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// readsyms.cc -- read input file symbols for gold

// Copyright 2006, 2007, 2008, 2009 Free Software Foundation, Inc.

// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 3 of the License, or

// (at your option) any later version.

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

// MA 02110-1301, USA.

#include "gold.h"

#include <cstring>

#include "elfcpp.h"

#include "options.h"

#include "dirsearch.h"

#include "symtab.h"

#include "object.h"

#include "archive.h"

#include "script.h"

#include "readsyms.h"

#include "plugin.h"

#include "layout.h"

#include "incremental.h"

namespace gold

{

// If we fail to open the object, then we won't create an Add_symbols

// task.  However, we still need to unblock the token, or else the

// link won't proceed to generate more error messages.  We can only

// unblock tokens when the workqueue lock is held, so we need a dummy

// task to do that.  The dummy task has to maintain the right sequence

// of blocks, so we need both this_blocker and next_blocker.

class Unblock_token : public Task

{

 public:

  Unblock_token(Task_token* this_blocker, Task_token* next_blocker)

    : this_blocker_(this_blocker), next_blocker_(next_blocker)

  { }

  ~Unblock_token()

  {

    if (this->this_blocker_ != NULL)

      delete this->this_blocker_;

  }

  Task_token*

  is_runnable()

  {

    if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())

      return this->this_blocker_;

    return NULL;

  }

  void

  locks(Task_locker* tl)

  { tl->add(this, this->next_blocker_); }

  void

  run(Workqueue*)

  { }

  std::string

  get_name() const

  { return "Unblock_token"; }

 private:

  Task_token* this_blocker_;

  Task_token* next_blocker_;

};

// Class read_symbols.

Read_symbols::~Read_symbols()

{

  // The this_blocker_ and next_blocker_ pointers are passed on to the

  // Add_symbols task.

}

// If appropriate, issue a warning about skipping an incompatible

// file.

void

Read_symbols::incompatible_warning(const Input_argument* input_argument,

                                   const Input_file* input_file)

{

  if (parameters->options().warn_search_mismatch())

    gold_warning("skipping incompatible %s while searching for %s",

                 input_file->filename().c_str(),

                 input_argument->file().name());

}

// Requeue a Read_symbols task to search for the next object with the

// same name.

void

Read_symbols::requeue(Workqueue* workqueue, Input_objects* input_objects,

                      Symbol_table* symtab, Layout* layout, Dirsearch* dirpath,

                      int dirindex, Mapfile* mapfile,

                      const Input_argument* input_argument,

                      Input_group* input_group, Task_token* next_blocker)

{

  // Bump the directory search index.

  ++dirindex;

  // We don't need to worry about this_blocker, since we already

  // reached it.  However, we are removing the blocker on next_blocker

  // because the calling task is completing.  So we need to add a new

  // blocker.  Since next_blocker may be shared by several tasks, we

  // need to increment the count with the workqueue lock held.

  workqueue->add_blocker(next_blocker);

  workqueue->queue(new Read_symbols(input_objects, symtab, layout, dirpath,

                                    dirindex, mapfile, input_argument,

                                    input_group, NULL, next_blocker));

}

// Return whether a Read_symbols task is runnable.  We can read an

// ordinary input file immediately.  For an archive specified using

// -l, we have to wait until the search path is complete.

Task_token*

Read_symbols::is_runnable()

{

  if (this->input_argument_->is_file()

      && this->input_argument_->file().may_need_search()

      && this->dirpath_->token()->is_blocked())

    return this->dirpath_->token();

  return NULL;

}

// Return a Task_locker for a Read_symbols task.  We don't need any

// locks here.

void

Read_symbols::locks(Task_locker*)

{

}

// Run a Read_symbols task.

void

Read_symbols::run(Workqueue* workqueue)

{

  // If we didn't queue a new task, then we need to explicitly unblock

  // the token.

