Command Buffer: read pixels into pixel pack buffer

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 <cmath>
@@ skipping 8878 matching lines @@
   GLsizei height = c.height;
   GLenum format = c.format;
   GLenum type = c.type;
   GLboolean async = static_cast<GLboolean>(c.async);
   if (width < 0 || height < 0) {
     LOCAL_SET_GL_ERROR(GL_INVALID_VALUE, "glReadPixels", "dimensions < 0");
     return error::kNoError;
   }
   typedef cmds::ReadPixels::Result Result;
   uint32 pixels_size;
-  if (state_.bound_pixel_pack_buffer.get()) {
-    // TODO(zmo): Need to handle the case of reading into a PIXEL_PACK_BUFFER
-    // in ES3, including more pack parameters. For now, generate a GL error.
-    LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glReadPixels",
-                       "ReadPixels to a pixel pack buffer isn't implemented");
-    return error::kNoError;
-  }
   if (!GLES2Util::ComputeImageDataSizes(
       width, height, 1, format, type, state_.pack_alignment, &pixels_size,
       NULL, NULL)) {
     return error::kOutOfBounds;
   }
-  void* pixels = GetSharedMemoryAs<void*>(
-      c.pixels_shm_id, c.pixels_shm_offset, pixels_size);
-  if (!pixels) {
-    return error::kOutOfBounds;
+
+  void* pixels = NULL;
+  Buffer* buffer = state_.bound_pixel_pack_buffer.get();
+  if (c.pixels_shm_id == 0) {
+    if (buffer) {
+      if (buffer->GetMappedRange()) {
+        LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glReadPixels",
+            "pixel pack buffer should not be mapped to client memory");
+        return error::kNoError;
+      }
+      if (buffer->size() < pixels_size) {

[Zhenyao Mo, 2015/12/02 19:36:41]

Right now the pixels_size we compute could be smaller than it actually requests,
because in ComputeImageDataSizes we don't consider ES3 unpack parameters. This
exposes a security risk that the buffer is not big enough but it passes the
check here.

I will have to ask this CL to wait until I land the CL I am working on to fix
this size issue.

[yunchao, 2015/12/03 17:39:14]

Acknowledged.

+        LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glReadPixels",
+            "pixel pack buffer is not large enough");
+        return error::kNoError;
+      }

[Zhenyao Mo, 2015/12/02 19:36:41]

It's worth checking the result_shm_id and result_shm_offset is both 0. Otherwise
return error::kInvalidArgs.

[yunchao, 2015/12/03 17:39:14]

Done.

+      pixels = reinterpret_cast<void *>(c.pixels_shm_offset);
+    } else {
+      LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glReadPixels",
+          "no pixel pack buffer bound");
+      return error::kNoError;
+    }
+  } else {
+    if (buffer) {
+      LOCAL_SET_GL_ERROR(GL_INVALID_OPERATION, "glReadPixels",
+          "pixel pack buffer should not bound");
+      return error::kNoError;
+    } else {
+      pixels = GetSharedMemoryAs<void*>(
+          c.pixels_shm_id, c.pixels_shm_offset, pixels_size);
+      if (!pixels) {
+        return error::kOutOfBounds;
+      }
+    }
   }
+
   Result* result = NULL;
   if (c.result_shm_id != 0) {
     result = GetSharedMemoryAs<Result*>(
         c.result_shm_id, c.result_shm_offset, sizeof(*result));
     if (!result) {
       return error::kOutOfBounds;
     }
   }
 
   if (!validators_->read_pixel_format.IsValid(format)) {
@@ skipping 114 matching lines @@
   }
 
   if (!CheckBoundFramebuffersValid("glReadPixels")) {
     return error::kNoError;
   }
 
   LOCAL_COPY_REAL_GL_ERRORS_TO_WRAPPER("glReadPixels");
 
   ScopedResolvedFrameBufferBinder binder(this, false, true);
 
-  if (x < 0 || y < 0 || max_x > max_size.width() || max_y > max_size.height()) {
+  if ((x < 0 || y < 0 || max_x > max_size.width() || max_y > max_size.height())
+      && c.pixels_shm_id != 0) {
     // The user requested an out of range area. Get the results 1 line
     // at a time.
     uint32 temp_size;
     uint32 unpadded_row_size;
     uint32 padded_row_size;
     if (!GLES2Util::ComputeImageDataSizes(
         width, 2, 1, format, type, state_.pack_alignment, &temp_size,
         &unpadded_row_size, &padded_row_size)) {
       LOCAL_SET_GL_ERROR(
           GL_INVALID_VALUE, "glReadPixels", "dimensions out of range");
@@ skipping 60 matching lines @@
         glDeleteBuffersARB(1, &buffer);
       }
     }
     glReadPixels(x, y, width, height, format, type, pixels);
   }
   GLenum error = LOCAL_PEEK_GL_ERROR("glReadPixels");
   if (error == GL_NO_ERROR) {
     if (result != NULL) {
       *result = true;
     }
-    FinishReadPixels(c, 0);
+    if (c.pixels_shm_id != 0) {

[Zhenyao Mo, 2015/12/02 19:36:41]

I think we should also avoid glGetError() if we read into a bound buffer.

[yunchao, 2015/12/03 17:39:14]

Done.

+      FinishReadPixels(c, 0);
+    }
   }
 
   return error::kNoError;
 }
 
 error::Error GLES2DecoderImpl::HandlePixelStorei(uint32 immediate_data_size,
                                                  const void* cmd_data) {
   const gles2::cmds::PixelStorei& c =
       *static_cast<const gles2::cmds::PixelStorei*>(cmd_data);
   GLenum pname = c.pname;
@@ skipping 6274 matching lines @@
   return error::kNoError;
 }
 
 // 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