text: //
  // Copyright (c) 2013-2014 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  
  // validationES.h: Validation functions for generic OpenGL ES entry point parameters
  
  #include "libANGLE/validationES.h"
  #include "libANGLE/validationES2.h"
  #include "libANGLE/validationES3.h"
  #include "libANGLE/Context.h"
  #include "libANGLE/Texture.h"
  #include "libANGLE/Framebuffer.h"
  #include "libANGLE/FramebufferAttachment.h"
  #include "libANGLE/formatutils.h"
  #include "libANGLE/Query.h"
  #include "libANGLE/Program.h"
  #include "libANGLE/Uniform.h"
  #include "libANGLE/TransformFeedback.h"
  #include "libANGLE/VertexArray.h"
  #include "libANGLE/renderer/BufferImpl.h"
  
  #include "common/mathutil.h"
  #include "common/utilities.h"
  
  namespace gl
  {
  
  bool ValidCap(const Context *context, GLenum cap)
  {
      switch (cap)
      {
        case GL_CULL_FACE:
        case GL_POLYGON_OFFSET_FILL:
        case GL_SAMPLE_ALPHA_TO_COVERAGE:
        case GL_SAMPLE_COVERAGE:
        case GL_SCISSOR_TEST:
        case GL_STENCIL_TEST:
        case GL_DEPTH_TEST:
        case GL_BLEND:
        case GL_DITHER:
          return true;
        case GL_PRIMITIVE_RESTART_FIXED_INDEX:
        case GL_RASTERIZER_DISCARD:
          return (context->getClientVersion() >= 3);
        default:
          return false;
      }
  }
  
  bool ValidTextureTarget(const Context *context, GLenum target)
  {
      switch (target)
      {
        case GL_TEXTURE_2D:
        case GL_TEXTURE_CUBE_MAP:
          return true;
  
        case GL_TEXTURE_3D:
        case GL_TEXTURE_2D_ARRAY:
          return (context->getClientVersion() >= 3);
  
        default:
          return false;
      }
  }
  
  // This function differs from ValidTextureTarget in that the target must be
  // usable as the destination of a 2D operation-- so a cube face is valid, but
  // GL_TEXTURE_CUBE_MAP is not.
  // Note: duplicate of IsInternalTextureTarget
  bool ValidTexture2DDestinationTarget(const Context *context, GLenum target)
  {
      switch (target)
      {
        case GL_TEXTURE_2D:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
          return true;
        case GL_TEXTURE_2D_ARRAY:
        case GL_TEXTURE_3D:
          return (context->getClientVersion() >= 3);
        default:
          return false;
      }
  }
  
  bool ValidFramebufferTarget(GLenum target)
  {
      static_assert(GL_DRAW_FRAMEBUFFER_ANGLE == GL_DRAW_FRAMEBUFFER && GL_READ_FRAMEBUFFER_ANGLE == GL_READ_FRAMEBUFFER,
                    "ANGLE framebuffer enums must equal the ES3 framebuffer enums.");
  
      switch (target)
      {
        case GL_FRAMEBUFFER:      return true;
        case GL_READ_FRAMEBUFFER: return true;
        case GL_DRAW_FRAMEBUFFER: return true;
        default:                  return false;
      }
  }
  
  bool ValidBufferTarget(const Context *context, GLenum target)
  {
      switch (target)
      {
        case GL_ARRAY_BUFFER:
        case GL_ELEMENT_ARRAY_BUFFER:
          return true;
  
        case GL_PIXEL_PACK_BUFFER:
        case GL_PIXEL_UNPACK_BUFFER:
          return context->getExtensions().pixelBufferObject;
  
        case GL_COPY_READ_BUFFER:
        case GL_COPY_WRITE_BUFFER:
        case GL_TRANSFORM_FEEDBACK_BUFFER:
        case GL_UNIFORM_BUFFER:
          return (context->getClientVersion() >= 3);
  
        default:
          return false;
      }
  }
  
  bool ValidBufferParameter(const Context *context, GLenum pname)
  {
      switch (pname)
      {
        case GL_BUFFER_USAGE:
        case GL_BUFFER_SIZE:
          return true;
  
        // GL_BUFFER_MAP_POINTER is a special case, and may only be
        // queried with GetBufferPointerv
        case GL_BUFFER_ACCESS_FLAGS:
        case GL_BUFFER_MAPPED:
        case GL_BUFFER_MAP_OFFSET:
        case GL_BUFFER_MAP_LENGTH:
          return (context->getClientVersion() >= 3);
  
        default:
          return false;
      }
  }
  
  bool ValidMipLevel(const Context *context, GLenum target, GLint level)
  {
      size_t maxDimension = 0;
      switch (target)
      {
        case GL_TEXTURE_2D:                  maxDimension = context->getCaps().max2DTextureSize;       break;
        case GL_TEXTURE_CUBE_MAP:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z: maxDimension = context->getCaps().maxCubeMapTextureSize;  break;
        case GL_TEXTURE_3D:                  maxDimension = context->getCaps().max3DTextureSize;       break;
        case GL_TEXTURE_2D_ARRAY:            maxDimension = context->getCaps().max2DTextureSize;       break;
        default: UNREACHABLE();
      }
  
      return level <= gl::log2(maxDimension);
  }
  
  bool ValidImageSize(const Context *context, GLenum target, GLint level,
                      GLsizei width, GLsizei height, GLsizei depth)
  {
      if (level < 0 || width < 0 || height < 0 || depth < 0)
      {
          return false;
      }
  
      if (!context->getExtensions().textureNPOT &&
          (level != 0 && (!gl::isPow2(width) || !gl::isPow2(height) || !gl::isPow2(depth))))
      {
          return false;
      }
  
      if (!ValidMipLevel(context, target, level))
      {
          return false;
      }
  
      return true;
  }
  
  bool ValidCompressedImageSize(const Context *context, GLenum internalFormat, GLsizei width, GLsizei height)
  {
      const gl::InternalFormat &formatInfo = gl::GetInternalFormatInfo(internalFormat);
      if (!formatInfo.compressed)
      {
          return false;
      }
  
      if (width  < 0 || (static_cast<GLuint>(width)  > formatInfo.compressedBlockWidth  && width  % formatInfo.compressedBlockWidth != 0) ||
          height < 0 || (static_cast<GLuint>(height) > formatInfo.compressedBlockHeight && height % formatInfo.compressedBlockHeight != 0))
      {
          return false;
      }
  
