gold/readsyms.cc

   1 // readsyms.cc -- read input file symbols for gold
   2
   3 // Copyright 2006, 2007 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 in the main thread, so we need a dummy task to do
  43 // that.  The dummy task has to maintain the right sequence of blocks,
  44 // 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   Is_runnable_type
  60   is_runnable(Workqueue*)
  61   {
  62     if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
  63       return IS_BLOCKED;
  64     return IS_RUNNABLE;
  65   }
  66
  67   Task_locker*
  68   locks(Workqueue* workqueue)
  69   { return new Task_locker_block(*this->next_blocker_, workqueue); }
  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::Is_runnable_type
  97 Read_symbols::is_runnable(Workqueue*)
  98 {
  99   if (this->input_argument_->is_file()
 100       && this->input_argument_->file().may_need_search()
 101       && this->dirpath_.token().is_blocked())
 102     return IS_BLOCKED;
 103
 104   return IS_RUNNABLE;
 105 }
 106
 107 // Return a Task_locker for a Read_symbols task.  We don't need any
 108 // locks here.
 109
 110 Task_locker*
 111 Read_symbols::locks(Workqueue*)
 112 {
 113   return NULL;
 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_front(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_))
 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   unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
 157
 158   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 159   if (filesize < read_size)
 160     read_size = filesize;
 161
 162   input_file->file().read(0, read_size, ehdr_buf);
 163
 164   if (read_size >= 4)
 165     {
 166       static unsigned char elfmagic[4] =
 167         {
 168           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 169           elfcpp::ELFMAG2, elfcpp::ELFMAG3
 170         };
 171       if (memcmp(ehdr_buf, elfmagic, 4) == 0)
 172         {
 173           // This is an ELF object.
 174
 175           Object* obj = make_elf_object(input_file->filename(),
 176                                         input_file, 0, ehdr_buf, read_size);
 177           if (obj == NULL)
 178             return false;
 179
 180           // We don't have a way to record a non-archive in an input
 181           // group.  If this is an ordinary object file, we can't
 182           // include it more than once anyhow.  If this is a dynamic
 183           // object, then including it a second time changes nothing.
 184           if (this->input_group_ != NULL && !obj->is_dynamic())
 185             {
 186               gold_error(_("%s: ordinary object found in input group"),
 187                          input_file->name());
 188               return false;
 189             }
 190
 191           Read_symbols_data* sd = new Read_symbols_data;
 192           obj->read_symbols(sd);
 193           workqueue->queue_front(new Add_symbols(this->input_objects_,
 194                                                  this->symtab_, this->layout_,
 195                                                  obj, sd,
 196                                                  this->this_blocker_,
 197                                                  this->next_blocker_));
 198
 199           // Opening the file locked it, so now we need to unlock it.
 200           input_file->file().unlock();
 201
 202           return true;
 203         }
 204     }
 205
 206   if (read_size >= Archive::sarmag)
 207     {
 208       if (memcmp(ehdr_buf, Archive::armag, Archive::sarmag) == 0)
 209         {
 210           // This is an archive.
 211           Archive* arch = new Archive(this->input_argument_->file().name(),
 212                                       input_file);
 213           arch->setup();
 214           workqueue->queue(new Add_archive_symbols(this->symtab_,
 215                                                    this->layout_,
 216                                                    this->input_objects_,
 217                                                    arch,
 218                                                    this->input_group_,
 219                                                    this->this_blocker_,
 220                                                    this->next_blocker_));
 221           return true;
 222         }
 223     }
 224
 225   // Try to parse this file as a script.
 226   if (read_input_script(workqueue, this->options_, this->symtab_,
 227                         this->layout_, this->dirpath_, this->input_objects_,
 228                         this->input_group_, this->input_argument_, input_file,
 229                         ehdr_buf, read_size, this->this_blocker_,
 230                         this->next_blocker_))
 231     return true;
 232
 233   // Here we have to handle any other input file types we need.
