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// inremental.h -- incremental linking support for gold   -*- C++ -*-

// Copyright 2009 Free Software Foundation, Inc.

// Written by Mikolaj Zalewski <mikolajz@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.

#ifndef GOLD_INCREMENTAL_H

#define GOLD_INCREMENTAL_H

#include <map>

#include <vector>

#include "elfcpp_file.h"

#include "stringpool.h"

#include "workqueue.h"

#include "fileread.h"

#include "output.h"

namespace gold

{

class Archive;

class Input_argument;

class Incremental_inputs_checker;

class Object;

class Output_section_data;

// Incremental input type as stored in .gnu_incremental_inputs.

enum Incremental_input_type

{

  INCREMENTAL_INPUT_INVALID = 0,

  INCREMENTAL_INPUT_OBJECT = 1,

  INCREMENTAL_INPUT_ARCHIVE = 2,

  INCREMENTAL_INPUT_SHARED_LIBRARY = 3,

  INCREMENTAL_INPUT_SCRIPT = 4

};

// An object representing the ELF file we edit during an incremental build.

// Similar to Object or Dynobj, but operates on Output_file and contains

// method specific to file edition (TBD). This is the abstract parent class

// implemented in Sized_incremental_binary<size, big_endian> for a specific

// endianness and size.

class Incremental_binary

{

 public:

  Incremental_binary(Output_file* output, Target* target)

    : output_(output), target_(target)

  { }

  virtual

  ~Incremental_binary()

  { }

  // Functions and types for the elfcpp::Elf_file interface.  This

  // permit us to use Incremental_binary as the File template parameter for

  // elfcpp::Elf_file.

  // The View class is returned by view.  It must support a single

  // method, data().  This is trivial, because Output_file::get_output_view

  // does what we need.

  class View

  {

   public:

    View(const unsigned char* p)

      : p_(p)

    { }

    const unsigned char*

    data() const

    { return this->p_; }

   private:

    const unsigned char* p_;

  };

  // Return a View.

  View

  view(off_t file_offset, section_size_type data_size)

  { return View(this->output_->get_input_view(file_offset, data_size)); }

  // A location in the file.

  struct Location

  {

    off_t file_offset;

    off_t data_size;

    Location(off_t fo, section_size_type ds)

      : file_offset(fo), data_size(ds)

    { }

    Location()

      : file_offset(0), data_size(0)

    { }

  };

  // Get a View given a Location.

  View view(Location loc)

  { return View(this->view(loc.file_offset, loc.data_size)); }

  // Report an error.

  void

  error(const char* format, ...) const ATTRIBUTE_PRINTF_2;

  // Find the .gnu_incremental_inputs section.  It selects the first section

  // of type SHT_GNU_INCREMENTAL_INPUTS.  Returns false if such a section

  // is not found.

  bool

  find_incremental_inputs_section(Location* location,

                                  unsigned int* strtab_shndx)

  { return do_find_incremental_inputs_section(location, strtab_shndx); }

  // Check the .gnu_incremental_inputs section to see whether an incremental

  // build is possible.

  // TODO: on success, should report what files needs to be rebuilt.

  // INCREMENTAL_INPUTS is used to read the canonical form of the command line

  // and read the input arguments.  TODO: for items that don't need to be

  // rebuilt, we should also copy the incremental input information.

  virtual bool

  check_inputs(Incremental_inputs* incremental_inputs)

  { return do_check_inputs(incremental_inputs); }

 protected:

  // Find incremental inputs section.

  virtual bool

  do_find_incremental_inputs_section(Location* location,

                                     unsigned int* strtab_shndx) = 0;

  // Check the .gnu_incremental_inputs section to see whether an incremental

  // build is possible.

  virtual bool

  do_check_inputs(Incremental_inputs* incremental_inputs) = 0;

 private:

  // Edited output file object.

  Output_file* output_;

  // Target of the output file.

  Target* target_;

};

template<int size, bool big_endian>

class Sized_incremental_binary : public Incremental_binary

{

 public:

  Sized_incremental_binary(Output_file* output,

                           const elfcpp::Ehdr<size, big_endian>& ehdr,

                           Target* target)

    : Incremental_binary(output, target), elf_file_(this, ehdr)

  { }

 protected:

  virtual bool

  do_find_incremental_inputs_section(Location* location,

                                     unsigned int* strtab_shndx);

  virtual bool

  do_check_inputs(Incremental_inputs* incremental_inputs);

 private:

  // Output as an ELF file.

  elfcpp::Elf_file<size, big_endian, Incremental_binary> elf_file_;

};

// Create an Incremental_binary object for FILE. Returns NULL is this is not

// possible, e.g. FILE is not an ELF file or has an unsupported target.

