[Mesa-dev] [PATCH 08/23] i965: Don't pollute the buffer object namespace in brw_meta_fast_clear

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

tl;dr: For many types of GL object, we can *NEVER* use the Gen function.

In OpenGL ES (all versions!) and OpenGL compatibility profile,
applications don't have to call Gen functions.  The GL spec is very
clear about how you can mix-and-match generated names and non-generated
names: you can use any name you want for a particular object type until
you call the Gen function for that object type.

Here's the problem scenario:

 - Application calls a meta function that generates a name.  The first
   Gen will probably return 1.

 - Application decides to use the same name for an object of the same
   type without calling Gen.  Many demo programs use names 1, 2, 3,
   etc. without calling Gen.

 - Application calls the meta function again, and the meta function
   replaces the data.  The application's data is lost, and the app
   fails.  Have fun debugging that.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92363
---
 src/mesa/drivers/dri/i965/brw_meta_fast_clear.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c b/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
index 7817f0b..ec810c2 100644
--- a/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
+++ b/src/mesa/drivers/dri/i965/brw_meta_fast_clear.c
@@ -57,7 +57,6 @@ struct brw_fast_clear_state {
    struct gl_buffer_object *buf_obj;
    struct gl_vertex_array_object *array_obj;
    GLuint vao;
-   GLuint vbo;
    GLuint shader_prog;
    GLint color_location;
 };
@@ -81,10 +80,11 @@ brw_fast_clear_init(struct brw_context *brw)
    memset(clear, 0, sizeof *clear);
    _mesa_GenVertexArrays(1, &clear->vao);
    _mesa_BindVertexArray(clear->vao);
-   _mesa_CreateBuffers(1, &clear->vbo);
 
-   clear->buf_obj = _mesa_lookup_bufferobj(ctx, clear->vbo);
-   assert(clear->buf_obj != NULL);
+   clear->buf_obj = ctx->Driver.NewBufferObject(ctx, 0xDEADBEEF);
+   if (clear->buf_obj == NULL)
+      return false;
+
    clear->array_obj = _mesa_lookup_vao(ctx, clear->vao);
    assert(clear->array_obj != NULL);
 
@@ -162,7 +162,7 @@ brw_meta_fast_clear_free(struct brw_context *brw)
    _mesa_make_current(&brw->ctx, NULL, NULL);
 
    _mesa_DeleteVertexArrays(1, &clear->vao);
-   _mesa_DeleteBuffers(1, &clear->vbo);
+   _mesa_reference_buffer_object(&brw->ctx, &clear->buf_obj, NULL);
    _mesa_DeleteProgram(clear->shader_prog);
    free(clear);
 
-- 
2.1.0