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// compressed_output.h -- compressed output sections for gold -*- C++ -*-
// Copyright 2007 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <iant@google.com>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
// We support compressing .debug_* sections on output. (And,
// potentially one day, other sections.) This is a form of
// relaxation. This file adds support for merging and emitting the
// compressed sections.
#ifndef GOLD_COMPRESSED_OUTPUT_H
#define GOLD_COMPRESSED_OUTPUT_H
#include <string>
#include <vector>
#include "output.h"
#include "merge.h"
namespace gold
{
class General_options;
// This is used for compressing a section before emitting it in the
// output file. This only works for unloaded sections, since it
// assumes the final section contents are available at
// set_final_data_size() time. For loaded sections (those that end up
// in segments), this is not true; relocations are applied after
// set_final_data_size() is called. However, for unloaded sections,
// we can -- and do -- postpone calling finalize_data_size() until
// after relocations are applies.
class Output_compressed_section_data : public Output_section_data
{
public:
Output_compressed_section_data(uint64_t addralign,
const General_options& options)
: Output_section_data(addralign), options_(options), data_(NULL)
{ }
protected:
// Add an input section.
bool
do_add_input_section(Relobj* object, unsigned int shndx);
// Set the final data size.
void
set_final_data_size();
// Change the name of the output section to reflect it's compressed.
const char*
do_modified_output_section_name(const char* name);
// Write the data to the file.
void
do_write(Output_file*);
private:
struct Object_entry
{
Relobj* object;
unsigned int shndx;
const unsigned char* contents;
off_t length;
Object_entry(Relobj* o, unsigned int s)
: object(o), shndx(s), contents(NULL), length(0)
{ }
};
const General_options& options_;
std::vector<Object_entry> objects_;
char* data_;
std::string new_section_name_;
};
// This is a special case for when the output section is a string
// section and does not have any relocations to apply to it.
template<typename Char_type>
class Output_compressed_string : public Output_merge_string<Char_type>
{
public:
Output_compressed_string(uint64_t addralign,
const General_options& options)
: Output_merge_string<Char_type>(addralign),
options_(options), compressed_data_(NULL)
{ }
~Output_compressed_string()
{ delete[] compressed_data_; }
protected:
// Add an input section.
bool
do_add_input_section(Relobj* object, unsigned int shndx);
// Set the final data size. Also compresses the buffer.
void
set_final_data_size();
// Change the name of the output section to reflect it's compressed.
const char*
do_modified_output_section_name(const char* name);
// Write the data to the file.
void
do_write(Output_file*);
private:
const General_options& options_;
char* compressed_data_;
// This is just a buffer to store the section name in "permanent" storage.
std::string new_section_name_;
};
} // End namespace gold.
#endif // !defined(GOLD_COMPRESSED_OUTPUT_H)
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