Incremental_binary*

open_incremental_binary(Output_file* file);

// Code invoked early during an incremental link that checks what files need

// to be relinked.

class Incremental_checker

{

 public:

  // Check if the file named OUTPUT_NAME can be linked incrementally.

  // INCREMENTAL_INPUTS must have the canonical form of the command line

  // and input arguments filled - at this point of linking other fields are

  // probably not filled yet.  TODO: for inputs that don't need to be

  // rebuilt, this function should fill the incremental input information.

  Incremental_checker(const char* output_name,

                      Incremental_inputs* incremental_inputs)

    : output_name_(output_name), incremental_inputs_(incremental_inputs)

  { }

  // Analyzes the output file to check if incremental linking is possible and

  // what files needs to be relinked.

  bool

  can_incrementally_link_output_file();

 private:

  // Name of the output file to analyze.

  const char* output_name_;

  // The Incremental_inputs object. At this stage of link, only the command

  // line and inputs are filled.

  Incremental_inputs* incremental_inputs_;

};

// This class contains the information needed during an incremental

// build about the inputs necessary to build the .gnu_incremental_inputs.

class Incremental_inputs

{

 public:

  Incremental_inputs()

    : lock_(new Lock()), inputs_(NULL), command_line_key_(0),

      strtab_(new Stringpool())

  { }

  ~Incremental_inputs() { delete this->strtab_; }

  // Record the command line.

  void

  report_command_line(int argc, const char* const* argv);

  // Record the input arguments obtained from parsing the command line.

  void

  report_inputs(const Input_arguments& inputs)

  { this->inputs_ = &inputs; }

  // Record that the input argument INPUT is an archive ARCHIVE.

  void

  report_archive(const Input_argument* input, Archive* archive);

  // Record that the input argument INPUT is to an object OBJ.

  void

  report_object(const Input_argument* input, Object* obj);

  // Record that the input argument INPUT is to an script SCRIPT.

  void

  report_script(const Input_argument* input, Timespec mtime,

                Script_info* script);

  // Prepare for layout.  Called from Layout::finalize.

  void

  finalize();

  // Create the content of the .gnu_incremental_inputs section.

  Output_section_data*

  create_incremental_inputs_section_data();

  // Return the .gnu_incremental_strtab stringpool.

  Stringpool*

  get_stringpool()

  { return this->strtab_; }

  // Return the canonical form of the command line, as will be stored in

  // .gnu_incremental_strtab.

  const std::string&

  command_line()

  { return this->command_line_; }

  // Return the input files found in the command line.

  const Input_arguments*

  inputs()

  { return this->inputs_; }

 private:

  // Code for each of the four possible variants of create_inputs_section_data.

  template<int size, bool big_endian>

  Output_section_data*

  sized_create_inputs_section_data();

  // Compute indexes in the order in which the inputs should appear in

  // .gnu_incremental_inputs and put file names to the stringtable.

  // This needs to be done after all the scripts are parsed.

  void

  finalize_inputs(Input_argument_list::const_iterator begin,

                  Input_argument_list::const_iterator end,

                  unsigned int* index);

  // Additional data about an input needed for an incremental link.

  // None of these pointers is owned by the structure.

  struct Input_info

  {

    Input_info()

      : type(INCREMENTAL_INPUT_INVALID), archive(NULL), filename_key(0),

        index(0)

    { }

    // Type of the file pointed by this argument.

    Incremental_input_type type;

    union

    {

      // Present if type == INCREMENTAL_INPUT_ARCHIVE.

      Archive* archive;

      // Present if type == INCREMENTAL_INPUT_OBJECT or

      // INCREMENTAL_INPUT_SHARED_LIBRARY.

      Object* object;

      // Present if type == INCREMENTAL_INPUT_SCRIPT.

      Script_info* script;

    };

    // Key of the filename string in the section stringtable.

    Stringpool::Key filename_key;

    // Position of the entry information in the output section.

    unsigned int index;

    // Last modification time of the file.

    Timespec mtime;

  };

  typedef std::map<const Input_argument*, Input_info> Inputs_info_map;

  // A lock guarding access to inputs_ during the first phase of linking, when

  // report_ function may be called from multiple threads.

  Lock* lock_;

  // The list of input arguments obtained from parsing the command line.

  const Input_arguments* inputs_;

  // A map containing additional information about the input elements.

  Inputs_info_map inputs_map_;

  // Canonical form of the command line, as will be stored in

  // .gnu_incremental_strtab.

  std::string command_line_;

  // The key of the command line string in the string pool.

  Stringpool::Key command_line_key_;

  // The .gnu_incremental_strtab string pool associated with the

  // .gnu_incremental_inputs.

  Stringpool* strtab_;

};

} // End namespace gold.

#endif // !defined(GOLD_INCREMENTAL_H)