gold/archive.h

   1 // archive.h -- archive support for gold      -*- C++ -*-
   2
   3 // Copyright (C) 2006-2014 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 struct 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), arg_serial_(0)
  52   { }
  53   Archive_member(Object* obj, Read_symbols_data* sd)
  54       : obj_(obj), sd_(sd), arg_serial_(0)
  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   // The serial number of the file in the argument list.
  61   unsigned int arg_serial_;
  62 };
  63
  64 // This class serves as a base class for Archive and Lib_group objects.
  65
  66 class Library_base
  67 {
  68  public:
  69   Library_base(Task* task)
  70     : task_(task), incremental_info_(NULL)
  71   { }
  72
  73   virtual
  74   ~Library_base()
  75   { }
  76
  77   // The file name.
  78   const std::string&
  79   filename() const
  80   { return this->do_filename(); }
  81
  82   // The modification time of the archive file.
  83   Timespec
  84   get_mtime()
  85   { return this->do_get_mtime(); }
  86
  87   // When we see a symbol in an archive we might decide to include the member,
  88   // not include the member or be undecided. This enum represents these
  89   // possibilities.
  90
  91   enum Should_include
  92   {
  93     SHOULD_INCLUDE_NO,
  94     SHOULD_INCLUDE_YES,
  95     SHOULD_INCLUDE_UNKNOWN
  96   };
  97
  98   static Should_include
  99   should_include_member(Symbol_table* symtab, Layout*, const char* sym_name,
 100                         Symbol** symp, std::string* why, char** tmpbufp,
 101                         size_t* tmpbuflen);
 102
 103   // Store a pointer to the incremental link info for the library.
 104   void
 105   set_incremental_info(Incremental_archive_entry* info)
 106   { this->incremental_info_ = info; }
 107
 108   // Return the pointer to the incremental link info for the library.
 109   Incremental_archive_entry*
 110   incremental_info() const
 111   { return this->incremental_info_; }
 112
 113   // Abstract base class for processing unused symbols.
 114   class Symbol_visitor_base
 115   {
 116    public:
 117     Symbol_visitor_base()
 118     { }
 119
 120     virtual
 121     ~Symbol_visitor_base()
 122     { }
 123
 124     // This function will be called for each unused global
 125     // symbol in a library, with a pointer to the symbol name.
 126     virtual void
 127     visit(const char* /* name */) = 0;
 128   };
 129
 130   // Iterator for unused global symbols in the library.
 131   // Calls v->visit() for each global symbol defined
 132   // in each unused library member, passing a pointer to
 133   // the symbol name.
 134   void
 135   for_all_unused_symbols(Symbol_visitor_base* v) const
 136   { this->do_for_all_unused_symbols(v); }
 137
 138  protected:
 139   // The task reading this archive.
 140   Task *task_;
 141
 142  private:
 143   // The file name.
 144   virtual const std::string&
 145   do_filename() const = 0;
 146
 147   // Return the modification time of the archive file.
 148   virtual Timespec
 149   do_get_mtime() = 0;
 150
 151   // Iterator for unused global symbols in the library.
 152   virtual void
 153   do_for_all_unused_symbols(Symbol_visitor_base* v) const = 0;
 154
 155   // The incremental link information for this archive.
 156   Incremental_archive_entry* incremental_info_;
 157 };
 158
 159 // This class represents an archive--generally a libNAME.a file.
 160 // Archives have a symbol table and a list of objects.
 161
 162 class Archive : public Library_base
 163 {
 164  public:
 165   Archive(const std::string& name, Input_file* input_file,
 166           bool is_thin_archive, Dirsearch* dirpath, Task* task);
 167
 168   // The length of the magic string at the start of an archive.
 169   static const int sarmag = 8;
 170
 171   // The magic string at the start of an archive.
 172   static const char armag[sarmag];
 173   static const char armagt[sarmag];
 174
 175   // The string expected at the end of an archive member header.
 176   static const char arfmag[2];
 177
 178   // The name of the object.  This is the name used on the command
 179   // line; e.g., if "-lgcc" is on the command line, this will be
 180   // "gcc".
