gold/archive.h

   1 // archive.h -- archive support for gold      -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008, 2010 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_ARCHIVE_H
  24 #define GOLD_ARCHIVE_H
  25
  26 #include <string>
  27 #include <vector>
  28
  29 #include "fileread.h"
  30 #include "workqueue.h"
  31
  32 namespace gold
  33 {
  34
  35 class Task;
  36 class Input_argument;
  37 class Input_file;
  38 class Input_objects;
  39 class Input_group;
  40 class Layout;
  41 class Symbol_table;
  42 class Object;
  43 class Read_symbols_data;
  44 class Input_file_lib;
  45 class Incremental_archive_entry;
  46
  47 // An entry in the archive map of offsets to members.
  48 struct Archive_member
  49 {
  50   Archive_member()
  51       : obj_(NULL), sd_(NULL)
  52   { }
  53   Archive_member(Object* obj, Read_symbols_data* sd)
  54       : obj_(obj), sd_(sd)
  55   { }
  56   // The object file.
  57   Object* obj_;
  58   // The data to pass from read_symbols() to add_symbols().
  59   Read_symbols_data* sd_;
  60 };
  61
  62 // This class represents an archive--generally a libNAME.a file.
  63 // Archives have a symbol table and a list of objects.
  64
  65 class Archive
  66 {
  67  public:
  68   Archive(const std::string& name, Input_file* input_file,
  69           bool is_thin_archive, Dirsearch* dirpath, Task* task);
  70
  71   // The length of the magic string at the start of an archive.
  72   static const int sarmag = 8;
  73
  74   // The magic string at the start of an archive.
  75   static const char armag[sarmag];
  76   static const char armagt[sarmag];
  77
  78   // The string expected at the end of an archive member header.
  79   static const char arfmag[2];
  80
  81   // The name of the object.  This is the name used on the command
  82   // line; e.g., if "-lgcc" is on the command line, this will be
  83   // "gcc".
  84   const std::string&
  85   name() const
  86   { return this->name_; }
  87
  88   // The input file.
  89   const Input_file*
  90   input_file() const
  91   { return this->input_file_; }
  92
  93   // The file name.
  94   const std::string&
  95   filename() const
  96   { return this->input_file_->filename(); }
  97
  98   // Set up the archive: read the symbol map.
  99   void
 100   setup();
 101
 102   // Get a reference to the underlying file.
 103   File_read&
 104   file()
 105   { return this->input_file_->file(); }
 106
 107   const File_read&
 108   file() const
 109   { return this->input_file_->file(); }
 110
 111   // Lock the underlying file.
 112   void
 113   lock(const Task* t)
 114   { this->input_file_->file().lock(t); }
 115
 116   // Unlock the underlying file.
 117   void
 118   unlock(const Task* t)
 119   { this->input_file_->file().unlock(t); }
 120
 121   // Return whether the underlying file is locked.
 122   bool
 123   is_locked() const
 124   { return this->input_file_->file().is_locked(); }
 125
 126   // Return the token, so that the task can be queued.
 127   Task_token*
 128   token()
 129   { return this->input_file_->file().token(); }
 130
 131   // Release the underlying file.
 132   void
 133   release()
 134   { this->input_file_->file().release(); }
 135
 136   // Clear uncached views in the underlying file.
 137   void
 138   clear_uncached_views()
 139   { this->input_file_->file().clear_uncached_views(); }
 140
 141   // Whether this is a thin archive.
 142   bool
 143   is_thin_archive() const
 144   { return this->is_thin_archive_; }
 145
 146   // Unlock any nested archives.
 147   void
 148   unlock_nested_archives();
 149
 150   // Select members from the archive as needed and add them to the
 151   // link.
 152   bool
 153   add_symbols(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 154
 155   // Dump statistical information to stderr.
 156   static void
 157   print_stats();
 158
 159   // Return the number of members in the archive.
 160   size_t
 161   count_members();
 162
 163   // Return the no-export flag.
 164   bool
 165   no_export()
 166   { return this->no_export_; }
 167
 168   // Store a pointer to the incremental link info for the archive.
