gold/dynobj.cc

   1 // dynobj.cc -- dynamic object support for gold
   2
   3 #include "gold.h"
   4
   5 #include <vector>
   6 #include <cstring>
   7
   8 #include "symtab.h"
   9 #include "dynobj.h"
  10
  11 namespace gold
  12 {
  13
  14 // Class Sized_dynobj.
  15
  16 template<int size, bool big_endian>
  17 Sized_dynobj<size, big_endian>::Sized_dynobj(
  18     const std::string& name,
  19     Input_file* input_file,
  20     off_t offset,
  21     const elfcpp::Ehdr<size, big_endian>& ehdr)
  22   : Dynobj(name, input_file, offset),
  23     elf_file_(this, ehdr),
  24     soname_()
  25 {
  26 }
  27
  28 // Set up the object.
  29
  30 template<int size, bool big_endian>
  31 void
  32 Sized_dynobj<size, big_endian>::setup(
  33     const elfcpp::Ehdr<size, big_endian>& ehdr)
  34 {
  35   this->set_target(ehdr.get_e_machine(), size, big_endian,
  36                    ehdr.get_e_ident()[elfcpp::EI_OSABI],
  37                    ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
  38
  39   const unsigned int shnum = this->elf_file_.shnum();
  40   this->set_shnum(shnum);
  41 }
  42
  43 // Find the SHT_DYNSYM section and the various version sections, and
  44 // the dynamic section, given the section headers.
  45
  46 template<int size, bool big_endian>
  47 void
  48 Sized_dynobj<size, big_endian>::find_dynsym_sections(
  49     const unsigned char* pshdrs,
  50     unsigned int* pdynsym_shndx,
  51     unsigned int* pversym_shndx,
  52     unsigned int* pverdef_shndx,
  53     unsigned int* pverneed_shndx,
  54     unsigned int* pdynamic_shndx)
  55 {
  56   *pdynsym_shndx = -1U;
  57   *pversym_shndx = -1U;
  58   *pverdef_shndx = -1U;
  59   *pverneed_shndx = -1U;
  60   *pdynamic_shndx = -1U;
  61
  62   const unsigned int shnum = this->shnum();
  63   const unsigned char* p = pshdrs;
  64   for (unsigned int i = 0; i < shnum; ++i, p += This::shdr_size)
  65     {
  66       typename This::Shdr shdr(p);
  67
  68       unsigned int* pi;
  69       switch (shdr.get_sh_type())
  70         {
  71         case elfcpp::SHT_DYNSYM:
  72           pi = pdynsym_shndx;
  73           break;
  74         case elfcpp::SHT_GNU_versym:
  75           pi = pversym_shndx;
  76           break;
  77         case elfcpp::SHT_GNU_verdef:
  78           pi = pverdef_shndx;
  79           break;
  80         case elfcpp::SHT_GNU_verneed:
  81           pi = pverneed_shndx;
  82           break;
  83         case elfcpp::SHT_DYNAMIC:
  84           pi = pdynamic_shndx;
  85           break;
  86         default:
  87           pi = NULL;
  88           break;
  89         }
  90
  91       if (pi == NULL)
  92         continue;
  93
  94       if (*pi != -1U)
  95         {
  96           fprintf(stderr,
  97                   _("%s: %s: unexpected duplicate type %u section: %u, %u\n"),
  98                   program_name, this->name().c_str(), shdr.get_sh_type(),
  99                   *pi, i);
 100           gold_exit(false);
 101         }
 102
 103       *pi = i;
 104     }
 105 }
 106
 107 // Read the contents of section SHNDX.  PSHDRS points to the section
 108 // headers.  TYPE is the expected section type.  LINK is the expected
 109 // section link.  Store the data in *VIEW and *VIEW_SIZE.  The
 110 // section's sh_info field is stored in *VIEW_INFO.