      return true;
  }
  
  bool ValidQueryType(const Context *context, GLenum queryType)
  {
      static_assert(GL_ANY_SAMPLES_PASSED == GL_ANY_SAMPLES_PASSED_EXT, "GL extension enums not equal.");
      static_assert(GL_ANY_SAMPLES_PASSED_CONSERVATIVE == GL_ANY_SAMPLES_PASSED_CONSERVATIVE_EXT, "GL extension enums not equal.");
  
      switch (queryType)
      {
        case GL_ANY_SAMPLES_PASSED:
        case GL_ANY_SAMPLES_PASSED_CONSERVATIVE:
          return true;
        case GL_TRANSFORM_FEEDBACK_PRIMITIVES_WRITTEN:
          return (context->getClientVersion() >= 3);
        default:
          return false;
      }
  }
  
  bool ValidProgram(Context *context, GLuint id)
  {
      // ES3 spec (section 2.11.1) -- "Commands that accept shader or program object names will generate the
      // error INVALID_VALUE if the provided name is not the name of either a shader or program object and
      // INVALID_OPERATION if the provided name identifies an object that is not the expected type."
  
      if (context->getProgram(id) != NULL)
      {
          return true;
      }
      else if (context->getShader(id) != NULL)
      {
          // ID is the wrong type
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
      else
      {
          // No shader/program object has this ID
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  }
  
  bool ValidateAttachmentTarget(gl::Context *context, GLenum attachment)
  {
      if (attachment >= GL_COLOR_ATTACHMENT0_EXT && attachment <= GL_COLOR_ATTACHMENT15_EXT)
      {
          const unsigned int colorAttachment = (attachment - GL_COLOR_ATTACHMENT0_EXT);
  
          if (colorAttachment >= context->getCaps().maxColorAttachments)
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
      }
      else
      {
          switch (attachment)
          {
            case GL_DEPTH_ATTACHMENT:
            case GL_STENCIL_ATTACHMENT:
              break;
  
            case GL_DEPTH_STENCIL_ATTACHMENT:
              if (context->getClientVersion() < 3)
              {
                  context->recordError(Error(GL_INVALID_ENUM));
                  return false;
              }
              break;
  
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
      }
  
      return true;
  }
  
  bool ValidateRenderbufferStorageParametersBase(gl::Context *context, GLenum target, GLsizei samples,
                                                 GLenum internalformat, GLsizei width, GLsizei height)
  {
      switch (target)
      {
        case GL_RENDERBUFFER:
          break;
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if (width < 0 || height < 0 || samples < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      const TextureCaps &formatCaps = context->getTextureCaps().get(internalformat);
      if (!formatCaps.renderable)
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      // ANGLE_framebuffer_multisample does not explicitly state that the internal format must be
      // sized but it does state that the format must be in the ES2.0 spec table 4.5 which contains
      // only sized internal formats.
      const gl::InternalFormat &formatInfo = gl::GetInternalFormatInfo(internalformat);
      if (formatInfo.pixelBytes == 0)
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if (static_cast<GLuint>(std::max(width, height)) > context->getCaps().maxRenderbufferSize)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      GLuint handle = context->getState().getRenderbufferId();
      if (handle == 0)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateRenderbufferStorageParametersANGLE(gl::Context *context, GLenum target, GLsizei samples,
                                                  GLenum internalformat, GLsizei width, GLsizei height)
  {
      ASSERT(samples == 0 || context->getExtensions().framebufferMultisample);
  
      // ANGLE_framebuffer_multisample states that the value of samples must be less than or equal
      // to MAX_SAMPLES_ANGLE (Context::getExtensions().maxSamples) otherwise GL_INVALID_VALUE is
      // generated.
      if (static_cast<GLuint>(samples) > context->getExtensions().maxSamples)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      // ANGLE_framebuffer_multisample states GL_OUT_OF_MEMORY is generated on a failure to create
      // the specified storage. This is different than ES 3.0 in which a sample number higher
      // than the maximum sample number supported  by this format generates a GL_INVALID_VALUE.
      const TextureCaps &formatCaps = context->getTextureCaps().get(internalformat);
      if (static_cast<GLuint>(samples) > formatCaps.getMaxSamples())
      {
          context->recordError(Error(GL_OUT_OF_MEMORY));
          return false;
      }
  
      return ValidateRenderbufferStorageParametersBase(context, target, samples, internalformat, width, height);
  }
  
  bool ValidateFramebufferRenderbufferParameters(gl::Context *context, GLenum target, GLenum attachment,
                                                 GLenum renderbuffertarget, GLuint renderbuffer)
  {
      if (!ValidFramebufferTarget(target))
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      gl::Framebuffer *framebuffer = context->getState().getTargetFramebuffer(target);
      GLuint framebufferHandle = context->getState().getTargetFramebuffer(target)->id();
  
      if (!framebuffer || (framebufferHandle == 0 && renderbuffer != 0))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (!ValidateAttachmentTarget(context, attachment))
      {
          return false;
      }
  
      // [OpenGL ES 2.0.25] Section 4.4.3 page 112
      // [OpenGL ES 3.0.2] Section 4.4.2 page 201
      // 'renderbuffer' must be either zero or the name of an existing renderbuffer object of
      // type 'renderbuffertarget', otherwise an INVALID_OPERATION error is generated.
      if (renderbuffer != 0)
      {
          if (!context->getRenderbuffer(renderbuffer))
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
      }
  
      return true;
  }
  
  static bool IsPartialBlit(gl::Context *context, gl::FramebufferAttachment *readBuffer, gl::FramebufferAttachment *writeBuffer,
                            GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
                            GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1)
  {
      if (srcX0 != 0 || srcY0 != 0 || dstX0 != 0 || dstY0 != 0 ||
          dstX1 != writeBuffer->getWidth() || dstY1 != writeBuffer->getHeight() ||
          srcX1 != readBuffer->getWidth() || srcY1 != readBuffer->getHeight())
      {
          return true;
      }
      else if (context->getState().isScissorTestEnabled())
      {
          const Rectangle &scissor = context->getState().getScissor();
  
          return scissor.x > 0 || scissor.y > 0 ||
                 scissor.width < writeBuffer->getWidth() ||
                 scissor.height < writeBuffer->getHeight();
      }
      else
      {
          return false;
      }
  }
  
