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                                                         arch,
 224                                                         this->input_group_,
 225                                                         this->this_blocker_,
 226                                                         this->next_blocker_));
 227           return true;
 228         }
 229     }
 230
 231   // Queue up a task to try to parse this file as a script.  We use a
 232   // separate task so that the script will be read in order with other
 233   // objects named on the command line.  Also so that we don't try to
 234   // read multiple scripts simultaneously, which could lead to
 235   // unpredictable changes to the General_options structure.
 236
 237   workqueue->queue_soon(new Read_script(this->options_,
 238                                         this->symtab_,
 239                                         this->layout_,
 240                                         this->dirpath_,
 241                                         this->input_objects_,
 242                                         this->input_group_,
 243                                         this->input_argument_,
 244                                         input_file,
 245                                         this->this_blocker_,
 246                                         this->next_blocker_));
 247   return true;
 248 }
 249
 250 // Handle a group.  We need to walk through the arguments over and
 251 // over until we don't see any new undefined symbols.  We do this by
 252 // setting off Read_symbols Tasks as usual, but recording the archive
 253 // entries instead of deleting them.  We also start a Finish_group
 254 // Task which runs after we've read all the symbols.  In that task we
 255 // process the archives in a loop until we are done.
 256
 257 void
 258 Read_symbols::do_group(Workqueue* workqueue)
 259 {
 260   Input_group* input_group = new Input_group();
 261
 262   const Input_file_group* group = this->input_argument_->group();
 263   Task_token* this_blocker = this->this_blocker_;
 264
 265   for (Input_file_group::const_iterator p = group->begin();
 266        p != group->end();
 267        ++p)
 268     {
 269       const Input_argument* arg = &*p;
 270       gold_assert(arg->is_file());
 271
 272       Task_token* next_blocker = new Task_token(true);
 273       next_blocker->add_blocker();
 274       workqueue->queue_soon(new Read_symbols(this->options_,
 275                                              this->input_objects_,
 276                                              this->symtab_, this->layout_,
 277                                              this->dirpath_, arg, input_group,
 278                                              this_blocker, next_blocker));
 279       this_blocker = next_blocker;
 280     }
 281
 282   const int saw_undefined = this->symtab_->saw_undefined();
 283   workqueue->queue_soon(new Finish_group(this->input_objects_,
 284                                          this->symtab_,
 285                                          this->layout_,
 286                                          input_group,
 287                                          saw_undefined,
 288                                          this_blocker,
 289                                          this->next_blocker_));
 290 }
 291
 292 // Return a debugging name for a Read_symbols task.
 293
 294 std::string
 295 Read_symbols::get_name() const
 296 {
 297   if (!this->input_argument_->is_group())
 298     {
 299       std::string ret("Read_symbols ");
 300       if (this->input_argument_->file().is_lib())
 301         ret += "-l";
 302       ret += this->input_argument_->file().name();
 303       return ret;
 304     }
 305
 306   std::string ret("Read_symbols group (");
 307   bool add_space = false;
 308   const Input_file_group* group = this->input_argument_->group();
 309   for (Input_file_group::const_iterator p = group->begin();
 310        p != group->end();
 311        ++p)
 312     {
 313       if (add_space)
 314         ret += ' ';
 315       ret += p->file().name();
 316       add_space = true;
 317     }
 318   return ret + ')';
 319 }
 320
 321 // Class Add_symbols.
 322
 323 Add_symbols::~Add_symbols()
 324 {
 325   if (this->this_blocker_ != NULL)
 326     delete this->this_blocker_;
 327   // next_blocker_ is deleted by the task associated with the next
 328   // input file.
 329 }
 330
 331 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 332 // lock the file.
 333
 334 Task_token*
 335 Add_symbols::is_runnable()
 336 {
 337   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 338     return this->this_blocker_;
 339   if (this->object_->is_locked())
 340     return this->object_->token();
 341   return NULL;
 342 }
 343
 344 void
 345 Add_symbols::locks(Task_locker* tl)
 346 {
 347   tl->add(this, this->next_blocker_);
 348   tl->add(this, this->object_->token());
 349 }
 350
 351 // Add the symbols in the object to the symbol table.
