1 // dynobj.h -- dynamic object support for gold -*- C++ -*- 2 3 // Copyright (C) 2006-2020 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 #ifndef GOLD_DYNOBJ_H 24 #define GOLD_DYNOBJ_H 25 26 #include <vector> 27 28 #include "stringpool.h" 29 #include "object.h" 30 31 namespace gold 32 { 33 34 class Version_script_info; 35 36 // A dynamic object (ET_DYN). This is an abstract base class itself. 37 // The implementations is the template class Sized_dynobj. 38 39 class Dynobj : public Object 40 { 41 public: 42 // We keep a list of all the DT_NEEDED entries we find. 43 typedef std::vector<std::string> Needed; 44 45 Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0); 46 47 // Return the name to use in a DT_NEEDED entry for this object. 48 const char* 49 soname() const 50 { return this->soname_.c_str(); } 51 52 // Return the list of DT_NEEDED strings. 53 const Needed& 54 needed() const 55 { return this->needed_; } 56 57 // Return whether this dynamic object has any DT_NEEDED entries 58 // which were not seen during the link. 59 bool 60 has_unknown_needed_entries() const 61 { 62 gold_assert(this->unknown_needed_ != UNKNOWN_NEEDED_UNSET); 63 return this->unknown_needed_ == UNKNOWN_NEEDED_TRUE; 64 } 65 66 // Set whether this dynamic object has any DT_NEEDED entries which 67 // were not seen during the link. 68 void 69 set_has_unknown_needed_entries(bool set) 70 { 71 gold_assert(this->unknown_needed_ == UNKNOWN_NEEDED_UNSET); 72 this->unknown_needed_ = set ? UNKNOWN_NEEDED_TRUE : UNKNOWN_NEEDED_FALSE; 73 } 74 75 // Return the word size of the object file. 76 int 77 elfsize() const 78 { gold_unreachable(); } 79 80 // Return TRUE if this is a big-endian object file. 81 bool 82 is_big_endian() const 83 { gold_unreachable(); } 84 85 // Compute the ELF hash code for a string. 86 static uint32_t 87 elf_hash(const char*); 88 89 // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN. 90 // DYNSYMS is the global dynamic symbols. LOCAL_DYNSYM_COUNT is the 91 // number of local dynamic symbols, which is the index of the first 92 // dynamic gobal symbol. 93 static void 94 create_elf_hash_table(const std::vector<Symbol*>& dynsyms, 95 unsigned int local_dynsym_count, 96 unsigned char** pphash, 97 unsigned int* phashlen); 98 99 // Create a GNU hash table, setting *PPHASH and *PHASHLEN. DYNSYMS 100 // is the global dynamic symbols. LOCAL_DYNSYM_COUNT is the number 101 // of local dynamic symbols, which is the index of the first dynamic 102 // gobal symbol. 103 static void 104 create_gnu_hash_table(const std::vector<Symbol*>& dynsyms, 105 unsigned int local_dynsym_count, 106 unsigned char** pphash, unsigned int* phashlen); 107 108 protected: 109 // Return a pointer to this object. 110 virtual Dynobj* 111 do_dynobj() 112 { return this; } 113 114 // Set the DT_SONAME string. 115 void 116 set_soname_string(const char* s) 117 { this->soname_.assign(s); } 118 119 // Add an entry to the list of DT_NEEDED strings. 120 void 121 add_needed(const char* s) 122 { this->needed_.push_back(std::string(s)); } 123 124 private: 125 // Compute the GNU hash code for a string. 126 static uint32_t 127 gnu_hash(const char*); 128 129 // Compute the number of hash buckets to use. 130 static unsigned int 131 compute_bucket_count(const std::vector<uint32_t>& hashcodes, 132 bool for_gnu_hash_table); 133 134 // Sized version of create_elf_hash_table. 135 template<int size, bool big_endian> 136 static void 137 sized_create_elf_hash_table(const std::vector<uint32_t>& bucket, 138 const std::vector<uint32_t>& chain, 139 unsigned char* phash, 140 unsigned int hashlen); 141 142 // Sized version of create_gnu_hash_table. 143 template<int size, bool big_endian> 144 static void 145 sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms, 146 const std::vector<uint32_t>& dynsym_hashvals, 147 unsigned int unhashed_dynsym_count, 148 unsigned char** pphash, 149 unsigned int* phashlen); 150 151 // Values for the has_unknown_needed_entries_ field. 