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// 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.
// This file contains the implementation of the command parser.
#include "gpu/command_buffer/service/cmd_parser.h"
#include <stddef.h>
#include "base/logging.h"
#include "base/trace_event/trace_event.h"
namespace gpu {
CommandParser::CommandParser(AsyncAPIInterface* handler)
: get_(0),
put_(0),
buffer_(NULL),
entry_count_(0),
handler_(handler) {
}
void CommandParser::SetBuffer(
void* shm_address,
size_t shm_size,
ptrdiff_t offset,
size_t size) {
// check proper alignments.
DCHECK_EQ(0, (reinterpret_cast<intptr_t>(shm_address)) % 4);
DCHECK_EQ(0, offset % 4);
DCHECK_EQ(0u, size % 4);
// check that the command buffer fits into the memory buffer.
DCHECK_GE(shm_size, offset + size);
get_ = 0;
put_ = 0;
char* buffer_begin = static_cast<char*>(shm_address) + offset;
buffer_ = reinterpret_cast<CommandBufferEntry*>(buffer_begin);
entry_count_ = size / 4;
}
// Process one command, reading the header from the command buffer, and
// forwarding the command index and the arguments to the handler.
// Note that:
// - validation needs to happen on a copy of the data (to avoid race
// conditions). This function only validates the header, leaving the arguments
// validation to the handler, so it can pass a reference to them.
// - get_ is modified *after* the command has been executed.
error::Error CommandParser::ProcessCommands(int num_commands) {
int num_entries = put_ < get_ ? entry_count_ - get_ : put_ - get_;
int entries_processed = 0;
error::Error result = handler_->DoCommands(
num_commands, buffer_ + get_, num_entries, &entries_processed);
get_ += entries_processed;
if (get_ == entry_count_)
get_ = 0;
return result;
}
// Processes all the commands, while the buffer is not empty. Stop if an error
// is encountered.
error::Error CommandParser::ProcessAllCommands() {
while (!IsEmpty()) {
error::Error error = ProcessCommands(kParseCommandsSlice);
if (error)
return error;
}
return error::kNoError;
}
// Decode multiple commands, and call the corresponding GL functions.
// NOTE: buffer is a pointer to the command buffer. As such, it could be
// changed by a (malicious) client at any time, so if validation has to happen,
// it should operate on a copy of them.
error::Error AsyncAPIInterface::DoCommands(unsigned int num_commands,
const void* buffer,
int num_entries,
int* entries_processed) {
int commands_to_process = num_commands;
error::Error result = error::kNoError;
const CommandBufferEntry* cmd_data =
static_cast<const CommandBufferEntry*>(buffer);
int process_pos = 0;
while (process_pos < num_entries && result == error::kNoError &&
commands_to_process--) {
CommandHeader header = cmd_data->value_header;
if (header.size == 0) {
DVLOG(1) << "Error: zero sized command in command buffer";
return error::kInvalidSize;
}
if (static_cast<int>(header.size) + process_pos > num_entries) {
DVLOG(1) << "Error: get offset out of bounds";
return error::kOutOfBounds;
}
const unsigned int command = header.command;
const unsigned int arg_count = header.size - 1;
result = DoCommand(command, arg_count, cmd_data);
if (result != error::kDeferCommandUntilLater) {
process_pos += header.size;
cmd_data += header.size;
}
}
if (entries_processed)
*entries_processed = process_pos;
return result;
}
} // namespace gpu
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