 111
 112 template<int size, bool big_endian>
 113 void
 114 Sized_dynobj<size, big_endian>::read_dynsym_section(
 115     const unsigned char* pshdrs,
 116     unsigned int shndx,
 117     elfcpp::SHT type,
 118     unsigned int link,
 119     File_view** view,
 120     off_t* view_size,
 121     unsigned int* view_info)
 122 {
 123   if (shndx == -1U)
 124     {
 125       *view = NULL;
 126       *view_size = 0;
 127       *view_info = 0;
 128       return;
 129     }
 130
 131   typename This::Shdr shdr(pshdrs + shndx * This::shdr_size);
 132
 133   assert(shdr.get_sh_type() == type);
 134
 135   if (shdr.get_sh_link() != link)
 136     {
 137       fprintf(stderr,
 138               _("%s: %s: unexpected link in section %u header: %u != %u\n"),
 139               program_name, this->name().c_str(), shndx,
 140               shdr.get_sh_link(), link);
 141       gold_exit(false);
 142     }
 143
 144   *view = this->get_lasting_view(shdr.get_sh_offset(), shdr.get_sh_size());
 145   *view_size = shdr.get_sh_size();
 146   *view_info = shdr.get_sh_info();
 147 }
 148
 149 // Set soname_ if this shared object has a DT_SONAME tag.  PSHDRS
 150 // points to the section headers.  DYNAMIC_SHNDX is the section index
 151 // of the SHT_DYNAMIC section.  STRTAB_SHNDX, STRTAB, and STRTAB_SIZE
 152 // are the section index and contents of a string table which may be
 153 // the one associated with the SHT_DYNAMIC section.
 154
 155 template<int size, bool big_endian>
 156 void
 157 Sized_dynobj<size, big_endian>::set_soname(const unsigned char* pshdrs,
 158                                            unsigned int dynamic_shndx,
 159                                            unsigned int strtab_shndx,
 160                                            const unsigned char* strtabu,
 161                                            off_t strtab_size)
 162 {
 163   typename This::Shdr dynamicshdr(pshdrs + dynamic_shndx * This::shdr_size);
 164   assert(dynamicshdr.get_sh_type() == elfcpp::SHT_DYNAMIC);
 165
 166   const off_t dynamic_size = dynamicshdr.get_sh_size();
 167   const unsigned char* pdynamic = this->get_view(dynamicshdr.get_sh_offset(),
 168                                                  dynamic_size);
 169
 170   const unsigned int link = dynamicshdr.get_sh_link();
 171   if (link != strtab_shndx)
 172     {
 173       if (link >= this->shnum())
 174         {
 175           fprintf(stderr,
 176                   _("%s: %s: DYNAMIC section %u link out of range: %u\n"),
 177                   program_name, this->name().c_str(),
 178                   dynamic_shndx, link);
 179           gold_exit(false);
 180         }
 181
 182       typename This::Shdr strtabshdr(pshdrs + link * This::shdr_size);
 183       if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
 184         {
 185           fprintf(stderr,
 186                   _("%s: %s: DYNAMIC section %u link %u is not a strtab\n"),
 187                   program_name, this->name().c_str(),
 188                   dynamic_shndx, link);
 189           gold_exit(false);
 190         }
 191
 192       strtab_size = strtabshdr.get_sh_size();
 193       strtabu = this->get_view(strtabshdr.get_sh_offset(), strtab_size);
 194     }
 195
 196   for (const unsigned char* p = pdynamic;
 197        p < pdynamic + dynamic_size;
 198        p += This::dyn_size)
 199     {
 200       typename This::Dyn dyn(p);
 201
 202       if (dyn.get_d_tag() == elfcpp::DT_SONAME)
 203         {
 204           off_t val = dyn.get_d_val();
 205           if (val >= strtab_size)
 206             {
 207               fprintf(stderr,
 208                       _("%s: %s: DT_SONAME value out of range: "
 209                         "%lld >= %lld\n"),
 210                       program_name, this->name().c_str(),
 211                       static_cast<long long>(val),
 212                       static_cast<long long>(strtab_size));
 213               gold_exit(false);
 214             }
 215
 216           const char* strtab = reinterpret_cast<const char*>(strtabu);
 217           this->soname_ = std::string(strtab + val);
 218           return;
 219         }
 220
 221       if (dyn.get_d_tag() == elfcpp::DT_NULL)
 222         return;
 223     }
 224
 225   fprintf(stderr, _("%s: %s: missing DT_NULL in dynamic segment\n"),
 226           program_name, this->name().c_str());
 227   gold_exit(false);
 228 }
 229
 230 // Read the symbols and sections from a dynamic object.  We read the
 231 // dynamic symbols, not the normal symbols.