 169   void
 170   set_incremental_info(Incremental_archive_entry* info)
 171   { this->incremental_info_ = info; }
 172
 173   // Return the pointer to the incremental link info for the archive.
 174   Incremental_archive_entry*
 175   incremental_info() const
 176   { return this->incremental_info_; }
 177
 178   // When we see a symbol in an archive we might decide to include the member,
 179   // not include the member or be undecided. This enum represents these
 180   // possibilities.
 181
 182   enum Should_include
 183   {
 184     SHOULD_INCLUDE_NO,
 185     SHOULD_INCLUDE_YES,
 186     SHOULD_INCLUDE_UNKNOWN
 187   };
 188
 189   static Should_include
 190   should_include_member(Symbol_table* symtab, Layout*, const char* sym_name,
 191                         Symbol** symp, std::string* why, char** tmpbufp,
 192                         size_t* tmpbuflen);
 193
 194  private:
 195   struct Armap_entry;
 196
 197  public:
 198   // Iterator class for unused global symbols.  This iterator is used
 199   // for incremental links.
 200
 201   class Unused_symbol_iterator
 202   {
 203    public:
 204     Unused_symbol_iterator(Archive* arch,
 205                            std::vector<Armap_entry>::const_iterator it)
 206       : arch_(arch), it_(it)
 207     { this->skip_used_symbols(); }
 208
 209     const char*
 210     operator*() const
 211     { return this->arch_->armap_names_.data() + this->it_->name_offset; }
 212
 213     Unused_symbol_iterator&
 214     operator++()
 215     {
 216       ++this->it_;
 217       this->skip_used_symbols();
 218       return *this;
 219     }
 220
 221     bool
 222     operator==(const Unused_symbol_iterator p) const
 223     { return this->it_ == p.it_; }
 224
 225     bool
 226     operator!=(const Unused_symbol_iterator p) const
 227     { return this->it_ != p.it_; }
 228
 229    private:
 230     // Skip over symbols defined by members that have been included.
 231     void
 232     skip_used_symbols()
 233     {
 234       while (this->it_ != this->arch_->armap_.end()
 235              && (this->arch_->seen_offsets_.find(this->it_->file_offset)
 236                  != this->arch_->seen_offsets_.end()))
 237         ++it_;
 238     }
 239
 240     // The underlying archive.
 241     Archive* arch_;
 242
 243     // The underlying iterator over all entries in the archive map.
 244     std::vector<Armap_entry>::const_iterator it_;
 245   };
 246
 247   // Return an iterator referring to the first unused symbol.
 248   Unused_symbol_iterator
 249   unused_symbols_begin()
 250   { return Unused_symbol_iterator(this, this->armap_.begin()); }
 251
 252   // Return an iterator referring to the end of the unused symbols.
 253   Unused_symbol_iterator
 254   unused_symbols_end()
 255   { return Unused_symbol_iterator(this, this->armap_.end()); }
 256
 257  private:
 258   Archive(const Archive&);
 259   Archive& operator=(const Archive&);
 260
 261   struct Archive_header;
 262
 263   // Total number of archives seen.
 264   static unsigned int total_archives;
 265   // Total number of archive members seen.
 266   static unsigned int total_members;
 267   // Number of archive members loaded.
 268   static unsigned int total_members_loaded;
 269
 270   // Get a view into the underlying file.
 271   const unsigned char*
 272   get_view(off_t start, section_size_type size, bool aligned, bool cache)
 273   { return this->input_file_->file().get_view(0, start, size, aligned, cache); }
 274
 275   // Read the archive symbol map.
 276   void
 277   read_armap(off_t start, section_size_type size);
 278
 279   // Read an archive member header at OFF.  CACHE is whether to cache
 280   // the file view.  Return the size of the member, and set *PNAME to
 281   // the name.
 282   off_t
 283   read_header(off_t off, bool cache, std::string* pname, off_t* nested_off);
 284
 285   // Interpret an archive header HDR at OFF.  Return the size of the
 286   // member, and set *PNAME to the name.
