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 #include "layout.h"
  37 #include "incremental.h"
  38
  39 namespace gold
  40 {
  41
  42 // If we fail to open the object, then we won't create an Add_symbols
  43 // task.  However, we still need to unblock the token, or else the
  44 // link won't proceed to generate more error messages.  We can only
  45 // unblock tokens when the workqueue lock is held, so we need a dummy
  46 // task to do that.  The dummy task has to maintain the right sequence
  47 // of blocks, so we need both this_blocker and next_blocker.
  48
  49 class Unblock_token : public Task
  50 {
  51  public:
  52   Unblock_token(Task_token* this_blocker, Task_token* next_blocker)
  53     : this_blocker_(this_blocker), next_blocker_(next_blocker)
  54   { }
  55
  56   ~Unblock_token()
  57   {
  58     if (this->this_blocker_ != NULL)
  59       delete this->this_blocker_;
  60   }
  61
  62   Task_token*
  63   is_runnable()
  64   {
  65     if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
  66       return this->this_blocker_;
  67     return NULL;
  68   }
  69
  70   void
  71   locks(Task_locker* tl)
  72   { tl->add(this, this->next_blocker_); }
  73
  74   void
  75   run(Workqueue*)
  76   { }
  77
  78   std::string
  79   get_name() const
  80   { return "Unblock_token"; }
  81
  82  private:
  83   Task_token* this_blocker_;
  84   Task_token* next_blocker_;
  85 };
  86
  87 // Class read_symbols.
  88
  89 Read_symbols::~Read_symbols()
  90 {
  91   // The this_blocker_ and next_blocker_ pointers are passed on to the
  92   // Add_symbols task.
  93 }
  94
  95 // If appropriate, issue a warning about skipping an incompatible
  96 // file.
  97
  98 void
  99 Read_symbols::incompatible_warning(const Input_argument* input_argument,
 100                                    const Input_file* input_file)
 101 {
 102   if (parameters->options().warn_search_mismatch())
 103     gold_warning("skipping incompatible %s while searching for %s",
 104                  input_file->filename().c_str(),
 105                  input_argument->file().name());
 106 }
 107
 108 // Requeue a Read_symbols task to search for the next object with the
 109 // same name.
 110
 111 void
 112 Read_symbols::requeue(Workqueue* workqueue, Input_objects* input_objects,
 113                       Symbol_table* symtab, Layout* layout, Dirsearch* dirpath,
 114                       int dirindex, Mapfile* mapfile,
 115                       const Input_argument* input_argument,
 116                       Input_group* input_group, Task_token* next_blocker)
 117 {
 118   // Bump the directory search index.
 119   ++dirindex;
 120
 121   // We don't need to worry about this_blocker, since we already
 122   // reached it.  However, we are removing the blocker on next_blocker
 123   // because the calling task is completing.  So we need to add a new
 124   // blocker.  Since next_blocker may be shared by several tasks, we
 125   // need to increment the count with the workqueue lock held.
 126   workqueue->add_blocker(next_blocker);
 127
 128   workqueue->queue(new Read_symbols(input_objects, symtab, layout, dirpath,
 129                                     dirindex, mapfile, input_argument,
 130                                     input_group, NULL, next_blocker));
 131 }
 132
 133 // Return whether a Read_symbols task is runnable.  We can read an
 134 // ordinary input file immediately.  For an archive specified using
 135 // -l, we have to wait until the search path is complete.
 136
 137 Task_token*
 138 Read_symbols::is_runnable()
 139 {
 140   if (this->input_argument_->is_file()
 141       && this->input_argument_->file().may_need_search()
 142       && this->dirpath_->token()->is_blocked())
 143     return this->dirpath_->token();
 144
 145   return NULL;
 146 }
 147
 148 // Return a Task_locker for a Read_symbols task.  We don't need any
 149 // locks here.
 150
 151 void
 152 Read_symbols::locks(Task_locker*)
 153 {
 154 }
 155
 156 // Run a Read_symbols task.
 157
 158 void
 159 Read_symbols::run(Workqueue* workqueue)
 160 {
 161   // If we didn't queue a new task, then we need to explicitly unblock
 162   // the token.
 163   if (!this->do_read_symbols(workqueue))
 164     workqueue->queue_soon(new Unblock_token(this->this_blocker_,
 165                                             this->next_blocker_));
 166 }
 167
 168 // Open the file and read the symbols.  Return true if a new task was
 169 // queued, false if that could not happen due to some error.