 232
 233 template<int size, bool big_endian>
 234 void
 235 Sized_dynobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
 236 {
 237   this->read_section_data(&this->elf_file_, sd);
 238
 239   const unsigned char* const pshdrs = sd->section_headers->data();
 240
 241   unsigned int dynsym_shndx;
 242   unsigned int versym_shndx;
 243   unsigned int verdef_shndx;
 244   unsigned int verneed_shndx;
 245   unsigned int dynamic_shndx;
 246   this->find_dynsym_sections(pshdrs, &dynsym_shndx, &versym_shndx,
 247                              &verdef_shndx, &verneed_shndx, &dynamic_shndx);
 248
 249   unsigned int strtab_shndx = -1U;
 250
 251   if (dynsym_shndx == -1U)
 252     {
 253       sd->symbols = NULL;
 254       sd->symbols_size = 0;
 255       sd->symbol_names = NULL;
 256       sd->symbol_names_size = 0;
 257     }
 258   else
 259     {
 260       // Get the dynamic symbols.
 261       typename This::Shdr dynsymshdr(pshdrs + dynsym_shndx * This::shdr_size);
 262       assert(dynsymshdr.get_sh_type() == elfcpp::SHT_DYNSYM);
 263
 264       sd->symbols = this->get_lasting_view(dynsymshdr.get_sh_offset(),
 265                                            dynsymshdr.get_sh_size());
 266       sd->symbols_size = dynsymshdr.get_sh_size();
 267
 268       // Get the symbol names.
 269       strtab_shndx = dynsymshdr.get_sh_link();
 270       if (strtab_shndx >= this->shnum())
 271         {
 272           fprintf(stderr,
 273                   _("%s: %s: invalid dynamic symbol table name index: %u\n"),
 274                   program_name, this->name().c_str(), strtab_shndx);
 275           gold_exit(false);
 276         }
 277       typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
 278       if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
 279         {
 280           fprintf(stderr,
 281                   _("%s: %s: dynamic symbol table name section "
 282                     "has wrong type: %u\n"),
 283                   program_name, this->name().c_str(),
 284                   static_cast<unsigned int>(strtabshdr.get_sh_type()));
 285           gold_exit(false);
 286         }
 287
 288       sd->symbol_names = this->get_lasting_view(strtabshdr.get_sh_offset(),
 289                                                 strtabshdr.get_sh_size());
 290       sd->symbol_names_size = strtabshdr.get_sh_size();
 291
 292       // Get the version information.
 293
 294       unsigned int dummy;
 295       this->read_dynsym_section(pshdrs, versym_shndx, elfcpp::SHT_GNU_versym,
 296                                 dynsym_shndx, &sd->versym, &sd->versym_size,
 297                                 &dummy);
 298
 299       // We require that the version definition and need section link
 300       // to the same string table as the dynamic symbol table.  This
 301       // is not a technical requirement, but it always happens in
 302       // practice.  We could change this if necessary.
 303
 304       this->read_dynsym_section(pshdrs, verdef_shndx, elfcpp::SHT_GNU_verdef,
 305                                 strtab_shndx, &sd->verdef, &sd->verdef_size,
 306                                 &sd->verdef_info);
 307
 308       this->read_dynsym_section(pshdrs, verneed_shndx, elfcpp::SHT_GNU_verneed,
 309                                 strtab_shndx, &sd->verneed, &sd->verneed_size,
 310                                 &sd->verneed_info);
 311     }
 312
 313   // Read the SHT_DYNAMIC section to find whether this shared object
 314   // has a DT_SONAME tag.  This doesn't really have anything to do
 315   // with reading the symbols, but this is a convenient place to do
 316   // it.
