2008-08-06 Cary Coutant <ccoutant@google.com>
[external/binutils.git] / gold / readsyms.cc
1 // readsyms.cc -- read input file symbols for gold
2
3 // Copyright 2006, 2007, 2008 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 when the workqueue lock is held, so we need a dummy
43 // task to do that.  The dummy task has to maintain the right sequence
44 // of blocks, 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   Task_token*
60   is_runnable()
61   {
62     if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
63       return this->this_blocker_;
64     return NULL;
65   }
66
67   void
68   locks(Task_locker* tl)
69   { tl->add(this, this->next_blocker_); }
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_token*
97 Read_symbols::is_runnable()
98 {
99   if (this->input_argument_->is_file()
100       && this->input_argument_->file().may_need_search()
101       && this->dirpath_->token()->is_blocked())
102     return this->dirpath_->token();
103
104   return NULL;
105 }
106
107 // Return a Task_locker for a Read_symbols task.  We don't need any
108 // locks here.
109
110 void
111 Read_symbols::locks(Task_locker*)
112 {
113 }
114
115 // Run a Read_symbols task.
116
117 void
118 Read_symbols::run(Workqueue* workqueue)
119 {
120   // If we didn't queue a new task, then we need to explicitly unblock
121   // the token.
122   if (!this->do_read_symbols(workqueue))
123     workqueue->queue_soon(new Unblock_token(this->this_blocker_,
124                                             this->next_blocker_));
125 }
126
127 // Open the file and read the symbols.  Return true if a new task was
128 // queued, false if that could not happen due to some error.
129
130 bool
131 Read_symbols::do_read_symbols(Workqueue* workqueue)
132 {
133   if (this->input_argument_->is_group())
134     {
135       gold_assert(this->input_group_ == NULL);
136       this->do_group(workqueue);
137       return true;
138     }
139
140   Input_file* input_file = new Input_file(&this->input_argument_->file());
141   if (!input_file->open(this->options_, *this->dirpath_, this))
142     return false;
143
144   // Read enough of the file to pick up the entire ELF header.
145
146   off_t filesize = input_file->file().filesize();
147
148   if (filesize == 0)
149     {
150       gold_error(_("%s: file is empty"),
151                  input_file->file().filename().c_str());
152       return false;
153     }
154
155   int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
156   if (filesize < read_size)
157     read_size = filesize;
158
159   const unsigned char* ehdr = input_file->file().get_view(0, 0, read_size,
160                                                           true, false);
161
162   if (read_size >= 4)
163     {
164       static unsigned char elfmagic[4] =
165         {
166           elfcpp::ELFMAG0, elfcpp::ELFMAG1,
167           elfcpp::ELFMAG2, elfcpp::ELFMAG3
168         };
169       if (memcmp(ehdr, elfmagic, 4) == 0)
170         {
171           // This is an ELF object.
172
173           Object* obj = make_elf_object(input_file->filename(),
174                                         input_file, 0, ehdr, read_size);
175           if (obj == NULL)
176             return false;
177
178           Read_symbols_data* sd = new Read_symbols_data;
179           obj->read_symbols(sd);
180
181           // Opening the file locked it, so now we need to unlock it.
182           // We need to unlock it before queuing the Add_symbols task,
183           // because the workqueue doesn't know about our lock on the
184           // file.  If we queue the Add_symbols task first, it will be
185           // stuck on the end of the file lock, but since the
186           // workqueue doesn't know about that lock, it will never
187           // release the Add_symbols task.
188
189           input_file->file().unlock(this);
190
191           // We use queue_next because everything is cached for this
192           // task to run right away if possible.
193
194           workqueue->queue_next(new Add_symbols(this->input_objects_,
195                                                 this->symtab_, this->layout_,
196                                                 obj, sd,
197                                                 this->this_blocker_,
198                                                 this->next_blocker_));
199
200           return true;
201         }
202     }
203
204   if (read_size >= Archive::sarmag)
205     {
206       bool is_thin_archive
207           = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;
208       if (is_thin_archive 
209           || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)
210         {
211           // This is an archive.