  bool ValidateBlitFramebufferParameters(gl::Context *context, GLint srcX0, GLint srcY0, GLint srcX1, GLint srcY1,
                                         GLint dstX0, GLint dstY0, GLint dstX1, GLint dstY1, GLbitfield mask,
                                         GLenum filter, bool fromAngleExtension)
  {
      switch (filter)
      {
        case GL_NEAREST:
          break;
        case GL_LINEAR:
          if (fromAngleExtension)
          {
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if ((mask & ~(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)) != 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (mask == 0)
      {
          // ES3.0 spec, section 4.3.2 specifies that a mask of zero is valid and no
          // buffers are copied.
          return false;
      }
  
      if (fromAngleExtension && (srcX1 - srcX0 != dstX1 - dstX0 || srcY1 - srcY0 != dstY1 - dstY0))
      {
          ERR("Scaling and flipping in BlitFramebufferANGLE not supported by this implementation.");
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      // ES3.0 spec, section 4.3.2 states that linear filtering is only available for the
      // color buffer, leaving only nearest being unfiltered from above
      if ((mask & ~GL_COLOR_BUFFER_BIT) != 0 && filter != GL_NEAREST)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (context->getState().getReadFramebuffer()->id() == context->getState().getDrawFramebuffer()->id())
      {
          if (fromAngleExtension)
          {
              ERR("Blits with the same source and destination framebuffer are not supported by this "
                  "implementation.");
          }
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      gl::Framebuffer *readFramebuffer = context->getState().getReadFramebuffer();
      gl::Framebuffer *drawFramebuffer = context->getState().getDrawFramebuffer();
  
      if (!readFramebuffer || !drawFramebuffer)
      {
          context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
          return false;
      }
  
      if (!readFramebuffer->checkStatus(context->getData()))
      {
          context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
          return false;
      }
  
      if (!drawFramebuffer->checkStatus(context->getData()))
      {
          context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
          return false;
      }
  
      if (drawFramebuffer->getSamples(context->getData()) != 0)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      bool sameBounds = srcX0 == dstX0 && srcY0 == dstY0 && srcX1 == dstX1 && srcY1 == dstY1;
  
      if (mask & GL_COLOR_BUFFER_BIT)
      {
          gl::FramebufferAttachment *readColorBuffer = readFramebuffer->getReadColorbuffer();
          gl::FramebufferAttachment *drawColorBuffer = drawFramebuffer->getFirstColorbuffer();
  
          if (readColorBuffer && drawColorBuffer)
          {
              GLenum readInternalFormat = readColorBuffer->getInternalFormat();
              const InternalFormat &readFormatInfo = GetInternalFormatInfo(readInternalFormat);
  
              for (GLuint i = 0; i < context->getCaps().maxColorAttachments; i++)
              {
                  if (drawFramebuffer->isEnabledColorAttachment(i))
                  {
                      GLenum drawInternalFormat = drawFramebuffer->getColorbuffer(i)->getInternalFormat();
                      const InternalFormat &drawFormatInfo = GetInternalFormatInfo(drawInternalFormat);
  
                      // The GL ES 3.0.2 spec (pg 193) states that:
                      // 1) If the read buffer is fixed point format, the draw buffer must be as well
                      // 2) If the read buffer is an unsigned integer format, the draw buffer must be as well
                      // 3) If the read buffer is a signed integer format, the draw buffer must be as well
                      if ( (readFormatInfo.componentType == GL_UNSIGNED_NORMALIZED || readFormatInfo.componentType == GL_SIGNED_NORMALIZED) &&
                          !(drawFormatInfo.componentType == GL_UNSIGNED_NORMALIZED || drawFormatInfo.componentType == GL_SIGNED_NORMALIZED))
                      {
                          context->recordError(Error(GL_INVALID_OPERATION));
                          return false;
                      }
  
                      if (readFormatInfo.componentType == GL_UNSIGNED_INT && drawFormatInfo.componentType != GL_UNSIGNED_INT)
                      {
                          context->recordError(Error(GL_INVALID_OPERATION));
                          return false;
                      }
  
                      if (readFormatInfo.componentType == GL_INT && drawFormatInfo.componentType != GL_INT)
                      {
                          context->recordError(Error(GL_INVALID_OPERATION));
                          return false;
                      }
  
                      if (readColorBuffer->getSamples() > 0 && (readInternalFormat != drawInternalFormat || !sameBounds))
                      {
                          context->recordError(Error(GL_INVALID_OPERATION));
                          return false;
                      }
                  }
              }
  
              if ((readFormatInfo.componentType == GL_INT || readFormatInfo.componentType == GL_UNSIGNED_INT) && filter == GL_LINEAR)
              {
                  context->recordError(Error(GL_INVALID_OPERATION));
                  return false;
              }
  
              if (fromAngleExtension)
              {
                  FramebufferAttachment *readColorAttachment = readFramebuffer->getReadColorbuffer();
                  if (!readColorAttachment ||
                      (!(readColorAttachment->type() == GL_TEXTURE && readColorAttachment->getTextureImageIndex()->type == GL_TEXTURE_2D) &&
                      readColorAttachment->type() != GL_RENDERBUFFER &&
                      readColorAttachment->type() != GL_FRAMEBUFFER_DEFAULT))
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
  
                  for (GLuint colorAttachment = 0; colorAttachment < context->getCaps().maxColorAttachments; ++colorAttachment)
                  {
                      if (drawFramebuffer->isEnabledColorAttachment(colorAttachment))
                      {
                          FramebufferAttachment *attachment = drawFramebuffer->getColorbuffer(colorAttachment);
                          ASSERT(attachment);
  
                          if (!(attachment->type() == GL_TEXTURE && attachment->getTextureImageIndex()->type == GL_TEXTURE_2D) &&
                              attachment->type() != GL_RENDERBUFFER &&
                              attachment->type() != GL_FRAMEBUFFER_DEFAULT)
                          {
                              context->recordError(Error(GL_INVALID_OPERATION));
                              return false;
                          }
  
                          // Return an error if the destination formats do not match
                          if (attachment->getInternalFormat() != readColorBuffer->getInternalFormat())
                          {
                              context->recordError(Error(GL_INVALID_OPERATION));
                              return false;
                          }
                      }
                  }
  
                  int readSamples = readFramebuffer->getSamples(context->getData());
  
                  if (readSamples != 0 && IsPartialBlit(context, readColorBuffer, drawColorBuffer,
                                                        srcX0, srcY0, srcX1, srcY1,
                                                        dstX0, dstY0, dstX1, dstY1))
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
              }
          }
      }
  
