gold/dirsearch.cc

   1 // dirsearch.cc -- directory searching 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 <cerrno>
  26 #include <cstring>
  27 #include <sys/types.h>
  28 #include <dirent.h>
  29
  30 #include "debug.h"
  31 #include "gold-threads.h"
  32 #include "options.h"
  33 #include "workqueue.h"
  34 #include "dirsearch.h"
  35
  36 namespace
  37 {
  38
  39 // Read all the files in a directory.
  40
  41 class Dir_cache
  42 {
  43  public:
  44   Dir_cache(const char* dirname)
  45     : dirname_(dirname), files_()
  46   { }
  47
  48   // Read the files in the directory.
  49   void read_files();
  50
  51   // Return whether a file (a base name) is present in the directory.
  52   bool find(const std::string&) const;
  53
  54  private:
  55   // We can not copy this class.
  56   Dir_cache(const Dir_cache&);
  57   Dir_cache& operator=(const Dir_cache&);
  58
  59   const char* dirname_;
  60   Unordered_set<std::string> files_;
  61 };
  62
  63 void
  64 Dir_cache::read_files()
  65 {
  66   DIR* d = opendir(this->dirname_);
  67   if (d == NULL)
  68     {
  69       // We ignore directories which do not exist.
  70       if (errno != ENOENT)
  71         gold::gold_error(_("%s: can not read directory: %s"),
  72                          this->dirname_, strerror(errno));
  73       return;
  74     }
  75
  76   dirent* de;
  77   while ((de = readdir(d)) != NULL)
  78     this->files_.insert(std::string(de->d_name));
  79
  80   if (closedir(d) != 0)
  81     gold::gold_warning("%s: closedir failed: %s", this->dirname_,
  82                        strerror(errno));
  83 }
  84
  85 bool
  86 Dir_cache::find(const std::string& basename) const
  87 {
  88   return this->files_.find(basename) != this->files_.end();
  89 }
  90
  91 // A mapping from directory names to caches.  A lock permits
  92 // concurrent update.  There is no lock for read operations--some
  93 // other mechanism must be used to prevent reads from conflicting with
  94 // writes.
  95
  96 class Dir_caches
  97 {
  98  public:
  99   Dir_caches()
 100     : lock_(), caches_()
 101   { }
 102
 103   ~Dir_caches();
 104
 105   // Add a cache for a directory.
 106   void add(const char*);
 107
 108   // Look up a directory in the cache.  This much be locked against
 109   // calls to Add.
 110   Dir_cache* lookup(const char*) const;
 111
 112  private:
 113   // We can not copy this class.
 114   Dir_caches(const Dir_caches&);
 115   Dir_caches& operator=(const Dir_caches&);
 116
 117   typedef Unordered_map<const char*, Dir_cache*> Cache_hash;
 118
 119   gold::Lock lock_;
 120   Cache_hash caches_;
 121 };
 122
 123 Dir_caches::~Dir_caches()
 124 {
 125   for (Cache_hash::iterator p = this->caches_.begin();
 126        p != this->caches_.end();
 127        ++p)
 128     delete p->second;
 129 }
 130
 131 void
 132 Dir_caches::add(const char* dirname)
 133 {
 134   {
 135     gold::Hold_lock hl(this->lock_);
 136     if (this->lookup(dirname) != NULL)
 137       return;
 138   }
 139
 140   Dir_cache* cache = new Dir_cache(dirname);
 141
 142   cache->read_files();
 143
 144   {
 145     gold::Hold_lock hl(this->lock_);
 146
 147     std::pair<const char*, Dir_cache*> v(dirname, cache);
 148     std::pair<Cache_hash::iterator, bool> p = this->caches_.insert(v);
 149     gold_assert(p.second);
 150   }
 151 }
 152
 153 Dir_cache*
 154 Dir_caches::lookup(const char* dirname) const
 155 {
 156   Cache_hash::const_iterator p = this->caches_.find(dirname);
 157   if (p == this->caches_.end())
 158     return NULL;
 159   return p->second;
 160 }
 161
 162 // The caches.
 163
 164 Dir_caches* caches;
 165
 166 // A Task to read the directory.
 167
 168 class Dir_cache_task : public gold::Task
 169 {
 170  public:
 171   Dir_cache_task(const char* dir, gold::Task_token& token)
 172     : dir_(dir), token_(token)
 173   { }
 174
 175   gold::Task_token*
 176   is_runnable();
 177
 178   void
 179   locks(gold::Task_locker*);
 180
 181   void
 182   run(gold::Workqueue*);
 183
 184   std::string
 185   get_name() const
 186   { return std::string("Dir_cache_task ") + this->dir_; }
 187
 188  private:
 189   const char* dir_;
 190   gold::Task_token& token_;
 191 };
 192
 193 // We can always run the task to read the directory.
 194
 195 gold::Task_token*
 196 Dir_cache_task::is_runnable()
 197 {
 198   return NULL;
 199 }
 200
 201 // Return the locks to hold.  We use a blocker lock to prevent file
 202 // lookups from starting until the directory contents have been read.
 203
 204 void
 205 Dir_cache_task::locks(gold::Task_locker* tl)
 206 {
 207   tl->add(this, &this->token_);
 208 }
 209
 210 // Run the task--read the directory contents.
 211
 212 void
 213 Dir_cache_task::run(gold::Workqueue*)
 214 {
 215   caches->add(this->dir_);
 216 }
 217
 218 }
 219
 220 namespace gold
 221 {
 222
 223 void
 224 Dirsearch::initialize(Workqueue* workqueue,
 225                       const General_options::Dir_list* directories)
 226 {
 227   gold_assert(caches == NULL);
 228   caches = new Dir_caches;
 229   this->directories_ = directories;
 230   for (General_options::Dir_list::const_iterator p = directories->begin();
 231        p != directories->end();
 232        ++p)
 233     {
 234       this->token_.add_blocker();
 235       workqueue->queue(new Dir_cache_task(p->name().c_str(), this->token_));
 236     }
 237 }
 238
 239 // NOTE: we only log failed file-lookup attempts here.  Successfully
 240 // lookups will eventually get logged in File_read::open.
 241
 242 std::string
 243 Dirsearch::find(const std::string& n1, const std::string& n2,
 244                 bool *is_in_sysroot) const
 245 {
 246   gold_assert(!this->token_.is_blocked());
 247
 248   for (General_options::Dir_list::const_iterator p =
 249          this->directories_->begin();
 250        p != this->directories_->end();
 251        ++p)
 252     {
 253       Dir_cache* pdc = caches->lookup(p->name().c_str());
 254       gold_assert(pdc != NULL);
 255       if (pdc->find(n1))
 256         {
 257           *is_in_sysroot = p->is_in_sysroot();
 258           return p->name() + '/' + n1;
 259         }
 260       else
 261         gold_debug(DEBUG_FILES, "Attempt to open %s/%s failed",
 262                    p->name().c_str(), n1.c_str());
 263
 264       if (!n2.empty())
 265         {
 266           if (pdc->find(n2))
 267             {
 268               *is_in_sysroot = p->is_in_sysroot();
 269               return p->name() + '/' + n2;
 270             }
 271           else
 272             gold_debug(DEBUG_FILES, "Attempt to open %s/%s failed",
 273                        p->name().c_str(), n2.c_str());
 274         }
 275     }
 276
 277   return std::string();
 278 }
 279
 280 } // End namespace gold.