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   unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
 156
 157   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 158   if (filesize < read_size)
 159     read_size = filesize;
 160
 161   input_file->file().read(0, read_size, ehdr_buf);
 162
 163   if (read_size >= 4)
 164     {
 165       static unsigned char elfmagic[4] =
 166         {
 167           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 168           elfcpp::ELFMAG2, elfcpp::ELFMAG3
 169         };
 170       if (memcmp(ehdr_buf, elfmagic, 4) == 0)
 171         {
 172           // This is an ELF object.
 173
 174           Object* obj = make_elf_object(input_file->filename(),
 175                                         input_file, 0, ehdr_buf, read_size);
 176           if (obj == NULL)
 177             return false;
 178
 179           Read_symbols_data* sd = new Read_symbols_data;
 180           obj->read_symbols(sd);
 181
 182           // Opening the file locked it, so now we need to unlock it.
 183           // We need to unlock it before queuing the Add_symbols task,
 184           // because the workqueue doesn't know about our lock on the
 185           // file.  If we queue the Add_symbols task first, it will be
 186           // stuck on the end of the file lock, but since the
 187           // workqueue doesn't know about that lock, it will never
 188           // release the Add_symbols task.
 189
 190           input_file->file().unlock(this);
 191
 192           // We use queue_next because everything is cached for this
 193           // task to run right away if possible.
 194
 195           workqueue->queue_next(new Add_symbols(this->input_objects_,
 196                                                 this->symtab_, this->layout_,
 197                                                 obj, sd,
 198                                                 this->this_blocker_,
 199                                                 this->next_blocker_));
 200
 201           return true;
 202         }
 203     }
 204
 205   if (read_size >= Archive::sarmag)
 206     {
 207       bool is_thin_archive
 208           = memcmp(ehdr_buf, Archive::armagt, Archive::sarmag) == 0;
 209       if (is_thin_archive
 210           || memcmp(ehdr_buf, Archive::armag, Archive::sarmag) == 0)
 211         {
 212           // This is an archive.
 213           Archive* arch = new Archive(this->input_argument_->file().name(),
 214                                       input_file, is_thin_archive,
 215                                       this->dirpath_, this);
 216           arch->setup();
 217
 218           // Unlock the archive so it can be used in the next task.
 219           arch->unlock(this);
 220
 221           workqueue->queue_next(new Add_archive_symbols(this->symtab_,
 222                                                         this->layout_,
 223                                                         this->input_objects_,
 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->input_group_,
 244                                         this->input_argument_,
 245                                         input_file,
 246                                         this->this_blocker_,
 247                                         this->next_blocker_));
 248   return true;
 249 }
 250
 251 // Handle a group.  We need to walk through the arguments over and
 252 // over until we don't see any new undefined symbols.  We do this by
 253 // setting off Read_symbols Tasks as usual, but recording the archive
 254 // entries instead of deleting them.  We also start a Finish_group
 255 // Task which runs after we've read all the symbols.  In that task we
 256 // process the archives in a loop until we are done.
 257
 258 void
 259 Read_symbols::do_group(Workqueue* workqueue)
 260 {
 261   Input_group* input_group = new Input_group();
 262
 263   const Input_file_group* group = this->input_argument_->group();
 264   Task_token* this_blocker = this->this_blocker_;
 265
 266   for (Input_file_group::const_iterator p = group->begin();
 267        p != group->end();
 268        ++p)
 269     {
 270       const Input_argument* arg = &*p;
 271       gold_assert(arg->is_file());
 272
 273       Task_token* next_blocker = new Task_token(true);
 274       next_blocker->add_blocker();
 275       workqueue->queue_soon(new Read_symbols(this->options_,
 276                                              this->input_objects_,
 277                                              this->symtab_, this->layout_,
 278                                              this->dirpath_, arg, input_group,
 279                                              this_blocker, next_blocker));
 280       this_blocker = next_blocker;
 281     }
 282
 283   const int saw_undefined = this->symtab_->saw_undefined();
 284   workqueue->queue_soon(new Finish_group(this->input_objects_,
 285                                          this->symtab_,
 286                                          this->layout_,
 287                                          input_group,
 288                                          saw_undefined,
 289                                          this_blocker,
 290                                          this->next_blocker_));
 291 }
 292
 293 // Return a debugging name for a Read_symbols task.
 294
 295 std::string
 296 Read_symbols::get_name() const
 297 {
 298   if (!this->input_argument_->is_group())
 299     {
 300       std::string ret("Read_symbols ");
 301       if (this->input_argument_->file().is_lib())
 302         ret += "-l";
 303       ret += this->input_argument_->file().name();
 304       return ret;
 305     }
 306
 307   std::string ret("Read_symbols group (");
 308   bool add_space = false;
 309   const Input_file_group* group = this->input_argument_->group();
 310   for (Input_file_group::const_iterator p = group->begin();
 311        p != group->end();
 312        ++p)
 313     {
 314       if (add_space)
 315         ret += ' ';
 316       ret += p->file().name();
 317       add_space = true;
 318     }
 319   return ret + ')';
 320 }
 321
 322 // Class Add_symbols.