      GLenum masks[] = {GL_DEPTH_BUFFER_BIT, GL_STENCIL_BUFFER_BIT};
      GLenum attachments[] = {GL_DEPTH_ATTACHMENT, GL_STENCIL_ATTACHMENT};
      for (size_t i = 0; i < 2; i++)
      {
          if (mask & masks[i])
          {
              gl::FramebufferAttachment *readBuffer = readFramebuffer->getAttachment(attachments[i]);
              gl::FramebufferAttachment *drawBuffer = drawFramebuffer->getAttachment(attachments[i]);
  
              if (readBuffer && drawBuffer)
              {
                  if (readBuffer->getInternalFormat() != drawBuffer->getInternalFormat())
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
  
                  if (readBuffer->getSamples() > 0 && !sameBounds)
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
  
                  if (fromAngleExtension)
                  {
                      if (IsPartialBlit(context, readBuffer, drawBuffer,
                                        srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1))
                      {
                          ERR("Only whole-buffer depth and stencil blits are supported by this implementation.");
                          context->recordError(Error(GL_INVALID_OPERATION)); // only whole-buffer copies are permitted
                          return false;
                      }
  
                      if (readBuffer->getSamples() != 0 || drawBuffer->getSamples() != 0)
                      {
                          context->recordError(Error(GL_INVALID_OPERATION));
                          return false;
                      }
                  }
              }
          }
      }
  
      return true;
  }
  
  bool ValidateGetVertexAttribParameters(Context *context, GLenum pname)
  {
      switch (pname)
      {
        case GL_VERTEX_ATTRIB_ARRAY_ENABLED:
        case GL_VERTEX_ATTRIB_ARRAY_SIZE:
        case GL_VERTEX_ATTRIB_ARRAY_STRIDE:
        case GL_VERTEX_ATTRIB_ARRAY_TYPE:
        case GL_VERTEX_ATTRIB_ARRAY_NORMALIZED:
        case GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING:
        case GL_CURRENT_VERTEX_ATTRIB:
          return true;
  
        case GL_VERTEX_ATTRIB_ARRAY_DIVISOR:
          // Don't verify ES3 context because GL_VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE uses
          // the same constant.
          static_assert(GL_VERTEX_ATTRIB_ARRAY_DIVISOR == GL_VERTEX_ATTRIB_ARRAY_DIVISOR_ANGLE,
                        "ANGLE extension enums not equal to GL enums.");
          return true;
  
        case GL_VERTEX_ATTRIB_ARRAY_INTEGER:
          if (context->getClientVersion() < 3)
          {
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          return true;
  
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  }
  
  bool ValidateTexParamParameters(gl::Context *context, GLenum pname, GLint param)
  {
      switch (pname)
      {
        case GL_TEXTURE_WRAP_R:
        case GL_TEXTURE_SWIZZLE_R:
        case GL_TEXTURE_SWIZZLE_G:
        case GL_TEXTURE_SWIZZLE_B:
        case GL_TEXTURE_SWIZZLE_A:
        case GL_TEXTURE_BASE_LEVEL:
        case GL_TEXTURE_MAX_LEVEL:
        case GL_TEXTURE_COMPARE_MODE:
        case GL_TEXTURE_COMPARE_FUNC:
        case GL_TEXTURE_MIN_LOD:
        case GL_TEXTURE_MAX_LOD:
          if (context->getClientVersion() < 3)
          {
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        default: break;
      }
  
      switch (pname)
      {
        case GL_TEXTURE_WRAP_S:
        case GL_TEXTURE_WRAP_T:
        case GL_TEXTURE_WRAP_R:
          switch (param)
          {
            case GL_REPEAT:
            case GL_CLAMP_TO_EDGE:
            case GL_MIRRORED_REPEAT:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
  
        case GL_TEXTURE_MIN_FILTER:
          switch (param)
          {
            case GL_NEAREST:
            case GL_LINEAR:
            case GL_NEAREST_MIPMAP_NEAREST:
            case GL_LINEAR_MIPMAP_NEAREST:
            case GL_NEAREST_MIPMAP_LINEAR:
            case GL_LINEAR_MIPMAP_LINEAR:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        case GL_TEXTURE_MAG_FILTER:
          switch (param)
          {
            case GL_NEAREST:
            case GL_LINEAR:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        case GL_TEXTURE_USAGE_ANGLE:
          switch (param)
          {
            case GL_NONE:
            case GL_FRAMEBUFFER_ATTACHMENT_ANGLE:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        case GL_TEXTURE_MAX_ANISOTROPY_EXT:
          if (!context->getExtensions().textureFilterAnisotropic)
          {
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
  
          // we assume the parameter passed to this validation method is truncated, not rounded
          if (param < 1)
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
          return true;
  
        case GL_TEXTURE_MIN_LOD:
        case GL_TEXTURE_MAX_LOD:
          // any value is permissible
          return true;
  
        case GL_TEXTURE_COMPARE_MODE:
          // Acceptable mode parameters from GLES 3.0.2 spec, table 3.17
          switch (param)
          {
            case GL_NONE:
            case GL_COMPARE_REF_TO_TEXTURE:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        case GL_TEXTURE_COMPARE_FUNC:
          // Acceptable function parameters from GLES 3.0.2 spec, table 3.17
          switch (param)
          {
            case GL_LEQUAL:
            case GL_GEQUAL:
            case GL_LESS:
            case GL_GREATER:
            case GL_EQUAL:
            case GL_NOTEQUAL:
            case GL_ALWAYS:
            case GL_NEVER:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        case GL_TEXTURE_SWIZZLE_R:
        case GL_TEXTURE_SWIZZLE_G:
        case GL_TEXTURE_SWIZZLE_B:
        case GL_TEXTURE_SWIZZLE_A:
          switch (param)
          {
            case GL_RED:
            case GL_GREEN:
            case GL_BLUE:
            case GL_ALPHA:
            case GL_ZERO:
            case GL_ONE:
              return true;
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
  
        case GL_TEXTURE_BASE_LEVEL:
        case GL_TEXTURE_MAX_LEVEL:
          if (param < 0)
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
          return true;
  
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  }
  
  bool ValidateSamplerObjectParameter(gl::Context *context, GLenum pname)
  {
      switch (pname)
      {
        case GL_TEXTURE_MIN_FILTER:
        case GL_TEXTURE_MAG_FILTER:
        case GL_TEXTURE_WRAP_S:
        case GL_TEXTURE_WRAP_T:
        case GL_TEXTURE_WRAP_R:
        case GL_TEXTURE_MIN_LOD:
        case GL_TEXTURE_MAX_LOD:
        case GL_TEXTURE_COMPARE_MODE:
        case GL_TEXTURE_COMPARE_FUNC:
          return true;
  
