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   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 195   if (filesize < read_size)
 196     read_size = filesize;
 197
 198   const unsigned char* ehdr = input_file->file().get_view(0, 0, read_size,
 199                                                           true, false);
 200
 201   if (read_size >= Archive::sarmag)
 202     {
 203       bool is_thin_archive
 204           = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
 205       if (is_thin_archive
 206           || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
 207         {
 208           // This is an archive.
 209           Archive* arch = new Archive(this->input_argument_->file().name(),
 210                                       input_file, is_thin_archive,
 211                                       this->dirpath_, this);
 212           arch->setup();
 213
 214           // Unlock the archive so it can be used in the next task.
 215           arch->unlock(this);
 216
 217           workqueue->queue_next(new Add_archive_symbols(this->symtab_,
 218                                                         this->layout_,
 219                                                         this->input_objects_,
 220                                                         this->dirpath_,
 221                                                         this->dirindex_,
 222                                                         this->mapfile_,
 223                                                         this->input_argument_,
 224                                                         arch,
 225                                                         this->input_group_,
 226                                                         this->this_blocker_,
 227                                                         this->next_blocker_));
 228           return true;
 229         }
 230     }
 231
 232   if (parameters->options().has_plugins())
 233     {
 234       Pluginobj* obj = parameters->options().plugins()->claim_file(input_file,
 235                                                                    0, filesize);
 236       if (obj != NULL)
 237         {
 238           // The input file was claimed by a plugin, and its symbols
 239           // have been provided by the plugin.
 240
 241           // We are done with the file at this point, so unlock it.
 242           obj->unlock(this);
 243
 244           workqueue->queue_next(new Add_symbols(this->input_objects_,
 245                                                 this->symtab_,
 246                                                 this->layout_,
 247                                                 this->dirpath_,
 248                                                 this->dirindex_,
 249                                                 this->mapfile_,
 250                                                 this->input_argument_,
 251                                                 this->input_group_,
 252                                                 obj,
 253                                                 NULL,
 254                                                 this->this_blocker_,
 255                                                 this->next_blocker_));
 256           return true;
 257         }
 258     }
 259
 260   if (read_size >= 4)
 261     {
 262       static unsigned char elfmagic[4] =
 263         {
 264           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 265           elfcpp::ELFMAG2, elfcpp::ELFMAG3
 266         };
 267       if (memcmp(ehdr, elfmagic, 4) == 0)
 268         {
 269           // This is an ELF object.
 270
 271           bool unconfigured;
 272           Object* obj = make_elf_object(input_file->filename(),
 273                                         input_file, 0, ehdr, read_size,
 274                                         &unconfigured);
 275           if (obj == NULL)
 276             {
 277               if (unconfigured && input_file->will_search_for())
 278                 {
 279                   Read_symbols::incompatible_warning(this->input_argument_,
 280                                                      input_file);
 281                   input_file->file().release();
 282                   input_file->file().unlock(this);
 283                   delete input_file;
 284                   ++this->dirindex_;
 285                   return this->do_read_symbols(workqueue);
 286                 }
 287               return false;
 288             }
 289
 290           Read_symbols_data* sd = new Read_symbols_data;
 291           obj->read_symbols(sd);
 292
 293           // Opening the file locked it, so now we need to unlock it.
 294           // We need to unlock it before queuing the Add_symbols task,
 295           // because the workqueue doesn't know about our lock on the
 296           // file.  If we queue the Add_symbols task first, it will be
 297           // stuck on the end of the file lock, but since the
 298           // workqueue doesn't know about that lock, it will never
 299           // release the Add_symbols task.
 300
 301           input_file->file().unlock(this);
 302
 303           // We use queue_next because everything is cached for this
 304           // task to run right away if possible.
 305
 306           workqueue->queue_next(new Add_symbols(this->input_objects_,
 307                                                 this->symtab_, this->layout_,
 308                                                 this->dirpath_,
 309                                                 this->dirindex_,
 310                                                 this->mapfile_,
 311                                                 this->input_argument_,
 312                                                 this->input_group_,
 313                                                 obj,
 314                                                 sd,
 315                                                 this->this_blocker_,
 316                                                 this->next_blocker_));
 317
 318           return true;
 319         }
 320     }
 321
 322   // Queue up a task to try to parse this file as a script.  We use a
 323   // separate task so that the script will be read in order with other
 324   // objects named on the command line.  Also so that we don't try to
 325   // read multiple scripts simultaneously, which could lead to
 326   // unpredictable changes to the General_options structure.
