gold/readsyms.cc

   1 // readsyms.cc -- read input file symbols for gold
   2
   3 // Copyright 2006, 2007, 2008 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 #include "gold.h"
  24
  25 #include <cstring>
  26
  27 #include "elfcpp.h"
  28 #include "options.h"
  29 #include "dirsearch.h"
  30 #include "symtab.h"
  31 #include "object.h"
  32 #include "archive.h"
  33 #include "script.h"
  34 #include "readsyms.h"
  35 #include "plugin.h"
  36
  37 namespace gold
  38 {
  39
  40 // If we fail to open the object, then we won't create an Add_symbols
  41 // task.  However, we still need to unblock the token, or else the
  42 // link won't proceed to generate more error messages.  We can only
  43 // unblock tokens when the workqueue lock is held, so we need a dummy
  44 // task to do that.  The dummy task has to maintain the right sequence
  45 // of blocks, so we need both this_blocker and next_blocker.
  46
  47 class Unblock_token : public Task
  48 {
  49  public:
  50   Unblock_token(Task_token* this_blocker, Task_token* next_blocker)
  51     : this_blocker_(this_blocker), next_blocker_(next_blocker)
  52   { }
  53
  54   ~Unblock_token()
  55   {
  56     if (this->this_blocker_ != NULL)
  57       delete this->this_blocker_;
  58   }
  59
  60   Task_token*
  61   is_runnable()
  62   {
  63     if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
  64       return this->this_blocker_;
  65     return NULL;
  66   }
  67
  68   void
  69   locks(Task_locker* tl)
  70   { tl->add(this, this->next_blocker_); }
  71
  72   void
  73   run(Workqueue*)
  74   { }
  75
  76   std::string
  77   get_name() const
  78   { return "Unblock_token"; }
  79
  80  private:
  81   Task_token* this_blocker_;
  82   Task_token* next_blocker_;
  83 };
  84
  85 // Class read_symbols.
  86
  87 Read_symbols::~Read_symbols()
  88 {
  89   // The this_blocker_ and next_blocker_ pointers are passed on to the
  90   // Add_symbols task.
  91 }
  92
  93 // Return whether a Read_symbols task is runnable.  We can read an
  94 // ordinary input file immediately.  For an archive specified using
  95 // -l, we have to wait until the search path is complete.
  96
  97 Task_token*
  98 Read_symbols::is_runnable()
  99 {
 100   if (this->input_argument_->is_file()
 101       && this->input_argument_->file().may_need_search()
 102       && this->dirpath_->token()->is_blocked())
 103     return this->dirpath_->token();
 104
 105   return NULL;
 106 }
 107
 108 // Return a Task_locker for a Read_symbols task.  We don't need any
 109 // locks here.
 110
 111 void
 112 Read_symbols::locks(Task_locker*)
 113 {
 114 }
 115
 116 // Run a Read_symbols task.
 117
 118 void
 119 Read_symbols::run(Workqueue* workqueue)
 120 {
 121   // If we didn't queue a new task, then we need to explicitly unblock
 122   // the token.
 123   if (!this->do_read_symbols(workqueue))
 124     workqueue->queue_soon(new Unblock_token(this->this_blocker_,
 125                                             this->next_blocker_));
 126 }
 127
 128 // Open the file and read the symbols.  Return true if a new task was
 129 // queued, false if that could not happen due to some error.
 130
 131 bool
 132 Read_symbols::do_read_symbols(Workqueue* workqueue)
 133 {
 134   if (this->input_argument_->is_group())
 135     {
 136       gold_assert(this->input_group_ == NULL);
 137       this->do_group(workqueue);
 138       return true;
 139     }
 140
 141   Input_file* input_file = new Input_file(&this->input_argument_->file());
 142   if (!input_file->open(this->options_, *this->dirpath_, this))
 143     return false;
 144
 145   // Read enough of the file to pick up the entire ELF header.