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  }
  
  bool ValidateReadPixelsParameters(gl::Context *context, GLint x, GLint y, GLsizei width, GLsizei height,
                                    GLenum format, GLenum type, GLsizei *bufSize, GLvoid *pixels)
  {
      gl::Framebuffer *framebuffer = context->getState().getReadFramebuffer();
      ASSERT(framebuffer);
  
      if (framebuffer->checkStatus(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
      {
          context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
          return false;
      }
  
      if (context->getState().getReadFramebuffer()->id() != 0 &&
          framebuffer->getSamples(context->getData()) != 0)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      const FramebufferAttachment *readBuffer = framebuffer->getReadColorbuffer();
      if (!readBuffer)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      GLenum currentFormat = framebuffer->getImplementationColorReadFormat();
      GLenum currentType = framebuffer->getImplementationColorReadType();
      GLenum currentInternalFormat = readBuffer->getInternalFormat();
      GLuint clientVersion = context->getClientVersion();
  
      bool validReadFormat = (clientVersion < 3) ? ValidES2ReadFormatType(context, format, type) :
                                                   ValidES3ReadFormatType(context, currentInternalFormat, format, type);
  
      if (!(currentFormat == format && currentType == type) && !validReadFormat)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      GLenum sizedInternalFormat = GetSizedInternalFormat(format, type);
      const InternalFormat &sizedFormatInfo = GetInternalFormatInfo(sizedInternalFormat);
  
      GLsizei outputPitch = sizedFormatInfo.computeRowPitch(type, width, context->getState().getPackAlignment(), 0);
      // sized query sanity check
      if (bufSize)
      {
          int requiredSize = outputPitch * height;
          if (requiredSize > *bufSize)
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
      }
  
      return true;
  }
  
  bool ValidateBeginQuery(gl::Context *context, GLenum target, GLuint id)
  {
      if (!ValidQueryType(context, target))
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if (id == 0)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      // From EXT_occlusion_query_boolean: If BeginQueryEXT is called with an <id>
      // of zero, if the active query object name for <target> is non-zero (for the
      // targets ANY_SAMPLES_PASSED_EXT and ANY_SAMPLES_PASSED_CONSERVATIVE_EXT, if
      // the active query for either target is non-zero), if <id> is the name of an
      // existing query object whose type does not match <target>, or if <id> is the
      // active query object name for any query type, the error INVALID_OPERATION is
      // generated.
  
      // Ensure no other queries are active
      // NOTE: If other queries than occlusion are supported, we will need to check
      // separately that:
      //    a) The query ID passed is not the current active query for any target/type
      //    b) There are no active queries for the requested target (and in the case
      //       of GL_ANY_SAMPLES_PASSED_EXT and GL_ANY_SAMPLES_PASSED_CONSERVATIVE_EXT,
      //       no query may be active for either if glBeginQuery targets either.
      if (context->getState().isQueryActive())
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      Query *queryObject = context->getQuery(id, true, target);
  
      // check that name was obtained with glGenQueries
      if (!queryObject)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      // check for type mismatch
      if (queryObject->getType() != target)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateEndQuery(gl::Context *context, GLenum target)
  {
      if (!ValidQueryType(context, target))
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      const Query *queryObject = context->getState().getActiveQuery(target);
  
      if (queryObject == NULL)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  static bool ValidateUniformCommonBase(gl::Context *context, GLenum targetUniformType,
                                        GLint location, GLsizei count, LinkedUniform **uniformOut)
  {
      if (count < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      gl::Program *program = context->getState().getProgram();
      if (!program)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (location == -1)
      {
          // Silently ignore the uniform command
          return false;
      }
  
      if (!program->isValidUniformLocation(location))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      LinkedUniform *uniform = program->getUniformByLocation(location);
  
      // attempting to write an array to a non-array uniform is an INVALID_OPERATION
      if (uniform->elementCount() == 1 && count > 1)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      *uniformOut = uniform;
      return true;
  }
  
  bool ValidateUniform(gl::Context *context, GLenum uniformType, GLint location, GLsizei count)
  {
      // Check for ES3 uniform entry points
      if (VariableComponentType(uniformType) == GL_UNSIGNED_INT && context->getClientVersion() < 3)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      LinkedUniform *uniform = NULL;
      if (!ValidateUniformCommonBase(context, uniformType, location, count, &uniform))
      {
          return false;
      }
  
      GLenum targetBoolType = VariableBoolVectorType(uniformType);
      bool samplerUniformCheck = (IsSamplerType(uniform->type) && uniformType == GL_INT);
      if (!samplerUniformCheck && uniformType != uniform->type && targetBoolType != uniform->type)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateUniformMatrix(gl::Context *context, GLenum matrixType, GLint location, GLsizei count,
                             GLboolean transpose)
  {
      // Check for ES3 uniform entry points
      int rows = VariableRowCount(matrixType);
      int cols = VariableColumnCount(matrixType);
      if (rows != cols && context->getClientVersion() < 3)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (transpose != GL_FALSE && context->getClientVersion() < 3)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      LinkedUniform *uniform = NULL;
      if (!ValidateUniformCommonBase(context, matrixType, location, count, &uniform))
      {
          return false;
      }
  
      if (uniform->type != matrixType)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateStateQuery(gl::Context *context, GLenum pname, GLenum *nativeType, unsigned int *numParams)
  {
      if (!context->getQueryParameterInfo(pname, nativeType, numParams))
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      const Caps &caps = context->getCaps();
  
      if (pname >= GL_DRAW_BUFFER0 && pname <= GL_DRAW_BUFFER15)
      {
          unsigned int colorAttachment = (pname - GL_DRAW_BUFFER0);
  
          if (colorAttachment >= caps.maxDrawBuffers)
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
      }
  
      switch (pname)
      {
        case GL_TEXTURE_BINDING_2D:
        case GL_TEXTURE_BINDING_CUBE_MAP:
        case GL_TEXTURE_BINDING_3D:
        case GL_TEXTURE_BINDING_2D_ARRAY:
          if (context->getState().getActiveSampler() >= caps.maxCombinedTextureImageUnits)
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
          break;
  
        case GL_IMPLEMENTATION_COLOR_READ_TYPE:
        case GL_IMPLEMENTATION_COLOR_READ_FORMAT:
          {
              Framebuffer *framebuffer = context->getState().getReadFramebuffer();
              ASSERT(framebuffer);
              if (framebuffer->checkStatus(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
              {
                  context->recordError(Error(GL_INVALID_OPERATION));
                  return false;
              }
  
