gold/readsyms.cc

   1 // readsyms.cc -- read input file symbols for gold
   2
   3 // Copyright 2006, 2007, 2008, 2009 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 // If appropriate, issue a warning about skipping an incompatible
  94 // file.
  95
  96 void
  97 Read_symbols::incompatible_warning(const Input_argument* input_argument,
  98                                    const Input_file* input_file)
  99 {
 100   if (parameters->options().warn_search_mismatch())
 101     gold_warning("skipping incompatible %s while searching for %s",
 102                  input_file->filename().c_str(),
 103                  input_argument->file().name());
 104 }
 105
 106 // Requeue a Read_symbols task to search for the next object with the
 107 // same name.
 108
 109 void
 110 Read_symbols::requeue(Workqueue* workqueue, Input_objects* input_objects,
 111                       Symbol_table* symtab, Layout* layout, Dirsearch* dirpath,
 112                       int dirindex, Mapfile* mapfile,
 113                       const Input_argument* input_argument,
 114                       Input_group* input_group, Task_token* next_blocker)
 115 {
 116   // Bump the directory search index.
 117   ++dirindex;
 118
 119   // We don't need to worry about this_blocker, since we already
 120   // reached it.  However, we are removing the blocker on next_blocker
 121   // because the calling task is completing.  So we need to add a new
 122   // blocker.  Since next_blocker may be shared by several tasks, we
 123   // need to increment the count with the workqueue lock held.
 124   workqueue->add_blocker(next_blocker);
 125
 126   workqueue->queue(new Read_symbols(input_objects, symtab, layout, dirpath,
 127                                     dirindex, mapfile, input_argument,
 128                                     input_group, NULL, next_blocker));
 129 }
 130
 131 // Return whether a Read_symbols task is runnable.  We can read an
 132 // ordinary input file immediately.  For an archive specified using
 133 // -l, we have to wait until the search path is complete.
 134
 135 Task_token*
 136 Read_symbols::is_runnable()
 137 {
 138   if (this->input_argument_->is_file()
 139       && this->input_argument_->file().may_need_search()
 140       && this->dirpath_->token()->is_blocked())
 141     return this->dirpath_->token();
 142
 143   return NULL;
 144 }
 145
 146 // Return a Task_locker for a Read_symbols task.  We don't need any
 147 // locks here.
 148
 149 void
 150 Read_symbols::locks(Task_locker*)
 151 {
 152 }
 153
 154 // Run a Read_symbols task.
 155
 156 void
 157 Read_symbols::run(Workqueue* workqueue)
 158 {
 159   // If we didn't queue a new task, then we need to explicitly unblock
 160   // the token.
 161   if (!this->do_read_symbols(workqueue))
 162     workqueue->queue_soon(new Unblock_token(this->this_blocker_,
 163                                             this->next_blocker_));
 164 }
 165
 166 // Open the file and read the symbols.  Return true if a new task was
 167 // queued, false if that could not happen due to some error.
 168
 169 bool
 170 Read_symbols::do_read_symbols(Workqueue* workqueue)
 171 {
 172   if (this->input_argument_->is_group())
 173     {
 174       gold_assert(this->input_group_ == NULL);
 175       this->do_group(workqueue);
 176       return true;
 177     }
 178
 179   Input_file* input_file = new Input_file(&this->input_argument_->file());
 180   if (!input_file->open(*this->dirpath_, this, &this->dirindex_))
 181     return false;
 182
 183   // Read enough of the file to pick up the entire ELF header.
 184
 185   off_t filesize = input_file->file().filesize();
 186
 187   if (filesize == 0)
 188     {
 189       gold_error(_("%s: file is empty"),
 190                  input_file->file().filename().c_str());
 191       return false;
 192     }
 193
 194   const unsigned char* ehdr;
 195   int read_size;
 196   bool is_elf = is_elf_object(input_file, 0, &ehdr, &read_size);
 197
 198   if (read_size >= Archive::sarmag)
 199     {
 200       bool is_thin_archive
 201           = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
 202       if (is_thin_archive
 203           || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
 204         {
 205           // This is an archive.
