mesa: Check that all buffers are bound in BeginTransformFeedback.

From the EXT_transform_feedback spec:

    The error INVALID_OPERATION is generated by
    BeginTransformFeedbackEXT if any transform feedback buffer object
    binding point used in transform feedback mode does not have a
    buffer object bound.

This required adding a new NumBuffers field to the
gl_transform_feedback_info struct, to keep track of how many transform
feedback buffers are required by the current program.

Fixes Piglit tests:
- EXT_transform_feedback/api-errors interleaved_unbound
- EXT_transform_feedback/api-errors separate_unbound_0_1
- EXT_transform_feedback/api-errors separate_unbound_0_2
- EXT_transform_feedback/api-errors separate_unbound_1_2

Reviewed-by: Brian Paul <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Reviewed-by: Eric Anholt <[email protected]>

1 files changed, 5 insertions, 2 deletions

diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 65870087bf5..9e8975e887f 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1865,11 +1865,14 @@ store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
                      tfeedback_decl *tfeedback_decls)
 {
    unsigned total_tfeedback_components = 0;
+   bool separate_attribs_mode =
+      prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS;
    memset(&prog->LinkedTransformFeedback, 0,
           sizeof(prog->LinkedTransformFeedback));
+   prog->LinkedTransformFeedback.NumBuffers =
+      separate_attribs_mode ? num_tfeedback_decls : 1;
    for (unsigned i = 0; i < num_tfeedback_decls; ++i) {
-      unsigned buffer =
-         prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS ? i : 0;
+      unsigned buffer = separate_attribs_mode ? i : 0;
       if (!tfeedback_decls[i].store(prog, &prog->LinkedTransformFeedback,
                                     buffer))
          return false;