gold/archive.h

   1 // archive.h -- archive support for gold      -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008, 2010, 2011 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 serves as a base class for Archive and Lib_group objects.
  63
  64 class Library_base
  65 {
  66  public:
  67   Library_base(Task* task)
  68     : task_(task), incremental_info_(NULL)
  69   { }
  70
  71   virtual
  72   ~Library_base()
  73   { }
  74
  75   // The file name.
  76   const std::string&
  77   filename() const
  78   { return this->do_filename(); }
  79
  80   // The modification time of the archive file.
  81   Timespec
  82   get_mtime()
  83   { return this->do_get_mtime(); }
  84
  85   // When we see a symbol in an archive we might decide to include the member,
  86   // not include the member or be undecided. This enum represents these
  87   // possibilities.
  88
  89   enum Should_include
  90   {
  91     SHOULD_INCLUDE_NO,
  92     SHOULD_INCLUDE_YES,
  93     SHOULD_INCLUDE_UNKNOWN
  94   };
  95
  96   static Should_include
  97   should_include_member(Symbol_table* symtab, Layout*, const char* sym_name,
  98                         Symbol** symp, std::string* why, char** tmpbufp,
  99                         size_t* tmpbuflen);
 100
 101   // Store a pointer to the incremental link info for the library.
 102   void
 103   set_incremental_info(Incremental_archive_entry* info)
 104   { this->incremental_info_ = info; }
 105
 106   // Return the pointer to the incremental link info for the library.
 107   Incremental_archive_entry*
 108   incremental_info() const
 109   { return this->incremental_info_; }
 110
 111   // Abstract base class for processing unused symbols.
 112   class Symbol_visitor_base
 113   {
 114    public:
 115     Symbol_visitor_base()
 116     { }
 117
 118     virtual
 119     ~Symbol_visitor_base()
 120     { }
 121
 122     // This function will be called for each unused global
 123     // symbol in a library, with a pointer to the symbol name.
 124     virtual void
 125     visit(const char* /* name */) = 0;
 126   };
 127
 128   // Iterator for unused global symbols in the library.
 129   // Calls v->visit() for each global symbol defined
 130   // in each unused library member, passing a pointer to
 131   // the symbol name.
 132   void
 133   for_all_unused_symbols(Symbol_visitor_base* v) const
 134   { this->do_for_all_unused_symbols(v); }
 135
 136  protected:
 137   // The task reading this archive.
 138   Task *task_;
 139
 140  private:
 141   // The file name.
 142   virtual const std::string&
 143   do_filename() const = 0;
 144
 145   // Return the modification time of the archive file.
 146   virtual Timespec
 147   do_get_mtime() = 0;
 148
 149   // Iterator for unused global symbols in the library.
 150   virtual void
 151   do_for_all_unused_symbols(Symbol_visitor_base* v) const = 0;
 152
 153   // The incremental link information for this archive.
 154   Incremental_archive_entry* incremental_info_;
 155 };
 156
 157 // This class represents an archive--generally a libNAME.a file.
 158 // Archives have a symbol table and a list of objects.
 159
 160 class Archive : public Library_base
 161 {
 162  public:
 163   Archive(const std::string& name, Input_file* input_file,
 164           bool is_thin_archive, Dirsearch* dirpath, Task* task);
 165
 166   // The length of the magic string at the start of an archive.
 167   static const int sarmag = 8;
 168
 169   // The magic string at the start of an archive.
 170   static const char armag[sarmag];
 171   static const char armagt[sarmag];
 172
 173   // The string expected at the end of an archive member header.
 174   static const char arfmag[2];
 175
 176   // The name of the object.  This is the name used on the command
 177   // line; e.g., if "-lgcc" is on the command line, this will be
 178   // "gcc".
 179   const std::string&
 180   name() const
 181   { return this->name_; }
 182
 183   // The input file.
 184   const Input_file*
 185   input_file() const
 186   { return this->input_file_; }
 187
 188   // Set up the archive: read the symbol map.
 189   void
 190   setup();
 191
 192   // Get a reference to the underlying file.
 193   File_read&
 194   file()
 195   { return this->input_file_->file(); }
 196
 197   const File_read&
 198   file() const
 199   { return this->input_file_->file(); }
 200
 201   // Lock the underlying file.
 202   void
 203   lock(const Task* t)
 204   { this->input_file_->file().lock(t); }
 205
 206   // Unlock the underlying file.
 207   void
 208   unlock(const Task* t)
 209   { this->input_file_->file().unlock(t); }
 210
 211   // Return whether the underlying file is locked.
 212   bool
 213   is_locked() const
 214   { return this->input_file_->file().is_locked(); }
 215
 216   // Return the token, so that the task can be queued.
 217   Task_token*
 218   token()
 219   { return this->input_file_->file().token(); }
 220
 221   // Release the underlying file.
 222   void
 223   release()
 224   { this->input_file_->file().release(); }
 225
 226   // Clear uncached views in the underlying file.
 227   void
 228   clear_uncached_views()
 229   { this->input_file_->file().clear_uncached_views(); }
 230
 231   // Whether this is a thin archive.
 232   bool
 233   is_thin_archive() const
 234   { return this->is_thin_archive_; }
 235
 236   // Unlock any nested archives.
 237   void
 238   unlock_nested_archives();
 239
 240   // Select members from the archive as needed and add them to the
 241   // link.
 242   bool
 243   add_symbols(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 244
 245   // Return whether the archive defines the symbol.
 246   bool
 247   defines_symbol(Symbol*) const;
 248
 249   // Dump statistical information to stderr.
 250   static void
 251   print_stats();
 252
 253   // Return the number of members in the archive.
 254   size_t
 255   count_members();
 256
 257   // Return the no-export flag.
 258   bool
 259   no_export()
 260   { return this->no_export_; }
 261
 262  private:
 263   Archive(const Archive&);
 264   Archive& operator=(const Archive&);
 265
 266   // The file name.
 267   const std::string&
 268   do_filename() const
 269   { return this->input_file_->filename(); }
 270
 271   // The modification time of the archive file.
 272   Timespec
 273   do_get_mtime()
 274   { return this->file().get_mtime(); }
 275
 276   struct Archive_header;
 277
 278   // Total number of archives seen.
 279   static unsigned int total_archives;
 280   // Total number of archive members seen.
 281   static unsigned int total_members;
 282   // Number of archive members loaded.
 283   static unsigned int total_members_loaded;
 284
 285   // Get a view into the underlying file.
 286   const unsigned char*
 287   get_view(off_t start, section_size_type size, bool aligned, bool cache)
 288   { return this->input_file_->file().get_view(0, start, size, aligned, cache); }
 289
 290   // Read the archive symbol map.
 291   void
 292   read_armap(off_t start, section_size_type size);
 293
 294   // Read an archive member header at OFF.  CACHE is whether to cache
 295   // the file view.  Return the size of the member, and set *PNAME to
 296   // the name.
 297   off_t
 298   read_header(off_t off, bool cache, std::string* pname, off_t* nested_off);
 299
 300   // Interpret an archive header HDR at OFF.  Return the size of the
 301   // member, and set *PNAME to the name.
 302   off_t
 303   interpret_header(const Archive_header* hdr, off_t off, std::string* pname,
 304                    off_t* nested_off) const;
 305
 306   // Get the file and offset for an archive member, which may be an
 307   // external member of a thin archive.  Set *INPUT_FILE to the
 308   // file containing the actual member, *MEMOFF to the offset
 309   // within that file (0 if not a nested archive), and *MEMBER_NAME
 310   // to the name of the archive member.  Return TRUE on success.
 311   bool
 312   get_file_and_offset(off_t off, Input_file** input_file, off_t* memoff,
 313                       off_t* memsize, std::string* member_name);
 314
 315   // Return an ELF object for the member at offset OFF.