212           Archive* arch = new Archive(this->input_argument_->file().name(),
213                                       input_file, is_thin_archive,
214                                       this->dirpath_, this);
215           arch->setup(this->input_objects_);
216           
217           // Unlock the archive so it can be used in the next task.
218           arch->unlock(this);
219
220           workqueue->queue_next(new Add_archive_symbols(this->symtab_,
221                                                         this->layout_,
222                                                         this->input_objects_,
223                                                         this->mapfile_,
224                                                         arch,
225                                                         this->input_group_,
226                                                         this->this_blocker_,
227                                                         this->next_blocker_));
228           return true;
229         }
230     }
231
232   // Queue up a task to try to parse this file as a script.  We use a
233   // separate task so that the script will be read in order with other
234   // objects named on the command line.  Also so that we don't try to
235   // read multiple scripts simultaneously, which could lead to
236   // unpredictable changes to the General_options structure.
237
238   workqueue->queue_soon(new Read_script(this->options_,
239                                         this->symtab_,
240                                         this->layout_,
241                                         this->dirpath_,
242                                         this->input_objects_,
243                                         this->mapfile_,
244                                         this->input_group_,
245                                         this->input_argument_,
246                                         input_file,
247                                         this->this_blocker_,
248                                         this->next_blocker_));
249   return true;
250 }
251
252 // Handle a group.  We need to walk through the arguments over and
253 // over until we don't see any new undefined symbols.  We do this by
254 // setting off Read_symbols Tasks as usual, but recording the archive
255 // entries instead of deleting them.  We also start a Finish_group
256 // Task which runs after we've read all the symbols.  In that task we
257 // process the archives in a loop until we are done.
258
259 void
260 Read_symbols::do_group(Workqueue* workqueue)
261 {
262   Input_group* input_group = new Input_group();
263
264   const Input_file_group* group = this->input_argument_->group();
265   Task_token* this_blocker = this->this_blocker_;
266
267   for (Input_file_group::const_iterator p = group->begin();
268        p != group->end();
269        ++p)
270     {
271       const Input_argument* arg = &*p;
272       gold_assert(arg->is_file());
273
274       Task_token* next_blocker = new Task_token(true);
275       next_blocker->add_blocker();
276       workqueue->queue_soon(new Read_symbols(this->options_,
277                                              this->input_objects_,
278                                              this->symtab_, this->layout_,
279                                              this->dirpath_, this->mapfile_,
280                                              arg, input_group,
281                                              this_blocker, next_blocker));
282       this_blocker = next_blocker;
283     }
284
285   const int saw_undefined = this->symtab_->saw_undefined();
286   workqueue->queue_soon(new Finish_group(this->input_objects_,
287                                          this->symtab_,
288                                          this->layout_,
289                                          this->mapfile_,
290                                          input_group,
291                                          saw_undefined,
292                                          this_blocker,
293                                          this->next_blocker_));
294 }
295
296 // Return a debugging name for a Read_symbols task.
297
298 std::string
299 Read_symbols::get_name() const
300 {
301   if (!this->input_argument_->is_group())
302     {
303       std::string ret("Read_symbols ");
304       if (this->input_argument_->file().is_lib())
305         ret += "-l";
306       ret += this->input_argument_->file().name();
307       return ret;
308     }
309
310   std::string ret("Read_symbols group (");
311   bool add_space = false;
312   const Input_file_group* group = this->input_argument_->group();
313   for (Input_file_group::const_iterator p = group->begin();
314        p != group->end();
315        ++p)
316     {
317       if (add_space)
318         ret += ' ';
319       ret += p->file().name();
320       add_space = true;
321     }
322   return ret + ')';
323 }
324
325 // Class Add_symbols.
326
327 Add_symbols::~Add_symbols()
328 {
329   if (this->this_blocker_ != NULL)
330     delete this->this_blocker_;
331   // next_blocker_ is deleted by the task associated with the next
332   // input file.
333 }
334
335 // We are blocked by this_blocker_.  We block next_blocker_.  We also
336 // lock the file.
