gold/binary.cc

   1 // binary.cc -- binary input files for gold
   2
   3 // Copyright (C) 2008-2015 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 #include "gold.h"
  24
  25 #include <cerrno>
  26 #include <cstring>
  27 #include "safe-ctype.h"
  28
  29 #include "elfcpp.h"
  30 #include "stringpool.h"
  31 #include "fileread.h"
  32 #include "output.h"
  33 #include "binary.h"
  34
  35 // Support for reading binary files as input.  These become blobs in
  36 // the final output.  These files are treated as though they have a
  37 // single .data section and define three symbols:
  38 // _binary_FILENAME_start, _binary_FILENAME_end, _binary_FILENAME_size.
  39 // The FILENAME is the name of the input file, with any
  40 // non-alphanumeric character changed to an underscore.
  41
  42 // We implement this by creating an ELF file in memory.
  43
  44 namespace gold
  45 {
  46
  47 // class Binary_to_elf.
  48
  49 Binary_to_elf::Binary_to_elf(elfcpp::EM machine, int size, bool big_endian,
  50                              const std::string& filename)
  51   : elf_machine_(machine), size_(size), big_endian_(big_endian),
  52     filename_(filename), data_(NULL), filesize_(0)
  53 {
  54 }
  55
  56 Binary_to_elf::~Binary_to_elf()
  57 {
  58   if (this->data_ != NULL)
  59     delete[] this->data_;
  60 }
  61
  62 // Given FILENAME, create a buffer which looks like an ELF file with
  63 // the contents of FILENAME as the contents of the only section.  The
  64 // TASK parameters is mainly for debugging, and records who holds
  65 // locks.
  66
  67 bool
  68 Binary_to_elf::convert(const Task* task)
  69 {
  70   if (this->size_ == 32)
  71     {
  72       if (!this->big_endian_)
  73         {
  74 #ifdef HAVE_TARGET_32_LITTLE
  75           return this->sized_convert<32, false>(task);
  76 #else
  77           gold_unreachable();
  78 #endif
  79         }
  80       else
  81         {
  82 #ifdef HAVE_TARGET_32_BIG
  83           return this->sized_convert<32, true>(task);
  84 #else
  85           gold_unreachable();
  86 #endif
  87         }
  88     }
  89   else if (this->size_ == 64)
  90     {
  91       if (!this->big_endian_)
  92         {
  93 #ifdef HAVE_TARGET_64_LITTLE
  94           return this->sized_convert<64, false>(task);
  95 #else
  96           gold_unreachable();
  97 #endif
  98         }
  99       else
 100         {
 101 #ifdef HAVE_TARGET_64_BIG
 102           return this->sized_convert<64, true>(task);
 103 #else
 104           gold_unreachable();
 105 #endif
 106         }
 107     }
 108   else
 109     gold_unreachable();
 110 }
 111
 112 // We are going to create:
 113 // * The ELF file header.
 114 // * Five sections: null section, .data, .symtab, .strtab, .shstrtab
 115 // * The contents of the file.
 116 // * Four symbols: null, begin, end, size.
 117 // * Three symbol names.
 118 // * Four section names.
 119
 120 template<int size, bool big_endian>
 121 bool
 122 Binary_to_elf::sized_convert(const Task* task)
 123 {
 124   // Read the input file.
 125
 126   File_read f;
 127   if (!f.open(task, this->filename_))
 128     {
 129       gold_error(_("cannot open %s: %s:"), this->filename_.c_str(),
 130                  strerror(errno));
 131       return false;
 132     }
 133
 134   section_size_type filesize = convert_to_section_size_type(f.filesize());
 135   const unsigned char* fileview;
 136   if (filesize == 0)
 137     fileview = NULL;
 138   else
 139     fileview = f.get_view(0, 0, filesize, false, false);
 140
 141   unsigned int align;
 142   if (size == 32)
 143     align = 4;
 144   else if (size == 64)
 145     align = 8;
 146   else
 147     gold_unreachable();
 148   section_size_type aligned_filesize = align_address(filesize, align);
 149
 150   // Build the stringpool for the symbol table.
 151
 152   std::string mangled_name = this->filename_;
 153   for (std::string::iterator p = mangled_name.begin();
 154        p != mangled_name.end();
 155        ++p)
 156     if (!ISALNUM(*p))
 157       *p = '_';
 158   mangled_name = "_binary_" + mangled_name;
 159   std::string start_symbol_name = mangled_name + "_start";
 160   std::string end_symbol_name = mangled_name + "_end";
 161   std::string size_symbol_name = mangled_name + "_size";
 162
 163   Stringpool strtab;
 164   strtab.add(start_symbol_name.c_str(), false, NULL);
 165   strtab.add(end_symbol_name.c_str(), false, NULL);
 166   strtab.add(size_symbol_name.c_str(), false, NULL);
 167   strtab.set_string_offsets();
 168
 169   // Build the stringpool for the section name table.