 181   const std::string&
 182   name() const
 183   { return this->name_; }
 184
 185   // The input file.
 186   const Input_file*
 187   input_file() const
 188   { return this->input_file_; }
 189
 190   // Set up the archive: read the symbol map.
 191   void
 192   setup();
 193
 194   // Get a reference to the underlying file.
 195   File_read&
 196   file()
 197   { return this->input_file_->file(); }
 198
 199   const File_read&
 200   file() const
 201   { return this->input_file_->file(); }
 202
 203   // Lock the underlying file.
 204   void
 205   lock(const Task* t)
 206   { this->input_file_->file().lock(t); }
 207
 208   // Unlock the underlying file.
 209   void
 210   unlock(const Task* t)
 211   { this->input_file_->file().unlock(t); }
 212
 213   // Return whether the underlying file is locked.
 214   bool
 215   is_locked() const
 216   { return this->input_file_->file().is_locked(); }
 217
 218   // Return the token, so that the task can be queued.
 219   Task_token*
 220   token()
 221   { return this->input_file_->file().token(); }
 222
 223   // Release the underlying file.
 224   void
 225   release()
 226   { this->input_file_->file().release(); }
 227
 228   // Clear uncached views in the underlying file.
 229   void
 230   clear_uncached_views()
 231   { this->input_file_->file().clear_uncached_views(); }
 232
 233   // Whether this is a thin archive.
 234   bool
 235   is_thin_archive() const
 236   { return this->is_thin_archive_; }
 237
 238   // Unlock any nested archives.
 239   void
 240   unlock_nested_archives();
 241
 242   // Select members from the archive as needed and add them to the
 243   // link.
 244   bool
 245   add_symbols(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 246
 247   // Return whether the archive defines the symbol.
 248   bool
 249   defines_symbol(Symbol*) const;
 250
 251   // Dump statistical information to stderr.
 252   static void
 253   print_stats();
 254
 255   // Return the number of members in the archive.
 256   size_t
 257   count_members();
 258
 259   // Return the no-export flag.
 260   bool
 261   no_export()
 262   { return this->no_export_; }
 263
 264  private:
 265   Archive(const Archive&);
 266   Archive& operator=(const Archive&);
 267
 268   // The file name.
 269   const std::string&
 270   do_filename() const
 271   { return this->input_file_->filename(); }
 272
 273   // The modification time of the archive file.
 274   Timespec
 275   do_get_mtime()
 276   { return this->file().get_mtime(); }
 277
 278   struct Archive_header;
 279
 280   // Total number of archives seen.
 281   static unsigned int total_archives;
 282   // Total number of archive members seen.
 283   static unsigned int total_members;
 284   // Number of archive members loaded.
 285   static unsigned int total_members_loaded;
 286
 287   // Get a view into the underlying file.
 288   const unsigned char*
 289   get_view(off_t start, section_size_type size, bool aligned, bool cache)
 290   { return this->input_file_->file().get_view(0, start, size, aligned, cache); }
 291
 292   // Read the archive symbol map.
 293   void
 294   read_armap(off_t start, section_size_type size);
 295
 296   // Read an archive member header at OFF.  CACHE is whether to cache
 297   // the file view.  Return the size of the member, and set *PNAME to
 298   // the name.
 299   off_t
 300   read_header(off_t off, bool cache, std::string* pname, off_t* nested_off);
 301
 302   // Interpret an archive header HDR at OFF.  Return the size of the
 303   // member, and set *PNAME to the name.
 304   off_t
 305   interpret_header(const Archive_header* hdr, off_t off, std::string* pname,
 306                    off_t* nested_off) const;
 307
 308   // Get the file and offset for an archive member, which may be an
 309   // external member of a thin archive.  Set *INPUT_FILE to the
 310   // file containing the actual member, *MEMOFF to the offset
 311   // within that file (0 if not a nested archive), and *MEMBER_NAME
 312   // to the name of the archive member.  Return TRUE on success.
 313   bool
 314   get_file_and_offset(off_t off, Input_file** input_file, off_t* memoff,
 315                       off_t* memsize, std::string* member_name);
 316
 317   // Return an ELF object for the member at offset OFF.