 234   gold_error(_("%s: not an object or archive"),
 235              input_file->file().filename().c_str());
 236
 237   return false;
 238 }
 239
 240 // Handle a group.  We need to walk through the arguments over and
 241 // over until we don't see any new undefined symbols.  We do this by
 242 // setting off Read_symbols Tasks as usual, but recording the archive
 243 // entries instead of deleting them.  We also start a Finish_group
 244 // Task which runs after we've read all the symbols.  In that task we
 245 // process the archives in a loop until we are done.
 246
 247 void
 248 Read_symbols::do_group(Workqueue* workqueue)
 249 {
 250   Input_group* input_group = new Input_group();
 251
 252   const Input_file_group* group = this->input_argument_->group();
 253   Task_token* this_blocker = this->this_blocker_;
 254   for (Input_file_group::const_iterator p = group->begin();
 255        p != group->end();
 256        ++p)
 257     {
 258       const Input_argument* arg = &*p;
 259       gold_assert(arg->is_file());
 260
 261       Task_token* next_blocker = new Task_token();
 262       next_blocker->add_blocker();
 263       workqueue->queue(new Read_symbols(this->options_, this->input_objects_,
 264                                         this->symtab_, this->layout_,
 265                                         this->dirpath_, arg, input_group,
 266                                         this_blocker, next_blocker));
 267       this_blocker = next_blocker;
 268     }
 269
 270   const int saw_undefined = this->symtab_->saw_undefined();
 271   workqueue->queue(new Finish_group(this->input_objects_,
 272                                     this->symtab_,
 273                                     this->layout_,
 274                                     input_group,
 275                                     saw_undefined,
 276                                     this_blocker,
 277                                     this->next_blocker_));
 278 }
 279
 280 // Return a debugging name for a Read_symbols task.
 281
 282 std::string
 283 Read_symbols::get_name() const
 284 {
 285   if (!this->input_argument_->is_group())
 286     {
 287       std::string ret("Read_symbols ");
 288       if (this->input_argument_->file().is_lib())
 289         ret += "-l";
 290       ret += this->input_argument_->file().name();
 291       return ret;
 292     }
 293
 294   std::string ret("Read_symbols group (");
 295   bool add_space = false;
 296   const Input_file_group* group = this->input_argument_->group();
 297   for (Input_file_group::const_iterator p = group->begin();
 298        p != group->end();
 299        ++p)
 300     {
 301       if (add_space)
 302         ret += ' ';
 303       ret += p->file().name();
 304       add_space = true;
 305     }
 306   return ret + ')';
 307 }
 308
 309 // Class Add_symbols.
 310
 311 Add_symbols::~Add_symbols()
 312 {
 313   if (this->this_blocker_ != NULL)
 314     delete this->this_blocker_;
 315   // next_blocker_ is deleted by the task associated with the next
 316   // input file.
 317 }
 318
 319 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 320 // lock the file.
 321
 322 Task::Is_runnable_type
 323 Add_symbols::is_runnable(Workqueue*)
 324 {
 325   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 326     return IS_BLOCKED;
 327   if (this->object_->is_locked())
 328     return IS_LOCKED;
 329   return IS_RUNNABLE;
 330 }
 331
 332 class Add_symbols::Add_symbols_locker : public Task_locker
 333 {
 334  public:
 335   Add_symbols_locker(Task_token& token, Workqueue* workqueue,
 336                      Object* object)
 337     : blocker_(token, workqueue), objlock_(*object)
 338   { }
 339
 340  private:
 341   Task_locker_block blocker_;
 342   Task_locker_obj<Object> objlock_;
 343 };
 344
 345 Task_locker*
 346 Add_symbols::locks(Workqueue* workqueue)
 347 {
 348   return new Add_symbols_locker(*this->next_blocker_, workqueue,
 349                                 this->object_);
 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     }
 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::Is_runnable_type
 384 Finish_group::is_runnable(Workqueue*)
 385 {
 386   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 387     return IS_BLOCKED;
 388   return IS_RUNNABLE;
 389 }
 390
 391 Task_locker*
 392 Finish_group::locks(Workqueue* workqueue)
 393 {
 394   return new Task_locker_block(*this->next_blocker_, workqueue);
 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(**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 } // End namespace gold.