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// dirsearch.cc -- directory searching for gold

// Copyright 2006, 2007, 2008 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 <cerrno>

#include <cstring>

#include <sys/types.h>

#include <dirent.h>

#include "debug.h"

#include "gold-threads.h"

#include "options.h"

#include "workqueue.h"

#include "dirsearch.h"

namespace

{

// Read all the files in a directory.

class Dir_cache

{

 public:

  Dir_cache(const char* dirname)

    : dirname_(dirname), files_()

  { }

  // Read the files in the directory.

  void read_files();

  // Return whether a file (a base name) is present in the directory.

  bool find(const std::string&) const;

 private:

  // We can not copy this class.

  Dir_cache(const Dir_cache&);

  Dir_cache& operator=(const Dir_cache&);

  const char* dirname_;

  Unordered_set<std::string> files_;

};

void

Dir_cache::read_files()

{

  DIR* d = opendir(this->dirname_);

  if (d == NULL)

    {

      // We ignore directories which do not exist.

      if (errno != ENOENT)

        gold::gold_error(_("%s: can not read directory: %s"),

                         this->dirname_, strerror(errno));

      return;

    }

  dirent* de;

  while ((de = readdir(d)) != NULL)

    this->files_.insert(std::string(de->d_name));

  if (closedir(d) != 0)

    gold::gold_warning("%s: closedir failed: %s", this->dirname_,

                       strerror(errno));

}

bool

Dir_cache::find(const std::string& basename) const

{

  return this->files_.find(basename) != this->files_.end();

}

// A mapping from directory names to caches.  A lock permits

// concurrent update.  There is no lock for read operations--some

// other mechanism must be used to prevent reads from conflicting with

// writes.

class Dir_caches

{

 public:

  Dir_caches()

    : lock_(), caches_()

  { }

  ~Dir_caches();

  // Add a cache for a directory.

  void add(const char*);

  // Look up a directory in the cache.  This much be locked against

  // calls to Add.

  Dir_cache* lookup(const char*) const;

 private:

  // We can not copy this class.

  Dir_caches(const Dir_caches&);

  Dir_caches& operator=(const Dir_caches&);

  typedef Unordered_map<const char*, Dir_cache*> Cache_hash;

  gold::Lock lock_;

  Cache_hash caches_;

};

Dir_caches::~Dir_caches()

{

  for (Cache_hash::iterator p = this->caches_.begin();

       p != this->caches_.end();

       ++p)

    delete p->second;

}

void

Dir_caches::add(const char* dirname)

{

  {

    gold::Hold_lock hl(this->lock_);

    if (this->lookup(dirname) != NULL)

      return;

  }

  Dir_cache* cache = new Dir_cache(dirname);

  cache->read_files();

  {

    gold::Hold_lock hl(this->lock_);

    std::pair<const char*, Dir_cache*> v(dirname, cache);

    std::pair<Cache_hash::iterator, bool> p = this->caches_.insert(v);

    gold_assert(p.second);

  }

}

Dir_cache*

Dir_caches::lookup(const char* dirname) const

{

  Cache_hash::const_iterator p = this->caches_.find(dirname);

  if (p == this->caches_.end())

    return NULL;

  return p->second;

}

// The caches.

Dir_caches* caches;

// A Task to read the directory.

class Dir_cache_task : public gold::Task

{

 public:

  Dir_cache_task(const char* dir, gold::Task_token& token)

    : dir_(dir), token_(token)

  { }

  gold::Task_token*

  is_runnable();

  void

  locks(gold::Task_locker*);

  void

  run(gold::Workqueue*);

  std::string

  get_name() const

  { return std::string("Dir_cache_task ") + this->dir_; }

 private:

  const char* dir_;

  gold::Task_token& token_;

};

// We can always run the task to read the directory.

gold::Task_token*

Dir_cache_task::is_runnable()

{

  return NULL;

}

// Return the locks to hold.  We use a blocker lock to prevent file

// lookups from starting until the directory contents have been read.

void

Dir_cache_task::locks(gold::Task_locker* tl)

{

  tl->add(this, &this->token_);

}

// Run the task--read the directory contents.

void

Dir_cache_task::run(gold::Workqueue*)

{

  caches->add(this->dir_);

}

}

namespace gold

{

// Initialize.

void

Dirsearch::initialize(Workqueue* workqueue,

                      const General_options::Dir_list* directories)

{

  gold_assert(caches == NULL);

  caches = new Dir_caches;

  this->directories_ = directories;

  for (General_options::Dir_list::const_iterator p = directories->begin();

       p != directories->end();

       ++p)

    {

      this->token_.add_blocker();

      workqueue->queue(new Dir_cache_task(p->name().c_str(), this->token_));

    }

}

// Search for a file.  NOTE: we only log failed file-lookup attempts

// here.  Successfully lookups will eventually get logged in

// File_read::open.

std::string

Dirsearch::find(const std::string& n1, const std::string& n2,

                bool* is_in_sysroot, int* pindex) const

{

  gold_assert(!this->token_.is_blocked());

  gold_assert(*pindex >= 0);

  for (unsigned int i = static_cast<unsigned int>(*pindex);

       i < this->directories_->size();

       ++i)

    {

      const Search_directory* p = &this->directories_->at(i);

      Dir_cache* pdc = caches->lookup(p->name().c_str());

      gold_assert(pdc != NULL);

      if (pdc->find(n1))

        {

          *is_in_sysroot = p->is_in_sysroot();

          *pindex = i;

          return p->name() + '/' + n1;

        }

      else

        gold_debug(DEBUG_FILES, "Attempt to open %s/%s failed",

                   p->name().c_str(), n1.c_str());

      if (!n2.empty())

        {

          if (pdc->find(n2))

            {

              *is_in_sysroot = p->is_in_sysroot();

              *pindex = i;

              return p->name() + '/' + n2;

            }

          else

            gold_debug(DEBUG_FILES, "Attempt to open %s/%s failed",

                       p->name().c_str(), n2.c_str());

        }

    }

  *pindex = -2;

  return std::string();

}

} // End namespace gold.