2 files changed, 58 insertions, 8 deletions

diff --git a/apps/plugin.c b/apps/plugin.c
index bfa497479c..0fab448584 100644
--- a/apps/plugin.c
+++ b/apps/plugin.c
@@ -52,6 +52,17 @@
 #define PREFIX(_x_) _x_
 #endif
 
+#define PLUGIN_BUFFER_SIZE 0x8000
+
+#ifdef SIMULATOR
+static unsigned char pluginbuf[PLUGIN_BUFFER_SIZE];
+#else
+extern unsigned char pluginbuf[];
+#endif
+
+static bool plugin_loaded = false;
+static int  plugin_size = 0;
+
 static int plugin_test(int api_version, int model, int memsize);
 
 static struct plugin_api rockbox_api = {
@@ -142,7 +153,8 @@ static struct plugin_api rockbox_api = {
     kbd_input,
     mpeg_current_track,
     atoi,
-    get_time
+    get_time,
+    plugin_get_buffer,
 };
 
 int plugin_load(char* plugin, void* parameter)
@@ -154,7 +166,6 @@ int plugin_load(char* plugin, void* parameter)
     void* pd;
     char path[256];
 #else
-    extern unsigned char pluginbuf[];
     int fd;
 #endif
 
@@ -196,22 +207,25 @@ int plugin_load(char* plugin, void* parameter)
     }
 
     plugin_start = (void*)&pluginbuf;
-    rc = read(fd, plugin_start, 0x8000);
+    plugin_size = read(fd, plugin_start, PLUGIN_BUFFER_SIZE);
     close(fd);
-    if (rc < 0) {
+    if (plugin_size < 0) {
         /* read error */
         snprintf(buf, sizeof buf, str(LANG_READ_FAILED), plugin);
         splash(HZ*2, 0, true, buf);
         return -1;
     }
-    if (rc == 0) {
+    if (plugin_size == 0) {
         /* loaded a 0-byte plugin, implying it's not for this model */
         splash(HZ*2, 0, true, str(LANG_PLUGIN_WRONG_MODEL));
         return -1;
     }
 #endif
 
+    plugin_loaded = true;
     rc = plugin_start(&rockbox_api, parameter);
+    plugin_loaded = false;
+
     switch (rc) {
         case PLUGIN_OK:
             break;
@@ -239,9 +253,33 @@ int plugin_load(char* plugin, void* parameter)
     return PLUGIN_OK;
 }
 
-int plugin_test(int api_version, int model, int memsize)
+/* Returns a pointer to the portion of the plugin buffer that is not already
+   being used.  If no plugin is loaded, returns the entire plugin buffer */
+void* plugin_get_buffer(int* buffer_size)
+{
+    int buffer_pos;
+
+    if (plugin_loaded)
+    {
+        if (plugin_size >= PLUGIN_BUFFER_SIZE)
+            return NULL;
+        
+        *buffer_size = PLUGIN_BUFFER_SIZE-plugin_size;
+        buffer_pos = plugin_size;
+    }
+    else
+    {
+        *buffer_size = PLUGIN_BUFFER_SIZE;
+        buffer_pos = 0;
+    }
+
+    return &pluginbuf[buffer_pos];
+}
+
+static int plugin_test(int api_version, int model, int memsize)
 {
-    if (api_version != PLUGIN_API_VERSION)
+    if (api_version < PLUGIN_MIN_API_VERSION ||
+        api_version > PLUGIN_API_VERSION)
         return PLUGIN_WRONG_API_VERSION;
 
     if (model != MODEL)
diff --git a/apps/plugin.h b/apps/plugin.h
index 3d6859b0d3..5bebcd701f 100644
--- a/apps/plugin.h
+++ b/apps/plugin.h
@@ -43,7 +43,11 @@
 #include "mpeg.h"
 
 /* increase this every time the api struct changes */
-#define PLUGIN_API_VERSION 6
+#define PLUGIN_API_VERSION 7
+
+/* update this to latest version if a change to the api struct breaks
+   backwards compatibility */
+#define PLUGIN_MIN_API_VERSION 6
 
 /* plugin return codes */
 enum plugin_status {
@@ -75,6 +79,12 @@ do { \
      return _rc_; \
 } while(0)
 
+/* NOTE: To support backwards compatibility, only add new functions at
+         the end of the structure.  Every time you add a new function,
+         remember to increase PLUGIN_API_VERSION.  If you make changes to the
+         existing APIs then also update PLUGIN_MIN_API_VERSION to current
+         version
+ */
 struct plugin_api {
     /* these two fields must always be first, to ensure
        TEST_PLUGIN_API will always work */
@@ -170,10 +180,12 @@ struct plugin_api {
     struct mp3entry* (*mpeg_current_track)(void);
     int (*atoi)(const char *str);
     struct tm* (*get_time)(void);
+    void* (*plugin_get_buffer)(int* buffer_size);
 };
 
 /* defined by the plugin loader (plugin.c) */
 int plugin_load(char* plugin, void* parameter);
+void* plugin_get_buffer(int *buffer_size);
 
 /* defined by the plugin */
 enum plugin_status plugin_start(struct plugin_api* rockbox, void* parameter)