From c2a0080f900a6bdcbfa97b201eea28ee3e46f3f4 Mon Sep 17 00:00:00 2001
From: Wim Taymans <wim.taymans@gmail.com>
Date: Thu, 25 Jul 2002 18:47:48 +0000
Subject: [PATCH] Also handle READONLY buffers in the copy_on_write function

Original commit message from CVS:
Also handle READONLY buffers in the copy_on_write function
---
 gst/gstbuffer.h |  4 ++--
 gst/gstdata.c   | 19 +++++++++++++------
 gst/gstdata.h   |  2 +-
 3 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/gst/gstbuffer.h b/gst/gstbuffer.h
index 21459b5e5d..debf665099 100644
--- a/gst/gstbuffer.h
+++ b/gst/gstbuffer.h
@@ -61,8 +61,8 @@ extern GType _gst_buffer_pool_type;
 #define GST_BUFFER_POOL_PRIVATE(buf)		(GST_BUFFER(buf)->pool_private)
 
 typedef enum {
-  GST_BUFFER_READONLY   = GST_DATA_FLAG_LAST,
-  GST_BUFFER_SUBBUFFER,
+  GST_BUFFER_READONLY   = GST_DATA_READONLY,
+  GST_BUFFER_SUBBUFFER  = GST_DATA_FLAG_LAST,
   GST_BUFFER_ORIGINAL,
   GST_BUFFER_DONTFREE,
   GST_BUFFER_DISCONTINOUS,
diff --git a/gst/gstdata.c b/gst/gstdata.c
index ac565a5c38..00cd6586db 100644
--- a/gst/gstdata.c
+++ b/gst/gstdata.c
@@ -79,7 +79,9 @@ gst_data_dispose (GstData *data)
  * Copies the given #GstData. This function will call the custom subclass
  * copy function or return NULL if no function was provided by the subclass.
  *
- * Returns: a copy of the data or NULL if the data cannot be copied.
+ * Returns: a copy of the data or NULL if the data cannot be copied. The refcount
+ * of the original buffer is not changed so you should unref it when you don't
+ * need it anymore.
  */
 GstData*
 gst_data_copy (const GstData *data) 
@@ -98,20 +100,25 @@ gst_data_copy (const GstData *data)
  * #GstData object can be written to safely.
  *
  * Returns: a copy of the data if the refcount is > 1, data if the refcount == 1
- * or NULL if the data could not be copied.
+ * or NULL if the data could not be copied. The refcount of the original buffer
+ * is decreased when a copy is made, so you are not supposed to use it after a
+ * call to this function.
  */
 GstData*
-gst_data_copy_on_write (const GstData *data) 
+gst_data_copy_on_write (GstData *data) 
 {
   gint refcount;
 
   GST_ATOMIC_INT_READ (&data->refcount, &refcount);
 
-  if (refcount == 1)
+  if (refcount == 1 && !GST_DATA_FLAG_IS_SET (data, GST_DATA_READONLY))
     return GST_DATA (data);
 	
-  if (data->copy)
-    return data->copy (data); 
+  if (data->copy) {
+    GstData *copy = data->copy (data); 
+    gst_data_unref (data);
+    return copy; 
+  }
 
   return NULL;
 }
diff --git a/gst/gstdata.h b/gst/gstdata.h
index 903f16c20d..12369415ac 100644
--- a/gst/gstdata.h
+++ b/gst/gstdata.h
@@ -87,7 +87,7 @@ void			gst_data_copy_into		(const GstData *data, GstData *target);
 
 /* basic operations on data */
 GstData*		gst_data_copy	 		(const GstData *data);
-GstData* 		gst_data_copy_on_write 		(const GstData *data);
+GstData* 		gst_data_copy_on_write 		(GstData *data);
 void 			gst_data_free	 		(GstData *data);
 
 /* reference counting */