  if (!this->do_read_symbols(workqueue))

    workqueue->queue_soon(new Unblock_token(this->this_blocker_,

                                            this->next_blocker_));

}

// Open the file and read the symbols.  Return true if a new task was

// queued, false if that could not happen due to some error.

bool

Read_symbols::do_read_symbols(Workqueue* workqueue)

{

  if (this->input_argument_->is_group())

    {

      gold_assert(this->input_group_ == NULL);

      this->do_group(workqueue);

      return true;

    }

  Input_file* input_file = new Input_file(&this->input_argument_->file());

  if (!input_file->open(*this->dirpath_, this, &this->dirindex_))

    return false;

  // Read enough of the file to pick up the entire ELF header.

  off_t filesize = input_file->file().filesize();

  if (filesize == 0)

    {

      gold_error(_("%s: file is empty"),

                 input_file->file().filename().c_str());

      return false;

    }

  const unsigned char* ehdr;

  int read_size;

  bool is_elf = is_elf_object(input_file, 0, &ehdr, &read_size);

  if (read_size >= Archive::sarmag)

    {

      bool is_thin_archive

          = memcmp(ehdr, Archive::armagt, Archive::sarmag) == 0;

      if (is_thin_archive

          || memcmp(ehdr, Archive::armag, Archive::sarmag) == 0)

        {

          // This is an archive.

          Archive* arch = new Archive(this->input_argument_->file().name(),

                                      input_file, is_thin_archive,

                                      this->dirpath_, this);

          arch->setup();

          if (this->layout_->incremental_inputs())

            {

              const Input_argument* ia = this->input_argument_;

              this->layout_->incremental_inputs()->report_archive(ia, arch);

            }

          // Unlock the archive so it can be used in the next task.

          arch->unlock(this);

          workqueue->queue_next(new Add_archive_symbols(this->symtab_,

                                                        this->layout_,

                                                        this->input_objects_,

                                                        this->dirpath_,

                                                        this->dirindex_,

                                                        this->mapfile_,

                                                        this->input_argument_,

                                                        arch,

                                                        this->input_group_,

                                                        this->this_blocker_,

                                                        this->next_blocker_));

          return true;

        }

    }

  if (parameters->options().has_plugins())

    {

      Pluginobj* obj = parameters->options().plugins()->claim_file(input_file,

                                                                   0, filesize);

      if (obj != NULL)

        {

          // The input file was claimed by a plugin, and its symbols

          // have been provided by the plugin.

          // We are done with the file at this point, so unlock it.

          obj->unlock(this);

          workqueue->queue_next(new Add_symbols(this->input_objects_,

                                                this->symtab_,

                                                this->layout_,

                                                this->dirpath_,

                                                this->dirindex_,

                                                this->mapfile_,

                                                this->input_argument_,

                                                this->input_group_,

                                                obj,

                                                NULL,

                                                this->this_blocker_,

                                                this->next_blocker_));

          return true;

        }

    }

  if (is_elf)

    {

      // This is an ELF object.

      bool unconfigured = false;

      bool* punconfigured = (input_file->will_search_for()

                             ? &unconfigured

                             : NULL);

      Object* obj = make_elf_object(input_file->filename(),

                                    input_file, 0, ehdr, read_size,

                                    punconfigured);

      if (obj == NULL)

        {

          if (unconfigured)

            {

              Read_symbols::incompatible_warning(this->input_argument_,

                                                 input_file);

              input_file->file().release();

              input_file->file().unlock(this);

              delete input_file;

              ++this->dirindex_;

              return this->do_read_symbols(workqueue);

            }

          return false;

        }

      Read_symbols_data* sd = new Read_symbols_data;

      obj->read_symbols(sd);

      if (this->layout_->incremental_inputs())

        {

          const Input_argument* ia = this->input_argument_;

          this->layout_->incremental_inputs()->report_object(ia, obj);

