memory: provide a mem_map_full that takes the GstMapInfo

Follow up of 7130230ddb

Provide the memory implementation the GstMapInfo that will be used to
map/unmap the memory.  This allows the memory implementation to use
some scratch space in GstMapInfo to e.g. track different map/unmap
behaviour or store extra implementation defined data about the map
in use.

https://bugzilla.gnome.org/show_bug.cgi?id=750319

docs/gst/gstreamer-sections.txt

@@ -1456,7 +1456,9 @@ GstMapInfo
 GST_MAP_INFO_INIT
 
 GstMemoryMapFunction
+GstMemoryMapFullFunction
 GstMemoryUnmapFunction
+GstMemoryUnmapFullFunction
 GstMemoryCopyFunction
 GstMemoryShareFunction
 GstMemoryIsSpanFunction

gst/gstallocator.h

@@ -97,6 +97,8 @@ typedef enum {
  * @mem_copy: the implementation of the GstMemoryCopyFunction
  * @mem_share: the implementation of the GstMemoryShareFunction
  * @mem_is_span: the implementation of the GstMemoryIsSpanFunction
+ * @mem_map_full: the implementation of the GstMemoryMapFullFunction.
+ *      Will be used instead of @mem_map if present. Since 1.6
  * @mem_unmap_full: the implementation of the GstMemoryUnmapFullFunction.
  *      Will be used instead of @mem_unmap if present. Since 1.6
  *
@@ -116,10 +118,11 @@ struct _GstAllocator
   GstMemoryShareFunction     mem_share;
   GstMemoryIsSpanFunction    mem_is_span;
 
+  GstMemoryMapFullFunction   mem_map_full;
   GstMemoryUnmapFullFunction mem_unmap_full;
 
   /*< private >*/
-  gpointer _gst_reserved[GST_PADDING - 1];
+  gpointer _gst_reserved[GST_PADDING - 2];
 
   GstAllocatorPrivate *priv;
 };

gst/gstmemory.c

@@ -294,15 +294,19 @@ gst_memory_map (GstMemory * mem, GstMapInfo * info, GstMapFlags flags)
   if (!gst_memory_lock (mem, (GstLockFlags) flags))
     goto lock_failed;
 
-  info->data = mem->allocator->mem_map (mem, mem->maxsize, flags);
+  info->flags = flags;
+  info->memory = mem;
+  info->size = mem->size;
+  info->maxsize = mem->maxsize - mem->offset;
+
+  if (mem->allocator->mem_map_full)
+    info->data = mem->allocator->mem_map_full (mem, info, mem->maxsize);
+  else
+    info->data = mem->allocator->mem_map (mem, mem->maxsize, flags);
 
   if (G_UNLIKELY (info->data == NULL))
     goto error;
 
-  info->memory = mem;
-  info->flags = flags;
-  info->size = mem->size;
-  info->maxsize = mem->maxsize - mem->offset;
   info->data = info->data + mem->offset;
 
   return TRUE;
@@ -339,7 +343,7 @@ gst_memory_unmap (GstMemory * mem, GstMapInfo * info)
   g_return_if_fail (info->memory == mem);
 
   if (mem->allocator->mem_unmap_full)
-    mem->allocator->mem_unmap_full (mem, info->flags);
+    mem->allocator->mem_unmap_full (mem, info);
   else
     mem->allocator->mem_unmap (mem);
   gst_memory_unlock (mem, (GstLockFlags) info->flags);

gst/gstmemory.h

@@ -232,6 +232,21 @@ typedef struct {
  */
 typedef gpointer    (*GstMemoryMapFunction)       (GstMemory *mem, gsize maxsize, GstMapFlags flags);
 
+/**
+ * GstMemoryMapFullFunction:
+ * @mem: a #GstMemory
+ * @info: the #GstMapInfo to map with
+ * @maxsize: size to map
+ *
+ * Get the memory of @mem that can be accessed according to the mode specified
+ * in @info's flags. The function should return a pointer that contains at least
+ * @maxsize bytes.
+ *
+ * Returns: a pointer to memory of which at least @maxsize bytes can be
+ * accessed according to the access pattern in @info's flags.
+ */
+typedef gpointer    (*GstMemoryMapFullFunction)       (GstMemory *mem, GstMapInfo * info, gsize maxsize);
+
 /**
  * GstMemoryUnmapFunction:
  * @mem: a #GstMemory
@@ -243,11 +258,11 @@ typedef void        (*GstMemoryUnmapFunction)     (GstMemory *mem);
 /**
  * GstMemoryUnmapFullFunction:
  * @mem: a #GstMemory
- * @flags: a #GstMapFlags
+ * @info: a #GstMapInfo
  *
- * Return the pointer previously retrieved with gst_memory_map() with @flags.
+ * Return the pointer previously retrieved with gst_memory_map() with @info.
  */
-typedef void        (*GstMemoryUnmapFullFunction)     (GstMemory *mem, GstMapFlags flags);
+typedef void        (*GstMemoryUnmapFullFunction)     (GstMemory *mem, GstMapInfo * info);
 
 /**
  * GstMemoryCopyFunction: