gold/fileread.cc

   1 // fileread.cc -- read files 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 <cstring>
  26 #include <cerrno>
  27 #include <fcntl.h>
  28 #include <unistd.h>
  29 #include <sys/mman.h>
  30 #include "filenames.h"
  31
  32 #include "options.h"
  33 #include "dirsearch.h"
  34 #include "fileread.h"
  35
  36 namespace gold
  37 {
  38
  39 // Class File_read::View.
  40
  41 File_read::View::~View()
  42 {
  43   gold_assert(!this->is_locked());
  44   if (!this->mapped_)
  45     delete[] this->data_;
  46   else
  47     {
  48       if (::munmap(const_cast<unsigned char*>(this->data_), this->size_) != 0)
  49         gold_warning(_("munmap failed: %s"), strerror(errno));
  50
  51       File_read::current_mapped_bytes -= this->size_;
  52     }
  53 }
  54
  55 void
  56 File_read::View::lock()
  57 {
  58   ++this->lock_count_;
  59 }
  60
  61 void
  62 File_read::View::unlock()
  63 {
  64   gold_assert(this->lock_count_ > 0);
  65   --this->lock_count_;
  66 }
  67
  68 bool
  69 File_read::View::is_locked()
  70 {
  71   return this->lock_count_ > 0;
  72 }
  73
  74 // Class File_read.
  75
  76 // The File_read static variables.
  77 unsigned long long File_read::total_mapped_bytes;
  78 unsigned long long File_read::current_mapped_bytes;
  79 unsigned long long File_read::maximum_mapped_bytes;
  80
  81 // The File_read class is designed to support file descriptor caching,
  82 // but this is not currently implemented.
  83
  84 File_read::~File_read()
  85 {
  86   gold_assert(this->token_.is_writable());
  87   if (this->descriptor_ >= 0)
  88     {
  89       if (close(this->descriptor_) < 0)
  90         gold_warning(_("close of %s failed: %s"),
  91                      this->name_.c_str(), strerror(errno));
  92       this->descriptor_ = -1;
  93     }
  94   this->name_.clear();
  95   this->clear_views(true);
  96 }
  97
  98 // Open the file.
  99
 100 bool
 101 File_read::open(const Task* task, const std::string& name)
 102 {
 103   gold_assert(this->token_.is_writable()
 104               && this->descriptor_ < 0
 105               && this->name_.empty());
 106   this->name_ = name;
 107
 108   this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
 109
 110   if (this->descriptor_ >= 0)
 111     {
 112       struct stat s;
 113       if (::fstat(this->descriptor_, &s) < 0)
 114         gold_error(_("%s: fstat failed: %s"),
 115                    this->name_.c_str(), strerror(errno));
 116       this->size_ = s.st_size;
 117     }
 118
 119   this->token_.add_writer(task);
 120
 121   return this->descriptor_ >= 0;
 122 }
 123
 124 // Open the file for testing purposes.
 125
 126 bool
 127 File_read::open(const Task* task, const std::string& name,
 128                 const unsigned char* contents, off_t size)
 129 {
 130   gold_assert(this->token_.is_writable()
 131               && this->descriptor_ < 0
 132               && this->name_.empty());
 133   this->name_ = name;
 134   this->contents_ = contents;
 135   this->size_ = size;
 136   this->token_.add_writer(task);
 137   return true;
 138 }
 139
 140 // Release the file.  This is called when we are done with the file in
 141 // a Task.
 142
 143 void
 144 File_read::release()
 145 {
 146   gold_assert(this->is_locked());
 147
 148   File_read::total_mapped_bytes += this->mapped_bytes_;
 149   File_read::current_mapped_bytes += this->mapped_bytes_;
 150   this->mapped_bytes_ = 0;
 151   if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)
 152     File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;
 153
 154   this->clear_views(false);
 155
 156   this->released_ = true;
 157 }
 158
 159 // Lock the file.
 160
 161 void
 162 File_read::lock(const Task* task)
 163 {
 164   gold_assert(this->released_);
 165   this->token_.add_writer(task);
 166   this->released_ = false;
 167 }
 168
 169 // Unlock the file.
 170
 171 void
 172 File_read::unlock(const Task* task)
 173 {
 174   this->release();
 175   this->token_.remove_writer(task);
 176 }
 177
 178 // Return whether the file is locked.
 179
 180 bool
 181 File_read::is_locked() const
 182 {
 183   if (!this->token_.is_writable())
 184     return true;
 185   // The file is not locked, so it should have been released.