 327
 328   workqueue->queue_soon(new Read_script(this->symtab_,
 329                                         this->layout_,
 330                                         this->dirpath_,
 331                                         this->dirindex_,
 332                                         this->input_objects_,
 333                                         this->mapfile_,
 334                                         this->input_group_,
 335                                         this->input_argument_,
 336                                         input_file,
 337                                         this->this_blocker_,
 338                                         this->next_blocker_));
 339   return true;
 340 }
 341
 342 // Handle a group.  We need to walk through the arguments over and
 343 // over until we don't see any new undefined symbols.  We do this by
 344 // setting off Read_symbols Tasks as usual, but recording the archive
 345 // entries instead of deleting them.  We also start a Finish_group
 346 // Task which runs after we've read all the symbols.  In that task we
 347 // process the archives in a loop until we are done.
 348
 349 void
 350 Read_symbols::do_group(Workqueue* workqueue)
 351 {
 352   Input_group* input_group = new Input_group();
 353
 354   const Input_file_group* group = this->input_argument_->group();
 355   Task_token* this_blocker = this->this_blocker_;
 356
 357   for (Input_file_group::const_iterator p = group->begin();
 358        p != group->end();
 359        ++p)
 360     {
 361       const Input_argument* arg = &*p;
 362       gold_assert(arg->is_file());
 363
 364       Task_token* next_blocker = new Task_token(true);
 365       next_blocker->add_blocker();
 366       workqueue->queue_soon(new Read_symbols(this->input_objects_,
 367                                              this->symtab_, this->layout_,
 368                                              this->dirpath_, this->dirindex_,
 369                                              this->mapfile_, arg, input_group,
 370                                              this_blocker, next_blocker));
 371       this_blocker = next_blocker;
 372     }
 373
 374   const int saw_undefined = this->symtab_->saw_undefined();
 375   workqueue->queue_soon(new Finish_group(this->input_objects_,
 376                                          this->symtab_,
 377                                          this->layout_,
 378                                          this->mapfile_,
 379                                          input_group,
 380                                          saw_undefined,
 381                                          this_blocker,
 382                                          this->next_blocker_));
 383 }
 384
 385 // Return a debugging name for a Read_symbols task.
 386
 387 std::string
 388 Read_symbols::get_name() const
 389 {
 390   if (!this->input_argument_->is_group())
 391     {
 392       std::string ret("Read_symbols ");
 393       if (this->input_argument_->file().is_lib())
 394         ret += "-l";
 395       ret += this->input_argument_->file().name();
 396       return ret;
 397     }
 398
 399   std::string ret("Read_symbols group (");
 400   bool add_space = false;
 401   const Input_file_group* group = this->input_argument_->group();
 402   for (Input_file_group::const_iterator p = group->begin();
 403        p != group->end();
 404        ++p)
 405     {
 406       if (add_space)
 407         ret += ' ';
 408       ret += p->file().name();
 409       add_space = true;
 410     }
 411   return ret + ')';
 412 }
 413
 414 // Class Add_symbols.
 415
 416 Add_symbols::~Add_symbols()
 417 {
 418   if (this->this_blocker_ != NULL)
 419     delete this->this_blocker_;
 420   // next_blocker_ is deleted by the task associated with the next
 421   // input file.
 422 }
 423
 424 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 425 // lock the file.
 426
 427 Task_token*
 428 Add_symbols::is_runnable()
 429 {
 430   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 431     return this->this_blocker_;
 432   if (this->object_->is_locked())
 433     return this->object_->token();
 434   return NULL;
 435 }
 436
 437 void
 438 Add_symbols::locks(Task_locker* tl)
 439 {
 440   tl->add(this, this->next_blocker_);
 441   tl->add(this, this->object_->token());
 442 }
 443
 444 // Add the symbols in the object to the symbol table.
 445
 446 void
 447 Add_symbols::run(Workqueue* workqueue)
 448 {
 449   Pluginobj* pluginobj = this->object_->pluginobj();
 450   if (pluginobj != NULL)
 451     {
 452       this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);
 453       return;
 454     }
 455
 456   // If this file has an incompatible format, try for another file
 457   // with the same name.