 318   Object*
 319   get_elf_object_for_member(off_t off, bool*);
 320
 321   // Read the symbols from all the archive members in the link.
 322   void
 323   read_all_symbols();
 324
 325   // Read the symbols from an archive member in the link.  OFF is the file
 326   // offset of the member header.
 327   void
 328   read_symbols(off_t off);
 329
 330   // Include all the archive members in the link.
 331   bool
 332   include_all_members(Symbol_table*, Layout*, Input_objects*, Mapfile*);
 333
 334   // Include an archive member in the link.
 335   bool
 336   include_member(Symbol_table*, Layout*, Input_objects*, off_t off,
 337                  Mapfile*, Symbol*, const char* why);
 338
 339   // Return whether we found this archive by searching a directory.
 340   bool
 341   searched_for() const
 342   { return this->input_file_->will_search_for(); }
 343
 344   // Iterate over archive members.
 345   class const_iterator;
 346
 347   const_iterator
 348   begin();
 349
 350   const_iterator
 351   end();
 352
 353   friend class const_iterator;
 354
 355   // Iterator for unused global symbols in the library.
 356   void
 357   do_for_all_unused_symbols(Symbol_visitor_base* v) const;
 358
 359   // An entry in the archive map of symbols to object files.
 360   struct Armap_entry
 361   {
 362     // The offset to the symbol name in armap_names_.
 363     off_t name_offset;
 364     // The file offset to the object in the archive.
 365     off_t file_offset;
 366   };
 367
 368   // A simple hash code for off_t values.
 369   class Seen_hash
 370   {
 371    public:
 372     size_t operator()(off_t val) const
 373     { return static_cast<size_t>(val); }
 374   };
 375
 376   // For keeping track of open nested archives in a thin archive file.
 377   typedef Unordered_map<std::string, Archive*> Nested_archive_table;
 378
 379   // Name of object as printed to user.
 380   std::string name_;
 381   // For reading the file.
 382   Input_file* input_file_;
 383   // The archive map.
 384   std::vector<Armap_entry> armap_;
 385   // The names in the archive map.
 386   std::string armap_names_;
 387   // The extended name table.
 388   std::string extended_names_;
 389   // Track which symbols in the archive map are for elements which are
 390   // defined or which have already been included in the link.
 391   std::vector<bool> armap_checked_;
 392   // Track which elements have been included by offset.
 393   Unordered_set<off_t, Seen_hash> seen_offsets_;
 394   // Table of objects whose symbols have been pre-read.
 395   std::map<off_t, Archive_member> members_;
 396   // True if this is a thin archive.
 397   const bool is_thin_archive_;
 398   // True if we have included at least one object from this archive.
 399   bool included_member_;
 400   // Table of nested archives, indexed by filename.
 401   Nested_archive_table nested_archives_;
 402   // The directory search path.
 403   Dirsearch* dirpath_;
 404   // Number of members in this archive;
 405   unsigned int num_members_;
 406   // True if we exclude this library archive from automatic export.
 407   bool no_export_;
 408   // True if this library has been included as a --whole-archive.
 409   bool included_all_members_;
 410 };
 411
 412 // This class is used to read an archive and pick out the desired
 413 // elements and add them to the link.
 414
 415 class Add_archive_symbols : public Task
 416 {
 417  public:
 418   Add_archive_symbols(Symbol_table* symtab, Layout* layout,
 419                       Input_objects* input_objects, Dirsearch* dirpath,
 420                       int dirindex, Mapfile* mapfile,
 421                       const Input_argument* input_argument,
 422                       Archive* archive, Input_group* input_group,
 423                       Task_token* this_blocker,
 424                       Task_token* next_blocker)
 425     : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 426       dirpath_(dirpath), dirindex_(dirindex), mapfile_(mapfile),
 427       input_argument_(input_argument), archive_(archive),
 428       input_group_(input_group), this_blocker_(this_blocker),
 429       next_blocker_(next_blocker)
 430   { }
 431
 432   ~Add_archive_symbols();
 433
 434   // The standard Task methods.
