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