deal with invalid readpixel format and type

gpu/command_buffer/service/gles2_cmd_decoder.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gpu/command_buffer/service/gles2_cmd_decoder.h"
 
 #include <limits.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
@@ skipping 5900 matching lines @@
                                           GL_INVALID_OPERATION)) {
         if (params) {
           *params = 0;
         }
         return true;
       }
       if (params) {
         ScopedGLErrorSuppressor suppressor("GLES2DecoderImpl::GetHelper",
                                            GetErrorState());
         glGetIntegerv(pname, params);
-        if (glGetError() != GL_NO_ERROR) {
+        bool is_valid_format = true;

[Zhenyao Mo, 2016/07/19 16:42:38]

You just need one is_valid, and you can initialize it to glGetError() ==
GL_NO_ERROR.

You only need to check if *params is legal if is_valid is true.

+        bool is_valid_type = true;
+        if (pname == GL_IMPLEMENTATION_COLOR_READ_FORMAT) {
+          is_valid_format = validators_->read_pixel_format.IsValid(*params);
+        } else {
+          is_valid_type = validators_->read_pixel_type.IsValid(*params);
+        }

[qiankun, 2016/07/19 09:16:29]

Maybe" ? : " is simpler than if-else. You just need to define one variable
is_valid_format_type.

+        if (glGetError() != GL_NO_ERROR || !is_valid_format ||
+            !is_valid_type) {

[yunchao, 2016/07/19 09:39:32]

What it returns if the format/type is invalid? 

           if (pname == GL_IMPLEMENTATION_COLOR_READ_FORMAT) {
             *params = GLES2Util::GetGLReadPixelsImplementationFormat(
                 GetBoundReadFrameBufferInternalFormat(),
                 GetBoundReadFrameBufferTextureType(),
                 feature_info_->feature_flags().ext_read_format_bgra);
           } else {
             *params = GLES2Util::GetGLReadPixelsImplementationType(
                 GetBoundReadFrameBufferInternalFormat(),
                 GetBoundReadFrameBufferTextureType());
           }
@@ skipping 11472 matching lines @@
 }
 
 // Include the auto-generated part of this file. We split this because it means
 // we can easily edit the non-auto generated parts right here in this file
 // instead of having to edit some template or the code generator.
 #include "base/macros.h"
 #include "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu