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// gold.cc -- main linker functions

// Copyright 2006, 2007, 2008, 2009, 2010 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 <cstdlib>

#include <cstdio>

#include <cstring>

#include <unistd.h>

#include <algorithm>

#include "libiberty.h"

#include "options.h"

#include "debug.h"

#include "workqueue.h"

#include "dirsearch.h"

#include "readsyms.h"

#include "symtab.h"

#include "common.h"

#include "object.h"

#include "layout.h"

#include "reloc.h"

#include "defstd.h"

#include "plugin.h"

#include "gc.h"

#include "icf.h"

#include "incremental.h"

namespace gold

{

class Object;

const char* program_name;

static Task*

process_incremental_input(Incremental_binary*, unsigned int, Input_objects*,

                          Symbol_table*, Layout*, Dirsearch*, Mapfile*,

                          Task_token*, Task_token*);

void

gold_exit(Exit_status status)

{

  if (parameters != NULL

      && parameters->options_valid()

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

    parameters->options().plugins()->cleanup();

  if (status != GOLD_OK && parameters != NULL && parameters->options_valid())

    unlink_if_ordinary(parameters->options().output_file_name());

  exit(status);

}

void

gold_nomem()

{

  // We are out of memory, so try hard to print a reasonable message.

  // Note that we don't try to translate this message, since the

  // translation process itself will require memory.

  // LEN only exists to avoid a pointless warning when write is

  // declared with warn_use_result, as when compiling with

  // -D_USE_FORTIFY on GNU/Linux.  Casting to void does not appear to

  // work, at least not with gcc 4.3.0.

  ssize_t len = write(2, program_name, strlen(program_name));

  if (len >= 0)

    {

      const char* const s = ": out of memory\n";

      len = write(2, s, strlen(s));

    }

  gold_exit(GOLD_ERR);

}

// Handle an unreachable case.

void

do_gold_unreachable(const char* filename, int lineno, const char* function)

{

  fprintf(stderr, _("%s: internal error in %s, at %s:%d\n"),

          program_name, function, filename, lineno);

  gold_exit(GOLD_ERR);

}

// This class arranges to run the functions done in the middle of the

// link.  It is just a closure.

class Middle_runner : public Task_function_runner

{

 public:

  Middle_runner(const General_options& options,

                const Input_objects* input_objects,

                Symbol_table* symtab,

                Layout* layout, Mapfile* mapfile)

    : options_(options), input_objects_(input_objects), symtab_(symtab),

      layout_(layout), mapfile_(mapfile)

  { }

  void

  run(Workqueue*, const Task*);

 private:

  const General_options& options_;

  const Input_objects* input_objects_;

  Symbol_table* symtab_;

  Layout* layout_;

  Mapfile* mapfile_;

};

void

Middle_runner::run(Workqueue* workqueue, const Task* task)

{

  queue_middle_tasks(this->options_, task, this->input_objects_, this->symtab_,

                     this->layout_, workqueue, this->mapfile_);

}

// This class arranges the tasks to process the relocs for garbage collection.

class Gc_runner : public Task_function_runner

{

  public:

   Gc_runner(const General_options& options,

             const Input_objects* input_objects,

             Symbol_table* symtab,

             Layout* layout, Mapfile* mapfile)

    : options_(options), input_objects_(input_objects), symtab_(symtab),

      layout_(layout), mapfile_(mapfile)

   { }

  void

  run(Workqueue*, const Task*);

 private:

  const General_options& options_;

  const Input_objects* input_objects_;

  Symbol_table* symtab_;

  Layout* layout_;

  Mapfile* mapfile_;

};

void

Gc_runner::run(Workqueue* workqueue, const Task* task)

{

  queue_middle_gc_tasks(this->options_, task, this->input_objects_,

                        this->symtab_, this->layout_, workqueue,

                        this->mapfile_);

}

// Queue up the initial set of tasks for this link job.

void

queue_initial_tasks(const General_options& options,

                    Dirsearch& search_path,

                    const Command_line& cmdline,

                    Workqueue* workqueue, Input_objects* input_objects,

                    Symbol_table* symtab, Layout* layout, Mapfile* mapfile)

{

  if (cmdline.begin() == cmdline.end())

    {

      if (options.printed_version())

        gold_exit(GOLD_OK);

      gold_fatal(_("no input files"));

    }

  int thread_count = options.thread_count_initial();

  if (thread_count == 0)

    thread_count = cmdline.number_of_input_files();

  workqueue->set_thread_count(thread_count);

  // For incremental links, the base output file.

  Incremental_binary* ibase = NULL;

  if (parameters->incremental())

    {

      if (options.relocatable())

        gold_error(_("incremental linking is incompatible with -r"));

      if (options.emit_relocs())

        gold_error(_("incremental linking is incompatible with --emit-relocs"));

      if (options.gc_sections())

        gold_error(_("incremental linking is incompatible with --gc-sections"));

      if (options.icf_enabled())

        gold_error(_("incremental linking is incompatible with --icf"));

      if (options.has_plugins())

        gold_error(_("incremental linking is incompatible with --plugin"));

      if (strcmp(options.compress_debug_sections(), "none") != 0)

        gold_error(_("incremental linking is incompatible with "

                     "--compress-debug-sections"));

      if (parameters->incremental_update())

        {

          Output_file* of = new Output_file(options.output_file_name());

          if (of->open_base_file(options.incremental_base(), true))

            {

              ibase = open_incremental_binary(of);

              if (ibase != NULL

                  && ibase->check_inputs(cmdline, layout->incremental_inputs()))

                ibase->init_layout(layout);

              else

                {

                  delete ibase;

                  ibase = NULL;

                  of->close();

                }

            }

          if (ibase == NULL)

            {

              if (set_parameters_incremental_full())

                gold_info(_("linking with --incremental-full"));

              else

                gold_fallback(_("restart link with --incremental-full"));

            }

        }

    }

  // Read the input files.  We have to add the symbols to the symbol

  // table in order.  We do this by creating a separate blocker for

  // each input file.  We associate the blocker with the following

  // input file, to give us a convenient place to delete it.

  Task_token* this_blocker = NULL;

  if (ibase == NULL)

    {

      // Normal link.  Queue a Read_symbols task for each input file

      // on the command line.

      for (Command_line::const_iterator p = cmdline.begin();

           p != cmdline.end();

           ++p)

        {

          Task_token* next_blocker = new Task_token(true);

          next_blocker->add_blocker();

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

                                            &search_path, 0, mapfile, &*p, NULL,

                                            NULL, this_blocker, next_blocker));

          this_blocker = next_blocker;

        }

    }

  else

    {

      // Incremental update link.  Process the list of input files

      // stored in the base file, and queue a task for each file:

      // a Read_symbols task for a changed file, and an Add_symbols task

      // for an unchanged file.  We need to mark all the space used by

      // unchanged files before we can start any tasks running.

      unsigned int input_file_count = ibase->input_file_count();

      std::vector<Task*> tasks;

      tasks.reserve(input_file_count);

      for (unsigned int i = 0; i < input_file_count; ++i)

        {

          Task_token* next_blocker = new Task_token(true);

          next_blocker->add_blocker();

          Task* t = process_incremental_input(ibase, i, input_objects, symtab,

                                              layout, &search_path, mapfile,

                                              this_blocker, next_blocker);

          tasks.push_back(t);

          this_blocker = next_blocker;

        }

      // Now we can queue the tasks.

      for (unsigned int i = 0; i < tasks.size(); i++)

        workqueue->queue(tasks[i]);

    }

  if (options.has_plugins())

    {

      Task_token* next_blocker = new Task_token(true);

      next_blocker->add_blocker();

      workqueue->queue(new Plugin_hook(options, input_objects, symtab, layout,

                                       &search_path, mapfile, this_blocker,

                                       next_blocker));

      this_blocker = next_blocker;

    }

  if (options.relocatable()

      && (options.gc_sections() || options.icf_enabled()))

    gold_error(_("cannot mix -r with --gc-sections or --icf"));

  if (options.gc_sections() || options.icf_enabled())