              FramebufferAttachment *attachment = framebuffer->getReadColorbuffer();
              if (!attachment)
              {
                  context->recordError(Error(GL_INVALID_OPERATION));
                  return false;
              }
          }
          break;
  
        default:
          break;
      }
  
      // pname is valid, but there are no parameters to return
      if (numParams == 0)
      {
          return false;
      }
  
      return true;
  }
  
  bool ValidateCopyTexImageParametersBase(gl::Context* context, GLenum target, GLint level, GLenum internalformat, bool isSubImage,
                                          GLint xoffset, GLint yoffset, GLint zoffset, GLint x, GLint y, GLsizei width, GLsizei height,
                                          GLint border, GLenum *textureFormatOut)
  {
  
      if (!ValidTexture2DDestinationTarget(context, target))
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if (level < 0 || xoffset < 0 || yoffset < 0 || zoffset < 0 || width < 0 || height < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (std::numeric_limits<GLsizei>::max() - xoffset < width || std::numeric_limits<GLsizei>::max() - yoffset < height)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (border != 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (!ValidMipLevel(context, target, level))
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      gl::Framebuffer *framebuffer = context->getState().getReadFramebuffer();
      if (framebuffer->checkStatus(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
      {
          context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
          return false;
      }
  
      if (context->getState().getReadFramebuffer()->id() != 0 && framebuffer->getSamples(context->getData()) != 0)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      const gl::Caps &caps = context->getCaps();
  
      GLuint maxDimension = 0;
      switch (target)
      {
        case GL_TEXTURE_2D:
          maxDimension = caps.max2DTextureSize;
          break;
  
        case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
        case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
        case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
          maxDimension = caps.maxCubeMapTextureSize;
          break;
  
        case GL_TEXTURE_2D_ARRAY:
          maxDimension = caps.max2DTextureSize;
          break;
  
        case GL_TEXTURE_3D:
          maxDimension = caps.max3DTextureSize;
          break;
  
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      gl::Texture *texture = context->getTargetTexture(IsCubeMapTextureTarget(target) ? GL_TEXTURE_CUBE_MAP : target);
      if (!texture)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (texture->isImmutable() && !isSubImage)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      const gl::InternalFormat &formatInfo = gl::GetInternalFormatInfo(internalformat);
  
      if (formatInfo.depthBits > 0)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (formatInfo.compressed && !ValidCompressedImageSize(context, internalformat, width, height))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (isSubImage)
      {
          if (static_cast<size_t>(xoffset + width) > texture->getWidth(target, level) ||
              static_cast<size_t>(yoffset + height) > texture->getHeight(target, level) ||
              static_cast<size_t>(zoffset) >= texture->getDepth(target, level))
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
      }
      else
      {
          if (IsCubeMapTextureTarget(target) && width != height)
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
  
          if (!formatInfo.textureSupport(context->getClientVersion(), context->getExtensions()))
          {
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
  
          int maxLevelDimension = (maxDimension >> level);
          if (static_cast<int>(width) > maxLevelDimension || static_cast<int>(height) > maxLevelDimension)
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
      }
  
      *textureFormatOut = texture->getInternalFormat(target, level);
      return true;
  }
  
  static bool ValidateDrawBase(Context *context, GLenum mode, GLsizei count, GLsizei maxVertex, GLsizei primcount)
  {
      switch (mode)
      {
        case GL_POINTS:
        case GL_LINES:
        case GL_LINE_LOOP:
        case GL_LINE_STRIP:
        case GL_TRIANGLES:
        case GL_TRIANGLE_STRIP:
        case GL_TRIANGLE_FAN:
          break;
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if (count < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      const State &state = context->getState();
  
      // Check for mapped buffers
      if (state.hasMappedBuffer(GL_ARRAY_BUFFER))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      const gl::DepthStencilState &depthStencilState = state.getDepthStencilState();
      if (depthStencilState.stencilWritemask != depthStencilState.stencilBackWritemask ||
          state.getStencilRef() != state.getStencilBackRef() ||
          depthStencilState.stencilMask != depthStencilState.stencilBackMask)
      {
          // Note: these separate values are not supported in WebGL, due to D3D's limitations.
          // See Section 6.10 of the WebGL 1.0 spec
          ERR("This ANGLE implementation does not support separate front/back stencil "
              "writemasks, reference values, or stencil mask values.");
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      const gl::Framebuffer *fbo = state.getDrawFramebuffer();
      if (!fbo || fbo->checkStatus(context->getData()) != GL_FRAMEBUFFER_COMPLETE)
      {
          context->recordError(Error(GL_INVALID_FRAMEBUFFER_OPERATION));
          return false;
      }
  
      gl::Program *program = state.getProgram();
      if (!program)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (!program->validateSamplers(NULL, context->getCaps()))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      // Buffer validations
      const VertexArray *vao = state.getVertexArray();
      for (int attributeIndex = 0; attributeIndex < MAX_VERTEX_ATTRIBS; attributeIndex++)
      {
          const VertexAttribute &attrib = vao->getVertexAttribute(attributeIndex);
          bool attribActive = (program->getSemanticIndex(attributeIndex) != -1);
          if (attribActive && attrib.enabled)
          {
              gl::Buffer *buffer = attrib.buffer.get();
  
              if (buffer)
              {
                  GLint64 attribStride = static_cast<GLint64>(ComputeVertexAttributeStride(attrib));
                  GLint64 maxVertexElement = 0;
  
                  if (attrib.divisor > 0)
                  {
                      maxVertexElement = static_cast<GLint64>(primcount) / static_cast<GLint64>(attrib.divisor);
                  }
                  else
                  {
                      maxVertexElement = static_cast<GLint64>(maxVertex);
                  }
  
                  GLint64 attribDataSize = maxVertexElement * attribStride;
  
                  // [OpenGL ES 3.0.2] section 2.9.4 page 40:
                  // We can return INVALID_OPERATION if our vertex attribute does not have
                  // enough backing data.
                  if (attribDataSize > buffer->getSize())
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
              }
              else if (attrib.pointer == NULL)
              {
                  // This is an application error that would normally result in a crash,
                  // but we catch it and return an error
                  context->recordError(Error(GL_INVALID_OPERATION, "An enabled vertex array has no buffer and no pointer."));
                  return false;
              }
          }
      }
  