152 enum Unknown_needed 153 { 154 UNKNOWN_NEEDED_UNSET, 155 UNKNOWN_NEEDED_TRUE, 156 UNKNOWN_NEEDED_FALSE 157 }; 158 159 // The DT_SONAME name, if any. 160 std::string soname_; 161 // The list of DT_NEEDED entries. 162 Needed needed_; 163 // Whether this dynamic object has any DT_NEEDED entries not seen 164 // during the link. 165 Unknown_needed unknown_needed_; 166 }; 167 168 // A dynamic object, size and endian specific version. 169 170 template<int size, bool big_endian> 171 class Sized_dynobj : public Dynobj 172 { 173 public: 174 typedef typename Sized_relobj_file<size, big_endian>::Symbols Symbols; 175 176 Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset, 177 const typename elfcpp::Ehdr<size, big_endian>&); 178 179 // Set up the object file based on TARGET. 180 void 181 setup(); 182 183 // Read the symbols. 184 void 185 do_read_symbols(Read_symbols_data*); 186 187 // Lay out the input sections. 188 void 189 do_layout(Symbol_table*, Layout*, Read_symbols_data*); 190 191 // Add the symbols to the symbol table. 192 void 193 do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*); 194 195 Archive::Should_include 196 do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*, 197 std::string* why); 198 199 // Iterate over global symbols, calling a visitor class V for each. 200 void 201 do_for_all_global_symbols(Read_symbols_data* sd, 202 Library_base::Symbol_visitor_base* v); 203 204 // Iterate over local symbols, calling a visitor class V for each GOT offset 205 // associated with a local symbol. 206 void 207 do_for_all_local_got_entries(Got_offset_list::Visitor* v) const; 208 209 // Get the size of a section. 210 uint64_t 211 do_section_size(unsigned int shndx) 212 { return this->elf_file_.section_size(shndx); } 213 214 // Get the name of a section. 215 std::string 216 do_section_name(unsigned int shndx) const 217 { return this->elf_file_.section_name(shndx); } 218 219 // Return a view of the contents of a section. Set *PLEN to the 220 // size. 221 const unsigned char* 222 do_section_contents(unsigned int shndx, section_size_type* plen, 223 bool cache) 224 { 225 Location loc(this->elf_file_.section_contents(shndx)); 226 *plen = convert_to_section_size_type(loc.data_size); 227 if (*plen == 0) 228 { 229 static const unsigned char empty[1] = { '\0' }; 230 return empty; 231 } 232 return this->get_view(loc.file_offset, *plen, true, cache); 233 } 234 235 // Return section flags. 236 uint64_t 237 do_section_flags(unsigned int shndx) 238 { return this->elf_file_.section_flags(shndx); } 239 240 // Not used for dynobj. 241 uint64_t 242 do_section_entsize(unsigned int ) 243 { gold_unreachable(); } 244 245 // Return section address. 246 uint64_t 247 do_section_address(unsigned int shndx) 248 { return this->elf_file_.section_addr(shndx); } 249 250 // Return section type. 251 unsigned int 252 do_section_type(unsigned int shndx) 253 { return this->elf_file_.section_type(shndx); } 254 255 // Return the section link field. 256 unsigned int 257 do_section_link(unsigned int shndx) 258 { return this->elf_file_.section_link(shndx); } 259 260 // Return the section link field. 261 unsigned int 262 do_section_info(unsigned int shndx) 263 { return this->elf_file_.section_info(shndx); } 264 265 // Return the section alignment. 266 uint64_t 267 do_section_addralign(unsigned int shndx) 268 { return this->elf_file_.section_addralign(shndx); } 269 270 // Return the Xindex structure to use. 271 Xindex* 272 do_initialize_xindex(); 273 274 // Get symbol counts. 275 void 276 do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const; 277 278 // Get the global symbols. 279 const Symbols* 280 do_get_global_symbols() const 281 { return this->symbols_; } 282 283 protected: 284 // Read the symbols. This is common code for all target-specific 285 // overrides of do_read_symbols(). 