 323
 324 Add_symbols::~Add_symbols()
 325 {
 326   if (this->this_blocker_ != NULL)
 327     delete this->this_blocker_;
 328   // next_blocker_ is deleted by the task associated with the next
 329   // input file.
 330 }
 331
 332 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 333 // lock the file.
 334
 335 Task_token*
 336 Add_symbols::is_runnable()
 337 {
 338   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 339     return this->this_blocker_;
 340   if (this->object_->is_locked())
 341     return this->object_->token();
 342   return NULL;
 343 }
 344
 345 void
 346 Add_symbols::locks(Task_locker* tl)
 347 {
 348   tl->add(this, this->next_blocker_);
 349   tl->add(this, this->object_->token());
 350 }
 351
 352 // Add the symbols in the object to the symbol table.
 353
 354 void
 355 Add_symbols::run(Workqueue*)
 356 {
 357   if (!this->input_objects_->add_object(this->object_))
 358     {
 359       // FIXME: We need to close the descriptor here.
 360       delete this->object_;
 361     }
 362   else
 363     {
 364       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 365       this->object_->add_symbols(this->symtab_, this->sd_);
 366       this->object_->release();
 367     }
 368   delete this->sd_;
 369   this->sd_ = NULL;
 370 }
 371
 372 // Class Finish_group.
 373
 374 Finish_group::~Finish_group()
 375 {
 376   if (this->this_blocker_ != NULL)
 377     delete this->this_blocker_;
 378   // next_blocker_ is deleted by the task associated with the next
 379   // input file following the group.
 380 }
 381
 382 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 383
 384 Task_token*
 385 Finish_group::is_runnable()
 386 {
 387   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 388     return this->this_blocker_;
 389   return NULL;
 390 }
 391
 392 void
 393 Finish_group::locks(Task_locker* tl)
 394 {
 395   tl->add(this, this->next_blocker_);
 396 }
 397
 398 // Loop over the archives until there are no new undefined symbols.
 399
 400 void
 401 Finish_group::run(Workqueue*)
 402 {
 403   int saw_undefined = this->saw_undefined_;
 404   while (saw_undefined != this->symtab_->saw_undefined())
 405     {
 406       saw_undefined = this->symtab_->saw_undefined();
 407
 408       for (Input_group::const_iterator p = this->input_group_->begin();
 409            p != this->input_group_->end();
 410            ++p)
 411         {
 412           Task_lock_obj<Archive> tl(this, *p);
 413
 414           (*p)->add_symbols(this->symtab_, this->layout_,
 415                             this->input_objects_);
 416         }
 417     }
 418
 419   // Delete all the archives now that we no longer need them.
 420   for (Input_group::const_iterator p = this->input_group_->begin();
 421        p != this->input_group_->end();
 422        ++p)
 423     delete *p;
 424   delete this->input_group_;
 425 }
 426
 427 // Class Read_script
 428
 429 Read_script::~Read_script()
 430 {
 431   if (this->this_blocker_ != NULL)
 432     delete this->this_blocker_;
 433   // next_blocker_ is deleted by the task associated with the next
 434   // input file.
 435 }
 436
 437 // We are blocked by this_blocker_.
 438
 439 Task_token*
 440 Read_script::is_runnable()
 441 {
 442   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 443     return this->this_blocker_;
 444   return NULL;
 445 }
 446
 447 // We don't unlock next_blocker_ here.  If the script names any input
 448 // files, then the last file will be responsible for unlocking it.
 449
 450 void
 451 Read_script::locks(Task_locker*)
 452 {
 453 }
 454
 455 // Read the script, if it is a script.
 456
 457 void
 458 Read_script::run(Workqueue* workqueue)
 459 {
 460   bool used_next_blocker;
 461   if (!read_input_script(workqueue, this->options_, this->symtab_,
 462                          this->layout_, this->dirpath_, this->input_objects_,
 463                          this->input_group_, this->input_argument_,
 464                          this->input_file_, this->next_blocker_,
 465                          &used_next_blocker))
 466     {
 467       // Here we have to handle any other input file types we need.
 468       gold_error(_("%s: not an object or archive"),
 469                  this->input_file_->file().filename().c_str());
 470     }
 471
 472   if (!used_next_blocker)
 473     {
 474       // Queue up a task to unlock next_blocker.  We can't just unlock
 475       // it here, as we don't hold the workqueue lock.
 476       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
 477     }
 478 }
 479
 480 // Return a debugging name for a Read_script task.
 481
 482 std::string
 483 Read_script::get_name() const
 484 {
 485   std::string ret("Read_script ");
 486   if (this->input_argument_->file().is_lib())
 487     ret += "-l";
 488   ret += this->input_argument_->file().name();
 489   return ret;
 490 }
 491
 492 } // End namespace gold.