 317   if (dynamic_shndx != -1U)
 318     this->set_soname(pshdrs, dynamic_shndx, strtab_shndx,
 319                      (sd->symbol_names == NULL
 320                       ? NULL
 321                       : sd->symbol_names->data()),
 322                      sd->symbol_names_size);
 323 }
 324
 325 // Lay out the input sections for a dynamic object.  We don't want to
 326 // include sections from a dynamic object, so all that we actually do
 327 // here is check for .gnu.warning sections.
 328
 329 template<int size, bool big_endian>
 330 void
 331 Sized_dynobj<size, big_endian>::do_layout(const General_options&,
 332                                           Symbol_table* symtab,
 333                                           Layout*,
 334                                           Read_symbols_data* sd)
 335 {
 336   const unsigned int shnum = this->shnum();
 337   if (shnum == 0)
 338     return;
 339
 340   // Get the section headers.
 341   const unsigned char* pshdrs = sd->section_headers->data();
 342
 343   // Get the section names.
 344   const unsigned char* pnamesu = sd->section_names->data();
 345   const char* pnames = reinterpret_cast<const char*>(pnamesu);
 346
 347   // Skip the first, dummy, section.
 348   pshdrs += This::shdr_size;
 349   for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
 350     {
 351       typename This::Shdr shdr(pshdrs);
 352
 353       if (shdr.get_sh_name() >= sd->section_names_size)
 354         {
 355           fprintf(stderr,
 356                   _("%s: %s: bad section name offset for section %u: %lu\n"),
 357                   program_name, this->name().c_str(), i,
 358                   static_cast<unsigned long>(shdr.get_sh_name()));
 359           gold_exit(false);
 360         }
 361
 362       const char* name = pnames + shdr.get_sh_name();
 363
 364       this->handle_gnu_warning_section(name, i, symtab);
 365     }
 366
 367   delete sd->section_headers;
 368   sd->section_headers = NULL;
 369   delete sd->section_names;
 370   sd->section_names = NULL;
 371 }
 372
 373 // Add an entry to the vector mapping version numbers to version
 374 // strings.
 375
 376 template<int size, bool big_endian>
 377 void
 378 Sized_dynobj<size, big_endian>::set_version_map(
 379     Version_map* version_map,
 380     unsigned int ndx,
 381     const char* name) const
 382 {
 383   assert(ndx < version_map->size());
 384   if ((*version_map)[ndx] != NULL)
 385     {
 386       fprintf(stderr, _("%s: %s: duplicate definition for version %u\n"),
 387               program_name, this->name().c_str(), ndx);
 388       gold_exit(false);
 389     }
 390   (*version_map)[ndx] = name;
 391 }
 392
 393 // Create a vector mapping version numbers to version strings.
 394
 395 template<int size, bool big_endian>
 396 void
 397 Sized_dynobj<size, big_endian>::make_version_map(
 398     Read_symbols_data* sd,
 399     Version_map* version_map) const
 400 {
 401   if (sd->verdef == NULL && sd->verneed == NULL)
 402     return;
 403
 404   // First find the largest version index.
 405   unsigned int maxver = 0;
 406
 407   if (sd->verdef != NULL)
 408     {
 409       const unsigned char* pverdef = sd->verdef->data();
 410       off_t verdef_size = sd->verdef_size;
 411       const unsigned int count = sd->verdef_info;
 412
 413       const unsigned char* p = pverdef;
 414       for (unsigned int i = 0; i < count; ++i)
 415         {
 416           elfcpp::Verdef<size, big_endian> verdef(p);
 417
 418           const unsigned int vd_ndx = verdef.get_vd_ndx();
 419
 420           // The GNU linker clears the VERSYM_HIDDEN bit.  I'm not
 421           // sure why.
