Generate INVALID_OPERATION if feedback loops exist in CopyTex{Sub}Image2D.

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 <stdio.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 1163 matching lines @@
   bool SetCapabilityState(GLenum cap, bool enabled);
 
   // Check that the currently bound framebuffers are valid.
   // Generates GL error if not.
   bool CheckBoundFramebuffersValid(const char* func_name);
 
   // Check that the currently bound read framebuffer has a color image
   // attached. Generates GL error if not.
   bool CheckBoundReadFramebufferColorAttachment(const char* func_name);
 
+  // Check that the currently bound read framebuffer's color image
+  // isn't the target texture of the glCopyTex{Sub}Image2D.
+  bool FormsTextureCopyingFeedbackLoop(TextureRef* texture, GLint level);
+
   // Check if a framebuffer meets our requirements.
   bool CheckFramebufferValid(
       Framebuffer* framebuffer,
       GLenum target,
       const char* func_name);
 
   // Checks if the current program exists and is valid. If not generates the
   // appropriate GL error.  Returns true if the current program is in a usable
   // state.
   bool CheckCurrentProgram(const char* function_name);
@@ skipping 2031 matching lines @@
   if (!framebuffer)
     return true;
   if (framebuffer->GetAttachment(GL_COLOR_ATTACHMENT0) == NULL) {
     LOCAL_SET_GL_ERROR(
         GL_INVALID_OPERATION, func_name, "no color image attached");
     return false;
   }
   return true;
 }
 
+bool GLES2DecoderImpl::FormsTextureCopyingFeedbackLoop(
+    TextureRef* texture, GLint level) {
+  Framebuffer* framebuffer = features().chromium_framebuffer_multisample ?
+      framebuffer_state_.bound_read_framebuffer.get() :
+      framebuffer_state_.bound_draw_framebuffer.get();
+  if (!framebuffer)
+    return false;
+  const Framebuffer::Attachment* attachment = framebuffer->GetAttachment(
+      GL_COLOR_ATTACHMENT0);
+  if (!attachment)
+    return false;
+  return attachment->FormsFeedbackLoop(texture, level);
+}
+
 gfx::Size GLES2DecoderImpl::GetBoundReadFrameBufferSize() {
   Framebuffer* framebuffer =
       GetFramebufferInfoForTarget(GL_READ_FRAMEBUFFER_EXT);
   if (framebuffer != NULL) {
     const Framebuffer::Attachment* attachment =
         framebuffer->GetAttachment(GL_COLOR_ATTACHMENT0);
     if (attachment) {
       return gfx::Size(attachment->width(), attachment->height());
     }
     return gfx::Size(0, 0);
@@ skipping 5343 matching lines @@
 
   if (!EnsureGPUMemoryAvailable(estimated_size)) {
     LOCAL_SET_GL_ERROR(GL_OUT_OF_MEMORY, "glCopyTexImage2D", "out of memory");
     return;
   }
 
   if (!CheckBoundReadFramebufferColorAttachment("glCopyTexImage2D")) {
     return;
   }
 
+  if (FormsTextureCopyingFeedbackLoop(texture_ref, level)) {
+    LOCAL_SET_GL_ERROR(
+        GL_INVALID_OPERATION, "glCopyTexImage2D", "feedback loops");

[bajones, 2014/10/13 22:22:09]

I feel like the error message here and below could be a little more explicit to
help confused developers. Maybe something like "Source and destination texture
are the same"? 

[Zhenyao Mo, 2014/10/13 22:31:40]

Done.

+    return;
+  }
+
   if (!CheckBoundFramebuffersValid("glCopyTexImage2D")) {
     return;
   }
 
   LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glCopyTexImage2D");
   ScopedResolvedFrameBufferBinder binder(this, false, true);
   gfx::Size size = GetBoundReadFrameBufferSize();
 
   if (texture->IsAttachedToFramebuffer()) {
     framebuffer_state_.clear_state_dirty = true;
@@ skipping 98 matching lines @@
     LOCAL_SET_GL_ERROR(
         GL_INVALID_OPERATION,
         "glCopySubImage2D", "can not be used with depth or stencil textures");
     return;
   }
 
   if (!CheckBoundReadFramebufferColorAttachment("glCopyTexSubImage2D")) {
     return;
   }
 
+  if (FormsTextureCopyingFeedbackLoop(texture_ref, level)) {
+    LOCAL_SET_GL_ERROR(
+        GL_INVALID_OPERATION, "glCopyTexSubImage2D", "feedback loops");
+    return;
+  }
+
   if (!CheckBoundFramebuffersValid("glCopyTexSubImage2D")) {
     return;
   }
 
   ScopedResolvedFrameBufferBinder binder(this, false, true);
   gfx::Size size = GetBoundReadFrameBufferSize();
   GLint copyX = 0;
   GLint copyY = 0;
   GLint copyWidth = 0;
   GLint copyHeight = 0;
@@ skipping 2423 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 "gpu/command_buffer/service/gles2_cmd_decoder_autogen.h"
 
 }  // namespace gles2
 }  // namespace gpu