1// nacl.h -- Native Client support for gold    -*- C++ -*-
2
3// Copyright (C) 2012-2017 Free Software Foundation, Inc.
4
5// This file is part of gold.
6
7// This program is free software; you can redistribute it and/or modify
8// it under the terms of the GNU General Public License as published by
9// the Free Software Foundation; either version 3 of the License, or
10// (at your option) any later version.
11
12// This program is distributed in the hope that it will be useful,
13// but WITHOUT ANY WARRANTY; without even the implied warranty of
14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15// GNU General Public License for more details.
16
17// You should have received a copy of the GNU General Public License
18// along with this program; if not, write to the Free Software
19// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
20// MA 02110-1301, USA.
21
22#include "elfcpp_file.h"
23#include "fileread.h"
24#include "layout.h"
25#include "target-select.h"
26#include "target.h"
27
28#ifndef GOLD_NACL_H
29#define GOLD_NACL_H
30
31namespace gold
32{
33
34class Sniff_file
35{
36 public:
37  Sniff_file(Input_file* input_file, off_t offset)
38    : file_(input_file->file()), offset_(offset)
39  { }
40
41  class Location
42  {
43   public:
44    Location(off_t file_offset, off_t data_size)
45      : offset_(file_offset), size_(data_size)
46    { }
47
48    inline off_t offset() const
49    { return this->offset_; }
50
51    inline section_size_type size() const
52    { return this->size_; }
53
54   private:
55    off_t offset_;
56    section_size_type size_;
57  };
58
59  class View
60  {
61   public:
62    View(File_read& file, off_t file_offset, off_t data_size)
63      : data_(file.get_view(file_offset, 0, data_size, true, false))
64    { }
65
66    const unsigned char* data()
67    { return this->data_; }
68
69   private:
70    const unsigned char* data_;
71  };
72
73  View view(off_t file_offset, off_t data_size)
74  {
75    return View(this->file_, this->offset_ + file_offset, data_size);
76  }
77
78  View view(Location loc)
79  {
80    return this->view(loc.offset(), loc.size());
81  }
82
83  // Report an error.
84  void
85  error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
86
87 private:
88  File_read& file_;
89  off_t offset_;
90};
91
92
93template<class base_selector, class nacl_target>
94class Target_selector_nacl : public base_selector
95{
96 public:
97  Target_selector_nacl(const char* nacl_abi_name,
98                       const char* bfd_name, const char* emulation)
99    : base_selector(), is_nacl_(false), nacl_abi_name_(nacl_abi_name),
100      bfd_name_(bfd_name), emulation_(emulation)
101  { }
102
103 protected:
104  virtual Target*
105  do_instantiate_target()
106  {
107    if (this->is_nacl_)
108      return new nacl_target();
109    return this->base_selector::do_instantiate_target();
110  }
111
112  virtual Target*
113  do_recognize(Input_file* file, off_t offset,
114               int machine, int osabi, int abiversion)
115  {
116    this->is_nacl_ = file != NULL && this->recognize_nacl_file(file, offset);
117    if (this->is_nacl_)
118      return this->instantiate_target();
119    return this->base_selector::do_recognize(file, offset,
120                                             machine, osabi, abiversion);
121  }
122
123  virtual Target*
124  do_recognize_by_bfd_name(const char* name)
125  {
126    gold_assert(this->bfd_name_ != NULL);
127    this->is_nacl_ = strcmp(name, this->bfd_name_) == 0;
128    if (this->is_nacl_)
129      return this->instantiate_target();
130    return this->base_selector::do_recognize_by_bfd_name(name);
131  }
132
133  virtual void
134  do_supported_bfd_names(std::vector<const char*>* names)
135  {
136    gold_assert(this->bfd_name_ != NULL);
137    this->base_selector::do_supported_bfd_names(names);
138    names->push_back(this->bfd_name_);
139  }
140
141  virtual void
142  do_supported_emulations(std::vector<const char*>* emulations)
143  {
144    gold_assert(this->emulation_ != NULL);
145    this->base_selector::do_supported_emulations(emulations);
146    emulations->push_back(this->emulation_);
147  }
148
149  virtual const char*
150  do_target_bfd_name(const Target* target)
151  {
152    return (!this->is_our_target(target)
153            ? NULL
154            : (this->is_nacl_
155               ? this->bfd_name_
156               : base_selector::do_target_bfd_name(target)));
157  }
158
159 private:
160  bool
161  recognize_nacl_file(Input_file* input_file, off_t offset)
162  {
163    if (this->is_big_endian())
164      {
165#if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
166# ifdef HAVE_TARGET_32_BIG
167        if (this->get_size() == 32)
168          return do_recognize_nacl_file<32, true>(input_file, offset);
169# endif
170# ifdef HAVE_TARGET_64_BIG
171        if (this->get_size() == 64)
172          return do_recognize_nacl_file<64, true>(input_file, offset);
173# endif
174#endif
175        gold_unreachable();
176      }
177    else
178      {
179#if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
180# ifdef HAVE_TARGET_32_LITTLE
181        if (this->get_size() == 32)
182          return do_recognize_nacl_file<32, false>(input_file, offset);
183# endif
184# ifdef HAVE_TARGET_64_LITTLE
185        if (this->get_size() == 64)
186          return do_recognize_nacl_file<64, false>(input_file, offset);
187# endif
188#endif
189        gold_unreachable();
190      }
191  }
192
193  template<int size, bool big_endian>
194  bool
195  do_recognize_nacl_file(Input_file* input_file, off_t offset)
196  {
197    Sniff_file file(input_file, offset);
198    elfcpp::Elf_file<size, big_endian, Sniff_file> elf_file(&file);
199    const unsigned int shnum = elf_file.shnum();
200    for (unsigned int shndx = 1; shndx < shnum; ++shndx)
201      {
202        if (elf_file.section_type(shndx) == elfcpp::SHT_NOTE)
203          {
204            Sniff_file::Location loc = elf_file.section_contents(shndx);
205            if (loc.size() < (3 * 4
206                              + align_address(sizeof "NaCl", 4)
207                              + align_address(nacl_abi_name_.size() + 1, 4)))
208              continue;
209            Sniff_file::View view(file.view(loc));
210            const unsigned char* note_data = view.data();
211            if ((elfcpp::Swap<32, big_endian>::readval(note_data + 0)
212                 == sizeof "NaCl")
213                && (elfcpp::Swap<32, big_endian>::readval(note_data + 4)
214                    == nacl_abi_name_.size() + 1)
215                && (elfcpp::Swap<32, big_endian>::readval(note_data + 8)
216                    == elfcpp::NT_VERSION))
217              {
218                const unsigned char* name = note_data + 12;
219                const unsigned char* desc = (name
220                                             + align_address(sizeof "NaCl", 4));
221                if (memcmp(name, "NaCl", sizeof "NaCl") == 0
222                    && memcmp(desc, nacl_abi_name_.c_str(),
223                              nacl_abi_name_.size() + 1) == 0)
224                  return true;
225              }
226          }
227      }
228    return false;
229  }
230
231  // Whether we decided this was the NaCl target variant.
232  bool is_nacl_;
233  // The string found in the NaCl ABI note.
234  std::string nacl_abi_name_;
235  // BFD name of NaCl target, for compatibility.
236  const char* const bfd_name_;
237  // GNU linker emulation for this NaCl target, for compatibility.
238  const char* const emulation_;
239};
240
241} // end namespace gold
242
243#endif // !defined(GOLD_NACL_H)
244