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  private:
  76   Task_token* this_blocker_;
  77   Task_token* next_blocker_;
  78 };
  79
  80 // Class read_symbols.
  81
  82 Read_symbols::~Read_symbols()
  83 {
  84   // The this_blocker_ and next_blocker_ pointers are passed on to the
  85   // Add_symbols task.
  86 }
  87
  88 // Return whether a Read_symbols task is runnable.  We can read an
  89 // ordinary input file immediately.  For an archive specified using
  90 // -l, we have to wait until the search path is complete.
  91
  92 Task::Is_runnable_type
  93 Read_symbols::is_runnable(Workqueue*)
  94 {
  95   if (this->input_argument_->is_file()
  96       && this->input_argument_->file().may_need_search()
  97       && this->dirpath_.token().is_blocked())
  98     return IS_BLOCKED;
  99
 100   return IS_RUNNABLE;
 101 }
 102
 103 // Return a Task_locker for a Read_symbols task.  We don't need any
 104 // locks here.
 105
 106 Task_locker*
 107 Read_symbols::locks(Workqueue*)
 108 {
 109   return NULL;
 110 }
 111
 112 // Run a Read_symbols task.
 113
 114 void
 115 Read_symbols::run(Workqueue* workqueue)
 116 {
 117   // If we didn't queue a new task, then we need to explicitly unblock
 118   // the token.
 119   if (!this->do_read_symbols(workqueue))
 120     workqueue->queue_front(new Unblock_token(this->this_blocker_,
 121                                              this->next_blocker_));
 122 }
 123
 124 // Open the file and read the symbols.  Return true if a new task was
 125 // queued, false if that could not happen due to some error.
 126
 127 bool
 128 Read_symbols::do_read_symbols(Workqueue* workqueue)
 129 {
 130   if (this->input_argument_->is_group())
 131     {
 132       gold_assert(this->input_group_ == NULL);
 133       this->do_group(workqueue);
 134       return true;
 135     }
 136
 137   Input_file* input_file = new Input_file(&this->input_argument_->file());
 138   if (!input_file->open(this->options_, this->dirpath_))
 139     return false;
 140
 141   // Read enough of the file to pick up the entire ELF header.
 142
 143   off_t filesize = input_file->file().filesize();
 144
 145   if (filesize == 0)
 146     {
 147       gold_error(_("%s: file is empty"),
 148                  input_file->file().filename().c_str());
 149       return false;
 150     }
 151
 152   unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
 153
 154   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
 155   if (filesize < read_size)
 156     read_size = filesize;
 157
 158   input_file->file().read(0, read_size, ehdr_buf);
 159
 160   if (read_size >= 4)
 161     {
 162       static unsigned char elfmagic[4] =
 163         {
 164           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
 165           elfcpp::ELFMAG2, elfcpp::ELFMAG3
 166         };
 167       if (memcmp(ehdr_buf, elfmagic, 4) == 0)
 168         {
 169           // This is an ELF object.
 170
 171           Object* obj = make_elf_object(input_file->filename(),
 172                                         input_file, 0, ehdr_buf, read_size);
 173           if (obj == NULL)
 174             return false;
 175
 176           // We don't have a way to record a non-archive in an input
 177           // group.  If this is an ordinary object file, we can't
 178           // include it more than once anyhow.  If this is a dynamic
 179           // object, then including it a second time changes nothing.
 180           if (this->input_group_ != NULL && !obj->is_dynamic())
 181             {
 182               gold_error(_("%s: ordinary object found in input group"),
 183                          input_file->name());
 184               return false;
 185             }
 186
 187           Read_symbols_data* sd = new Read_symbols_data;
 188           obj->read_symbols(sd);
 189           workqueue->queue_front(new Add_symbols(this->input_objects_,
 190                                                  this->symtab_, this->layout_,
 191                                                  obj, sd,
 192                                                  this->this_blocker_,
 193                                                  this->next_blocker_));
 194
 195           // Opening the file locked it, so now we need to unlock it.
 196           input_file->file().unlock();
 197
 198           return true;
 199         }
 200     }
 201
 202   if (read_size >= Archive::sarmag)
 203     {
 204       if (memcmp(ehdr_buf, Archive::armag, Archive::sarmag) == 0)
 205         {
 206           // This is an archive.
 207           Archive* arch = new Archive(this->input_argument_->file().name(),
 208                                       input_file);
 209           arch->setup();
 210           workqueue->queue(new Add_archive_symbols(this->symtab_,
 211                                                    this->layout_,
 212                                                    this->input_objects_,
 213                                                    arch,
 214                                                    this->input_group_,
 215                                                    this->this_blocker_,
 216                                                    this->next_blocker_));
 217           return true;
 218         }
 219     }
 220
 221   // Try to parse this file as a script.
 222   if (read_input_script(workqueue, this->options_, this->symtab_,
 223                         this->layout_, this->dirpath_, this->input_objects_,
 224                         this->input_group_, this->input_argument_, input_file,
 225                         ehdr_buf, read_size, this->this_blocker_,
 226                         this->next_blocker_))
 227     return true;
 228
 229   // Here we have to handle any other input file types we need.
