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