gold/dirsearch.cc

   1 // dirsearch.cc -- directory searching 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 <cerrno>
  26 #include <sys/types.h>
  27 #include <dirent.h>
  28
  29 #include "gold-threads.h"
  30 #include "dirsearch.h"
  31
  32 namespace
  33 {
  34
  35 // Read all the files in a directory.
  36
  37 class Dir_cache
  38 {
  39  public:
  40   Dir_cache(const char* dirname)
  41     : dirname_(dirname), files_()
  42   { }
  43
  44   // Read the files in the directory.
  45   void read_files();
  46
  47   // Return whether a file (a base name) is present in the directory.
  48   bool find(const std::string&) const;
  49
  50  private:
  51   // We can not copy this class.
  52   Dir_cache(const Dir_cache&);
  53   Dir_cache& operator=(const Dir_cache&);
  54
  55   const char* dirname_;
  56   Unordered_set<std::string> files_;
  57 };
  58
  59 void
  60 Dir_cache::read_files()
  61 {
  62   DIR* d = opendir(this->dirname_);
  63   if (d == NULL)
  64     {
  65       // We ignore directories which do not exist.
  66       if (errno == ENOENT)
  67         return;
  68
  69       char *s = NULL;
  70       if (asprintf(&s, _("can not read directory %s"), this->dirname_) < 0)
  71         gold::gold_nomem();
  72       gold::gold_fatal(s, true);
  73     }
  74
  75   dirent* de;
  76   while ((de = readdir(d)) != NULL)
  77     this->files_.insert(std::string(de->d_name));
  78
  79   if (closedir(d) != 0)
  80     gold::gold_fatal("closedir failed", true);
  81 }
  82
  83 bool
  84 Dir_cache::find(const std::string& basename) const
  85 {
  86   return this->files_.find(basename) != this->files_.end();
  87 }
  88
  89 // A mapping from directory names to caches.  A lock permits
  90 // concurrent update.  There is no lock for read operations--some
  91 // other mechanism must be used to prevent reads from conflicting with
  92 // writes.
  93
  94 class Dir_caches
  95 {
  96  public:
  97   Dir_caches()
  98     : lock_(), caches_()
  99   { }
 100
 101   ~Dir_caches();
 102
 103   // Add a cache for a directory.
 104   void add(const char*);
 105
 106   // Look up a directory in the cache.  This much be locked against
 107   // calls to Add.
 108   Dir_cache* lookup(const char*) const;
 109
 110  private:
 111   // We can not copy this class.
 112   Dir_caches(const Dir_caches&);
 113   Dir_caches& operator=(const Dir_caches&);
 114
 115   typedef Unordered_map<const char*, Dir_cache*> Cache_hash;
 116
 117   gold::Lock lock_;
 118   Cache_hash caches_;
 119 };
 120
 121 Dir_caches::~Dir_caches()
 122 {
 123   for (Cache_hash::iterator p = this->caches_.begin();
 124        p != this->caches_.end();
 125        ++p)
 126     delete p->second;
 127 }
 128
 129 void
 130 Dir_caches::add(const char* dirname)
 131 {
 132   {
 133     gold::Hold_lock hl(this->lock_);
 134     if (this->lookup(dirname) != NULL)
 135       return;
 136   }
 137
 138   Dir_cache* cache = new Dir_cache(dirname);
 139
 140   cache->read_files();
 141
 142   {
 143     gold::Hold_lock hl(this->lock_);
 144
 145     std::pair<const char*, Dir_cache*> v(dirname, cache);
 146     std::pair<Cache_hash::iterator, bool> p = this->caches_.insert(v);
 147     gold_assert(p.second);
 148   }
 149 }
 150
 151 Dir_cache*
 152 Dir_caches::lookup(const char* dirname) const
 153 {
 154   Cache_hash::const_iterator p = this->caches_.find(dirname);
 155   if (p == this->caches_.end())
 156     return NULL;
 157   return p->second;
 158 }
 159
 160 // The caches.
 161
 162 Dir_caches caches;
 163
 164 // A Task to read the directory.
 165
 166 class Dir_cache_task : public gold::Task
 167 {
 168  public:
 169   Dir_cache_task(const char* dir, gold::Task_token& token)
 170     : dir_(dir), token_(token)
 171   { }
 172
 173   Is_runnable_type is_runnable(gold::Workqueue*);
 174
 175   gold::Task_locker* locks(gold::Workqueue*);
 176
 177   void run(gold::Workqueue*);
 178
 179  private:
 180   const char* dir_;
 181   gold::Task_token& token_;
 182 };
 183
 184 // We can always run the task to read the directory.
 185
 186 gold::Task::Is_runnable_type
 187 Dir_cache_task::is_runnable(gold::Workqueue*)
 188 {
 189   return IS_RUNNABLE;
 190 }
 191
 192 // Return the locks to hold.  We use a blocker lock to prevent file
 193 // lookups from starting until the directory contents have been read.
 194
 195 gold::Task_locker*
 196 Dir_cache_task::locks(gold::Workqueue* workqueue)
 197 {
 198   return new gold::Task_locker_block(this->token_, workqueue);
 199 }
 200
 201 // Run the task--read the directory contents.
 202
 203 void
 204 Dir_cache_task::run(gold::Workqueue*)
 205 {
 206   caches.add(this->dir_);
 207 }
 208
 209 }
 210
 211 namespace gold
 212 {
 213
 214 Dirsearch::Dirsearch()
 215   : directories_(), token_()
 216 {
 217 }
 218
 219 void
 220 Dirsearch::add(Workqueue* workqueue, const char* d)
 221 {
 222   this->directories_.push_back(d);
 223   this->token_.add_blocker();
 224   workqueue->queue(new Dir_cache_task(d, this->token_));
 225 }
 226
 227 void
 228 Dirsearch::add(Workqueue* workqueue, const General_options::Dir_list& list)
 229 {
 230   for (General_options::Dir_list::const_iterator p = list.begin();
 231        p != list.end();
 232        ++p)
 233     this->add(workqueue, *p);
 234 }
 235
 236 std::string
 237 Dirsearch::find(const std::string& n1, const std::string& n2) const
 238 {
 239   gold_assert(!this->token_.is_blocked());
 240
 241   for (std::list<const char*>::const_iterator p = this->directories_.begin();
 242        p != this->directories_.end();
 243        ++p)
 244     {
 245       Dir_cache* pdc = caches.lookup(*p);
 246       gold_assert(pdc != NULL);
 247       if (pdc->find(n1))
 248         return std::string(*p) + '/' + n1;
 249       if (!n2.empty() && pdc->find(n2))
 250         return std::string(*p) + '/' + n2;
 251     }
 252
 253   return std::string();
 254 }
 255
 256 } // End namespace gold.