286 void 287 base_read_symbols(Read_symbols_data*); 288 289 private: 290 // For convenience. 291 typedef Sized_dynobj<size, big_endian> This; 292 static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size; 293 static const int sym_size = elfcpp::Elf_sizes<size>::sym_size; 294 static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size; 295 typedef elfcpp::Shdr<size, big_endian> Shdr; 296 typedef elfcpp::Dyn<size, big_endian> Dyn; 297 298 // Adjust a section index if necessary. 299 unsigned int 300 adjust_shndx(unsigned int shndx) 301 { 302 if (shndx >= elfcpp::SHN_LORESERVE) 303 shndx += this->elf_file_.large_shndx_offset(); 304 return shndx; 305 } 306 307 // Find the dynamic symbol table and the version sections, given the 308 // section headers. 309 void 310 find_dynsym_sections(const unsigned char* pshdrs, 311 unsigned int* pversym_shndx, 312 unsigned int* pverdef_shndx, 313 unsigned int* pverneed_shndx, 314 unsigned int* pdynamic_shndx); 315 316 // Read the dynamic symbol section SHNDX. 317 void 318 read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx, 319 elfcpp::SHT type, unsigned int link, 320 File_view** view, section_size_type* view_size, 321 unsigned int* view_info); 322 323 // Read the dynamic tags. 324 void 325 read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx, 326 unsigned int strtab_shndx, const unsigned char* strtabu, 327 off_t strtab_size); 328 329 // Mapping from version number to version name. 330 typedef std::vector<const char*> Version_map; 331 332 // Create the version map. 333 void 334 make_version_map(Read_symbols_data* sd, Version_map*) const; 335 336 // Add version definitions to the version map. 337 void 338 make_verdef_map(Read_symbols_data* sd, Version_map*) const; 339 340 // Add version references to the version map. 341 void 342 make_verneed_map(Read_symbols_data* sd, Version_map*) const; 343 344 // Add an entry to the version map. 345 void 346 set_version_map(Version_map*, unsigned int ndx, const char* name) const; 347 348 // General access to the ELF file. 349 elfcpp::Elf_file<size, big_endian, Object> elf_file_; 350 // The section index of the dynamic symbol table. 351 unsigned int dynsym_shndx_; 352 // The entries in the symbol table for the symbols. We only keep 353 // this if we need it to print symbol information. 354 Symbols* symbols_; 355 // Number of defined symbols. 356 size_t defined_count_; 357 }; 358 359 // A base class for Verdef and Verneed_version which just handles the 360 // version index which will be stored in the SHT_GNU_versym section. 361 362 class Version_base 363 { 364 public: 365 Version_base() 366 : index_(-1U) 367 { } 368 369 virtual 370 ~Version_base() 371 { } 372 373 // Return the version index. 374 unsigned int 375 index() const 376 { 377 gold_assert(this->index_ != -1U); 378 return this->index_; 379 } 380 381 // Set the version index. 382 void 383 set_index(unsigned int index) 384 { 385 gold_assert(this->index_ == -1U); 386 this->index_ = index; 387 } 388 389 // Clear the weak flag in a version definition. 390 virtual void 391 clear_weak() = 0; 392 393 private: 394 Version_base(const Version_base&); 395 Version_base& operator=(const Version_base&); 396 397 // The index of the version definition or reference. 398 unsigned int index_; 399 }; 400 401 // This class handles a version being defined in the file we are 402 // generating. 403 404 class Verdef : public Version_base 405 { 406 public: 407 Verdef(const char* name, const std::vector<std::string>& deps, 408 bool is_base, bool is_weak, bool is_info, bool is_symbol_created) 409 : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak), 410 is_info_(is_info), is_symbol_created_(is_symbol_created) 411 { } 412 413 // Return the version name. 414 const char* 415 name() const 416 { return this->name_; } 417 418 // Return the number of dependencies. 