    {

      workqueue->queue(new Task_function(new Gc_runner(options,

                                                       input_objects,

                                                       symtab,

                                                       layout,

                                                       mapfile),

                                         this_blocker,

                                         "Task_function Gc_runner"));

    }

  else

    {

      workqueue->queue(new Task_function(new Middle_runner(options,

                                                           input_objects,

                                                           symtab,

                                                           layout,

                                                           mapfile),

                                         this_blocker,

                                         "Task_function Middle_runner"));

    }

}

// Process an incremental input file: if it is unchanged from the previous

// link, return a task to add its symbols from the base file's incremental

// info; if it has changed, return a normal Read_symbols task.  We create a

// task for every input file, if only to report the file for rebuilding the

// incremental info.

static Task*

process_incremental_input(Incremental_binary* ibase,

                          unsigned int input_file_index,

                          Input_objects* input_objects,

                          Symbol_table* symtab,

                          Layout* layout,

                          Dirsearch* search_path,

                          Mapfile* mapfile,

                          Task_token* this_blocker,

                          Task_token* next_blocker)

{

  const Incremental_binary::Input_reader* input_reader =

      ibase->get_input_reader(input_file_index);

  Incremental_input_type input_type = input_reader->type();

  // Get the input argument corresponding to this input file, matching on

  // the argument serial number.  If the input file cannot be matched

  // to an existing input argument, synthesize a new one.

  const Input_argument* input_argument =

      ibase->get_input_argument(input_file_index);

  if (input_argument == NULL)

    {

      Input_file_argument file(input_reader->filename(),

                               Input_file_argument::INPUT_FILE_TYPE_FILE,

                               "", false, parameters->options());

      Input_argument* arg = new Input_argument(file);

      arg->set_script_info(ibase->get_script_info(input_file_index));

      input_argument = arg;

    }

  gold_debug(DEBUG_INCREMENTAL, "Incremental object: %s, type %d",

             input_reader->filename(), input_type);

  if (input_type == INCREMENTAL_INPUT_SCRIPT)

    {

      // Incremental_binary::check_inputs should have cancelled the

      // incremental update if the script has changed.

      gold_assert(!ibase->file_has_changed(input_file_index));

      return new Check_script(layout, ibase, input_file_index, input_reader,

                              this_blocker, next_blocker);

    }

  if (input_type == INCREMENTAL_INPUT_ARCHIVE)

    {

      Incremental_library* lib = ibase->get_library(input_file_index);

      gold_assert(lib != NULL);

      if (lib->filename() == "/group/"

          || !ibase->file_has_changed(input_file_index))

        {

          // Queue a task to check that no references have been added to any

          // of the library's unused symbols.

          return new Check_library(symtab, layout, ibase, input_file_index,

                                   input_reader, this_blocker, next_blocker);

        }

      else

        {

          // Queue a Read_symbols task to process the archive normally.

          return new Read_symbols(input_objects, symtab, layout, search_path,

                                  0, mapfile, input_argument, NULL, NULL,

                                  this_blocker, next_blocker);

        }

    }

  if (input_type == INCREMENTAL_INPUT_ARCHIVE_MEMBER)

    {

      // For archive members, check the timestamp of the containing archive.

      Incremental_library* lib = ibase->get_library(input_file_index);

      gold_assert(lib != NULL);

      // Process members of a --start-lib/--end-lib group as normal objects.

      if (lib->filename() != "/group/")

        {

          if (ibase->file_has_changed(lib->input_file_index()))

            {

              return new Read_member(input_objects, symtab, layout, mapfile,

                                     input_reader, this_blocker, next_blocker);

            }

          else

            {

              // The previous contributions from this file will be kept.

              // Mark the pieces of output sections contributed by this

              // object.

              ibase->reserve_layout(input_file_index);

              Object* obj = make_sized_incremental_object(ibase,

                                                          input_file_index,

                                                          input_type,

                                                          input_reader);

              return new Add_symbols(input_objects, symtab, layout,

                                     search_path, 0, mapfile, input_argument,

                                     obj, lib, NULL, this_blocker,

                                     next_blocker);

            }

        }

    }

  // Normal object file or shared library.  Check if the file has changed

  // since the last incremental link.

  if (ibase->file_has_changed(input_file_index))

    {

      return new Read_symbols(input_objects, symtab, layout, search_path, 0,

                              mapfile, input_argument, NULL, NULL,

                              this_blocker, next_blocker);

    }

  else

    {

      // The previous contributions from this file will be kept.

