[Mesa-dev] [PATCH] mesa: Return 0 for XFB_VARYING_MAX_LENGTH if no varyings

[Matt Turner]

We add one for the null terminator, but if we don't have any varyings,
it doesn't make sense to have a null terminator.

Fixes part of es3conform's transform_feedback_init_defaults test.
---
 src/mesa/main/shaderapi.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/mesa/main/shaderapi.c b/src/mesa/main/shaderapi.c
index 7271150..19051d6 100644
--- a/src/mesa/main/shaderapi.c
+++ b/src/mesa/main/shaderapi.c
@@ -538,11 +538,14 @@ get_programiv(struct gl_context *ctx, GLuint program, GLenum pname, GLint *param
          break;
       *params = shProg->TransformFeedback.NumVarying;
       return;
-   case GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH:
+   case GL_TRANSFORM_FEEDBACK_VARYING_MAX_LENGTH: {
+      GLint max_length;
       if (!has_xfb)
          break;
-      *params = longest_feedback_varying_name(shProg) + 1;
+      max_length = longest_feedback_varying_name(shProg);
+      *params = max_length == 0 ? 0 : max_length + 1;
       return;
+   }
    case GL_TRANSFORM_FEEDBACK_BUFFER_MODE:
       if (!has_xfb)
          break;
-- 
1.7.8.6