 170
 171 bool
 172 Read_symbols::do_read_symbols(Workqueue* workqueue)
 173 {
 174   if (this->input_argument_->is_group())
 175     {
 176       gold_assert(this->input_group_ == NULL);
 177       this->do_group(workqueue);
 178       return true;
 179     }
 180
 181   Input_file* input_file = new Input_file(&this->input_argument_->file());
 182   if (!input_file->open(*this->dirpath_, this, &this->dirindex_))
 183     return false;
 184
 185   // Read enough of the file to pick up the entire ELF header.
 186
 187   off_t filesize = input_file->file().filesize();
 188
 189   if (filesize == 0)
 190     {
 191       gold_error(_("%s: file is empty"),
 192                  input_file->file().filename().c_str());
 193       return false;
 194     }
 195
 196   const unsigned char* ehdr;
 197   int read_size;
 198   bool is_elf = is_elf_object(input_file, 0, &ehdr, &read_size);
 199
 200   if (read_size >= Archive::sarmag)
 201     {
 202       bool is_thin_archive
 203           = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
 204       if (is_thin_archive
 205           || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
 206         {
 207           // This is an archive.
 208           Archive* arch = new Archive(this->input_argument_->file().name(),
 209                                       input_file, is_thin_archive,
 210                                       this->dirpath_, this);
 211           arch->setup();
 212
 213           if (this->layout_->incremental_inputs())
 214             {
 215               const Input_argument* ia = this->input_argument_;
 216               this->layout_->incremental_inputs()->report_archive(ia, arch);
 217             }
 218
 219           // Unlock the archive so it can be used in the next task.
 220           arch->unlock(this);
 221
 222           workqueue->queue_next(new Add_archive_symbols(this->symtab_,
 223                                                         this->layout_,
 224                                                         this->input_objects_,
 225                                                         this->dirpath_,
 226                                                         this->dirindex_,
 227                                                         this->mapfile_,
 228                                                         this->input_argument_,
 229                                                         arch,
 230                                                         this->input_group_,
 231                                                         this->this_blocker_,
 232                                                         this->next_blocker_));
 233           return true;
 234         }
 235     }
 236
 237   if (parameters->options().has_plugins())
 238     {
 239       Pluginobj* obj = parameters->options().plugins()->claim_file(input_file,
 240                                                                    0, filesize);
 241       if (obj != NULL)
 242         {
 243           // The input file was claimed by a plugin, and its symbols
 244           // have been provided by the plugin.
 245
 246           // We are done with the file at this point, so unlock it.
 247           obj->unlock(this);
 248
 249           workqueue->queue_next(new Add_symbols(this->input_objects_,
 250                                                 this->symtab_,
 251                                                 this->layout_,
 252                                                 this->dirpath_,
 253                                                 this->dirindex_,
 254                                                 this->mapfile_,
 255                                                 this->input_argument_,
 256                                                 this->input_group_,
 257                                                 obj,
 258                                                 NULL,
 259                                                 this->this_blocker_,
 260                                                 this->next_blocker_));
 261           return true;
 262         }
 263     }
 264
 265   if (is_elf)
 266     {
 267       // This is an ELF object.
 268
 269       bool unconfigured;
 270       Object* obj = make_elf_object(input_file->filename(),
 271                                     input_file, 0, ehdr, read_size,
 272                                     &unconfigured);
 273       if (obj == NULL)
 274         {
 275           if (unconfigured && input_file->will_search_for())
 276             {
 277               Read_symbols::incompatible_warning(this->input_argument_,
 278                                                  input_file);
 279               input_file->file().release();
 280               input_file->file().unlock(this);
 281               delete input_file;
 282               ++this->dirindex_;
 283               return this->do_read_symbols(workqueue);
 284             }
 285           return false;
 286         }
 287
 288       Read_symbols_data* sd = new Read_symbols_data;
 289       obj->read_symbols(sd);
 290
 291       if (this->layout_->incremental_inputs())
 292         {
 293           const Input_argument* ia = this->input_argument_;
 294           this->layout_->incremental_inputs()->report_object(ia, obj);
 295         }
 296
 297       // Opening the file locked it, so now we need to unlock it.  We
 298       // need to unlock it before queuing the Add_symbols task,
 299       // because the workqueue doesn't know about our lock on the
 300       // file.  If we queue the Add_symbols task first, it will be
 301       // stuck on the end of the file lock, but since the workqueue
 302       // doesn't know about that lock, it will never release the
 303       // Add_symbols task.
 304
 305       input_file->file().unlock(this);
 306
 307       // We use queue_next because everything is cached for this
 308       // task to run right away if possible.