337
338 Task_token*
339 Add_symbols::is_runnable()
340 {
341   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
342     return this->this_blocker_;
343   if (this->object_->is_locked())
344     return this->object_->token();
345   return NULL;
346 }
347
348 void
349 Add_symbols::locks(Task_locker* tl)
350 {
351   tl->add(this, this->next_blocker_);
352   tl->add(this, this->object_->token());
353 }
354
355 // Add the symbols in the object to the symbol table.
356
357 void
358 Add_symbols::run(Workqueue*)
359 {
360   if (!this->input_objects_->add_object(this->object_))
361     {
362       // FIXME: We need to close the descriptor here.
363       delete this->object_;
364     }
365   else
366     {
367       this->object_->layout(this->symtab_, this->layout_, this->sd_);
368       this->object_->add_symbols(this->symtab_, this->sd_);
369       this->object_->release();
370     }
371   delete this->sd_;
372   this->sd_ = NULL;
373 }
374
375 // Class Finish_group.
376
377 Finish_group::~Finish_group()
378 {
379   if (this->this_blocker_ != NULL)
380     delete this->this_blocker_;
381   // next_blocker_ is deleted by the task associated with the next
382   // input file following the group.
383 }
384
385 // We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
386
387 Task_token*
388 Finish_group::is_runnable()
389 {
390   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
391     return this->this_blocker_;
392   return NULL;
393 }
394
395 void
396 Finish_group::locks(Task_locker* tl)
397 {
398   tl->add(this, this->next_blocker_);
399 }
400
401 // Loop over the archives until there are no new undefined symbols.
402
403 void
404 Finish_group::run(Workqueue*)
405 {
406   int saw_undefined = this->saw_undefined_;
407   while (saw_undefined != this->symtab_->saw_undefined())
408     {
409       saw_undefined = this->symtab_->saw_undefined();
410
411       for (Input_group::const_iterator p = this->input_group_->begin();
412            p != this->input_group_->end();
413            ++p)
414         {
415           Task_lock_obj<Archive> tl(this, *p);
416
417           (*p)->add_symbols(this->symtab_, this->layout_,
418                             this->input_objects_, this->mapfile_);
419         }
420     }
421
422   // Delete all the archives now that we no longer need them.
423   for (Input_group::const_iterator p = this->input_group_->begin();
424        p != this->input_group_->end();
425        ++p)
426     delete *p;
427   delete this->input_group_;
428 }
429
430 // Class Read_script
431
432 Read_script::~Read_script()
433 {
434   if (this->this_blocker_ != NULL)
435     delete this->this_blocker_;
436   // next_blocker_ is deleted by the task associated with the next
437   // input file.
438 }
439
440 // We are blocked by this_blocker_.
441
442 Task_token*
443 Read_script::is_runnable()
444 {
445   if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
446     return this->this_blocker_;
447   return NULL;
448 }
449
450 // We don't unlock next_blocker_ here.  If the script names any input
451 // files, then the last file will be responsible for unlocking it.
452
453 void
454 Read_script::locks(Task_locker*)
455 {
456 }
457
458 // Read the script, if it is a script.
459
460 void
461 Read_script::run(Workqueue* workqueue)
462 {
463   bool used_next_blocker;
464   if (!read_input_script(workqueue, this->options_, this->symtab_,
465                          this->layout_, this->dirpath_, this->input_objects_,
466                          this->mapfile_, this->input_group_,
467                          this->input_argument_, this->input_file_,
468                          this->next_blocker_, &used_next_blocker))
469     {
470       // Here we have to handle any other input file types we need.
471       gold_error(_("%s: not an object or archive"),
472                  this->input_file_->file().filename().c_str());
473     }
474
475   if (!used_next_blocker)
476     {
477       // Queue up a task to unlock next_blocker.  We can't just unlock
478       // it here, as we don't hold the workqueue lock.
479       workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));
480     }
481 }
482
483 // Return a debugging name for a Read_script task.
484
485 std::string
486 Read_script::get_name() const
487 {
488   std::string ret("Read_script ");
489   if (this->input_argument_->file().is_lib())
490     ret += "-l";
491   ret += this->input_argument_->file().name();
492   return ret;
493 }
494
495 } // End namespace gold.