 230   gold_error(_("%s: not an object or archive"),
 231              input_file->file().filename().c_str());
 232
 233   return false;
 234 }
 235
 236 // Handle a group.  We need to walk through the arguments over and
 237 // over until we don't see any new undefined symbols.  We do this by
 238 // setting off Read_symbols Tasks as usual, but recording the archive
 239 // entries instead of deleting them.  We also start a Finish_group
 240 // Task which runs after we've read all the symbols.  In that task we
 241 // process the archives in a loop until we are done.
 242
 243 void
 244 Read_symbols::do_group(Workqueue* workqueue)
 245 {
 246   Input_group* input_group = new Input_group();
 247
 248   const Input_file_group* group = this->input_argument_->group();
 249   Task_token* this_blocker = this->this_blocker_;
 250   for (Input_file_group::const_iterator p = group->begin();
 251        p != group->end();
 252        ++p)
 253     {
 254       const Input_argument* arg = &*p;
 255       gold_assert(arg->is_file());
 256
 257       Task_token* next_blocker = new Task_token();
 258       next_blocker->add_blocker();
 259       workqueue->queue(new Read_symbols(this->options_, this->input_objects_,
 260                                         this->symtab_, this->layout_,
 261                                         this->dirpath_, arg, input_group,
 262                                         this_blocker, next_blocker));
 263       this_blocker = next_blocker;
 264     }
 265
 266   const int saw_undefined = this->symtab_->saw_undefined();
 267   workqueue->queue(new Finish_group(this->input_objects_,
 268                                     this->symtab_,
 269                                     this->layout_,
 270                                     input_group,
 271                                     saw_undefined,
 272                                     this_blocker,
 273                                     this->next_blocker_));
 274 }
 275
 276 // Class Add_symbols.
 277
 278 Add_symbols::~Add_symbols()
 279 {
 280   if (this->this_blocker_ != NULL)
 281     delete this->this_blocker_;
 282   // next_blocker_ is deleted by the task associated with the next
 283   // input file.
 284 }
 285
 286 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 287 // lock the file.
 288
 289 Task::Is_runnable_type
 290 Add_symbols::is_runnable(Workqueue*)
 291 {
 292   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 293     return IS_BLOCKED;
 294   if (this->object_->is_locked())
 295     return IS_LOCKED;
 296   return IS_RUNNABLE;
 297 }
 298
 299 class Add_symbols::Add_symbols_locker : public Task_locker
 300 {
 301  public:
 302   Add_symbols_locker(Task_token& token, Workqueue* workqueue,
 303                      Object* object)
 304     : blocker_(token, workqueue), objlock_(*object)
 305   { }
 306
 307  private:
 308   Task_locker_block blocker_;
 309   Task_locker_obj<Object> objlock_;
 310 };
 311
 312 Task_locker*
 313 Add_symbols::locks(Workqueue* workqueue)
 314 {
 315   return new Add_symbols_locker(*this->next_blocker_, workqueue,
 316                                 this->object_);
 317 }
 318
 319 // Add the symbols in the object to the symbol table.
 320
 321 void
 322 Add_symbols::run(Workqueue*)
 323 {
 324   if (!this->input_objects_->add_object(this->object_))
 325     {
 326       // FIXME: We need to close the descriptor here.
 327       delete this->object_;
 328     }
 329   else
 330     {
 331       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 332       this->object_->add_symbols(this->symtab_, this->sd_);
 333     }
 334   delete this->sd_;
 335   this->sd_ = NULL;
 336 }
 337
 338 // Class Finish_group.
 339
 340 Finish_group::~Finish_group()
 341 {
 342   if (this->this_blocker_ != NULL)
 343     delete this->this_blocker_;
 344   // next_blocker_ is deleted by the task associated with the next
 345   // input file following the group.
 346 }
 347
 348 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 349
 350 Task::Is_runnable_type
 351 Finish_group::is_runnable(Workqueue*)
 352 {
 353   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 354     return IS_BLOCKED;
 355   return IS_RUNNABLE;
 356 }
 357
 358 Task_locker*
 359 Finish_group::locks(Workqueue* workqueue)
 360 {
 361   return new Task_locker_block(*this->next_blocker_, workqueue);
 362 }
 363
 364 // Loop over the archives until there are no new undefined symbols.
 365
 366 void
 367 Finish_group::run(Workqueue*)
 368 {
 369   int saw_undefined = this->saw_undefined_;
 370   while (saw_undefined != this->symtab_->saw_undefined())
 371     {
 372       saw_undefined = this->symtab_->saw_undefined();
 373
 374       for (Input_group::const_iterator p = this->input_group_->begin();
 375            p != this->input_group_->end();
 376            ++p)
 377         {
 378           Task_lock_obj<Archive> tl(**p);
 379
 380           (*p)->add_symbols(this->symtab_, this->layout_,
 381                             this->input_objects_);
 382         }
 383     }
 384
 385   // Delete all the archives now that we no longer need them.
 386   for (Input_group::const_iterator p = this->input_group_->begin();
 387        p != this->input_group_->end();
 388        ++p)
 389     delete *p;
 390   delete this->input_group_;
 391 }
 392
 393 } // End namespace gold.