gold/dirsearch.cc

   1 // dirsearch.cc -- directory searching for gold
   2
   3 #include "gold.h"
   4
   5 #include <cerrno>
   6 #include <sys/types.h>
   7 #include <dirent.h>
   8
   9 #include "gold-threads.h"
  10 #include "dirsearch.h"
  11
  12 namespace
  13 {
  14
  15 // Read all the files in a directory.
  16
  17 class Dir_cache
  18 {
  19  public:
  20   Dir_cache(const char* dirname)
  21     : dirname_(dirname), files_()
  22   { }
  23
  24   // Read the files in the directory.
  25   void read_files();
  26
  27   // Return whether a file (a base name) is present in the directory.
  28   bool find(const std::string&) const;
  29
  30  private:
  31   // We can not copy this class.
  32   Dir_cache(const Dir_cache&);
  33   Dir_cache& operator=(const Dir_cache&);
  34
  35   const char* dirname_;
  36   Unordered_set<std::string> files_;
  37 };
  38
  39 void
  40 Dir_cache::read_files()
  41 {
  42   DIR* d = opendir(this->dirname_);
  43   if (d == NULL)
  44     {
  45       // We ignore directories which do not exist.
  46       if (errno == ENOENT)
  47         return;
  48
  49       char *s = NULL;
  50       if (asprintf(&s, _("can not read directory %s"), this->dirname_) < 0)
  51         gold::gold_nomem();
  52       gold::gold_fatal(s, true);
  53     }
  54
  55   dirent* de;
  56   while ((de = readdir(d)) != NULL)
  57     this->files_.insert(std::string(de->d_name));
  58
  59   if (closedir(d) != 0)
  60     gold::gold_fatal("closedir failed", true);
  61 }
  62
  63 bool
  64 Dir_cache::find(const std::string& basename) const
  65 {
  66   return this->files_.find(basename) != this->files_.end();
  67 }
  68
  69 // A mapping from directory names to caches.  A lock permits
  70 // concurrent update.  There is no lock for read operations--some
  71 // other mechanism must be used to prevent reads from conflicting with
  72 // writes.
  73
  74 class Dir_caches
  75 {
  76  public:
  77   Dir_caches()
  78     : lock_(), caches_()
  79   { }
  80
  81   ~Dir_caches();
  82
  83   // Add a cache for a directory.
  84   void add(const char*);
  85
  86   // Look up a directory in the cache.  This much be locked against
  87   // calls to Add.
  88   Dir_cache* lookup(const char*) const;
  89
  90  private:
  91   // We can not copy this class.
  92   Dir_caches(const Dir_caches&);
  93   Dir_caches& operator=(const Dir_caches&);
  94
  95   typedef Unordered_map<const char*, Dir_cache*> Cache_hash;
  96
  97   gold::Lock lock_;
  98   Cache_hash caches_;
  99 };
 100
 101 Dir_caches::~Dir_caches()
 102 {
 103   for (Cache_hash::iterator p = this->caches_.begin();
 104        p != this->caches_.end();
 105        ++p)
 106     delete p->second;
 107 }
 108
 109 void
 110 Dir_caches::add(const char* dirname)
 111 {
 112   {
 113     gold::Hold_lock hl(this->lock_);
 114     if (this->lookup(dirname) != NULL)
 115       return;
 116   }
 117
 118   Dir_cache* cache = new Dir_cache(dirname);
 119
 120   cache->read_files();
 121
 122   {
 123     gold::Hold_lock hl(this->lock_);
 124
 125     std::pair<const char*, Dir_cache*> v(dirname, cache);
 126     std::pair<Cache_hash::iterator, bool> p = this->caches_.insert(v);
 127     assert(p.second);
 128   }
 129 }
 130
 131 Dir_cache*
 132 Dir_caches::lookup(const char* dirname) const
 133 {
 134   Cache_hash::const_iterator p = this->caches_.find(dirname);
 135   if (p == this->caches_.end())
 136     return NULL;
 137   return p->second;
 138 }
 139
 140 // The caches.
 141
 142 Dir_caches caches;
 143
 144 // A Task to read the directory.
 145
 146 class Dir_cache_task : public gold::Task
 147 {
 148  public:
 149   Dir_cache_task(const char* dir, gold::Task_token& token)
 150     : dir_(dir), token_(token)
 151   { }
 152
 153   Is_runnable_type is_runnable(gold::Workqueue*);
 154
 155   gold::Task_locker* locks(gold::Workqueue*);
 156
 157   void run(gold::Workqueue*);
 158
 159  private:
 160   const char* dir_;
 161   gold::Task_token& token_;
 162 };
 163
 164 // We can always run the task to read the directory.
 165
 166 gold::Task::Is_runnable_type
 167 Dir_cache_task::is_runnable(gold::Workqueue*)
 168 {
 169   return IS_RUNNABLE;
 170 }
 171
 172 // Return the locks to hold.  We use a blocker lock to prevent file
 173 // lookups from starting until the directory contents have been read.
 174
 175 gold::Task_locker*
 176 Dir_cache_task::locks(gold::Workqueue* workqueue)
 177 {
 178   return new gold::Task_locker_block(this->token_, workqueue);
 179 }
 180
 181 // Run the task--read the directory contents.
 182
 183 void
 184 Dir_cache_task::run(gold::Workqueue*)
 185 {
 186   caches.add(this->dir_);
 187 }
 188
 189 }
 190
 191 namespace gold
 192 {
 193
 194 Dirsearch::Dirsearch()
 195   : directories_(), token_()
 196 {
 197 }
 198
 199 void
 200 Dirsearch::add(Workqueue* workqueue, const char* d)
 201 {
 202   this->directories_.push_back(d);
 203   this->token_.add_blocker();
 204   workqueue->queue(new Dir_cache_task(d, this->token_));
 205 }
 206
 207 void
 208 Dirsearch::add(Workqueue* workqueue, const General_options::Dir_list& list)
 209 {
 210   for (General_options::Dir_list::const_iterator p = list.begin();
 211        p != list.end();
 212        ++p)
 213     this->add(workqueue, *p);
 214 }
 215
 216 std::string
 217 Dirsearch::find(const std::string& n1, const std::string& n2) const
 218 {
 219   assert(!this->token_.is_blocked());
 220
 221   for (std::list<const char*>::const_iterator p = this->directories_.begin();
 222        p != this->directories_.end();
 223        ++p)
 224     {
 225       Dir_cache* pdc = caches.lookup(*p);
 226       assert(pdc != NULL);
 227       if (pdc->find(n1))
 228         return std::string(*p) + '/' + n1;
 229       if (!n2.empty() && pdc->find(n2))
 230         return std::string(*p) + '/' + n2;
 231     }
 232
 233   return std::string();
 234 }
 235
 236 } // End namespace gold.