 309
 310       workqueue->queue_next(new Add_symbols(this->input_objects_,
 311                                             this->symtab_, this->layout_,
 312                                             this->dirpath_,
 313                                             this->dirindex_,
 314                                             this->mapfile_,
 315                                             this->input_argument_,
 316                                             this->input_group_,
 317                                             obj,
 318                                             sd,
 319                                             this->this_blocker_,
 320                                             this->next_blocker_));
 321
 322       return true;
 323     }
 324
 325   // Queue up a task to try to parse this file as a script.  We use a
 326   // separate task so that the script will be read in order with other
 327   // objects named on the command line.  Also so that we don't try to
 328   // read multiple scripts simultaneously, which could lead to
 329   // unpredictable changes to the General_options structure.
 330
 331   workqueue->queue_soon(new Read_script(this->symtab_,
 332                                         this->layout_,
 333                                         this->dirpath_,
 334                                         this->dirindex_,
 335                                         this->input_objects_,
 336                                         this->mapfile_,
 337                                         this->input_group_,
 338                                         this->input_argument_,
 339                                         input_file,
 340                                         this->this_blocker_,
 341                                         this->next_blocker_));
 342   return true;
 343 }
 344
 345 // Handle a group.  We need to walk through the arguments over and
 346 // over until we don't see any new undefined symbols.  We do this by
 347 // setting off Read_symbols Tasks as usual, but recording the archive
 348 // entries instead of deleting them.  We also start a Finish_group
 349 // Task which runs after we've read all the symbols.  In that task we
 350 // process the archives in a loop until we are done.
 351
 352 void
 353 Read_symbols::do_group(Workqueue* workqueue)
 354 {
 355   Input_group* input_group = new Input_group();
 356
 357   const Input_file_group* group = this->input_argument_->group();
 358   Task_token* this_blocker = this->this_blocker_;
 359
 360   for (Input_file_group::const_iterator p = group->begin();
 361        p != group->end();
 362        ++p)
 363     {
 364       const Input_argument* arg = &*p;
 365       gold_assert(arg->is_file());
 366
 367       Task_token* next_blocker = new Task_token(true);
 368       next_blocker->add_blocker();
 369       workqueue->queue_soon(new Read_symbols(this->input_objects_,
 370                                              this->symtab_, this->layout_,
 371                                              this->dirpath_, this->dirindex_,
 372                                              this->mapfile_, arg, input_group,
 373                                              this_blocker, next_blocker));
 374       this_blocker = next_blocker;
 375     }
 376
 377   const int saw_undefined = this->symtab_->saw_undefined();
 378   workqueue->queue_soon(new Finish_group(this->input_objects_,
 379                                          this->symtab_,
 380                                          this->layout_,
 381                                          this->mapfile_,
 382                                          input_group,
 383                                          saw_undefined,
 384                                          this_blocker,
 385                                          this->next_blocker_));
 386 }
 387
 388 // Return a debugging name for a Read_symbols task.
 389
 390 std::string
 391 Read_symbols::get_name() const
 392 {
 393   if (!this->input_argument_->is_group())
 394     {
 395       std::string ret("Read_symbols ");
 396       if (this->input_argument_->file().is_lib())
 397         ret += "-l";
 398       ret += this->input_argument_->file().name();
 399       return ret;
 400     }
 401
 402   std::string ret("Read_symbols group (");
 403   bool add_space = false;
 404   const Input_file_group* group = this->input_argument_->group();
 405   for (Input_file_group::const_iterator p = group->begin();
 406        p != group->end();
 407        ++p)
 408     {
 409       if (add_space)
 410         ret += ' ';
 411       ret += p->file().name();
 412       add_space = true;
 413     }
 414   return ret + ')';
 415 }
 416
 417 // Class Add_symbols.
 418
 419 Add_symbols::~Add_symbols()
 420 {
 421   if (this->this_blocker_ != NULL)
 422     delete this->this_blocker_;
 423   // next_blocker_ is deleted by the task associated with the next
 424   // input file.
 425 }
 426
 427 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 428 // lock the file.
 429
 430 Task_token*
 431 Add_symbols::is_runnable()
 432 {
 433   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 434     return this->this_blocker_;
 435   if (this->object_->is_locked())
 436     return this->object_->token();
 437   return NULL;
 438 }
 439
 440 void
 441 Add_symbols::locks(Task_locker* tl)
 442 {
 443   tl->add(this, this->next_blocker_);
 444   tl->add(this, this->object_->token());
 445 }
 446
 447 // Add the symbols in the object to the symbol table.
 448
 449 void
 450 Add_symbols::run(Workqueue* workqueue)
 451 {
 452   Pluginobj* pluginobj = this->object_->pluginobj();
 453   if (pluginobj != NULL)
 454     {
 455       this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);
 456       return;
 457     }
 458
 459   // If this file has an incompatible format, try for another file
 460   // with the same name.
 461   if (this->object_->searched_for()
 462       && !parameters->is_compatible_target(this->object_->target()))
 463     {
 464       Read_symbols::incompatible_warning(this->input_argument_,
 465                                          this->object_->input_file());
 466       Read_symbols::requeue(workqueue, this->input_objects_, this->symtab_,
 467                             this->layout_, this->dirpath_, this->dirindex_,
 468                             this->mapfile_, this->input_argument_,
 469                             this->input_group_, this->next_blocker_);
 470       this->object_->release();
 471       delete this->object_;
 472     }
 473   else if (!this->input_objects_->add_object(this->object_))
 474     {
 475       this->object_->release();
 476       delete this->object_;
 477     }
 478   else
 479     {
 480       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 481       this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);
 482       this->object_->release();
 483     }
 484   delete this->sd_;
 485   this->sd_ = NULL;
 486 }
 487
 488 // Class Finish_group.
 489
 490 Finish_group::~Finish_group()
 491 {
 492   if (this->this_blocker_ != NULL)
 493     delete this->this_blocker_;
 494   // next_blocker_ is deleted by the task associated with the next
 495   // input file following the group.
 496 }
 497
 498 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 499
 500 Task_token*
 501 Finish_group::is_runnable()
 502 {
 503   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 504     return this->this_blocker_;
 505   return NULL;
 506 }
 507
 508 void
 509 Finish_group::locks(Task_locker* tl)
 510 {
 511   tl->add(this, this->next_blocker_);
 512 }
 513
 514 // Loop over the archives until there are no new undefined symbols.
 515
 516 void
 517 Finish_group::run(Workqueue*)
 518 {
 519   int saw_undefined = this->saw_undefined_;
 520   while (saw_undefined != this->symtab_->saw_undefined())
 521     {
 522       saw_undefined = this->symtab_->saw_undefined();
 523
 524       for (Input_group::const_iterator p = this->input_group_->begin();
 525            p != this->input_group_->end();
 526            ++p)
 527         {
 528           Task_lock_obj<Archive> tl(this, *p);
 529
 530           (*p)->add_symbols(this->symtab_, this->layout_,
 531                             this->input_objects_, this->mapfile_);
 532         }
 533     }
 534
 535   // Delete all the archives now that we no longer need them.
 536   for (Input_group::const_iterator p = this->input_group_->begin();
 537        p != this->input_group_->end();
 538        ++p)
 539     delete *p;
 540   delete this->input_group_;
 541 }
 542
 543 // Class Read_script
 544
 545 Read_script::~Read_script()
 546 {
 547   if (this->this_blocker_ != NULL)
 548     delete this->this_blocker_;
 549   // next_blocker_ is deleted by the task associated with the next
 550   // input file.
 551 }
 552
 553 // We are blocked by this_blocker_.
 554
 555 Task_token*
 556 Read_script::is_runnable()
 557 {
 558   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 559     return this->this_blocker_;
 560   return NULL;
 561 }
 562
 563 // We don't unlock next_blocker_ here.  If the script names any input
 564 // files, then the last file will be responsible for unlocking it.
 565
 566 void
 567 Read_script::locks(Task_locker*)
 568 {
 569 }
 570
 571 // Read the script, if it is a script.
 572
 573 void
 574 Read_script::run(Workqueue* workqueue)
 575 {
 576   bool used_next_blocker;
 577   if (!read_input_script(workqueue, this->symtab_, this->layout_,
 578                          this->dirpath_, this->dirindex_, this->input_objects_,
 579                          this->mapfile_, this->input_group_,
 580                          this->input_argument_, this->input_file_,
 581                          this->next_blocker_, &used_next_blocker))
 582     {
 583       // Here we have to handle any other input file types we need.
 584       gold_error(_("%s: not an object or archive"),
 585                  this->input_file_->file().filename().c_str());
 586     }
 587
 588   if (!used_next_blocker)
 589     {
 590       // Queue up a task to unlock next_blocker.  We can't just unlock
 591       // it here, as we don't hold the workqueue lock.
 592       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
 593     }
 594 }
 595
 596 // Return a debugging name for a Read_script task.
 597
 598 std::string
 599 Read_script::get_name() const
 600 {
 601   std::string ret("Read_script ");
 602   if (this->input_argument_->file().is_lib())
 603     ret += "-l";
 604   ret += this->input_argument_->file().name();
 605   return ret;
 606 }
 607
 608 } // End namespace gold.