 170
 171   Stringpool shstrtab;
 172   shstrtab.add(".data", false, NULL);
 173   shstrtab.add(".symtab", false, NULL);
 174   shstrtab.add(".strtab", false, NULL);
 175   shstrtab.add(".shstrtab", false, NULL);
 176   shstrtab.set_string_offsets();
 177
 178   // Work out the size of the generated file, and the offsets of the
 179   // various sections, and allocate a buffer.
 180
 181   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 182
 183   size_t output_size = (elfcpp::Elf_sizes<size>::ehdr_size
 184                         + 5 * elfcpp::Elf_sizes<size>::shdr_size);
 185   size_t data_offset = output_size;
 186   output_size += aligned_filesize;
 187   size_t symtab_offset = output_size;
 188   output_size += 4 * sym_size;
 189   size_t strtab_offset = output_size;
 190   output_size += strtab.get_strtab_size();
 191   size_t shstrtab_offset = output_size;
 192   output_size += shstrtab.get_strtab_size();
 193
 194   unsigned char* buffer = new unsigned char[output_size];
 195
 196   // Write out the data.
 197
 198   unsigned char* pout = buffer;
 199
 200   this->write_file_header<size, big_endian>(&pout);
 201
 202   this->write_section_header<size, big_endian>("", &shstrtab, elfcpp::SHT_NULL,
 203                                                0, 0, 0, 0, 0,
 204                                                0, 0, &pout);
 205   // Having the section be named ".data", having it be writable, and
 206   // giving it an alignment of 1 is because the GNU linker does it
 207   // that way, and existing linker script expect it.
 208   this->write_section_header<size, big_endian>(".data", &shstrtab,
 209                                                elfcpp::SHT_PROGBITS,
 210                                                (elfcpp::SHF_ALLOC
 211                                                 | elfcpp::SHF_WRITE),
 212                                                data_offset,
 213                                                filesize, 0, 0,
 214                                                1, 0, &pout);
 215   this->write_section_header<size, big_endian>(".symtab", &shstrtab,
 216                                                elfcpp::SHT_SYMTAB,
 217                                                0, symtab_offset, 4 * sym_size,
 218                                                3, 1, align, sym_size, &pout);
 219   this->write_section_header<size, big_endian>(".strtab", &shstrtab,
 220                                                elfcpp::SHT_STRTAB,
 221                                                0, strtab_offset,
 222                                                strtab.get_strtab_size(),
 223                                                0, 0, 1, 0, &pout);
 224   this->write_section_header<size, big_endian>(".shstrtab", &shstrtab,
 225                                                elfcpp::SHT_STRTAB,
 226                                                0, shstrtab_offset,
 227                                                shstrtab.get_strtab_size(),
 228                                                0, 0, 1, 0, &pout);
 229
 230   if (filesize > 0)
 231     {
 232       memcpy(pout, fileview, filesize);
 233       pout += filesize;
 234       memset(pout, 0, aligned_filesize - filesize);
 235       pout += aligned_filesize - filesize;
 236     }
 237
 238   this->write_symbol<size, big_endian>("", &strtab, 0, 0, 0, &pout);
 239   this->write_symbol<size, big_endian>(start_symbol_name, &strtab, 0, filesize,
 240                                        1, &pout);
 241   this->write_symbol<size, big_endian>(end_symbol_name, &strtab, filesize, 0,
 242                                        1, &pout);
 243   this->write_symbol<size, big_endian>(size_symbol_name, &strtab, filesize, 0,
 244                                        elfcpp::SHN_ABS, &pout);
 245
 246   strtab.write_to_buffer(pout, strtab.get_strtab_size());
 247   pout += strtab.get_strtab_size();
 248
 249   shstrtab.write_to_buffer(pout, shstrtab.get_strtab_size());
 250   pout += shstrtab.get_strtab_size();
 251
 252   gold_assert(static_cast<size_t>(pout - buffer) == output_size);
 253
 254   this->data_ = buffer;
 255   this->filesize_ = output_size;
 256
 257   f.unlock(task);
 258
 259   return true;
 260 }
 261
 262 // Write out the file header.