      // Mark the pieces of output sections contributed by this object.

      ibase->reserve_layout(input_file_index);

      Object* obj = make_sized_incremental_object(ibase,

                                                  input_file_index,

                                                  input_type,

                                                  input_reader);

      return new Add_symbols(input_objects, symtab, layout, search_path, 0,

                             mapfile, input_argument, obj, NULL, NULL,

                             this_blocker, next_blocker);

    }

}

// Queue up a set of tasks to be done before queueing the middle set

// of tasks.  This is only necessary when garbage collection

// (--gc-sections) of unused sections is desired.  The relocs are read

// and processed here early to determine the garbage sections before the

// relocs can be scanned in later tasks.

void

queue_middle_gc_tasks(const General_options& options,

                      const Task* ,

                      const Input_objects* input_objects,

                      Symbol_table* symtab,

                      Layout* layout,

                      Workqueue* workqueue,

                      Mapfile* mapfile)

{

  // Read_relocs for all the objects must be done and processed to find

  // unused sections before any scanning of the relocs can take place.

  Task_token* this_blocker = NULL;

  for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();

       p != input_objects->relobj_end();

       ++p)

    {

      Task_token* next_blocker = new Task_token(true);

      next_blocker->add_blocker();

      workqueue->queue(new Read_relocs(symtab, layout, *p, this_blocker,

                                       next_blocker));

      this_blocker = next_blocker;

    }

  // If we are given only archives in input, we have no regular

  // objects and THIS_BLOCKER is NULL here.  Create a dummy

  // blocker here so that we can run the middle tasks immediately.

  if (this_blocker == NULL)

    {

      gold_assert(input_objects->number_of_relobjs() == 0);

      this_blocker = new Task_token(true);

    }

  workqueue->queue(new Task_function(new Middle_runner(options,

                                                       input_objects,

                                                       symtab,

                                                       layout,

                                                       mapfile),

                                     this_blocker,

                                     "Task_function Middle_runner"));

}

// Queue up the middle set of tasks.  These are the tasks which run

// after all the input objects have been found and all the symbols

// have been read, but before we lay out the output file.

void

queue_middle_tasks(const General_options& options,

                   const Task* task,

                   const Input_objects* input_objects,

                   Symbol_table* symtab,

                   Layout* layout,

                   Workqueue* workqueue,

                   Mapfile* mapfile)

{

  // Add any symbols named with -u options to the symbol table.

  symtab->add_undefined_symbols_from_command_line(layout);

  // If garbage collection was chosen, relocs have been read and processed

  // at this point by pre_middle_tasks.  Layout can then be done for all 

  // objects.

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

    {

      // Find the start symbol if any.

      Symbol* start_sym = symtab->lookup(parameters->entry());

      if (start_sym != NULL)

        {

          bool is_ordinary;

          unsigned int shndx = start_sym->shndx(&is_ordinary);

          if (is_ordinary)

            {

              symtab->gc()->worklist().push(

                Section_id(start_sym->object(), shndx));

            }

        }

      // Symbols named with -u should not be considered garbage.

      symtab->gc_mark_undef_symbols(layout);

      gold_assert(symtab->gc() != NULL);

      // Do a transitive closure on all references to determine the worklist.

      symtab->gc()->do_transitive_closure();

    }

  // If identical code folding (--icf) is chosen it makes sense to do it 

  // only after garbage collection (--gc-sections) as we do not want to 

  // be folding sections that will be garbage.

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

    {

      symtab->icf()->find_identical_sections(input_objects, symtab);

    }

  // Call Object::layout for the second time to determine the 

  // output_sections for all referenced input sections.  When 

  // --gc-sections or --icf is turned on, Object::layout is 

  // called twice.  It is called the first time when the 

  // symbols are added.