 206           Archive* arch = new Archive(this->input_argument_->file().name(),
 207                                       input_file, is_thin_archive,
 208                                       this->dirpath_, this);
 209           arch->setup();
 210
 211           // Unlock the archive so it can be used in the next task.
 212           arch->unlock(this);
 213
 214           workqueue->queue_next(new Add_archive_symbols(this->symtab_,
 215                                                         this->layout_,
 216                                                         this->input_objects_,
 217                                                         this->dirpath_,
 218                                                         this->dirindex_,
 219                                                         this->mapfile_,
 220                                                         this->input_argument_,
 221                                                         arch,
 222                                                         this->input_group_,
 223                                                         this->this_blocker_,
 224                                                         this->next_blocker_));
 225           return true;
 226         }
 227     }
 228
 229   if (parameters->options().has_plugins())
 230     {
 231       Pluginobj* obj = parameters->options().plugins()->claim_file(input_file,
 232                                                                    0, filesize);
 233       if (obj != NULL)
 234         {
 235           // The input file was claimed by a plugin, and its symbols
 236           // have been provided by the plugin.
 237
 238           // We are done with the file at this point, so unlock it.
 239           obj->unlock(this);
 240
 241           workqueue->queue_next(new Add_symbols(this->input_objects_,
 242                                                 this->symtab_,
 243                                                 this->layout_,
 244                                                 this->dirpath_,
 245                                                 this->dirindex_,
 246                                                 this->mapfile_,
 247                                                 this->input_argument_,
 248                                                 this->input_group_,
 249                                                 obj,
 250                                                 NULL,
 251                                                 this->this_blocker_,
 252                                                 this->next_blocker_));
 253           return true;
 254         }
 255     }
 256
 257   if (is_elf)
 258     {
 259       // This is an ELF object.
 260
 261       bool unconfigured;
 262       Object* obj = make_elf_object(input_file->filename(),
 263                                     input_file, 0, ehdr, read_size,
 264                                     &unconfigured);
 265       if (obj == NULL)
 266         {
 267           if (unconfigured && input_file->will_search_for())
 268             {
 269               Read_symbols::incompatible_warning(this->input_argument_,
 270                                                  input_file);
 271               input_file->file().release();
 272               input_file->file().unlock(this);
 273               delete input_file;
 274               ++this->dirindex_;
 275               return this->do_read_symbols(workqueue);
 276             }
 277           return false;
 278         }
 279
 280       Read_symbols_data* sd = new Read_symbols_data;
 281       obj->read_symbols(sd);
 282
 283       // Opening the file locked it, so now we need to unlock it.  We
 284       // need to unlock it before queuing the Add_symbols task,
 285       // because the workqueue doesn't know about our lock on the
 286       // file.  If we queue the Add_symbols task first, it will be
 287       // stuck on the end of the file lock, but since the workqueue
 288       // doesn't know about that lock, it will never release the
 289       // Add_symbols task.
 290
 291       input_file->file().unlock(this);
 292
 293       // We use queue_next because everything is cached for this
 294       // task to run right away if possible.
 295
 296       workqueue->queue_next(new Add_symbols(this->input_objects_,
 297                                             this->symtab_, this->layout_,
 298                                             this->dirpath_,
 299                                             this->dirindex_,
 300                                             this->mapfile_,
 301                                             this->input_argument_,
 302                                             this->input_group_,
 303                                             obj,
 304                                             sd,
 305                                             this->this_blocker_,
 306                                             this->next_blocker_));
 307
 308       return true;
 309     }
 310
 311   // Queue up a task to try to parse this file as a script.  We use a
 312   // separate task so that the script will be read in order with other
 313   // objects named on the command line.  Also so that we don't try to
 314   // read multiple scripts simultaneously, which could lead to
 315   // unpredictable changes to the General_options structure.