419 unsigned int 420 count_dependencies() const 421 { return this->deps_.size(); } 422 423 // Add a dependency to this version. The NAME should be 424 // canonicalized in the dynamic Stringpool. 425 void 426 add_dependency(const char* name) 427 { this->deps_.push_back(name); } 428 429 // Return whether this definition is weak. 430 bool 431 is_weak() const 432 { return this->is_weak_; } 433 434 // Clear the weak flag. 435 void 436 clear_weak() 437 { this->is_weak_ = false; } 438 439 // Return whether this definition is informational. 440 bool 441 is_info() const 442 { return this->is_info_; } 443 444 // Return whether a version symbol has been created for this 445 // definition. 446 bool 447 is_symbol_created() const 448 { return this->is_symbol_created_; } 449 450 // Write contents to buffer. 451 template<int size, bool big_endian> 452 unsigned char* 453 write(const Stringpool*, bool is_last, unsigned char*) const; 454 455 private: 456 Verdef(const Verdef&); 457 Verdef& operator=(const Verdef&); 458 459 // The type of the list of version dependencies. Each dependency 460 // should be canonicalized in the dynamic Stringpool. 461 typedef std::vector<std::string> Deps; 462 463 // The name of this version. This should be canonicalized in the 464 // dynamic Stringpool. 465 const char* name_; 466 // A list of other versions which this version depends upon. 467 Deps deps_; 468 // Whether this is the base version. 469 bool is_base_; 470 // Whether this version is weak. 471 bool is_weak_; 472 // Whether this version is informational. 473 bool is_info_; 474 // Whether a version symbol has been created. 475 bool is_symbol_created_; 476 }; 477 478 // A referened version. This will be associated with a filename by 479 // Verneed. 480 481 class Verneed_version : public Version_base 482 { 483 public: 484 Verneed_version(const char* version) 485 : version_(version) 486 { } 487 488 // Return the version name. 489 const char* 490 version() const 491 { return this->version_; } 492 493 // Clear the weak flag. This is invalid for a reference. 494 void 495 clear_weak() 496 { gold_unreachable(); } 497 498 private: 499 Verneed_version(const Verneed_version&); 500 Verneed_version& operator=(const Verneed_version&); 501 502 const char* version_; 503 }; 504 505 // Version references in a single dynamic object. 506 507 class Verneed 508 { 509 public: 510 Verneed(const char* filename) 511 : filename_(filename), need_versions_() 512 { } 513 514 ~Verneed(); 515 516 // Return the file name. 517 const char* 518 filename() const 519 { return this->filename_; } 520 521 // Return the number of versions. 522 unsigned int 523 count_versions() const 524 { return this->need_versions_.size(); } 525 526 // Add a version name. The name should be canonicalized in the 527 // dynamic Stringpool. If the name is already present, this does 528 // nothing. 529 Verneed_version* 530 add_name(const char* name); 531 532 // Set the version indexes, starting at INDEX. Return the updated 533 // INDEX. 534 unsigned int 535 finalize(unsigned int index); 536 537 // Write contents to buffer. 538 template<int size, bool big_endian> 539 unsigned char* 540 write(const Stringpool*, bool is_last, unsigned char*) const; 541 542 private: 543 Verneed(const Verneed&); 544 Verneed& operator=(const Verneed&); 545 546 // The type of the list of version names. Each name should be 547 // canonicalized in the dynamic Stringpool. 548 typedef std::vector<Verneed_version*> Need_versions; 549 550 // The filename of the dynamic object. This should be 551 // canonicalized in the dynamic Stringpool. 552 const char* filename_; 553 // The list of version names. 554 Need_versions need_versions_; 555 }; 556 557 // This class handles version definitions and references which go into 558 // the output file. 559 560 class Versions 561 { 562 public: 563 Versions(const Version_script_info&, Stringpool*); 564 565 ~Versions(); 566 567 // SYM is going into the dynamic symbol table and has a version. 568 // Record the appropriate version information. 