        }

      // Opening the file locked it, so now we need to unlock it.  We

      // need to unlock it before queuing the Add_symbols task,

      // because the workqueue doesn't know about our lock on the

      // file.  If we queue the Add_symbols task first, it will be

      // stuck on the end of the file lock, but since the workqueue

      // doesn't know about that lock, it will never release the

      // Add_symbols task.

      input_file->file().unlock(this);

      // We use queue_next because everything is cached for this

      // task to run right away if possible.

      workqueue->queue_next(new Add_symbols(this->input_objects_,

                                            this->symtab_, this->layout_,

                                            this->dirpath_,

                                            this->dirindex_,

                                            this->mapfile_,

                                            this->input_argument_,

                                            this->input_group_,

                                            obj,

                                            sd,

                                            this->this_blocker_,

                                            this->next_blocker_));

      return true;

    }

  // Queue up a task to try to parse this file as a script.  We use a

  // separate task so that the script will be read in order with other

  // objects named on the command line.  Also so that we don't try to

  // read multiple scripts simultaneously, which could lead to

  // unpredictable changes to the General_options structure.

  workqueue->queue_soon(new Read_script(this->symtab_,

                                        this->layout_,

                                        this->dirpath_,

                                        this->dirindex_,

                                        this->input_objects_,

                                        this->mapfile_,

                                        this->input_group_,

                                        this->input_argument_,

                                        input_file,

                                        this->this_blocker_,

                                        this->next_blocker_));

  return true;

}

// Handle a group.  We need to walk through the arguments over and

// over until we don't see any new undefined symbols.  We do this by

// setting off Read_symbols Tasks as usual, but recording the archive

// entries instead of deleting them.  We also start a Finish_group

// Task which runs after we've read all the symbols.  In that task we

// process the archives in a loop until we are done.

void

Read_symbols::do_group(Workqueue* workqueue)

{

  Input_group* input_group = new Input_group();

  const Input_file_group* group = this->input_argument_->group();

  Task_token* this_blocker = this->this_blocker_;

  for (Input_file_group::const_iterator p = group->begin();

       p != group->end();

       ++p)

    {

      const Input_argument* arg = &*p;

      gold_assert(arg->is_file());

      Task_token* next_blocker = new Task_token(true);

      next_blocker->add_blocker();

      workqueue->queue_soon(new Read_symbols(this->input_objects_,

                                             this->symtab_, this->layout_,

                                             this->dirpath_, this->dirindex_,

                                             this->mapfile_, arg, input_group,

                                             this_blocker, next_blocker));

      this_blocker = next_blocker;

    }

  const int saw_undefined = this->symtab_->saw_undefined();

  workqueue->queue_soon(new Finish_group(this->input_objects_,

                                         this->symtab_,

                                         this->layout_,

                                         this->mapfile_,

                                         input_group,

                                         saw_undefined,

                                         this_blocker,

                                         this->next_blocker_));

}

// Return a debugging name for a Read_symbols task.

std::string

Read_symbols::get_name() const

{

  if (!this->input_argument_->is_group())

    {

      std::string ret("Read_symbols ");

      if (this->input_argument_->file().is_lib())

        ret += "-l";

      else if (this->input_argument_->file().is_searched_file())

        ret += "-l:";

      ret += this->input_argument_->file().name();

      return ret;

    }

  std::string ret("Read_symbols group (");

  bool add_space = false;

  const Input_file_group* group = this->input_argument_->group();

  for (Input_file_group::const_iterator p = group->begin();

       p != group->end();

       ++p)

    {

      if (add_space)

        ret += ' ';

      ret += p->file().name();

      add_space = true;

    }

  return ret + ')';

}

// Class Add_symbols.

Add_symbols::~Add_symbols()

{

  if (this->this_blocker_ != NULL)

    delete this->this_blocker_;

  // next_blocker_ is deleted by the task associated with the next

  // input file.

}

// We are blocked by this_blocker_.  We block next_blocker_.  We also

// lock the file.