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

      || parameters->options().icf_enabled())

    {

      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();

           p != input_objects->relobj_end();

           ++p)

        {

          Task_lock_obj<Object> tlo(task, *p);

          (*p)->layout(symtab, layout, NULL);

        }

    }

  // Layout deferred objects due to plugins.

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

    {

      Plugin_manager* plugins = parameters->options().plugins();

      gold_assert(plugins != NULL);

      plugins->layout_deferred_objects();

    }

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

      || parameters->options().icf_enabled())

    {

      for (Input_objects::Relobj_iterator p = input_objects->relobj_begin();

           p != input_objects->relobj_end();

           ++p)

        {

          // Update the value of output_section stored in rd.

          Read_relocs_data* rd = (*p)->get_relocs_data();

          for (Read_relocs_data::Relocs_list::iterator q = rd->relocs.begin();

               q != rd->relocs.end();

               ++q)

            {

              q->output_section = (*p)->output_section(q->data_shndx);

              q->needs_special_offset_handling =

                      (*p)->is_output_section_offset_invalid(q->data_shndx);

            }

        }

    }

  // We have to support the case of not seeing any input objects, and

  // generate an empty file.  Existing builds depend on being able to

  // pass an empty archive to the linker and get an empty object file

  // out.  In order to do this we need to use a default target.

  if (input_objects->number_of_input_objects() == 0

      && layout->incremental_base() == NULL)

    parameters_force_valid_target();

  int thread_count = options.thread_count_middle();

  if (thread_count == 0)

    thread_count = std::max(2, input_objects->number_of_input_objects());

  workqueue->set_thread_count(thread_count);

  // Now we have seen all the input files.

  const bool doing_static_link =

    (!input_objects->any_dynamic()

     && !parameters->options().output_is_position_independent());

  set_parameters_doing_static_link(doing_static_link);

  if (!doing_static_link && options.is_static())

    {

      // We print out just the first .so we see; there may be others.

      gold_assert(input_objects->dynobj_begin() != input_objects->dynobj_end());

      gold_error(_("cannot mix -static with dynamic object %s"),

                 (*input_objects->dynobj_begin())->name().c_str());

    }

  if (!doing_static_link && parameters->options().relocatable())

    gold_fatal(_("cannot mix -r with dynamic object %s"),

               (*input_objects->dynobj_begin())->name().c_str());

  if (!doing_static_link

      && options.oformat_enum() != General_options::OBJECT_FORMAT_ELF)

    gold_fatal(_("cannot use non-ELF output format with dynamic object %s"),

               (*input_objects->dynobj_begin())->name().c_str());

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

    {

      Input_objects::Relobj_iterator p = input_objects->relobj_begin();

      if (p != input_objects->relobj_end())

        {

          bool uses_split_stack = (*p)->uses_split_stack();

          for (++p; p != input_objects->relobj_end(); ++p)

            {

              if ((*p)->uses_split_stack() != uses_split_stack)

                gold_fatal(_("cannot mix split-stack '%s' and "

                             "non-split-stack '%s' when using -r"),

                           (*input_objects->relobj_begin())->name().c_str(),

                           (*p)->name().c_str());

            }

        }

    }

  // For incremental updates, record the existing GOT and PLT entries,

  // and the COPY relocations.

  if (parameters->incremental_update())

    {

      Incremental_binary* ibase = layout->incremental_base();

      ibase->process_got_plt(symtab, layout);

      ibase->emit_copy_relocs(symtab);

    }

  if (is_debugging_enabled(DEBUG_SCRIPT))

    layout->script_options()->print(stderr);

  // For each dynamic object, record whether we've seen all the

  // dynamic objects that it depends upon.

  input_objects->check_dynamic_dependencies();

  // See if any of the input definitions violate the One Definition Rule.

  // TODO: if this is too slow, do this as a task, rather than inline.

  symtab->detect_odr_violations(task, options.output_file_name());

  // Do the --no-undefined-version check.

  if (!parameters->options().undefined_version())

    {

      Script_options* so = layout->script_options();

      so->version_script_info()->check_unmatched_names(symtab);

    }

  // Create any automatic note sections.

  layout->create_notes();

  // Create any output sections required by any linker script.