      // Uniform buffer validation
      for (unsigned int uniformBlockIndex = 0; uniformBlockIndex < program->getActiveUniformBlockCount(); uniformBlockIndex++)
      {
          const gl::UniformBlock *uniformBlock = program->getUniformBlockByIndex(uniformBlockIndex);
          GLuint blockBinding = program->getUniformBlockBinding(uniformBlockIndex);
          const gl::Buffer *uniformBuffer = state.getIndexedUniformBuffer(blockBinding);
  
          if (!uniformBuffer)
          {
              // undefined behaviour
              context->recordError(Error(GL_INVALID_OPERATION, "It is undefined behaviour to have a used but unbound uniform buffer."));
              return false;
          }
  
          size_t uniformBufferSize = state.getIndexedUniformBufferSize(blockBinding);
  
          if (uniformBufferSize == 0)
          {
              // Bind the whole buffer.
              uniformBufferSize = uniformBuffer->getSize();
          }
  
          if (uniformBufferSize < uniformBlock->dataSize)
          {
              // undefined behaviour
              context->recordError(Error(GL_INVALID_OPERATION, "It is undefined behaviour to use a uniform buffer that is too small."));
              return false;
          }
      }
  
      // No-op if zero count
      return (count > 0);
  }
  
  bool ValidateDrawArrays(Context *context, GLenum mode, GLint first, GLsizei count, GLsizei primcount)
  {
      if (first < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      const State &state = context->getState();
      gl::TransformFeedback *curTransformFeedback = state.getCurrentTransformFeedback();
      if (curTransformFeedback && curTransformFeedback->isStarted() && !curTransformFeedback->isPaused() &&
          curTransformFeedback->getDrawMode() != mode)
      {
          // It is an invalid operation to call DrawArrays or DrawArraysInstanced with a draw mode
          // that does not match the current transform feedback object's draw mode (if transform feedback
          // is active), (3.0.2, section 2.14, pg 86)
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (!ValidateDrawBase(context, mode, count, count, primcount))
      {
          return false;
      }
  
      return true;
  }
  
  bool ValidateDrawArraysInstanced(Context *context, GLenum mode, GLint first, GLsizei count, GLsizei primcount)
  {
      if (primcount < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (!ValidateDrawArrays(context, mode, first, count, primcount))
      {
          return false;
      }
  
      // No-op if zero primitive count
      return (primcount > 0);
  }
  
  static bool ValidateDrawInstancedANGLE(Context *context)
  {
      // Verify there is at least one active attribute with a divisor of zero
      const gl::State& state = context->getState();
  
      gl::Program *program = state.getProgram();
  
      const VertexArray *vao = state.getVertexArray();
      for (int attributeIndex = 0; attributeIndex < MAX_VERTEX_ATTRIBS; attributeIndex++)
      {
          const VertexAttribute &attrib = vao->getVertexAttribute(attributeIndex);
          bool active = (program->getSemanticIndex(attributeIndex) != -1);
          if (active && attrib.divisor == 0)
          {
              return true;
          }
      }
  
      context->recordError(Error(GL_INVALID_OPERATION, "ANGLE_instanced_arrays requires that at least one active attribute"
                                                       "has a divisor of zero."));
      return false;
  }
  
  bool ValidateDrawArraysInstancedANGLE(Context *context, GLenum mode, GLint first, GLsizei count, GLsizei primcount)
  {
      if (!ValidateDrawInstancedANGLE(context))
      {
          return false;
      }
  
      return ValidateDrawArraysInstanced(context, mode, first, count, primcount);
  }
  
  bool ValidateDrawElements(Context *context, GLenum mode, GLsizei count, GLenum type,
                            const GLvoid* indices, GLsizei primcount, rx::RangeUI *indexRangeOut)
  {
      switch (type)
      {
        case GL_UNSIGNED_BYTE:
        case GL_UNSIGNED_SHORT:
          break;
        case GL_UNSIGNED_INT:
          if (!context->getExtensions().elementIndexUint)
          {
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
          break;
        default:
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      const State &state = context->getState();
  
      gl::TransformFeedback *curTransformFeedback = state.getCurrentTransformFeedback();
      if (curTransformFeedback && curTransformFeedback->isStarted() && !curTransformFeedback->isPaused())
      {
          // It is an invalid operation to call DrawElements, DrawRangeElements or DrawElementsInstanced
          // while transform feedback is active, (3.0.2, section 2.14, pg 86)
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      // Check for mapped buffers
      if (state.hasMappedBuffer(GL_ELEMENT_ARRAY_BUFFER))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      const gl::VertexArray *vao = state.getVertexArray();
      gl::Buffer *elementArrayBuffer = vao->getElementArrayBuffer();
      if (!indices && !elementArrayBuffer)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (elementArrayBuffer)
      {
          const gl::Type &typeInfo = gl::GetTypeInfo(type);
  
          GLint64 offset = reinterpret_cast<GLint64>(indices);
          GLint64 byteCount = static_cast<GLint64>(typeInfo.bytes) * static_cast<GLint64>(count)+offset;
  
          // check for integer overflows
          if (static_cast<GLuint>(count) > (std::numeric_limits<GLuint>::max() / typeInfo.bytes) ||
              byteCount > static_cast<GLint64>(std::numeric_limits<GLuint>::max()))
          {
              context->recordError(Error(GL_OUT_OF_MEMORY));
              return false;
          }
  
