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