gold/compressed_output.h

   1 // compressed_output.h -- compressed output sections for gold  -*- C++ -*-
   2
   3 // Copyright (C) 2007-2018 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 // We support compressing .debug_* sections on output.  (And,
  24 // potentially one day, other sections.)  This is a form of
  25 // relaxation.  This file adds support for merging and emitting the
  26 // compressed sections.
  27
  28 #ifndef GOLD_COMPRESSED_OUTPUT_H
  29 #define GOLD_COMPRESSED_OUTPUT_H
  30
  31 #include <string>
  32
  33 #include "output.h"
  34
  35 namespace gold
  36 {
  37
  38 class General_options;
  39
  40 // Read the compression header of a compressed debug section and return
  41 // the uncompressed size.
  42
  43 extern uint64_t
  44 get_uncompressed_size(const unsigned char*, section_size_type);
  45
  46 // Decompress a compressed debug section directly into the output file.
  47
  48 extern bool
  49 decompress_input_section(const unsigned char*, unsigned long, unsigned char*,
  50                          unsigned long, int, bool, elfcpp::Elf_Xword);
  51
  52 // This is used for a section whose data should be compressed.  It is
  53 // a regular Output_section which computes its contents into a buffer
  54 // and then postprocesses it.
  55
  56 class Output_compressed_section : public Output_section
  57 {
  58  public:
  59   Output_compressed_section(const General_options* options,
  60                             const char* name, elfcpp::Elf_Word flags,
  61                             elfcpp::Elf_Xword type)
  62     : Output_section(name, flags, type),
  63       options_(options)
  64   { this->set_requires_postprocessing(); }
  65
  66  protected:
  67   // Set the final data size.
  68   void
  69   set_final_data_size();
  70
  71   // Write out the compressed contents.
  72   void
  73   do_write(Output_file*);
  74
  75  private:
  76   // The options--this includes the compression type.
  77   const General_options* options_;
  78   // The compressed data.
  79   unsigned char* data_;
  80   // The new section name if we do compress.
  81   std::string new_section_name_;
  82 };
  83
  84 } // End namespace gold.
  85
  86 #endif // !defined(GOLD_COMPRESSED_OUTPUT_H)