 146
 147   off_t filesize = input_file->file().filesize();
 148
 149   if (filesize == 0)
 150     {
 151       gold_error(_("%s: file is empty"),
 152                  input_file->file().filename().c_str());
 153       return false;
 154     }
 155
 156   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 157   if (filesize < read_size)
 158     read_size = filesize;
 159
 160   const unsigned char* ehdr = input_file->file().get_view(0, 0, read_size,
 161                                                           true, false);
 162
 163   if (read_size >= Archive::sarmag)
 164     {
 165       bool is_thin_archive
 166           = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
 167       if (is_thin_archive
 168           || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
 169         {
 170           // This is an archive.
 171           Archive* arch = new Archive(this->input_argument_->file().name(),
 172                                       input_file, is_thin_archive,
 173                                       this->dirpath_, this);
 174           arch->setup(this->input_objects_);
 175
 176           // Unlock the archive so it can be used in the next task.
 177           arch->unlock(this);
 178
 179           workqueue->queue_next(new Add_archive_symbols(this->symtab_,
 180                                                         this->layout_,
 181                                                         this->input_objects_,
 182                                                         this->mapfile_,
 183                                                         arch,
 184                                                         this->input_group_,
 185                                                         this->this_blocker_,
 186                                                         this->next_blocker_));
 187           return true;
 188         }
 189     }
 190
 191   if (parameters->options().has_plugins())
 192     {
 193       Pluginobj* obj = parameters->options().plugins()->claim_file(input_file,
 194                                                                    0, filesize);
 195       if (obj != NULL)
 196         {
 197           // The input file was claimed by a plugin, and its symbols
 198           // have been provided by the plugin.
 199           input_file->file().claim_for_plugin();
 200           input_file->file().unlock(this);
 201           workqueue->queue_next(new Add_plugin_symbols(this->symtab_,
 202                                                        this->layout_,
 203                                                        obj,
 204                                                        this->this_blocker_,
 205                                                        this->next_blocker_));
 206           return true;
 207         }
 208     }
 209
 210   if (read_size >= 4)
 211     {
 212       static unsigned char elfmagic[4] =
 213         {
 214           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 215           elfcpp::ELFMAG2, elfcpp::ELFMAG3
 216         };
 217       if (memcmp(ehdr, elfmagic, 4) == 0)
 218         {
 219           // This is an ELF object.
 220
 221           Object* obj = make_elf_object(input_file->filename(),
 222                                         input_file, 0, ehdr, read_size);
 223           if (obj == NULL)
 224             return false;
 225
 226           Read_symbols_data* sd = new Read_symbols_data;
 227           obj->read_symbols(sd);
 228
 229           // Opening the file locked it, so now we need to unlock it.
 230           // We need to unlock it before queuing the Add_symbols task,
 231           // because the workqueue doesn't know about our lock on the
 232           // file.  If we queue the Add_symbols task first, it will be
 233           // stuck on the end of the file lock, but since the
 234           // workqueue doesn't know about that lock, it will never
 235           // release the Add_symbols task.
 236
 237           input_file->file().unlock(this);
 238
 239           // We use queue_next because everything is cached for this
 240           // task to run right away if possible.
 241
 242           workqueue->queue_next(new Add_symbols(this->input_objects_,
 243                                                 this->symtab_, this->layout_,
 244                                                 obj, sd,
 245                                                 this->this_blocker_,
 246                                                 this->next_blocker_));
 247
 248           return true;
 249         }
 250     }
 251
 252   // Queue up a task to try to parse this file as a script.  We use a
 253   // separate task so that the script will be read in order with other
 254   // objects named on the command line.  Also so that we don't try to
 255   // read multiple scripts simultaneously, which could lead to
 256   // unpredictable changes to the General_options structure.
