Merge branch 'is_modified' into 'master'

config: add is-modified helper

See merge request videolan/vlc!1365

include/vlc_configuration.h

@@ -251,6 +251,26 @@ VLC_API void config_ResetAll(void);
  */
 VLC_API module_config_t *config_FindConfig(const char *name) VLC_USED;
 
+/**
+ * Check item's modified state.
+ *
+ * This function checks whether or not an item's saved state is considered to
+ * be default or modified. Currently we consider state to be modified only if
+ * the value is different from it's default value.
+ *
+ * \warning The check is performed without locking. Callers are responsibile for
+ * ensuring thread safety. Note that whilst most item attributes remain constant
+ * throughout the lifetime of the core config database, the `value` attribute
+ * stands out as mutable and therefore is a thread safety concern. Safe use of
+ * this function thus requires either holding the config lock (applicable within
+ * the core only), or otherwise having suitably exclusive access to the item's
+ * value.
+ *
+ * \param item Configuration item
+ * \retval true if modified, false if unmodified (default).
+ */
+VLC_API bool vlc_config_ItemIsModified(const module_config_t *item);
+
 /**
  * System directory identifiers
  */

src/config/core.c

@@ -470,6 +470,37 @@ module_config_t *config_FindConfig(const char *name)
     return (param != NULL) ? &param->item : NULL;
 }
 
+bool vlc_config_ItemIsModified(const module_config_t *item)
+{
+    bool is_modified;
+    switch (CONFIG_CLASS(item->i_type))
+    {
+        case CONFIG_ITEM_FLOAT:
+            is_modified = (item->value.f != item->orig.f);
+            break;
+        case CONFIG_ITEM_BOOL:
+        case CONFIG_ITEM_INTEGER:
+            is_modified = (item->value.i != item->orig.i);
+            break;
+        case CONFIG_ITEM_STRING:
+        {
+            bool orig_is_empty = (item->orig.psz == NULL || item->orig.psz[0] == '\0');
+            bool curr_is_empty = (item->value.psz == NULL || item->value.psz[0] == '\0');
+            if (orig_is_empty)
+                is_modified = !curr_is_empty;
+            else if (curr_is_empty)
+                is_modified = true;
+            else
+                is_modified = (strcmp(item->value.psz, item->orig.psz) != 0);
+            break;
+        }
+        default:
+            vlc_assert_unreachable();
+            break;
+    }
+    return is_modified;
+}
+
 /**
  * Destroys an array of configuration items.
  * \param tab start of array of items

src/libvlccore.sym

@@ -74,6 +74,7 @@ config_GetIntChoices
 config_GetPsz
 config_GetPszChoices
 config_GetType
+vlc_config_ItemIsModified
 config_PutFloat
 config_PutInt
 config_PutPsz