 287   off_t
 288   interpret_header(const Archive_header* hdr, off_t off, std::string* pname,
 289                    off_t* nested_off) const;
 290
 291   // Get the file and offset for an archive member, which may be an
 292   // external member of a thin archive.  Set *INPUT_FILE to the
 293   // file containing the actual member, *MEMOFF to the offset
 294   // within that file (0 if not a nested archive), and *MEMBER_NAME
 295   // to the name of the archive member.  Return TRUE on success.
 296   bool
 297   get_file_and_offset(off_t off, Input_file** input_file, off_t* memoff,
 298                       off_t* memsize, std::string* member_name);
 299
 300   // Return an ELF object for the member at offset OFF.
 301   Object*
 302   get_elf_object_for_member(off_t off, bool*);
 303
 304   // Read the symbols from all the archive members in the link.
 305   void
 306   read_all_symbols();
 307
 308   // Read the symbols from an archive member in the link.  OFF is the file
 309   // offset of the member header.
 310   void
 311   read_symbols(off_t off);
 312
 313   // Include all the archive members in the link.
 314   bool
 315   include_all_members(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 316
 317   // Include an archive member in the link.
 318   bool
 319   include_member(Symbol_table*, Layout*, Input_objects*, off_t off,
 320                  Mapfile*, Symbol*, const char* why);
 321
 322   // Return whether we found this archive by searching a directory.
 323   bool
 324   searched_for() const
 325   { return this->input_file_->will_search_for(); }
 326
 327   // Iterate over archive members.
 328   class const_iterator;
 329
 330   const_iterator
 331   begin();
 332
 333   const_iterator
 334   end();
 335
 336   friend class const_iterator;
 337
 338   // An entry in the archive map of symbols to object files.
 339   struct Armap_entry
 340   {
 341     // The offset to the symbol name in armap_names_.
 342     off_t name_offset;
 343     // The file offset to the object in the archive.
 344     off_t file_offset;
 345   };
 346
 347   // A simple hash code for off_t values.
 348   class Seen_hash
 349   {
 350    public:
 351     size_t operator()(off_t val) const
 352     { return static_cast<size_t>(val); }
 353   };
 354
 355   // For keeping track of open nested archives in a thin archive file.
 356   typedef Unordered_map<std::string, Archive*> Nested_archive_table;
 357
 358   // Name of object as printed to user.
 359   std::string name_;
 360   // For reading the file.
 361   Input_file* input_file_;
 362   // The archive map.
 363   std::vector<Armap_entry> armap_;
 364   // The names in the archive map.
 365   std::string armap_names_;
 366   // The extended name table.
 367   std::string extended_names_;
 368   // Track which symbols in the archive map are for elements which are
 369   // defined or which have already been included in the link.
 370   std::vector<bool> armap_checked_;
 371   // Track which elements have been included by offset.
 372   Unordered_set<off_t, Seen_hash> seen_offsets_;
 373   // Table of objects whose symbols have been pre-read.
 374   std::map<off_t, Archive_member> members_;
 375   // True if this is a thin archive.
 376   const bool is_thin_archive_;
 377   // True if we have included at least one object from this archive.
 378   bool included_member_;
 379   // Table of nested archives, indexed by filename.
 380   Nested_archive_table nested_archives_;
 381   // The directory search path.
 382   Dirsearch* dirpath_;
 383   // The task reading this archive.
 384   Task *task_;
 385   // Number of members in this archive;
 386   unsigned int num_members_;
 387   // True if we exclude this library archive from automatic export.
 388   bool no_export_;
 389   // The incremental link information for this archive.
 390   Incremental_archive_entry* incremental_info_;
 391 };
 392
 393 // This class is used to read an archive and pick out the desired
 394 // elements and add them to the link.