Task_token*

Add_symbols::is_runnable()

{

  if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())

    return this->this_blocker_;

  if (this->object_->is_locked())

    return this->object_->token();

  return NULL;

}

void

Add_symbols::locks(Task_locker* tl)

{

  tl->add(this, this->next_blocker_);

  tl->add(this, this->object_->token());

}

// Add the symbols in the object to the symbol table.

void

Add_symbols::run(Workqueue*)

{

  Pluginobj* pluginobj = this->object_->pluginobj();

  if (pluginobj != NULL)

    {

      this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);

      return;

    }

  if (!this->input_objects_->add_object(this->object_))

    {

      this->object_->release();

      delete this->object_;

    }

  else

    {

      this->object_->layout(this->symtab_, this->layout_, this->sd_);

      this->object_->add_symbols(this->symtab_, this->sd_, this->layout_);

      this->object_->release();

    }

  delete this->sd_;

  this->sd_ = NULL;

}

// Class Finish_group.

Finish_group::~Finish_group()

{

  if (this->this_blocker_ != NULL)

    delete this->this_blocker_;

  // next_blocker_ is deleted by the task associated with the next

  // input file following the group.

}

// We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.

Task_token*

Finish_group::is_runnable()

{

  if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())

    return this->this_blocker_;

  return NULL;

}

void

Finish_group::locks(Task_locker* tl)

{

  tl->add(this, this->next_blocker_);

}

// Loop over the archives until there are no new undefined symbols.

void

Finish_group::run(Workqueue*)

{

  int saw_undefined = this->saw_undefined_;

  while (saw_undefined != this->symtab_->saw_undefined())

    {

      saw_undefined = this->symtab_->saw_undefined();

      for (Input_group::const_iterator p = this->input_group_->begin();

           p != this->input_group_->end();

           ++p)

        {

          Task_lock_obj<Archive> tl(this, *p);

          (*p)->add_symbols(this->symtab_, this->layout_,

                            this->input_objects_, this->mapfile_);

        }

    }

  // Delete all the archives now that we no longer need them.

  for (Input_group::const_iterator p = this->input_group_->begin();

       p != this->input_group_->end();

       ++p)

    delete *p;

  delete this->input_group_;

}

// Class Read_script

Read_script::~Read_script()

{

  if (this->this_blocker_ != NULL)

    delete this->this_blocker_;

  // next_blocker_ is deleted by the task associated with the next

  // input file.

}

// We are blocked by this_blocker_.

Task_token*

Read_script::is_runnable()

{

  if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())

    return this->this_blocker_;

  return NULL;

}

// We don't unlock next_blocker_ here.  If the script names any input

// files, then the last file will be responsible for unlocking it.

void

Read_script::locks(Task_locker*)

{

}

// Read the script, if it is a script.

void

Read_script::run(Workqueue* workqueue)

{

  bool used_next_blocker;

  if (!read_input_script(workqueue, this->symtab_, this->layout_,

                         this->dirpath_, this->dirindex_, this->input_objects_,

                         this->mapfile_, this->input_group_,

                         this->input_argument_, this->input_file_,

                         this->next_blocker_, &used_next_blocker))

    {

      // Here we have to handle any other input file types we need.

      gold_error(_("%s: not an object or archive"),

                 this->input_file_->file().filename().c_str());

    }

  if (!used_next_blocker)

    {

      // Queue up a task to unlock next_blocker.  We can't just unlock

      // it here, as we don't hold the workqueue lock.

      workqueue->queue_soon(new Unblock_token(NULL, this->next_blocker_));

    }

}

// Return a debugging name for a Read_script task.

std::string

Read_script::get_name() const

{

  std::string ret("Read_script ");

  if (this->input_argument_->file().is_lib())

    ret += "-l";

  else if (this->input_argument_->file().is_searched_file())

    ret += "-l:";

  ret += this->input_argument_->file().name();

  return ret;

}

} // End namespace gold.