Fix glGetActiveUniform/Attrib crashes due to state inconsistency

gpu/blink/webgraphicscontext3d_impl.cc

Index: gpu/blink/webgraphicscontext3d_impl.cc
diff --git a/gpu/blink/webgraphicscontext3d_impl.cc b/gpu/blink/webgraphicscontext3d_impl.cc
index 581e10298ec45f87436452ae2fd3410e465e8eab..06185ffc373602c27c67df3abb08bc75658af622 100644
--- a/gpu/blink/webgraphicscontext3d_impl.cc
+++ b/gpu/blink/webgraphicscontext3d_impl.cc
@@ -361,11 +361,12 @@ bool WebGraphicsContext3DImpl::getActiveAttrib(
       program, GL_ACTIVE_ATTRIBUTE_MAX_LENGTH, &max_name_length);
   if (max_name_length < 0)
     return false;
-  scoped_ptr<GLchar[]> name(new GLchar[max_name_length]);
-  if (!name) {
-    synthesizeGLError(GL_OUT_OF_MEMORY);

[Zhenyao Mo, 2015/03/07 01:00:08]

This is unnecessary because we always crash when "new" fails.

+  if (max_name_length == 0) {
+    // No active attributes exist.
+    synthesizeGLError(GL_INVALID_VALUE);

[no sievers, 2015/03/09 19:10:08]

This seems correct if the program is not valid. But what if the linked shader is
valid but does not reference any attributes or uniforms?

[no sievers, 2015/03/09 19:13:54]

nm, we do call getProgramiv() but this is obviously the right error for
getActiveAttrib/Uniform then too.

lgtm

[Zhenyao Mo, 2015/03/09 19:58:28]

If the linked program has zero attribs or uniforms, then no matter what the
index value is, it is wrong, so an INVALID_VALUE is guaranteed.

     return false;
   }
+  scoped_ptr<GLchar[]> name(new GLchar[max_name_length]);
   GLsizei length = 0;
   GLint size = -1;
   GLenum type = 0;
@@ -387,11 +388,12 @@ bool WebGraphicsContext3DImpl::getActiveUniform(
       program, GL_ACTIVE_UNIFORM_MAX_LENGTH, &max_name_length);
   if (max_name_length < 0)
     return false;
-  scoped_ptr<GLchar[]> name(new GLchar[max_name_length]);
-  if (!name) {
-    synthesizeGLError(GL_OUT_OF_MEMORY);
+  if (max_name_length == 0) {
+    // No active uniforms exist.
+    synthesizeGLError(GL_INVALID_VALUE);
     return false;
   }
+  scoped_ptr<GLchar[]> name(new GLchar[max_name_length]);
   GLsizei length = 0;
   GLint size = -1;
   GLenum type = 0;