 316   Object*
 317   get_elf_object_for_member(off_t off, bool*);
 318
 319   // Read the symbols from all the archive members in the link.
 320   void
 321   read_all_symbols();
 322
 323   // Read the symbols from an archive member in the link.  OFF is the file
 324   // offset of the member header.
 325   void
 326   read_symbols(off_t off);
 327
 328   // Include all the archive members in the link.
 329   bool
 330   include_all_members(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 331
 332   // Include an archive member in the link.
 333   bool
 334   include_member(Symbol_table*, Layout*, Input_objects*, off_t off,
 335                  Mapfile*, Symbol*, const char* why);
 336
 337   // Return whether we found this archive by searching a directory.
 338   bool
 339   searched_for() const
 340   { return this->input_file_->will_search_for(); }
 341
 342   // Iterate over archive members.
 343   class const_iterator;
 344
 345   const_iterator
 346   begin();
 347
 348   const_iterator
 349   end();
 350
 351   friend class const_iterator;
 352
 353   // Iterator for unused global symbols in the library.
 354   void
 355   do_for_all_unused_symbols(Symbol_visitor_base* v) const;
 356
 357   // An entry in the archive map of symbols to object files.
 358   struct Armap_entry
 359   {
 360     // The offset to the symbol name in armap_names_.
 361     off_t name_offset;
 362     // The file offset to the object in the archive.
 363     off_t file_offset;
 364   };
 365
 366   // A simple hash code for off_t values.
 367   class Seen_hash
 368   {
 369    public:
 370     size_t operator()(off_t val) const
 371     { return static_cast<size_t>(val); }
 372   };
 373
 374   // For keeping track of open nested archives in a thin archive file.
 375   typedef Unordered_map<std::string, Archive*> Nested_archive_table;
 376
 377   // Name of object as printed to user.
 378   std::string name_;
 379   // For reading the file.
 380   Input_file* input_file_;
 381   // The archive map.
 382   std::vector<Armap_entry> armap_;
 383   // The names in the archive map.
 384   std::string armap_names_;
 385   // The extended name table.
 386   std::string extended_names_;
 387   // Track which symbols in the archive map are for elements which are
 388   // defined or which have already been included in the link.
 389   std::vector<bool> armap_checked_;
 390   // Track which elements have been included by offset.
 391   Unordered_set<off_t, Seen_hash> seen_offsets_;
 392   // Table of objects whose symbols have been pre-read.
 393   std::map<off_t, Archive_member> members_;
 394   // True if this is a thin archive.
 395   const bool is_thin_archive_;
 396   // True if we have included at least one object from this archive.
 397   bool included_member_;
 398   // Table of nested archives, indexed by filename.
 399   Nested_archive_table nested_archives_;
 400   // The directory search path.
 401   Dirsearch* dirpath_;
 402   // Number of members in this archive;
 403   unsigned int num_members_;
 404   // True if we exclude this library archive from automatic export.
 405   bool no_export_;
 406 };
 407
 408 // This class is used to read an archive and pick out the desired
 409 // elements and add them to the link.
 410
 411 class Add_archive_symbols : public Task
 412 {
 413  public:
 414   Add_archive_symbols(Symbol_table* symtab, Layout* layout,
 415                       Input_objects* input_objects, Dirsearch* dirpath,
 416                       int dirindex, Mapfile* mapfile,
 417                       const Input_argument* input_argument,
 418                       Archive* archive, Input_group* input_group,
 419                       Task_token* this_blocker,
 420                       Task_token* next_blocker)
 421     : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 422       dirpath_(dirpath), dirindex_(dirindex), mapfile_(mapfile),
 423       input_argument_(input_argument), archive_(archive),
 424       input_group_(input_group), this_blocker_(this_blocker),
 425       next_blocker_(next_blocker)
 426   { }
 427
 428   ~Add_archive_symbols();
 429
 430   // The standard Task methods.
