plugins: Simplify plugin/codec API versioning

Replace the minimum version bound with a check on the size of
the API struct. The version only needs to be incremented for
ABI breaking changes. Additions to the API won't need to touch
the version number, resulting in fewer merge conflicts.

Change-Id: I916a04a7bf5890dcf5d615ce30087643165f8e1f

1 files changed, 11 insertions, 10 deletions

diff --git a/apps/plugin.h b/apps/plugin.h
index 286a5e2794..cf6a1bc4e4 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -157,13 +157,12 @@ int plugin_open(const char *plugin, const char *parameter);
 
 #define PLUGIN_MAGIC 0x526F634B /* RocK */
 
-/* increase this every time the api struct changes */
-#define PLUGIN_API_VERSION 265
-
-/* update this to latest version if a change to the api struct breaks
-   backwards compatibility (and please take the opportunity to sort in any
-   new function which are "waiting" at the end of the function table) */
-#define PLUGIN_MIN_API_VERSION 260
+/*
+ * Increment this whenever a change breaks the plugin ABI,
+ * when this happens please take the opportunity to sort in
+ * any new functions "waiting" at the end of the list.
+ */
+#define PLUGIN_API_VERSION 266
 
 /* 239 Marks the removal of ARCHOS HWCODEC and CHARCELL */
 
@@ -962,6 +961,7 @@ struct plugin_header {
     struct lc_header lc_hdr; /* must be the first */
     enum plugin_status(*entry_point)(const void*);
     const struct plugin_api **api;
+    size_t api_size;
 };
 
 #ifdef PLUGIN
@@ -973,14 +973,15 @@ extern unsigned char plugin_end_addr[];
         const struct plugin_header __header \
         __attribute__ ((section (".header")))= { \
         { PLUGIN_MAGIC, TARGET_ID, PLUGIN_API_VERSION, \
-        plugin_start_addr, plugin_end_addr }, plugin__start, &rb };
+          plugin_start_addr, plugin_end_addr, }, \
+        plugin__start, &rb, sizeof(struct plugin_api) };
 #else /* PLATFORM_HOSTED */
 #define PLUGIN_HEADER \
         const struct plugin_api *rb DATA_ATTR; \
         const struct plugin_header __header \
         __attribute__((visibility("default"))) = { \
-        { PLUGIN_MAGIC, TARGET_ID, PLUGIN_API_VERSION, NULL, NULL }, \
-        plugin__start, &rb };
+            { PLUGIN_MAGIC, TARGET_ID, PLUGIN_API_VERSION, NULL, NULL }, \
+            plugin__start, &rb, sizeof(struct plugin_api) };
 #endif /* CONFIG_PLATFORM */
 #endif /* PLUGIN */