 263
 264 template<int size, bool big_endian>
 265 void
 266 Binary_to_elf::write_file_header(unsigned char** ppout)
 267 {
 268   elfcpp::Ehdr_write<size, big_endian> oehdr(*ppout);
 269
 270   unsigned char e_ident[elfcpp::EI_NIDENT];
 271   memset(e_ident, 0, elfcpp::EI_NIDENT);
 272   e_ident[elfcpp::EI_MAG0] = elfcpp::ELFMAG0;
 273   e_ident[elfcpp::EI_MAG1] = elfcpp::ELFMAG1;
 274   e_ident[elfcpp::EI_MAG2] = elfcpp::ELFMAG2;
 275   e_ident[elfcpp::EI_MAG3] = elfcpp::ELFMAG3;
 276   if (size == 32)
 277     e_ident[elfcpp::EI_CLASS] = elfcpp::ELFCLASS32;
 278   else if (size == 64)
 279     e_ident[elfcpp::EI_CLASS] = elfcpp::ELFCLASS64;
 280   else
 281     gold_unreachable();
 282   e_ident[elfcpp::EI_DATA] = (big_endian
 283                               ? elfcpp::ELFDATA2MSB
 284                               : elfcpp::ELFDATA2LSB);
 285   e_ident[elfcpp::EI_VERSION] = elfcpp::EV_CURRENT;
 286   oehdr.put_e_ident(e_ident);
 287
 288   oehdr.put_e_type(elfcpp::ET_REL);
 289   oehdr.put_e_machine(this->elf_machine_);
 290   oehdr.put_e_version(elfcpp::EV_CURRENT);
 291   oehdr.put_e_entry(0);
 292   oehdr.put_e_phoff(0);
 293   oehdr.put_e_shoff(elfcpp::Elf_sizes<size>::ehdr_size);
 294   oehdr.put_e_flags(0);
 295   oehdr.put_e_ehsize(elfcpp::Elf_sizes<size>::ehdr_size);
 296   oehdr.put_e_phentsize(0);
 297   oehdr.put_e_phnum(0);
 298   oehdr.put_e_shentsize(elfcpp::Elf_sizes<size>::shdr_size);
 299   oehdr.put_e_shnum(5);
 300   oehdr.put_e_shstrndx(4);
 301
 302   *ppout += elfcpp::Elf_sizes<size>::ehdr_size;
 303 }
 304
 305 // Write out a section header.
 306
 307 template<int size, bool big_endian>
 308 void
 309 Binary_to_elf::write_section_header(
 310     const char* name,
 311     const Stringpool* shstrtab,
 312     elfcpp::SHT type,
 313     unsigned int flags,
 314     section_size_type offset,
 315     section_size_type section_size,
 316     unsigned int link,
 317     unsigned int info,
 318     unsigned int addralign,
 319     unsigned int entsize,
 320     unsigned char** ppout)
 321 {
 322   elfcpp::Shdr_write<size, big_endian> oshdr(*ppout);
 323
 324   oshdr.put_sh_name(*name == '\0' ? 0 : shstrtab->get_offset(name));
 325   oshdr.put_sh_type(type);
 326   oshdr.put_sh_flags(flags);
 327   oshdr.put_sh_addr(0);
 328   oshdr.put_sh_offset(offset);
 329   oshdr.put_sh_size(section_size);
 330   oshdr.put_sh_link(link);
 331   oshdr.put_sh_info(info);
 332   oshdr.put_sh_addralign(addralign);
 333   oshdr.put_sh_entsize(entsize);
 334
 335   *ppout += elfcpp::Elf_sizes<size>::shdr_size;
 336 }
 337
 338 // Write out a symbol.
 339
 340 template<int size, bool big_endian>
 341 void
 342 Binary_to_elf::write_symbol(
 343     const std::string& name,
 344     const Stringpool* strtab,
 345     section_size_type value,
 346     typename elfcpp::Elf_types<32>::Elf_WXword st_size,
 347     unsigned int shndx,
 348     unsigned char** ppout)
 349 {
 350   unsigned char* pout = *ppout;
 351
 352   elfcpp::Sym_write<size, big_endian> osym(pout);
 353   osym.put_st_name(name.empty() ? 0 : strtab->get_offset(name.c_str()));
 354   osym.put_st_value(value);
 355   osym.put_st_size(st_size);
 356   osym.put_st_info(name.empty() ? elfcpp::STB_LOCAL : elfcpp::STB_GLOBAL,
 357                    elfcpp::STT_NOTYPE);
 358   osym.put_st_other(elfcpp::STV_DEFAULT, 0);
 359   osym.put_st_shndx(shndx);
 360
 361   *ppout += elfcpp::Elf_sizes<size>::sym_size;
 362 }
 363
 364 } // End namespace gold.