 395
 396 class Add_archive_symbols : public Task
 397 {
 398  public:
 399   Add_archive_symbols(Symbol_table* symtab, Layout* layout,
 400                       Input_objects* input_objects, Dirsearch* dirpath,
 401                       int dirindex, Mapfile* mapfile,
 402                       const Input_argument* input_argument,
 403                       Archive* archive, Input_group* input_group,
 404                       Task_token* this_blocker,
 405                       Task_token* next_blocker)
 406     : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 407       dirpath_(dirpath), dirindex_(dirindex), mapfile_(mapfile),
 408       input_argument_(input_argument), archive_(archive),
 409       input_group_(input_group), this_blocker_(this_blocker),
 410       next_blocker_(next_blocker)
 411   { }
 412
 413   ~Add_archive_symbols();
 414
 415   // The standard Task methods.
 416
 417   Task_token*
 418   is_runnable();
 419
 420   void
 421   locks(Task_locker*);
 422
 423   void
 424   run(Workqueue*);
 425
 426   std::string
 427   get_name() const
 428   {
 429     if (this->archive_ == NULL)
 430       return "Add_archive_symbols";
 431     return "Add_archive_symbols " + this->archive_->file().filename();
 432   }
 433
 434  private:
 435   Symbol_table* symtab_;
 436   Layout* layout_;
 437   Input_objects* input_objects_;
 438   Dirsearch* dirpath_;
 439   int dirindex_;
 440   Mapfile* mapfile_;
 441   const Input_argument* input_argument_;
 442   Archive* archive_;
 443   Input_group* input_group_;
 444   Task_token* this_blocker_;
 445   Task_token* next_blocker_;
 446 };
 447
 448 // This class represents the files surrunded by a --start-lib ... --end-lib.
 449
 450 class Lib_group
 451 {
 452  public:
 453   Lib_group(const Input_file_lib* lib, Task* task);
 454
 455   // Select members from the lib group as needed and add them to the link.
 456   void
 457   add_symbols(Symbol_table*, Layout*, Input_objects*);
 458
 459   // Include a member of the lib group in the link.
 460   void
 461   include_member(Symbol_table*, Layout*, Input_objects*, const Archive_member&);
 462
 463   Archive_member*
 464   get_member(int i)
 465   {
 466     return &this->members_[i];
 467   }
 468
 469   // Dump statistical information to stderr.
 470   static void
 471   print_stats();
 472
 473   // Total number of archives seen.
 474   static unsigned int total_lib_groups;
 475   // Total number of archive members seen.
 476   static unsigned int total_members;
 477   // Number of archive members loaded.
 478   static unsigned int total_members_loaded;
 479
 480  private:
 481   // For reading the files.
 482   const Input_file_lib* lib_;
 483   // The task reading this lib group.
 484   Task *task_;
 485   // Table of the objects in the group.
 486   std::vector<Archive_member> members_;
 487 };
 488
 489 // This class is used to pick out the desired elements and add them to the link.
 490
 491 class Add_lib_group_symbols : public Task
 492 {
 493  public:
 494   Add_lib_group_symbols(Symbol_table* symtab, Layout* layout,
 495                         Input_objects* input_objects,
 496                         Lib_group* lib, Task_token* next_blocker)
 497       : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 498         lib_(lib), this_blocker_(NULL), next_blocker_(next_blocker)
 499   { }
 500
 501   ~Add_lib_group_symbols();
 502
 503   // The standard Task methods.
 504
 505   Task_token*
 506   is_runnable();
 507
 508   void
 509   locks(Task_locker*);
 510
 511   void
 512   run(Workqueue*);
 513
 514   // Set the blocker to use for this task.
 515   void
 516   set_blocker(Task_token* this_blocker)
 517   {
 518     gold_assert(this->this_blocker_ == NULL);
 519     this->this_blocker_ = this_blocker;
 520   }
 521
 522   std::string
 523   get_name() const
 524   {
 525     return "Add_lib_group_symbols";
 526   }
 527
 528  private:
 529   Symbol_table* symtab_;
 530   Layout* layout_;
 531   Input_objects* input_objects_;
 532   Lib_group * lib_;
 533   Task_token* this_blocker_;
 534   Task_token* next_blocker_;
 535 };
 536
 537 } // End namespace gold.
 538
 539 #endif // !defined(GOLD_ARCHIVE_H)