          // Check for reading past the end of the bound buffer object
          if (byteCount > elementArrayBuffer->getSize())
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
      }
      else if (!indices)
      {
          // Catch this programming error here
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      // Use max index to validate if our vertex buffers are large enough for the pull.
      // TODO: offer fast path, with disabled index validation.
      // TODO: also disable index checking on back-ends that are robust to out-of-range accesses.
      if (elementArrayBuffer)
      {
          uintptr_t offset = reinterpret_cast<uintptr_t>(indices);
          if (!elementArrayBuffer->getIndexRangeCache()->findRange(type, offset, count, indexRangeOut))
          {
              rx::BufferImpl *bufferImpl = elementArrayBuffer->getImplementation();
              const uint8_t *dataPointer = NULL;
              Error error = bufferImpl->getData(&dataPointer);
              if (error.isError())
              {
                  context->recordError(error);
                  return false;
              }
  
              const uint8_t *offsetPointer = dataPointer + offset;
              *indexRangeOut = rx::IndexRangeCache::ComputeRange(type, offsetPointer, count);
              elementArrayBuffer->getIndexRangeCache()->addRange(type, offset, count, *indexRangeOut);
          }
      }
      else
      {
          *indexRangeOut = rx::IndexRangeCache::ComputeRange(type, indices, count);
      }
  
      if (!ValidateDrawBase(context, mode, count, static_cast<GLsizei>(indexRangeOut->end), primcount))
      {
          return false;
      }
  
      return true;
  }
  
  bool ValidateDrawElementsInstanced(Context *context,
                                     GLenum mode, GLsizei count, GLenum type,
                                     const GLvoid *indices, GLsizei primcount,
                                     rx::RangeUI *indexRangeOut)
  {
      if (primcount < 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (!ValidateDrawElements(context, mode, count, type, indices, primcount, indexRangeOut))
      {
          return false;
      }
  
      // No-op zero primitive count
      return (primcount > 0);
  }
  
  bool ValidateDrawElementsInstancedANGLE(Context *context, GLenum mode, GLsizei count, GLenum type,
                                          const GLvoid *indices, GLsizei primcount, rx::RangeUI *indexRangeOut)
  {
      if (!ValidateDrawInstancedANGLE(context))
      {
          return false;
      }
  
      return ValidateDrawElementsInstanced(context, mode, count, type, indices, primcount, indexRangeOut);
  }
  
  bool ValidateFramebufferTextureBase(Context *context, GLenum target, GLenum attachment,
                                      GLuint texture, GLint level)
  {
      if (!ValidFramebufferTarget(target))
      {
          context->recordError(Error(GL_INVALID_ENUM));
          return false;
      }
  
      if (!ValidateAttachmentTarget(context, attachment))
      {
          return false;
      }
  
      if (texture != 0)
      {
          gl::Texture *tex = context->getTexture(texture);
  
          if (tex == NULL)
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
  
          if (level < 0)
          {
              context->recordError(Error(GL_INVALID_VALUE));
              return false;
          }
      }
  
      const gl::Framebuffer *framebuffer = context->getState().getTargetFramebuffer(target);
      GLuint framebufferHandle = context->getState().getTargetFramebuffer(target)->id();
  
      if (framebufferHandle == 0 || !framebuffer)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateFramebufferTexture2D(Context *context, GLenum target, GLenum attachment,
                                    GLenum textarget, GLuint texture, GLint level)
  {
      // Attachments are required to be bound to level 0 in ES2
      if (context->getClientVersion() < 3 && level != 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (!ValidateFramebufferTextureBase(context, target, attachment, texture, level))
      {
          return false;
      }
  
      if (texture != 0)
      {
          gl::Texture *tex = context->getTexture(texture);
          ASSERT(tex);
  
          const gl::Caps &caps = context->getCaps();
  
          switch (textarget)
          {
            case GL_TEXTURE_2D:
              {
                  if (level > gl::log2(caps.max2DTextureSize))
                  {
                      context->recordError(Error(GL_INVALID_VALUE));
                      return false;
                  }
                  if (tex->getTarget() != GL_TEXTURE_2D)
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
              }
              break;
  
            case GL_TEXTURE_CUBE_MAP_POSITIVE_X:
            case GL_TEXTURE_CUBE_MAP_NEGATIVE_X:
            case GL_TEXTURE_CUBE_MAP_POSITIVE_Y:
            case GL_TEXTURE_CUBE_MAP_NEGATIVE_Y:
            case GL_TEXTURE_CUBE_MAP_POSITIVE_Z:
            case GL_TEXTURE_CUBE_MAP_NEGATIVE_Z:
              {
                  if (level > gl::log2(caps.maxCubeMapTextureSize))
                  {
                      context->recordError(Error(GL_INVALID_VALUE));
                      return false;
                  }
                  if (tex->getTarget() != GL_TEXTURE_CUBE_MAP)
                  {
                      context->recordError(Error(GL_INVALID_OPERATION));
                      return false;
                  }
              }
              break;
  
            default:
              context->recordError(Error(GL_INVALID_ENUM));
              return false;
          }
  
          const gl::InternalFormat &internalFormatInfo = gl::GetInternalFormatInfo(tex->getInternalFormat(textarget, level));
          if (internalFormatInfo.compressed)
          {
              context->recordError(Error(GL_INVALID_OPERATION));
              return false;
          }
      }
  
      return true;
  }
  
  bool ValidateGetUniformBase(Context *context, GLuint program, GLint location)
  {
      if (program == 0)
      {
          context->recordError(Error(GL_INVALID_VALUE));
          return false;
      }
  
      if (!ValidProgram(context, program))
      {
          return false;
      }
  
      gl::Program *programObject = context->getProgram(program);
  
      if (!programObject || !programObject->isLinked())
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      if (!programObject->isValidUniformLocation(location))
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateGetUniformfv(Context *context, GLuint program, GLint location, GLfloat* params)
  {
      return ValidateGetUniformBase(context, program, location);
  }
  
  bool ValidateGetUniformiv(Context *context, GLuint program, GLint location, GLint* params)
  {
      return ValidateGetUniformBase(context, program, location);
  }
  
  static bool ValidateSizedGetUniform(Context *context, GLuint program, GLint location, GLsizei bufSize)
  {
      if (!ValidateGetUniformBase(context, program, location))
      {
          return false;
      }
  
      gl::Program *programObject = context->getProgram(program);
      ASSERT(programObject);
  
      // sized queries -- ensure the provided buffer is large enough
      LinkedUniform *uniform = programObject->getUniformByLocation(location);
      size_t requiredBytes = VariableExternalSize(uniform->type);
      if (static_cast<size_t>(bufSize) < requiredBytes)
      {
          context->recordError(Error(GL_INVALID_OPERATION));
          return false;
      }
  
      return true;
  }
  
  bool ValidateGetnUniformfvEXT(Context *context, GLuint program, GLint location, GLsizei bufSize, GLfloat* params)
  {
      return ValidateSizedGetUniform(context, program, location, bufSize);
  }
  
  bool ValidateGetnUniformivEXT(Context *context, GLuint program, GLint location, GLsizei bufSize, GLint* params)
  {
      return ValidateSizedGetUniform(context, program, location, bufSize);
  }
  
  }
  