 435
 436   Task_token*
 437   is_runnable();
 438
 439   void
 440   locks(Task_locker*);
 441
 442   void
 443   run(Workqueue*);
 444
 445   std::string
 446   get_name() const
 447   {
 448     if (this->archive_ == NULL)
 449       return "Add_archive_symbols";
 450     return "Add_archive_symbols " + this->archive_->file().filename();
 451   }
 452
 453  private:
 454   Symbol_table* symtab_;
 455   Layout* layout_;
 456   Input_objects* input_objects_;
 457   Dirsearch* dirpath_;
 458   int dirindex_;
 459   Mapfile* mapfile_;
 460   const Input_argument* input_argument_;
 461   Archive* archive_;
 462   Input_group* input_group_;
 463   Task_token* this_blocker_;
 464   Task_token* next_blocker_;
 465 };
 466
 467 // This class represents the files surrounded by a --start-lib ... --end-lib.
 468
 469 class Lib_group : public Library_base
 470 {
 471  public:
 472   Lib_group(const Input_file_lib* lib, Task* task);
 473
 474   // Select members from the lib group as needed and add them to the link.
 475   void
 476   add_symbols(Symbol_table*, Layout*, Input_objects*);
 477
 478   // Include a member of the lib group in the link.
 479   void
 480   include_member(Symbol_table*, Layout*, Input_objects*, const Archive_member&);
 481
 482   Archive_member*
 483   get_member(int i)
 484   {
 485     return &this->members_[i];
 486   }
 487
 488   // Total number of archives seen.
 489   static unsigned int total_lib_groups;
 490   // Total number of archive members seen.
 491   static unsigned int total_members;
 492   // Number of archive members loaded.
 493   static unsigned int total_members_loaded;
 494
 495   // Dump statistical information to stderr.
 496   static void
 497   print_stats();
 498
 499  private:
 500   // The file name.
 501   const std::string&
 502   do_filename() const;
 503
 504   // A Lib_group does not have a modification time, since there is no
 505   // real library file.
 506   Timespec
 507   do_get_mtime()
 508   { return Timespec(0, 0); }
 509
 510   // Iterator for unused global symbols in the library.
 511   void
 512   do_for_all_unused_symbols(Symbol_visitor_base*) const;
 513
 514   // Table of the objects in the group.
 515   std::vector<Archive_member> members_;
 516 };
 517
 518 // This class is used to pick out the desired elements and add them to the link.
 519
 520 class Add_lib_group_symbols : public Task
 521 {
 522  public:
 523   Add_lib_group_symbols(Symbol_table* symtab, Layout* layout,
 524                         Input_objects* input_objects,
 525                         Lib_group* lib, Task_token* next_blocker)
 526       : symtab_(symtab), layout_(layout), input_objects_(input_objects),
 527         lib_(lib), readsyms_blocker_(NULL), this_blocker_(NULL),
 528         next_blocker_(next_blocker)
 529   { }
 530
 531   ~Add_lib_group_symbols();
 532
 533   // The standard Task methods.
 534
 535   Task_token*
 536   is_runnable();
 537
 538   void
 539   locks(Task_locker*);
 540
 541   void
 542   run(Workqueue*);
 543
 544   // Set the blocker to use for this task.
 545   void
 546   set_blocker(Task_token* readsyms_blocker, Task_token* this_blocker)
 547   {
 548     gold_assert(this->readsyms_blocker_ == NULL && this->this_blocker_ == NULL);
 549     this->readsyms_blocker_ = readsyms_blocker;
 550     this->this_blocker_ = this_blocker;
 551   }
 552
 553   std::string
 554   get_name() const
 555   {
 556     return "Add_lib_group_symbols";
 557   }
 558
 559  private:
 560   Symbol_table* symtab_;
 561   Layout* layout_;
 562   Input_objects* input_objects_;
 563   Lib_group* lib_;
 564   Task_token* readsyms_blocker_;
 565   Task_token* this_blocker_;
 566   Task_token* next_blocker_;
 567 };
 568
 569 } // End namespace gold.
 570
 571 #endif // !defined(GOLD_ARCHIVE_H)