 431
 432   Task_token*
 433   is_runnable();
 434
 435   void
 436   locks(Task_locker*);
 437
 438   void
 439   run(Workqueue*);
 440
 441   std::string
 442   get_name() const
 443   {
 444     if (this->archive_ == NULL)
 445       return "Add_archive_symbols";
 446     return "Add_archive_symbols " + this->archive_->file().filename();
 447   }
 448
 449  private:
 450   Symbol_table* symtab_;
 451   Layout* layout_;
 452   Input_objects* input_objects_;
 453   Dirsearch* dirpath_;
 454   int dirindex_;
 455   Mapfile* mapfile_;
 456   const Input_argument* input_argument_;
 457   Archive* archive_;
 458   Input_group* input_group_;
 459   Task_token* this_blocker_;
 460   Task_token* next_blocker_;
 461 };
 462
 463 // This class represents the files surrounded by a --start-lib ... --end-lib.
 464
 465 class Lib_group : public Library_base
 466 {
 467  public:
 468   Lib_group(const Input_file_lib* lib, Task* task);
 469
 470   // Select members from the lib group as needed and add them to the link.
 471   void
 472   add_symbols(Symbol_table*, Layout*, Input_objects*);
 473
 474   // Include a member of the lib group in the link.
 475   void
 476   include_member(Symbol_table*, Layout*, Input_objects*, const Archive_member&);
 477
 478   Archive_member*
 479   get_member(int i)
 480   {
 481     return &this->members_[i];
 482   }
 483
 484   // Total number of archives seen.
 485   static unsigned int total_lib_groups;
 486   // Total number of archive members seen.
 487   static unsigned int total_members;
 488   // Number of archive members loaded.
 489   static unsigned int total_members_loaded;
 490
 491   // Dump statistical information to stderr.
 492   static void
 493   print_stats();
 494
 495  private:
 496   // The file name.
 497   const std::string&
 498   do_filename() const;
 499
 500   // A Lib_group does not have a modification time, since there is no
 501   // real library file.
 502   Timespec
 503   do_get_mtime()
 504   { return Timespec(0, 0); }
 505
 506   // Iterator for unused global symbols in the library.
 507   void
 508   do_for_all_unused_symbols(Symbol_visitor_base*) const;
 509
 510   // For reading the files.
 511   const Input_file_lib* lib_;
 512   // Table of the objects in the group.
 513   std::vector<Archive_member> members_;
 514 };
 515
 516 // This class is used to pick out the desired elements and add them to the link.
 517
 518 class Add_lib_group_symbols : public Task
 519 {
 520  public:
 521   Add_lib_group_symbols(Symbol_table* symtab, Layout* layout,
 522                         Input_objects* input_objects,
 523                         Lib_group* lib, Task_token* next_blocker)
 524       : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 525         lib_(lib), readsyms_blocker_(NULL), this_blocker_(NULL),
 526         next_blocker_(next_blocker)
 527   { }
 528
 529   ~Add_lib_group_symbols();
 530
 531   // The standard Task methods.
 532
 533   Task_token*
 534   is_runnable();
 535
 536   void
 537   locks(Task_locker*);
 538
 539   void
 540   run(Workqueue*);
 541
 542   // Set the blocker to use for this task.
 543   void
 544   set_blocker(Task_token* readsyms_blocker, Task_token* this_blocker)
 545   {
 546     gold_assert(this->readsyms_blocker_ == NULL && this->this_blocker_ == NULL);
 547     this->readsyms_blocker_ = readsyms_blocker;
 548     this->this_blocker_ = this_blocker;
 549   }
 550
 551   std::string
 552   get_name() const
 553   {
 554     return "Add_lib_group_symbols";
 555   }
 556
 557  private:
 558   Symbol_table* symtab_;
 559   Layout* layout_;
 560   Input_objects* input_objects_;
 561   Lib_group* lib_;
 562   Task_token* readsyms_blocker_;
 563   Task_token* this_blocker_;
 564   Task_token* next_blocker_;
 565 };
 566
 567 } // End namespace gold.
 568
 569 #endif // !defined(GOLD_ARCHIVE_H)