gold/fileread.cc

   1 // fileread.cc -- read files for gold
   2
   3 #include "gold.h"
   4
   5 #include <cassert>
   6 #include <cstring>
   7 #include <cerrno>
   8 #include <fcntl.h>
   9 #include <unistd.h>
  10
  11 #include "options.h"
  12 #include "dirsearch.h"
  13 #include "fileread.h"
  14
  15 namespace gold
  16 {
  17
  18 // Class File_read::View.
  19
  20 File_read::View::~View()
  21 {
  22   assert(!this->is_locked());
  23   delete[] this->data_;
  24 }
  25
  26 void
  27 File_read::View::lock()
  28 {
  29   ++this->lock_count_;
  30 }
  31
  32 void
  33 File_read::View::unlock()
  34 {
  35   assert(this->lock_count_ > 0);
  36   --this->lock_count_;
  37 }
  38
  39 bool
  40 File_read::View::is_locked()
  41 {
  42   return this->lock_count_ > 0;
  43 }
  44
  45 // Class File_read.
  46
  47 // The File_read class is designed to support file descriptor caching,
  48 // but this is not currently implemented.
  49
  50 File_read::~File_read()
  51 {
  52   assert(this->lock_count_ == 0);
  53   if (this->descriptor_ >= 0)
  54     {
  55       if (close(this->descriptor_) < 0)
  56         fprintf(stderr, _("%s: warning: close(%s) failed: %s"),
  57                 program_name, this->name_.c_str(), strerror(errno));
  58       this->descriptor_ = -1;
  59     }
  60   this->name_.clear();
  61   this->clear_views(true);
  62 }
  63
  64 bool
  65 File_read::open(const std::string& name)
  66 {
  67   assert(this->lock_count_ == 0
  68          && this->descriptor_ < 0
  69          && this->name_.empty());
  70   this->name_ = name;
  71   this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
  72   ++this->lock_count_;
  73   return this->descriptor_ >= 0;
  74 }
  75
  76 int
  77 File_read::get_descriptor()
  78 {
  79   assert(this->lock_count_ > 0);
  80   return this->descriptor_;
  81 }
  82
  83 void
  84 File_read::lock()
  85 {
  86   ++this->lock_count_;
  87 }
  88
  89 void
  90 File_read::unlock()
  91 {
  92   assert(this->lock_count_ > 0);
  93   --this->lock_count_;
  94 }
  95
  96 bool
  97 File_read::is_locked()
  98 {
  99   return this->lock_count_ > 0;
 100 }
 101
 102 // See if we have a view which covers the file starting at START for
 103 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 104
 105 inline File_read::View*
 106 File_read::find_view(off_t start, off_t size)
 107 {
 108   off_t page = File_read::page_offset(start);
 109   Views::iterator p = this->views_.find(page);
 110   if (p == this->views_.end())
 111     return NULL;
 112   if (p->second->size() - (start - page) < size)
 113     return NULL;
 114   return p->second;
 115 }
 116
 117 // Read data from the file.  Return the number of bytes read.  If
 118 // PBYTES is not NULL, store the number of bytes in *PBYTES, otherwise
 119 // require that we read exactly the number of bytes requested.
 120
 121 off_t
 122 File_read::do_read(off_t start, off_t size, void* p, off_t* pbytes)
 123 {
 124   assert(this->lock_count_ > 0);
 125   int o = this->descriptor_;
 126
 127   if (lseek(o, start, SEEK_SET) < 0)
 128     {
 129       fprintf(stderr, _("%s: %s: lseek to %lld failed: %s"),
 130               program_name, this->filename().c_str(),
 131               static_cast<long long>(start),
 132               strerror(errno));
 133       gold_exit(false);
 134     }
 135
 136   off_t bytes = ::read(o, p, size);
 137   if (bytes < 0)
 138     {
 139       fprintf(stderr, _("%s: %s: read failed: %s\n"),
 140               program_name, this->filename().c_str(), strerror(errno));
 141       gold_exit(false);
 142     }
 143
 144   if (pbytes != NULL)
 145     *pbytes = bytes;
 146   else if (bytes != size)
 147     {
 148       fprintf(stderr,
 149               _("%s: %s: file too short: read only %lld of %lld "
 150                 "bytes at %lld\n"),
 151               program_name, this->filename().c_str(),
 152               static_cast<long long>(bytes),
 153               static_cast<long long>(size),
 154               static_cast<long long>(start));
 155       gold_exit(false);
 156     }
 157
 158   return bytes;
 159 }
 160
 161 void
 162 File_read::read(off_t start, off_t size, void* p, off_t* pbytes)
 163 {
 164   assert(this->lock_count_ > 0);
 165
 166   File_read::View* pv = this->find_view(start, size);
 167   if (pv != NULL)
 168     {
 169       memcpy(p, pv->data() + (start - pv->start()), size);
 170       if (pbytes != NULL)
 171         *pbytes = size;
 172       return;
 173     }
 174
 175   this->do_read(start, size, p, pbytes);
 176 }
 177
 178 // Find an existing view or make a new one.
