Add a note about size limits of private structures

Also add some assertions to check these limits, instead of
failing silently.  Bug 604479.
This commit is contained in:
Matthias Clasen 2010-09-03 18:11:08 -04:00
parent db4fb1b115
commit 42080449d0

View File

@ -4372,13 +4372,20 @@ g_type_init (void)
* @g_class: class structure for an instantiatable type
* @private_size: size of private structure.
*
* Registers a private structure for an instantiatable type;
* when an object is allocated, the private structures for
* Registers a private structure for an instantiatable type.
*
* When an object is allocated, the private structures for
* the type and all of its parent types are allocated
* sequentially in the same memory block as the public
* structures. This function should be called in the
* type's class_init() function. The private structure can
* be retrieved using the G_TYPE_INSTANCE_GET_PRIVATE() macro.
* structures.
*
* Note that the accumulated size of the private structures of
* a type and all its parent types cannot excced 64kB.
*
* This function should be called in the type's class_init() function.
* The private structure can be retrieved using the
* G_TYPE_INSTANCE_GET_PRIVATE() macro.
*
* The following example shows attaching a private structure
* <structname>MyObjectPrivate</structname> to an object
* <structname>MyObject</structname> defined in the standard GObject
@ -4433,6 +4440,7 @@ g_type_class_add_private (gpointer g_class,
gsize offset;
g_return_if_fail (private_size > 0);
g_return_if_fail (private_size <= 0xffff);
if (!node || !node->is_instantiatable || !node->data || node->data->class.class != g_class)
{
@ -4454,6 +4462,9 @@ g_type_class_add_private (gpointer g_class,
G_WRITE_LOCK (&type_rw_lock);
offset = ALIGN_STRUCT (node->data->instance.private_size);
g_assert (offset + private_size <= 0xffff);
node->data->instance.private_size = offset + private_size;
G_WRITE_UNLOCK (&type_rw_lock);