 352
 353 void
 354 Add_symbols::run(Workqueue*)
 355 {
 356   if (!this->input_objects_->add_object(this->object_))
 357     {
 358       // FIXME: We need to close the descriptor here.
 359       delete this->object_;
 360     }
 361   else
 362     {
 363       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 364       this->object_->add_symbols(this->symtab_, this->sd_);
 365       this->object_->release();
 366     }
 367   delete this->sd_;
 368   this->sd_ = NULL;
 369 }
 370
 371 // Class Finish_group.
 372
 373 Finish_group::~Finish_group()
 374 {
 375   if (this->this_blocker_ != NULL)
 376     delete this->this_blocker_;
 377   // next_blocker_ is deleted by the task associated with the next
 378   // input file following the group.
 379 }
 380
 381 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 382
 383 Task_token*
 384 Finish_group::is_runnable()
 385 {
 386   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 387     return this->this_blocker_;
 388   return NULL;
 389 }
 390
 391 void
 392 Finish_group::locks(Task_locker* tl)
 393 {
 394   tl->add(this, this->next_blocker_);
 395 }
 396
 397 // Loop over the archives until there are no new undefined symbols.
 398
 399 void
 400 Finish_group::run(Workqueue*)
 401 {
 402   int saw_undefined = this->saw_undefined_;
 403   while (saw_undefined != this->symtab_->saw_undefined())
 404     {
 405       saw_undefined = this->symtab_->saw_undefined();
 406
 407       for (Input_group::const_iterator p = this->input_group_->begin();
 408            p != this->input_group_->end();
 409            ++p)
 410         {
 411           Task_lock_obj<Archive> tl(this, *p);
 412
 413           (*p)->add_symbols(this->symtab_, this->layout_,
 414                             this->input_objects_);
 415         }
 416     }
 417
 418   // Delete all the archives now that we no longer need them.
 419   for (Input_group::const_iterator p = this->input_group_->begin();
 420        p != this->input_group_->end();
 421        ++p)
 422     delete *p;
 423   delete this->input_group_;
 424 }
 425
 426 // Class Read_script
 427
 428 Read_script::~Read_script()
 429 {
 430   if (this->this_blocker_ != NULL)
 431     delete this->this_blocker_;
 432   // next_blocker_ is deleted by the task associated with the next
 433   // input file.
 434 }
 435
 436 // We are blocked by this_blocker_.
 437
 438 Task_token*
 439 Read_script::is_runnable()
 440 {
 441   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 442     return this->this_blocker_;
 443   return NULL;
 444 }
 445
 446 // We don't unlock next_blocker_ here.  If the script names any input
 447 // files, then the last file will be responsible for unlocking it.
 448
 449 void
 450 Read_script::locks(Task_locker*)
 451 {
 452 }
 453
 454 // Read the script, if it is a script.
 455
 456 void
 457 Read_script::run(Workqueue* workqueue)
 458 {
 459   bool used_next_blocker;
 460   if (!read_input_script(workqueue, this->options_, this->symtab_,
 461                          this->layout_, this->dirpath_, this->input_objects_,
 462                          this->input_group_, this->input_argument_,
 463                          this->input_file_, this->next_blocker_,
 464                          &used_next_blocker))
 465     {
 466       // Here we have to handle any other input file types we need.
 467       gold_error(_("%s: not an object or archive"),
 468                  this->input_file_->file().filename().c_str());
 469     }
 470
 471   if (!used_next_blocker)
 472     {
 473       // Queue up a task to unlock next_blocker.  We can't just unlock
 474       // it here, as we don't hold the workqueue lock.
 475       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
 476     }
 477 }
 478
 479 // Return a debugging name for a Read_script task.
 480
 481 std::string
 482 Read_script::get_name() const
 483 {
 484   std::string ret("Read_script ");
 485   if (this->input_argument_->file().is_lib())
 486     ret += "-l";
 487   ret += this->input_argument_->file().name();
 488   return ret;
 489 }
 490
 491 } // End namespace gold.