gold/binary.cc

   1 // binary.cc -- binary input files for gold
   2
   3 // Copyright 2008 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_end.
  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 = f.get_view(0, 0, filesize, false, false);
 136
 137   unsigned int align;
 138   if (size == 32)
 139     align = 4;
 140   else if (size == 64)
 141     align = 8;
 142   else
 143     gold_unreachable();
 144   section_size_type aligned_filesize = align_address(filesize, align);
 145
 146   // Build the stringpool for the symbol table.
 147
 148   std::string mangled_name = this->filename_;
 149   for (std::string::iterator p = mangled_name.begin();
 150        p != mangled_name.end();
 151        ++p)
 152     if (!ISALNUM(*p))
 153       *p = '_';
 154   mangled_name = "_binary_" + mangled_name;
 155   std::string start_symbol_name = mangled_name + "_start";
 156   std::string end_symbol_name = mangled_name + "_end";
 157   std::string size_symbol_name = mangled_name + "_size";
 158
 159   Stringpool strtab;
 160   strtab.add(start_symbol_name.c_str(), false, NULL);
 161   strtab.add(end_symbol_name.c_str(), false, NULL);
 162   strtab.add(size_symbol_name.c_str(), false, NULL);
 163   strtab.set_string_offsets();
 164
 165   // Build the stringpool for the section name table.
 166
 167   Stringpool shstrtab;
 168   shstrtab.add(".data", false, NULL);
 169   shstrtab.add(".symtab", false, NULL);
 170   shstrtab.add(".strtab", false, NULL);
 171   shstrtab.add(".shstrtab", false, NULL);
 172   shstrtab.set_string_offsets();
 173
 174   // Work out the size of the generated file, and the offsets of the
 175   // various sections, and allocate a buffer.
 176
 177   const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 178
 179   size_t output_size = (elfcpp::Elf_sizes<size>::ehdr_size
 180                         + 5 * elfcpp::Elf_sizes<size>::shdr_size);
 181   size_t data_offset = output_size;
 182   output_size += aligned_filesize;
 183   size_t symtab_offset = output_size;
 184   output_size += 4 * sym_size;
 185   size_t strtab_offset = output_size;
 186   output_size += strtab.get_strtab_size();
 187   size_t shstrtab_offset = output_size;
 188   output_size += shstrtab.get_strtab_size();
 189
 190   unsigned char* buffer = new unsigned char[output_size];
 191
 192   // Write out the data.
 193
 194   unsigned char* pout = buffer;
 195
 196   this->write_file_header<size, big_endian>(&pout);
 197
 198   this->write_section_header<size, big_endian>("", &shstrtab, elfcpp::SHT_NULL,
 199                                                0, 0, 0, 0, 0,
 200                                                0, 0, &pout);
 201   // Having the section be named ".data" and having it be writable is
 202   // because th GNU linker does it that way, and existing linker
 203   // script expect it.
 204   this->write_section_header<size, big_endian>(".data", &shstrtab,
 205                                                elfcpp::SHT_PROGBITS,
 206                                                (elfcpp::SHF_ALLOC
 207                                                 | elfcpp::SHF_WRITE),
 208                                                data_offset,
 209                                                filesize, 0, 0,
 210                                                align, 0, &pout);
 211   this->write_section_header<size, big_endian>(".symtab", &shstrtab,
 212                                                elfcpp::SHT_SYMTAB,
 213                                                0, symtab_offset, 4 * sym_size,
 214                                                3, 1, align, sym_size, &pout);
 215   this->write_section_header<size, big_endian>(".strtab", &shstrtab,
 216                                                elfcpp::SHT_STRTAB,
 217                                                0, strtab_offset,
 218                                                strtab.get_strtab_size(),
 219                                                0, 0, 1, 0, &pout);
 220   this->write_section_header<size, big_endian>(".shstrtab", &shstrtab,
 221                                                elfcpp::SHT_STRTAB,
 222                                                0, shstrtab_offset,
 223                                                shstrtab.get_strtab_size(),
 224                                                0, 0, 1, 0, &pout);
 225
 226   memcpy(pout, fileview, filesize);
 227   pout += filesize;
 228   memset(pout, 0, aligned_filesize - filesize);
 229   pout += aligned_filesize - filesize;
 230
 231   this->write_symbol<size, big_endian>("", &strtab, 0, 0, &pout);
 232   this->write_symbol<size, big_endian>(start_symbol_name, &strtab, 0, 1,
 233                                        &pout);
 234   this->write_symbol<size, big_endian>(end_symbol_name, &strtab, filesize, 1,
 235                                        &pout);
 236   this->write_symbol<size, big_endian>(size_symbol_name, &strtab, filesize,
 237                                        elfcpp::SHN_ABS, &pout);
 238
 239   strtab.write_to_buffer(pout, strtab.get_strtab_size());
 240   pout += strtab.get_strtab_size();
 241
 242   shstrtab.write_to_buffer(pout, shstrtab.get_strtab_size());
 243   pout += shstrtab.get_strtab_size();
 244
 245   gold_assert(static_cast<size_t>(pout - buffer) == output_size);
 246
 247   this->data_ = buffer;
 248   this->filesize_ = output_size;
 249
 250   f.unlock(task);
 251
 252   return true;
 253 }
 254
 255 // Write out the file header.