 179
 180 File_read::View*
 181 File_read::find_or_make_view(off_t start, off_t size, off_t* pbytes)
 182 {
 183   assert(this->lock_count_ > 0);
 184
 185   off_t poff = File_read::page_offset(start);
 186
 187   File_read::View* const vnull = NULL;
 188   std::pair<Views::iterator, bool> ins =
 189     this->views_.insert(std::make_pair(poff, vnull));
 190
 191   if (!ins.second)
 192     {
 193       // There was an existing view at this offset.
 194       File_read::View* v = ins.first->second;
 195       if (v->size() - (start - v->start()) >= size)
 196         {
 197           if (pbytes != NULL)
 198             *pbytes = size;
 199           return v;
 200         }
 201
 202       // This view is not large enough.
 203       this->saved_views_.push_back(v);
 204     }
 205
 206   // We need to read data from the file.
 207
 208   off_t psize = File_read::pages(size + (start - poff));
 209   unsigned char* p = new unsigned char[psize];
 210
 211   off_t got_bytes;
 212   off_t bytes = this->do_read(poff, psize, p, &got_bytes);
 213
 214   File_read::View* v = new File_read::View(poff, bytes, p);
 215
 216   ins.first->second = v;
 217
 218   if (bytes - (start - poff) >= size)
 219     {
 220       if (pbytes != NULL)
 221         *pbytes = size;
 222       return v;
 223     }
 224
 225   if (pbytes != NULL)
 226     {
 227       *pbytes = bytes - (start - poff);
 228       return v;
 229     }
 230
 231   fprintf(stderr,
 232           _("%s: %s: file too short: read only %lld of %lld bytes at %lld\n"),
 233           program_name, this->filename().c_str(),
 234           static_cast<long long>(bytes - (start - poff)),
 235           static_cast<long long>(size),
 236           static_cast<long long>(start));
 237   gold_exit(false);
 238 }
 239
 240 // This implementation of get_view just reads into a memory buffer,
 241 // which we store on view_list_.  At some point we should support
 242 // mmap.
 243
 244 const unsigned char*
 245 File_read::get_view(off_t start, off_t size, off_t* pbytes)
 246 {
 247   assert(this->lock_count_ > 0);
 248   File_read::View* pv = this->find_or_make_view(start, size, pbytes);
 249   return pv->data() + (start - pv->start());
 250 }
 251
 252 File_view*
 253 File_read::get_lasting_view(off_t start, off_t size, off_t* pbytes)
 254 {
 255   assert(this->lock_count_ > 0);
 256   File_read::View* pv = this->find_or_make_view(start, size, pbytes);
 257   pv->lock();
 258   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 259 }
 260
 261 // Remove all the file views.
 262
 263 void
 264 File_read::clear_views(bool destroying)
 265 {
 266   for (Views::iterator p = this->views_.begin();
 267        p != this->views_.end();
 268        ++p)
 269     {
 270       if (!p->second->is_locked())
 271         delete p->second;
 272       else
 273         {
 274           assert(!destroying);
 275           this->saved_views_.push_back(p->second);
 276         }
 277     }
 278   this->views_.clear();
 279
 280   Saved_views::iterator p = this->saved_views_.begin();
 281   while (p != this->saved_views_.end())
 282     {
 283       if (!(*p)->is_locked())
 284         {
 285           delete *p;
 286           p = this->saved_views_.erase(p);
 287         }
 288       else
 289         {
 290           assert(!destroying);
 291           ++p;
 292         }
 293     }
 294 }
 295
 296 // Class File_view.
 297
 298 File_view::~File_view()
 299 {
 300   assert(this->file_.is_locked());
 301   this->view_->unlock();
 302 }
 303
 304 // Class Input_file.
 305
 306 void
 307 Input_file::open(const General_options& options, const Dirsearch& dirpath)
 308 {
 309   std::string name;
 310   if (!this->input_argument_.is_lib())
 311     name = this->input_argument_.name();
 312   else
 313     {
 314       std::string n1("lib");
 315       n1 += this->input_argument_.name();
 316       std::string n2;
 317       if (!options.is_static())
 318         n2 = n1 + ".so";
 319       n1 += ".a";
 320       name = dirpath.find(n1, n2);
 321       if (name.empty())
 322         {
 323           fprintf(stderr, _("%s: cannot find %s\n"), program_name,
 324                   this->input_argument_.name());
 325           gold_exit(false);
 326         }
 327     }
 328
 329   if (!this->file_.open(name))
 330     {
 331       fprintf(stderr, _("%s: cannot open %s: %s\n"), program_name,
 332               name.c_str(), strerror(errno));
 333       gold_exit(false);
 334     }
 335 }
 336
 337 } // End namespace gold.