 422
 423           if (vd_ndx > maxver)
 424             maxver = vd_ndx;
 425
 426           const unsigned int vd_next = verdef.get_vd_next();
 427           if ((p - pverdef) + vd_next >= verdef_size)
 428             {
 429               fprintf(stderr,
 430                       _("%s: %s: verdef vd_next field out of range: %u\n"),
 431                       program_name, this->name().c_str(), vd_next);
 432               gold_exit(false);
 433             }
 434
 435           p += vd_next;
 436         }
 437     }
 438
 439   if (sd->verneed != NULL)
 440     {
 441       const unsigned char* pverneed = sd->verneed->data();
 442       off_t verneed_size = sd->verneed_size;
 443       const unsigned int count = sd->verneed_info;
 444
 445       const unsigned char* p = pverneed;
 446       for (unsigned int i = 0; i < count; ++i)
 447         {
 448           elfcpp::Verneed<size, big_endian> verneed(p);
 449
 450           const unsigned int vn_aux = verneed.get_vn_aux();
 451           if ((p - pverneed) + vn_aux >= verneed_size)
 452             {
 453               fprintf(stderr,
 454                       _("%s: %s: verneed vn_aux field out of range: %u\n"),
 455                       program_name, this->name().c_str(), vn_aux);
 456               gold_exit(false);
 457             }
 458
 459           const unsigned int vn_cnt = verneed.get_vn_cnt();
 460           const unsigned char* pvna = p + vn_aux;
 461           for (unsigned int j = 0; j < vn_cnt; ++j)
 462             {
 463               elfcpp::Vernaux<size, big_endian> vernaux(pvna);
 464
 465               const unsigned int vna_other = vernaux.get_vna_other();
 466               if (vna_other > maxver)
 467                 maxver = vna_other;
 468
 469               const unsigned int vna_next = vernaux.get_vna_next();
 470               if ((pvna - pverneed) + vna_next >= verneed_size)
 471                 {
 472                   fprintf(stderr,
 473                           _("%s: %s: verneed vna_next field "
 474                             "out of range: %u\n"),
 475                           program_name, this->name().c_str(), vna_next);
 476                   gold_exit(false);
 477                 }
 478
 479               pvna += vna_next;
 480             }
 481
 482           const unsigned int vn_next = verneed.get_vn_next();
 483           if ((p - pverneed) + vn_next >= verneed_size)
 484             {
 485               fprintf(stderr,
 486                       _("%s: %s: verneed vn_next field out of range: %u\n"),
 487                       program_name, this->name().c_str(), vn_next);
 488               gold_exit(false);
 489             }
 490
 491           p += vn_next;
 492         }
 493     }
 494
 495   // Now MAXVER is the largest version index we have seen.
 496
 497   version_map->resize(maxver + 1);
 498
 499   const char* names = reinterpret_cast<const char*>(sd->symbol_names->data());
 500   off_t names_size = sd->symbol_names_size;
 501
 502   if (sd->verdef != NULL)
 503     {
 504       const unsigned char* pverdef = sd->verdef->data();
 505       off_t verdef_size = sd->verdef_size;
 506       const unsigned int count = sd->verdef_info;
 507
 508       const unsigned char* p = pverdef;
 509       for (unsigned int i = 0; i < count; ++i)
 510         {
 511           elfcpp::Verdef<size, big_endian> verdef(p);
 512
 513           const unsigned int vd_cnt = verdef.get_vd_cnt();
 514           if (vd_cnt < 1)
 515             {
 516               fprintf(stderr, _("%s: %s: verdef vd_cnt field too small: %u\n"),
 517                       program_name, this->name().c_str(), vd_cnt);
 518               gold_exit(false);
 519             }
 520
 521           const unsigned int vd_aux = verdef.get_vd_aux();
 522           if ((p - pverdef) + vd_aux >= verdef_size)
 523             {
 524               fprintf(stderr,
 525                       _("%s: %s: verdef vd_aux field out of range: %u\n"),
 526                       program_name, this->name().c_str(), vd_aux);
 527               gold_exit(false);
 528             }
 529
 530           const unsigned char* pvda = p + vd_aux;
 531           elfcpp::Verdaux<size, big_endian> verdaux(pvda);
 532
 533           const unsigned int vda_name = verdaux.get_vda_name();
 534           if (vda_name >= names_size)
 535             {
 536               fprintf(stderr,
 537                       _("%s: %s: verdaux vda_name field out of range: %u\n"),
