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 // Class read_symbols.
  40
  41 Read_symbols::~Read_symbols()
  42 {
  43   // The this_blocker_ and next_blocker_ pointers are passed on to the
  44   // Add_symbols task.
  45 }
  46
  47 // Return whether a Read_symbols task is runnable.  We can read an
  48 // ordinary input file immediately.  For an archive specified using
  49 // -l, we have to wait until the search path is complete.
  50
  51 Task::Is_runnable_type
  52 Read_symbols::is_runnable(Workqueue*)
  53 {
  54   if (this->input_argument_->is_file()
  55       && this->input_argument_->file().is_lib()
  56       && this->dirpath_.token().is_blocked())
  57     return IS_BLOCKED;
  58
  59   return IS_RUNNABLE;
  60 }
  61
  62 // Return a Task_locker for a Read_symbols task.  We don't need any
  63 // locks here.
  64
  65 Task_locker*
  66 Read_symbols::locks(Workqueue*)
  67 {
  68   return NULL;
  69 }
  70
  71 // Run a Read_symbols task.  This is where we actually read the
  72 // symbols and relocations.
  73
  74 void
  75 Read_symbols::run(Workqueue* workqueue)
  76 {
  77   if (this->input_argument_->is_group())
  78     {
  79       gold_assert(this->input_group_ == NULL);
  80       this->do_group(workqueue);
  81       return;
  82     }
  83
  84   Input_file* input_file = new Input_file(&this->input_argument_->file());
  85   input_file->open(this->options_, this->dirpath_);
  86
  87   // Read enough of the file to pick up the entire ELF header.
  88
  89   const int ehdr_size = elfcpp::Elf_sizes<64>::ehdr_size;
  90   unsigned char ehdr_buf[ehdr_size];
  91   off_t bytes;
  92   input_file->file().read_up_to(0, ehdr_size, ehdr_buf, &bytes);
  93
  94   if (bytes >= 4)
  95     {
  96       static unsigned char elfmagic[4] =
  97         {
  98           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
  99           elfcpp::ELFMAG2, elfcpp::ELFMAG3
 100         };
 101       if (memcmp(ehdr_buf, elfmagic, 4) == 0)
 102         {
 103           // This is an ELF object.
 104
 105           Object* obj = make_elf_object(input_file->filename(),
 106                                         input_file, 0, ehdr_buf, bytes);
 107
 108           // We don't have a way to record a non-archive in an input
 109           // group.  If this is an ordinary object file, we can't
 110           // include it more than once anyhow.  If this is a dynamic
 111           // object, then including it a second time changes nothing.
 112           if (this->input_group_ != NULL && !obj->is_dynamic())
 113             {
 114               fprintf(stderr,
 115                       _("%s: %s: ordinary object found in input group\n"),
 116                       program_name, input_file->name());
 117               gold_exit(false);
 118             }
 119
 120           Read_symbols_data* sd = new Read_symbols_data;
 121           obj->read_symbols(sd);
 122           workqueue->queue_front(new Add_symbols(this->input_objects_,
 123                                                  this->symtab_, this->layout_,
 124                                                  obj, sd,
 125                                                  this->this_blocker_,
 126                                                  this->next_blocker_));
 127
 128           // Opening the file locked it, so now we need to unlock it.
 129           input_file->file().unlock();
 130
 131           return;
 132         }
 133     }
 134
 135   if (bytes >= Archive::sarmag)
 136     {
 137       if (memcmp(ehdr_buf, Archive::armag, Archive::sarmag) == 0)
 138         {
 139           // This is an archive.
 140           Archive* arch = new Archive(this->input_argument_->file().name(),
 141                                       input_file);
 142           arch->setup();
 143           workqueue->queue(new Add_archive_symbols(this->symtab_,
 144                                                    this->layout_,
 145                                                    this->input_objects_,
 146                                                    arch,
 147                                                    this->input_group_,
 148                                                    this->this_blocker_,
 149                                                    this->next_blocker_));
 150           return;
 151         }
 152     }
 153
 154   if (bytes == 0)
 155     {
 156       fprintf(stderr, _("%s: %s: file is empty\n"),
 157               program_name, input_file->file().filename().c_str());
 158       gold_exit(false);
 159     }
 160
 161   // Try to parse this file as a script.
 162   if (read_input_script(workqueue, this->options_, this->symtab_,
 163                         this->layout_, this->dirpath_, this->input_objects_,
 164                         this->input_group_, this->input_argument_, input_file,
 165                         ehdr_buf, bytes, this->this_blocker_,
 166                         this->next_blocker_))
 167     return;
 168
 169   // Here we have to handle any other input file types we need.
 170   fprintf(stderr, _("%s: %s: not an object or archive\n"),
 171           program_name, input_file->file().filename().c_str());
 172   gold_exit(false);
 173 }
 174
 175 // Handle a group.  We need to walk through the arguments over and
 176 // over until we don't see any new undefined symbols.  We do this by
 177 // setting off Read_symbols Tasks as usual, but recording the archive
 178 // entries instead of deleting them.  We also start a Finish_group
 179 // Task which runs after we've read all the symbols.  In that task we
 180 // process the archives in a loop until we are done.
