
             settings->state_slot);
 }
 
+static void command_event_undo_save_state(char *s, size_t len)
+{
+   if (!content_undo_save_state())
+   {
+      snprintf(s, len, "%s \"%s\".",
+            msg_hash_to_str(MSG_FAILED_TO_SAVE_UNDO),
+            "from internal buffer");
+   }
+}
+
 /**
  * event_load_state
  * @path            : Path to state.
@@ -1624,29 +1613,9 @@ static void command_event_save_state(const char *path,
  *
  * Loads a state with path being @path.
  **/
-static void command_event_load_state(const char *path, char *s, size_t len, bool undo)
+static void command_event_load_state(const char *path, char *s, size_t len)
 {
    settings_t *settings = config_get_ptr();
-   char buf[PATH_MAX_LENGTH] = {0};
-
-   /* save a state before loading (unless it's an undo operation already) 
-    * so the state can be recovered
-    */
-   if (!undo)
-   {
-      strlcpy(buf, path, sizeof(buf));
-      snprintf(buf, sizeof(buf), "%s", path);
-      path_remove_extension(buf);
-      snprintf(buf, sizeof(buf), "%s.undo", buf);
-
-      if (!content_save_state(buf))
-      {
-         snprintf(s, len, "%s \"%s\".",
-               msg_hash_to_str(MSG_FAILED_TO_SAVE_UNDO),
-               path);
-         return;
-      }
-   }
 
    if (!content_load_state(path))
    {
@@ -1659,18 +1628,25 @@ static void command_event_load_state(const char *path, char *s, size_t len, bool
    if (settings->state_slot < 0)
       snprintf(s, len, "%s #-1 (auto).",
             msg_hash_to_str(MSG_LOADED_STATE_FROM_SLOT));
-   else if (!undo)
+   else
       snprintf(s, len, "%s #%d.", msg_hash_to_str(MSG_LOADED_STATE_FROM_SLOT),
             settings->state_slot);
-   else
-      snprintf(s, len, "%s #-1 (undo).", msg_hash_to_str(MSG_LOADED_STATE_FROM_SLOT));
+}
+
+static void command_event_undo_load_state(char *s, size_t len)
+{
+   if (!content_undo_load_state())
+   {
+      snprintf(s, len, "%s \"%s\".",
+            msg_hash_to_str(MSG_FAILED_TO_LOAD_UNDO),
+            "from internal buffer");
+   }
 }
 
 static void command_event_main_state(unsigned cmd)
 {
    retro_ctx_size_info_t info;
    char path[PATH_MAX_LENGTH] = {0};
-   char buf[PATH_MAX_LENGTH]  = {0};
    char msg[128]              = {0};
    global_t *global           = global_get_ptr();
    settings_t *settings       = config_get_ptr();
@@ -1694,33 +1670,13 @@ static void command_event_main_state(unsigned cmd)
             command_event_save_state(path, msg, sizeof(msg));
             break;
          case CMD_EVENT_LOAD_STATE:
-            command_event_load_state(path, msg, sizeof(msg), false);
+            command_event_load_state(path, msg, sizeof(msg));
             break;
          case CMD_EVENT_UNDO_LOAD_STATE:
-            strlcpy(buf, path, sizeof(buf));
-            path_remove_extension(buf);
-            snprintf(buf, sizeof(buf), "%s.undo", buf);
-
-            if (path_file_exists(buf))
-               command_event_load_state(buf, msg, sizeof(msg), true);
-            else
-            {
-               snprintf(msg, sizeof(msg), "%s.",
-                  msg_hash_to_str(MSG_FAILED_TO_LOAD_UNDO));
-            }
+            command_event_undo_load_state(msg, sizeof(msg));
             break;
          case CMD_EVENT_UNDO_SAVE_STATE:
-            strlcpy(buf, path, sizeof(buf));
-            path_remove_extension(buf);
-            snprintf(buf, sizeof(buf), "%s.last", buf);
-
-            if (path_file_exists(buf))
-               command_event_load_state(buf, msg, sizeof(msg), true);
-            else
-            {
-               snprintf(msg, sizeof(msg), "%s.",
-                  msg_hash_to_str(MSG_FAILED_TO_LOAD_UNDO));
-            }
+            command_event_undo_save_state(msg, sizeof(msg));
             break;
       }
    }
@@ -1823,6 +1779,7 @@ bool command_event(enum event_command cmd, void *data)
 #ifndef HAVE_DYNAMIC
          command_event(CMD_EVENT_QUIT, NULL);
 #endif
+         content_reset_savestate_backups();
          break;
       case CMD_EVENT_LOAD_STATE:
          /* Immutable - disallow savestate load when
@@ -2122,9 +2079,12 @@ bool command_event(enum event_command cmd, void *data)
             if (hwr)
                memset(hwr, 0, sizeof(*hwr));
 
+            content_reset_savestate_backups();
+
             break;
          }
       case CMD_EVENT_CORE_INIT:
+         content_reset_savestate_backups();
          if (!command_event_init_core((enum rarch_core_type*)data))
             return false;
          break;

content.h

@@ -56,9 +56,10 @@ bool content_save_state_with_backup(const char *path, bool save_to_disk);
 /* Copy a save state. */
 bool content_rename_state(const char *origin, const char *dest);
 
-/* Load a state backup from disk to memory. */
+/* Undoes the last load state operation that was done */
 bool content_undo_load_state();
 
+/* Restores the last savestate file which was overwritten */
 bool content_undo_save_state();
 
 bool content_does_not_need_content(void);

tasks/task_save_state.c

@@ -182,7 +182,7 @@ bool content_undo_load_state()
 
 bool content_undo_save_state()
 {
-   filestream_write_file(old_save_file.path, old_save_file.data, old_save_file.size);
+   bool ret = filestream_write_file(old_save_file.path, old_save_file.data, old_save_file.size);
 
    /* Wipe the save file buffer as it's intended to be one use only */
    old_save_file.path[0] = '\0';
@@ -193,7 +193,7 @@ bool content_undo_save_state()
 
    old_save_file.data = 0;
 
-   return true;
+   return ret;
 }
 
 
@@ -434,3 +434,31 @@ bool content_rename_state(const char *origin, const char *dest)
    RARCH_LOG ("Error %d renaming file %s", ret, origin);
    return false;
 }
+
+/*
+* Resets the state and savefile backups
+* TODO/FIXME: Figure out when and where this should be called
+*
+*/
+bool content_reset_savestate_backups()
+{
+   if (old_save_file.data)
+   {
+      free(old_save_file.data);
+      old_save_file.data = NULL;
+   }
+
+   old_save_file.path[0] = '\0';
+   old_save_file.size = 0;
+
+   if (old_state_buf.data)
+   {
+      free(old_state_buf.data);
+      old_state_buf.data = NULL;
+   }
+
+   old_state_buf.path[0] = '\0';
+   old_state_buf.size = 0;
+
+   return true;
+}