 458   if (this->object_->searched_for()
 459       && !parameters->is_compatible_target(this->object_->target()))
 460     {
 461       Read_symbols::incompatible_warning(this->input_argument_,
 462                                          this->object_->input_file());
 463       Read_symbols::requeue(workqueue, this->input_objects_, this->symtab_,
 464                             this->layout_, this->dirpath_, this->dirindex_,
 465                             this->mapfile_, this->input_argument_,
 466                             this->input_group_, this->next_blocker_);
 467       this->object_->release();
 468       delete this->object_;
 469     }
 470   else if (!this->input_objects_->add_object(this->object_))
 471     {
 472       this->object_->release();
 473       delete this->object_;
 474     }
 475   else
 476     {
 477       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 478       this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);
 479       this->object_->release();
 480     }
 481   delete this->sd_;
 482   this->sd_ = NULL;
 483 }
 484
 485 // Class Finish_group.
 486
 487 Finish_group::~Finish_group()
 488 {
 489   if (this->this_blocker_ != NULL)
 490     delete this->this_blocker_;
 491   // next_blocker_ is deleted by the task associated with the next
 492   // input file following the group.
 493 }
 494
 495 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 496
 497 Task_token*
 498 Finish_group::is_runnable()
 499 {
 500   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 501     return this->this_blocker_;
 502   return NULL;
 503 }
 504
 505 void
 506 Finish_group::locks(Task_locker* tl)
 507 {
 508   tl->add(this, this->next_blocker_);
 509 }
 510
 511 // Loop over the archives until there are no new undefined symbols.
 512
 513 void
 514 Finish_group::run(Workqueue*)
 515 {
 516   int saw_undefined = this->saw_undefined_;
 517   while (saw_undefined != this->symtab_->saw_undefined())
 518     {
 519       saw_undefined = this->symtab_->saw_undefined();
 520
 521       for (Input_group::const_iterator p = this->input_group_->begin();
 522            p != this->input_group_->end();
 523            ++p)
 524         {
 525           Task_lock_obj<Archive> tl(this, *p);
 526
 527           (*p)->add_symbols(this->symtab_, this->layout_,
 528                             this->input_objects_, this->mapfile_);
 529         }
 530     }
 531
 532   // Delete all the archives now that we no longer need them.
 533   for (Input_group::const_iterator p = this->input_group_->begin();
 534        p != this->input_group_->end();
 535        ++p)
 536     delete *p;
 537   delete this->input_group_;
 538 }
 539
 540 // Class Read_script
 541
 542 Read_script::~Read_script()
 543 {
 544   if (this->this_blocker_ != NULL)
 545     delete this->this_blocker_;
 546   // next_blocker_ is deleted by the task associated with the next
 547   // input file.
 548 }
 549
 550 // We are blocked by this_blocker_.
 551
 552 Task_token*
 553 Read_script::is_runnable()
 554 {
 555   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 556     return this->this_blocker_;
 557   return NULL;
 558 }
 559
 560 // We don't unlock next_blocker_ here.  If the script names any input
 561 // files, then the last file will be responsible for unlocking it.
 562
 563 void
 564 Read_script::locks(Task_locker*)
 565 {
 566 }
 567
 568 // Read the script, if it is a script.
 569
 570 void
 571 Read_script::run(Workqueue* workqueue)
 572 {
 573   bool used_next_blocker;
 574   if (!read_input_script(workqueue, this->symtab_, this->layout_,
 575                          this->dirpath_, this->dirindex_, this->input_objects_,
 576                          this->mapfile_, this->input_group_,
 577                          this->input_argument_, this->input_file_,
 578                          this->next_blocker_, &used_next_blocker))
 579     {
 580       // Here we have to handle any other input file types we need.
 581       gold_error(_("%s: not an object or archive"),
 582                  this->input_file_->file().filename().c_str());
 583     }
 584
 585   if (!used_next_blocker)
 586     {
 587       // Queue up a task to unlock next_blocker.  We can't just unlock
 588       // it here, as we don't hold the workqueue lock.
 589       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
 590     }
 591 }
 592
 593 // Return a debugging name for a Read_script task.
 594
 595 std::string
 596 Read_script::get_name() const
 597 {
 598   std::string ret("Read_script ");
 599   if (this->input_argument_->file().is_lib())
 600     ret += "-l";
 601   ret += this->input_argument_->file().name();
 602   return ret;
 603 }
 604
 605 } // End namespace gold.