 256
 257 template<int size, bool big_endian>
 258 void
 259 Binary_to_elf::write_file_header(unsigned char** ppout)
 260 {
 261   elfcpp::Ehdr_write<size, big_endian> oehdr(*ppout);
 262
 263   unsigned char e_ident[elfcpp::EI_NIDENT];
 264   memset(e_ident, 0, elfcpp::EI_NIDENT);
 265   e_ident[elfcpp::EI_MAG0] = elfcpp::ELFMAG0;
 266   e_ident[elfcpp::EI_MAG1] = elfcpp::ELFMAG1;
 267   e_ident[elfcpp::EI_MAG2] = elfcpp::ELFMAG2;
 268   e_ident[elfcpp::EI_MAG3] = elfcpp::ELFMAG3;
 269   if (size == 32)
 270     e_ident[elfcpp::EI_CLASS] = elfcpp::ELFCLASS32;
 271   else if (size == 64)
 272     e_ident[elfcpp::EI_CLASS] = elfcpp::ELFCLASS64;
 273   else
 274     gold_unreachable();
 275   e_ident[elfcpp::EI_DATA] = (big_endian
 276                               ? elfcpp::ELFDATA2MSB
 277                               : elfcpp::ELFDATA2LSB);
 278   e_ident[elfcpp::EI_VERSION] = elfcpp::EV_CURRENT;
 279   oehdr.put_e_ident(e_ident);
 280
 281   oehdr.put_e_type(elfcpp::ET_REL);
 282   oehdr.put_e_machine(this->elf_machine_);
 283   oehdr.put_e_version(elfcpp::EV_CURRENT);
 284   oehdr.put_e_entry(0);
 285   oehdr.put_e_phoff(0);
 286   oehdr.put_e_shoff(elfcpp::Elf_sizes<size>::ehdr_size);
 287   oehdr.put_e_flags(0);
 288   oehdr.put_e_ehsize(elfcpp::Elf_sizes<size>::ehdr_size);
 289   oehdr.put_e_phentsize(0);
 290   oehdr.put_e_phnum(0);
 291   oehdr.put_e_shentsize(elfcpp::Elf_sizes<size>::shdr_size);
 292   oehdr.put_e_shnum(5);
 293   oehdr.put_e_shstrndx(4);
 294
 295   *ppout += elfcpp::Elf_sizes<size>::ehdr_size;
 296 }
 297
 298 // Write out a section header.
 299
 300 template<int size, bool big_endian>
 301 void
 302 Binary_to_elf::write_section_header(
 303     const char* name,
 304     const Stringpool* shstrtab,
 305     elfcpp::SHT type,
 306     unsigned int flags,
 307     section_size_type offset,
 308     section_size_type section_size,
 309     unsigned int link,
 310     unsigned int info,
 311     unsigned int addralign,
 312     unsigned int entsize,
 313     unsigned char** ppout)
 314 {
 315   elfcpp::Shdr_write<size, big_endian> oshdr(*ppout);
 316
 317   oshdr.put_sh_name(*name == '\0' ? 0 : shstrtab->get_offset(name));
 318   oshdr.put_sh_type(type);
 319   oshdr.put_sh_flags(flags);
 320   oshdr.put_sh_addr(0);
 321   oshdr.put_sh_offset(offset);
 322   oshdr.put_sh_size(section_size);
 323   oshdr.put_sh_link(link);
 324   oshdr.put_sh_info(info);
 325   oshdr.put_sh_addralign(addralign);
 326   oshdr.put_sh_entsize(entsize);
 327
 328   *ppout += elfcpp::Elf_sizes<size>::shdr_size;
 329 }
 330
 331 // Write out a symbol.
 332
 333 template<int size, bool big_endian>
 334 void
 335 Binary_to_elf::write_symbol(
 336     const std::string& name,
 337     const Stringpool* strtab,
 338     section_size_type value,
 339     unsigned int shndx,
 340     unsigned char** ppout)
 341 {
 342   unsigned char* pout = *ppout;
 343
 344   elfcpp::Sym_write<size, big_endian> osym(pout);
 345   osym.put_st_name(name.empty() ? 0 : strtab->get_offset(name.c_str()));
 346   osym.put_st_value(value);
 347   osym.put_st_size(0);
 348   osym.put_st_info(name.empty() ? elfcpp::STB_LOCAL : elfcpp::STB_GLOBAL,
 349                    elfcpp::STT_NOTYPE);
 350   osym.put_st_other(elfcpp::STV_DEFAULT, 0);
 351   osym.put_st_shndx(shndx);
 352
 353   *ppout += elfcpp::Elf_sizes<size>::sym_size;
 354 }
 355
 356 } // End namespace gold.