 538                       program_name, this->name().c_str(), vda_name);
 539               gold_exit(false);
 540             }
 541
 542           this->set_version_map(version_map, verdef.get_vd_ndx(),
 543                                 names + vda_name);
 544
 545           const unsigned int vd_next = verdef.get_vd_next();
 546           if ((p - pverdef) + vd_next >= verdef_size)
 547             {
 548               fprintf(stderr,
 549                       _("%s: %s: verdef vd_next field out of range: %u\n"),
 550                       program_name, this->name().c_str(), vd_next);
 551               gold_exit(false);
 552             }
 553
 554           p += vd_next;
 555         }
 556     }
 557
 558   if (sd->verneed != NULL)
 559     {
 560       const unsigned char* pverneed = sd->verneed->data();
 561       const unsigned int count = sd->verneed_info;
 562
 563       const unsigned char* p = pverneed;
 564       for (unsigned int i = 0; i < count; ++i)
 565         {
 566           elfcpp::Verneed<size, big_endian> verneed(p);
 567
 568           const unsigned int vn_aux = verneed.get_vn_aux();
 569           const unsigned int vn_cnt = verneed.get_vn_cnt();
 570           const unsigned char* pvna = p + vn_aux;
 571           for (unsigned int j = 0; j < vn_cnt; ++j)
 572             {
 573               elfcpp::Vernaux<size, big_endian> vernaux(pvna);
 574
 575               const unsigned int vna_name = vernaux.get_vna_name();
 576               if (vna_name >= names_size)
 577                 {
 578                   fprintf(stderr,
 579                           _("%s: %s: vernaux vna_name field "
 580                             "out of range: %u\n"),
 581                           program_name, this->name().c_str(), vna_name);
 582                   gold_exit(false);
 583                 }
 584
 585               this->set_version_map(version_map, vernaux.get_vna_other(),
 586                                     names + vna_name);
 587
 588               pvna += vernaux.get_vna_next();
 589             }
 590
 591           p += verneed.get_vn_next();
 592         }
 593     }
 594 }
 595
 596 // Add the dynamic symbols to the symbol table.
 597
 598 template<int size, bool big_endian>
 599 void
 600 Sized_dynobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
 601                                                Read_symbols_data* sd)
 602 {
 603   if (sd->symbols == NULL)
 604     {
 605       assert(sd->symbol_names == NULL);
 606       assert(sd->versym == NULL && sd->verdef == NULL && sd->verneed == NULL);
 607       return;
 608     }
 609
 610   const int sym_size = This::sym_size;
 611   const size_t symcount = sd->symbols_size / sym_size;
 612   if (symcount * sym_size != sd->symbols_size)
 613     {
 614       fprintf(stderr,
 615               _("%s: %s: size of dynamic symbols is not "
 616                 "multiple of symbol size\n"),
 617               program_name, this->name().c_str());
 618       gold_exit(false);
 619     }
 620
 621   Version_map version_map;
 622   this->make_version_map(sd, &version_map);
 623
 624   const char* sym_names =
 625     reinterpret_cast<const char*>(sd->symbol_names->data());
 626   symtab->add_from_dynobj(this, sd->symbols->data(), symcount,
 627                           sym_names, sd->symbol_names_size,
 628                           (sd->versym == NULL
 629                            ? NULL
 630                            : sd->versym->data()),
 631                           sd->versym_size,
 632                           &version_map);
 633
 634   delete sd->symbols;
 635   sd->symbols = NULL;
 636   delete sd->symbol_names;
 637   sd->symbol_names = NULL;
 638   if (sd->versym != NULL)
 639     {
 640       delete sd->versym;
 641       sd->versym = NULL;
 642     }
 643   if (sd->verdef != NULL)
 644     {
 645       delete sd->verdef;
 646       sd->verdef = NULL;
 647     }
 648   if (sd->verneed != NULL)
 649     {
 650       delete sd->verneed;
 651       sd->verneed = NULL;
 652     }
 653 }
 654
 655 // Instantiate the templates we need.  We could use the configure
 656 // script to restrict this to only the ones for implemented targets.
 657
 658 template
 659 class Sized_dynobj<32, false>;
 660
 661 template
 662 class Sized_dynobj<32, true>;
 663
 664 template
 665 class Sized_dynobj<64, false>;
 666
 667 template
 668 class Sized_dynobj<64, true>;
 669
 670 } // End namespace gold.