 257
 258   workqueue->queue_soon(new Read_script(this->options_,
 259                                         this->symtab_,
 260                                         this->layout_,
 261                                         this->dirpath_,
 262                                         this->input_objects_,
 263                                         this->mapfile_,
 264                                         this->input_group_,
 265                                         this->input_argument_,
 266                                         input_file,
 267                                         this->this_blocker_,
 268                                         this->next_blocker_));
 269   return true;
 270 }
 271
 272 // Handle a group.  We need to walk through the arguments over and
 273 // over until we don't see any new undefined symbols.  We do this by
 274 // setting off Read_symbols Tasks as usual, but recording the archive
 275 // entries instead of deleting them.  We also start a Finish_group
 276 // Task which runs after we've read all the symbols.  In that task we
 277 // process the archives in a loop until we are done.
 278
 279 void
 280 Read_symbols::do_group(Workqueue* workqueue)
 281 {
 282   Input_group* input_group = new Input_group();
 283
 284   const Input_file_group* group = this->input_argument_->group();
 285   Task_token* this_blocker = this->this_blocker_;
 286
 287   for (Input_file_group::const_iterator p = group->begin();
 288        p != group->end();
 289        ++p)
 290     {
 291       const Input_argument* arg = &*p;
 292       gold_assert(arg->is_file());
 293
 294       Task_token* next_blocker = new Task_token(true);
 295       next_blocker->add_blocker();
 296       workqueue->queue_soon(new Read_symbols(this->options_,
 297                                              this->input_objects_,
 298                                              this->symtab_, this->layout_,
 299                                              this->dirpath_, this->mapfile_,
 300                                              arg, input_group,
 301                                              this_blocker, next_blocker));
 302       this_blocker = next_blocker;
 303     }
 304
 305   const int saw_undefined = this->symtab_->saw_undefined();
 306   workqueue->queue_soon(new Finish_group(this->input_objects_,
 307                                          this->symtab_,
 308                                          this->layout_,
 309                                          this->mapfile_,
 310                                          input_group,
 311                                          saw_undefined,
 312                                          this_blocker,
 313                                          this->next_blocker_));
 314 }
 315
 316 // Return a debugging name for a Read_symbols task.
 317
 318 std::string
 319 Read_symbols::get_name() const
 320 {
 321   if (!this->input_argument_->is_group())
 322     {
 323       std::string ret("Read_symbols ");
 324       if (this->input_argument_->file().is_lib())
 325         ret += "-l";
 326       ret += this->input_argument_->file().name();
 327       return ret;
 328     }
 329
 330   std::string ret("Read_symbols group (");
 331   bool add_space = false;
 332   const Input_file_group* group = this->input_argument_->group();
 333   for (Input_file_group::const_iterator p = group->begin();
 334        p != group->end();
 335        ++p)
 336     {
 337       if (add_space)
 338         ret += ' ';
 339       ret += p->file().name();
 340       add_space = true;
 341     }
 342   return ret + ')';
 343 }
 344
 345 // Class Add_symbols.
 346
 347 Add_symbols::~Add_symbols()
 348 {
 349   if (this->this_blocker_ != NULL)
 350     delete this->this_blocker_;
 351   // next_blocker_ is deleted by the task associated with the next
 352   // input file.
 353 }
 354
 355 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 356 // lock the file.
 357
 358 Task_token*
 359 Add_symbols::is_runnable()
 360 {
 361   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 362     return this->this_blocker_;
 363   if (this->object_->is_locked())
 364     return this->object_->token();
 365   return NULL;
 366 }
 367
 368 void
 369 Add_symbols::locks(Task_locker* tl)
 370 {
 371   tl->add(this, this->next_blocker_);
 372   tl->add(this, this->object_->token());
 373 }
 374
 375 // Add the symbols in the object to the symbol table.
 376
 377 void
 378 Add_symbols::run(Workqueue*)
 379 {
 380   if (!this->input_objects_->add_object(this->object_))
 381     {
 382       // FIXME: We need to close the descriptor here.