 316
 317   workqueue->queue_soon(new Read_script(this->symtab_,
 318                                         this->layout_,
 319                                         this->dirpath_,
 320                                         this->dirindex_,
 321                                         this->input_objects_,
 322                                         this->mapfile_,
 323                                         this->input_group_,
 324                                         this->input_argument_,
 325                                         input_file,
 326                                         this->this_blocker_,
 327                                         this->next_blocker_));
 328   return true;
 329 }
 330
 331 // Handle a group.  We need to walk through the arguments over and
 332 // over until we don't see any new undefined symbols.  We do this by
 333 // setting off Read_symbols Tasks as usual, but recording the archive
 334 // entries instead of deleting them.  We also start a Finish_group
 335 // Task which runs after we've read all the symbols.  In that task we
 336 // process the archives in a loop until we are done.
 337
 338 void
 339 Read_symbols::do_group(Workqueue* workqueue)
 340 {
 341   Input_group* input_group = new Input_group();
 342
 343   const Input_file_group* group = this->input_argument_->group();
 344   Task_token* this_blocker = this->this_blocker_;
 345
 346   for (Input_file_group::const_iterator p = group->begin();
 347        p != group->end();
 348        ++p)
 349     {
 350       const Input_argument* arg = &*p;
 351       gold_assert(arg->is_file());
 352
 353       Task_token* next_blocker = new Task_token(true);
 354       next_blocker->add_blocker();
 355       workqueue->queue_soon(new Read_symbols(this->input_objects_,
 356                                              this->symtab_, this->layout_,
 357                                              this->dirpath_, this->dirindex_,
 358                                              this->mapfile_, arg, input_group,
 359                                              this_blocker, next_blocker));
 360       this_blocker = next_blocker;
 361     }
 362
 363   const int saw_undefined = this->symtab_->saw_undefined();
 364   workqueue->queue_soon(new Finish_group(this->input_objects_,
 365                                          this->symtab_,
 366                                          this->layout_,
 367                                          this->mapfile_,
 368                                          input_group,
 369                                          saw_undefined,
 370                                          this_blocker,
 371                                          this->next_blocker_));
 372 }
 373
 374 // Return a debugging name for a Read_symbols task.
 375
 376 std::string
 377 Read_symbols::get_name() const
 378 {
 379   if (!this->input_argument_->is_group())
 380     {
 381       std::string ret("Read_symbols ");
 382       if (this->input_argument_->file().is_lib())
 383         ret += "-l";
 384       ret += this->input_argument_->file().name();
 385       return ret;
 386     }
 387
 388   std::string ret("Read_symbols group (");
 389   bool add_space = false;
 390   const Input_file_group* group = this->input_argument_->group();
 391   for (Input_file_group::const_iterator p = group->begin();
 392        p != group->end();
 393        ++p)
 394     {
 395       if (add_space)
 396         ret += ' ';
 397       ret += p->file().name();
 398       add_space = true;
 399     }
 400   return ret + ')';
 401 }
 402
 403 // Class Add_symbols.
 404
 405 Add_symbols::~Add_symbols()
 406 {
 407   if (this->this_blocker_ != NULL)
 408     delete this->this_blocker_;
 409   // next_blocker_ is deleted by the task associated with the next
 410   // input file.
 411 }
 412
 413 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 414 // lock the file.
 415
 416 Task_token*
 417 Add_symbols::is_runnable()
 418 {
 419   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 420     return this->this_blocker_;
 421   if (this->object_->is_locked())
 422     return this->object_->token();
 423   return NULL;
 424 }
 425
 426 void
 427 Add_symbols::locks(Task_locker* tl)
 428 {
 429   tl->add(this, this->next_blocker_);
 430   tl->add(this, this->object_->token());
 431 }
 432
 433 // Add the symbols in the object to the symbol table.
 434
 435 void
 436 Add_symbols::run(Workqueue* workqueue)
 437 {
 438   Pluginobj* pluginobj = this->object_->pluginobj();
 439   if (pluginobj != NULL)
 440     {
 441       this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);
 442       return;
 443     }
 444
 445   // If this file has an incompatible format, try for another file
 446   // with the same name.
