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