569 void 570 record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym); 571 572 // Set the version indexes. DYNSYM_INDEX is the index we should use 573 // for the next dynamic symbol. We add new dynamic symbols to SYMS 574 // and return an updated DYNSYM_INDEX. 575 unsigned int 576 finalize(Symbol_table* symtab, unsigned int dynsym_index, 577 std::vector<Symbol*>* syms); 578 579 // Return whether there are any version definitions. 580 bool 581 any_defs() const 582 { return !this->defs_.empty(); } 583 584 // Return whether there are any version references. 585 bool 586 any_needs() const 587 { return !this->needs_.empty(); } 588 589 // Build an allocated buffer holding the contents of the symbol 590 // version section (.gnu.version). 591 template<int size, bool big_endian> 592 void 593 symbol_section_contents(const Symbol_table*, const Stringpool*, 594 unsigned int local_symcount, 595 const std::vector<Symbol*>& syms, 596 unsigned char**, unsigned int*) const; 597 598 // Build an allocated buffer holding the contents of the version 599 // definition section (.gnu.version_d). 600 template<int size, bool big_endian> 601 void 602 def_section_contents(const Stringpool*, unsigned char**, 603 unsigned int* psize, unsigned int* pentries) const; 604 605 // Build an allocated buffer holding the contents of the version 606 // reference section (.gnu.version_r). 607 template<int size, bool big_endian> 608 void 609 need_section_contents(const Stringpool*, unsigned char**, 610 unsigned int* psize, unsigned int* pentries) const; 611 612 const Version_script_info& 613 version_script() const 614 { return this->version_script_; } 615 616 private: 617 Versions(const Versions&); 618 Versions& operator=(const Versions&); 619 620 // The type of the list of version definitions. 621 typedef std::vector<Verdef*> Defs; 622 623 // The type of the list of version references. 624 typedef std::vector<Verneed*> Needs; 625 626 // Handle a symbol SYM defined with version VERSION. 627 void 628 add_def(Stringpool*, const Symbol* sym, const char* version, 629 Stringpool::Key); 630 631 // Add a reference to version NAME in file FILENAME. 632 void 633 add_need(Stringpool*, const char* filename, const char* name, 634 Stringpool::Key); 635 636 // Get the dynamic object to use for SYM. 637 Dynobj* 638 get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const; 639 640 // Return the version index to use for SYM. 641 unsigned int 642 version_index(const Symbol_table*, const Stringpool*, 643 const Symbol* sym) const; 644 645 // Define the base version of a shared library. 646 void 647 define_base_version(Stringpool* dynpool); 648 649 // We keep a hash table mapping canonicalized name/version pairs to 650 // a version base. 651 typedef std::pair<Stringpool::Key, Stringpool::Key> Key; 652 653 struct Version_table_hash 654 { 655 size_t 656 operator()(const Key& k) const 657 { return k.first + k.second; } 658 }; 659 660 struct Version_table_eq 661 { 662 bool 663 operator()(const Key& k1, const Key& k2) const 664 { return k1.first == k2.first && k1.second == k2.second; } 665 }; 666 667 typedef Unordered_map<Key, Version_base*, Version_table_hash, 668 Version_table_eq> Version_table; 669 670 // The version definitions. 671 Defs defs_; 672 // The version references. 673 Needs needs_; 674 // The mapping from a canonicalized version/filename pair to a 675 // version index. The filename may be NULL. 676 Version_table version_table_; 677 // Whether the version indexes have been set. 678 bool is_finalized_; 679 // Contents of --version-script, if passed, or NULL. 680 const Version_script_info& version_script_; 681 // Whether we need to insert a base version. This is only used for 682 // shared libraries and is cleared when the base version is defined. 683 bool needs_base_version_; 684 }; 685 686 } // End namespace gold. 687 688 #endif // !defined(GOLD_DYNOBJ_H) 689