 447   if (this->object_->searched_for()
 448       && !parameters->is_compatible_target(this->object_->target()))
 449     {
 450       Read_symbols::incompatible_warning(this->input_argument_,
 451                                          this->object_->input_file());
 452       Read_symbols::requeue(workqueue, this->input_objects_, this->symtab_,
 453                             this->layout_, this->dirpath_, this->dirindex_,
 454                             this->mapfile_, this->input_argument_,
 455                             this->input_group_, this->next_blocker_);
 456       this->object_->release();
 457       delete this->object_;
 458     }
 459   else if (!this->input_objects_->add_object(this->object_))
 460     {
 461       this->object_->release();
 462       delete this->object_;
 463     }
 464   else
 465     {
 466       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 467       this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);
 468       this->object_->release();
 469     }
 470   delete this->sd_;
 471   this->sd_ = NULL;
 472 }
 473
 474 // Class Finish_group.
 475
 476 Finish_group::~Finish_group()
 477 {
 478   if (this->this_blocker_ != NULL)
 479     delete this->this_blocker_;
 480   // next_blocker_ is deleted by the task associated with the next
 481   // input file following the group.
 482 }
 483
 484 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 485
 486 Task_token*
 487 Finish_group::is_runnable()
 488 {
 489   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 490     return this->this_blocker_;
 491   return NULL;
 492 }
 493
 494 void
 495 Finish_group::locks(Task_locker* tl)
 496 {
 497   tl->add(this, this->next_blocker_);
 498 }
 499
 500 // Loop over the archives until there are no new undefined symbols.
 501
 502 void
 503 Finish_group::run(Workqueue*)
 504 {
 505   int saw_undefined = this->saw_undefined_;
 506   while (saw_undefined != this->symtab_->saw_undefined())
 507     {
 508       saw_undefined = this->symtab_->saw_undefined();
 509
 510       for (Input_group::const_iterator p = this->input_group_->begin();
 511            p != this->input_group_->end();
 512            ++p)
 513         {
 514           Task_lock_obj<Archive> tl(this, *p);
 515
 516           (*p)->add_symbols(this->symtab_, this->layout_,
 517                             this->input_objects_, this->mapfile_);
 518         }
 519     }
 520
 521   // Delete all the archives now that we no longer need them.
 522   for (Input_group::const_iterator p = this->input_group_->begin();
 523        p != this->input_group_->end();
 524        ++p)
 525     delete *p;
 526   delete this->input_group_;
 527 }
 528
 529 // Class Read_script
 530
 531 Read_script::~Read_script()
 532 {
 533   if (this->this_blocker_ != NULL)
 534     delete this->this_blocker_;
 535   // next_blocker_ is deleted by the task associated with the next
 536   // input file.
 537 }
 538
 539 // We are blocked by this_blocker_.
 540
 541 Task_token*
 542 Read_script::is_runnable()
 543 {
 544   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 545     return this->this_blocker_;
 546   return NULL;
 547 }
 548
 549 // We don't unlock next_blocker_ here.  If the script names any input
 550 // files, then the last file will be responsible for unlocking it.
 551
 552 void
 553 Read_script::locks(Task_locker*)
 554 {
 555 }
 556
 557 // Read the script, if it is a script.
 558
 559 void
 560 Read_script::run(Workqueue* workqueue)
 561 {
 562   bool used_next_blocker;
 563   if (!read_input_script(workqueue, this->symtab_, this->layout_,
 564                          this->dirpath_, this->dirindex_, this->input_objects_,
 565                          this->mapfile_, this->input_group_,
 566                          this->input_argument_, this->input_file_,
 567                          this->next_blocker_, &used_next_blocker))
 568     {
 569       // Here we have to handle any other input file types we need.
 570       gold_error(_("%s: not an object or archive"),
 571                  this->input_file_->file().filename().c_str());
 572     }
 573
 574   if (!used_next_blocker)
 575     {
 576       // Queue up a task to unlock next_blocker.  We can't just unlock
 577       // it here, as we don't hold the workqueue lock.
 578       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
 579     }
 580 }
 581
 582 // Return a debugging name for a Read_script task.
 583
 584 std::string
 585 Read_script::get_name() const
 586 {
 587   std::string ret("Read_script ");
 588   if (this->input_argument_->file().is_lib())
 589     ret += "-l";
 590   ret += this->input_argument_->file().name();
 591   return ret;
 592 }
 593
 594 } // End namespace gold.