 383       delete this->object_;
 384     }
 385   else
 386     {
 387       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 388       this->object_->add_symbols(this->symtab_, this->sd_);
 389       this->object_->release();
 390     }
 391   delete this->sd_;
 392   this->sd_ = NULL;
 393 }
 394
 395 // Class Finish_group.
 396
 397 Finish_group::~Finish_group()
 398 {
 399   if (this->this_blocker_ != NULL)
 400     delete this->this_blocker_;
 401   // next_blocker_ is deleted by the task associated with the next
 402   // input file following the group.
 403 }
 404
 405 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 406
 407 Task_token*
 408 Finish_group::is_runnable()
 409 {
 410   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 411     return this->this_blocker_;
 412   return NULL;
 413 }
 414
 415 void
 416 Finish_group::locks(Task_locker* tl)
 417 {
 418   tl->add(this, this->next_blocker_);
 419 }
 420
 421 // Loop over the archives until there are no new undefined symbols.
 422
 423 void
 424 Finish_group::run(Workqueue*)
 425 {
 426   int saw_undefined = this->saw_undefined_;
 427   while (saw_undefined != this->symtab_->saw_undefined())
 428     {
 429       saw_undefined = this->symtab_->saw_undefined();
 430
 431       for (Input_group::const_iterator p = this->input_group_->begin();
 432            p != this->input_group_->end();
 433            ++p)
 434         {
 435           Task_lock_obj<Archive> tl(this, *p);
 436
 437           (*p)->add_symbols(this->symtab_, this->layout_,
 438                             this->input_objects_, this->mapfile_);
 439         }
 440     }
 441
 442   // Delete all the archives now that we no longer need them.
 443   for (Input_group::const_iterator p = this->input_group_->begin();
 444        p != this->input_group_->end();
 445        ++p)
 446     delete *p;
 447   delete this->input_group_;
 448 }
 449
 450 // Class Read_script
 451
 452 Read_script::~Read_script()
 453 {
 454   if (this->this_blocker_ != NULL)
 455     delete this->this_blocker_;
 456   // next_blocker_ is deleted by the task associated with the next
 457   // input file.
 458 }
 459
 460 // We are blocked by this_blocker_.
 461
 462 Task_token*
 463 Read_script::is_runnable()
 464 {
 465   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 466     return this->this_blocker_;
 467   return NULL;
 468 }
 469
 470 // We don't unlock next_blocker_ here.  If the script names any input
 471 // files, then the last file will be responsible for unlocking it.
 472
 473 void
 474 Read_script::locks(Task_locker*)
 475 {
 476 }
 477
 478 // Read the script, if it is a script.
 479
 480 void
 481 Read_script::run(Workqueue* workqueue)
 482 {
 483   bool used_next_blocker;
 484   if (!read_input_script(workqueue, this->options_, this->symtab_,
 485                          this->layout_, this->dirpath_, this->input_objects_,
 486                          this->mapfile_, this->input_group_,
 487                          this->input_argument_, this->input_file_,
 488                          this->next_blocker_, &used_next_blocker))
 489     {
 490       // Here we have to handle any other input file types we need.
 491       gold_error(_("%s: not an object or archive"),
 492                  this->input_file_->file().filename().c_str());
 493     }
 494
 495   if (!used_next_blocker)
 496     {
 497       // Queue up a task to unlock next_blocker.  We can't just unlock
 498       // it here, as we don't hold the workqueue lock.
 499       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
 500     }
 501 }
 502
 503 // Return a debugging name for a Read_script task.
 504
 505 std::string
 506 Read_script::get_name() const
 507 {
 508   std::string ret("Read_script ");
 509   if (this->input_argument_->file().is_lib())
 510     ret += "-l";
 511   ret += this->input_argument_->file().name();
 512   return ret;
 513 }
 514
 515 } // End namespace gold.