 181
 182 void
 183 Read_symbols::do_group(Workqueue* workqueue)
 184 {
 185   Input_group* input_group = new Input_group();
 186
 187   const Input_file_group* group = this->input_argument_->group();
 188   Task_token* this_blocker = this->this_blocker_;
 189   for (Input_file_group::const_iterator p = group->begin();
 190        p != group->end();
 191        ++p)
 192     {
 193       const Input_argument* arg = &*p;
 194       gold_assert(arg->is_file());
 195
 196       Task_token* next_blocker = new Task_token();
 197       next_blocker->add_blocker();
 198       workqueue->queue(new Read_symbols(this->options_, this->input_objects_,
 199                                         this->symtab_, this->layout_,
 200                                         this->dirpath_, arg, input_group,
 201                                         this_blocker, next_blocker));
 202       this_blocker = next_blocker;
 203     }
 204
 205   const int saw_undefined = this->symtab_->saw_undefined();
 206   workqueue->queue(new Finish_group(this->input_objects_,
 207                                     this->symtab_,
 208                                     this->layout_,
 209                                     input_group,
 210                                     saw_undefined,
 211                                     this_blocker,
 212                                     this->next_blocker_));
 213 }
 214
 215 // Class Add_symbols.
 216
 217 Add_symbols::~Add_symbols()
 218 {
 219   if (this->this_blocker_ != NULL)
 220     delete this->this_blocker_;
 221   // next_blocker_ is deleted by the task associated with the next
 222   // input file.
 223 }
 224
 225 // We are blocked by this_blocker_.  We block next_blocker_.  We also
 226 // lock the file.
 227
 228 Task::Is_runnable_type
 229 Add_symbols::is_runnable(Workqueue*)
 230 {
 231   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 232     return IS_BLOCKED;
 233   if (this->object_->is_locked())
 234     return IS_LOCKED;
 235   return IS_RUNNABLE;
 236 }
 237
 238 class Add_symbols::Add_symbols_locker : public Task_locker
 239 {
 240  public:
 241   Add_symbols_locker(Task_token& token, Workqueue* workqueue,
 242                      Object* object)
 243     : blocker_(token, workqueue), objlock_(*object)
 244   { }
 245
 246  private:
 247   Task_locker_block blocker_;
 248   Task_locker_obj<Object> objlock_;
 249 };
 250
 251 Task_locker*
 252 Add_symbols::locks(Workqueue* workqueue)
 253 {
 254   return new Add_symbols_locker(*this->next_blocker_, workqueue,
 255                                 this->object_);
 256 }
 257
 258 // Add the symbols in the object to the symbol table.
 259
 260 void
 261 Add_symbols::run(Workqueue*)
 262 {
 263   if (!this->input_objects_->add_object(this->object_))
 264     {
 265       // FIXME: We need to close the descriptor here.
 266       delete this->object_;
 267     }
 268   else
 269     {
 270       this->object_->layout(this->symtab_, this->layout_, this->sd_);
 271       this->object_->add_symbols(this->symtab_, this->sd_);
 272     }
 273   delete this->sd_;
 274   this->sd_ = NULL;
 275 }
 276
 277 // Class Finish_group.
 278
 279 Finish_group::~Finish_group()
 280 {
 281   if (this->this_blocker_ != NULL)
 282     delete this->this_blocker_;
 283   // next_blocker_ is deleted by the task associated with the next
 284   // input file following the group.
 285 }
 286
 287 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
 288
 289 Task::Is_runnable_type
 290 Finish_group::is_runnable(Workqueue*)
 291 {
 292   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
 293     return IS_BLOCKED;
 294   return IS_RUNNABLE;
 295 }
 296
 297 Task_locker*
 298 Finish_group::locks(Workqueue* workqueue)
 299 {
 300   return new Task_locker_block(*this->next_blocker_, workqueue);
 301 }
 302
 303 // Loop over the archives until there are no new undefined symbols.
 304
 305 void
 306 Finish_group::run(Workqueue*)
 307 {
 308   int saw_undefined = this->saw_undefined_;
 309   while (saw_undefined != this->symtab_->saw_undefined())
 310     {
 311       saw_undefined = this->symtab_->saw_undefined();
 312
 313       for (Input_group::const_iterator p = this->input_group_->begin();
 314            p != this->input_group_->end();
 315            ++p)
 316         {
 317           Task_lock_obj<Archive> tl(**p);
 318
 319           (*p)->add_symbols(this->symtab_, this->layout_,
 320                             this->input_objects_);
 321         }
 322     }
 323
 324   // Delete all the archives now that we no longer need them.
 325   for (Input_group::const_iterator p = this->input_group_->begin();
 326        p != this->input_group_->end();
 327        ++p)
 328     delete *p;
 329   delete this->input_group_;
 330 }
 331
 332 } // End namespace gold.