 186   gold_assert(this->released_);
 187   return false;
 188 }
 189
 190 // See if we have a view which covers the file starting at START for
 191 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 192
 193 inline File_read::View*
 194 File_read::find_view(off_t start, section_size_type size) const
 195 {
 196   off_t page = File_read::page_offset(start);
 197   Views::const_iterator p = this->views_.find(page);
 198   if (p == this->views_.end())
 199     return NULL;
 200   if (p->second->size() - (start - page) < size)
 201     return NULL;
 202   return p->second;
 203 }
 204
 205 // Read SIZE bytes from the file starting at offset START.  Read into
 206 // the buffer at P.
 207
 208 void
 209 File_read::do_read(off_t start, section_size_type size, void* p) const
 210 {
 211   ssize_t bytes;
 212   if (this->contents_ != NULL)
 213     {
 214       bytes = this->size_ - start;
 215       if (static_cast<section_size_type>(bytes) >= size)
 216         {
 217           memcpy(p, this->contents_ + start, size);
 218           return;
 219         }
 220     }
 221   else
 222     {
 223       bytes = ::pread(this->descriptor_, p, size, start);
 224       if (static_cast<section_size_type>(bytes) == size)
 225         return;
 226
 227       if (bytes < 0)
 228         {
 229           gold_fatal(_("%s: pread failed: %s"),
 230                      this->filename().c_str(), strerror(errno));
 231           return;
 232         }
 233     }
 234
 235   gold_fatal(_("%s: file too short: read only %lld of %lld bytes at %lld"),
 236              this->filename().c_str(),
 237              static_cast<long long>(bytes),
 238              static_cast<long long>(size),
 239              static_cast<long long>(start));
 240 }
 241
 242 // Read data from the file.
 243
 244 void
 245 File_read::read(off_t start, section_size_type size, void* p) const
 246 {
 247   File_read::View* pv = this->find_view(start, size);
 248   if (pv != NULL)
 249     {
 250       memcpy(p, pv->data() + (start - pv->start()), size);
 251       return;
 252     }
 253
 254   this->do_read(start, size, p);
 255 }
 256
 257 // Find an existing view or make a new one.
 258
 259 File_read::View*
 260 File_read::find_or_make_view(off_t start, section_size_type size, bool cache)
 261 {
 262   gold_assert(!this->token_.is_writable());
 263   this->released_ = false;
 264
 265   off_t poff = File_read::page_offset(start);
 266
 267   File_read::View* const vnull = NULL;
 268   std::pair<Views::iterator, bool> ins =
 269     this->views_.insert(std::make_pair(poff, vnull));
 270
 271   if (!ins.second)
 272     {
 273       // There was an existing view at this offset.
 274       File_read::View* v = ins.first->second;
 275       if (v->size() - (start - v->start()) >= size)
 276         {
 277           if (cache)
 278             v->set_cache();
 279           return v;
 280         }
 281
 282       // This view is not large enough.
 283       this->saved_views_.push_back(v);
 284     }
 285
 286   // We need to read data from the file.  We read full pages for
 287   // greater efficiency on small files.
 288
 289   section_size_type psize = File_read::pages(size + (start - poff));
 290
 291   if (poff + static_cast<off_t>(psize) >= this->size_)
 292     {
 293       psize = this->size_ - poff;
 294       gold_assert(psize >= size);
 295     }
 296
 297   File_read::View* v;
 298
 299   if (this->contents_ != NULL)
 300     {
 301       unsigned char* p = new unsigned char[psize];
 302       this->do_read(poff, psize, p);
 303       v = new File_read::View(poff, psize, p, cache, false);
 304     }
 305   else
 306     {
 307       void* p = ::mmap(NULL, psize, PROT_READ, MAP_SHARED,
 308                        this->descriptor_, poff);
 309       if (p == MAP_FAILED)
 310         gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),
 311                    this->filename().c_str(),
 312                    static_cast<long long>(poff),
 313                    static_cast<long long>(psize),
 314                    strerror(errno));
 315
 316       this->mapped_bytes_ += psize;
 317
 318       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 319       v = new File_read::View(poff, psize, pbytes, cache, true);
 320     }
 321
 322   ins.first->second = v;
 323   return v;
 324 }
 325
 326 // Get a view into the file.
 327
 328 const unsigned char*
 329 File_read::get_view(off_t start, section_size_type size, bool cache)
 330 {
 331   File_read::View* pv = this->find_or_make_view(start, size, cache);
 332   return pv->data() + (start - pv->start());
 333 }
 334
 335 File_view*
 336 File_read::get_lasting_view(off_t start, section_size_type size, bool cache)
 337 {
 338   File_read::View* pv = this->find_or_make_view(start, size, cache);
 339   pv->lock();
 340   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 341 }
 342
 343 // Remove all the file views.
 344
 345 void
 346 File_read::clear_views(bool destroying)
 347 {
 348   Views::iterator p = this->views_.begin();
 349   while (p != this->views_.end())
 350     {
 351       if (!p->second->is_locked()
 352           && (destroying || !p->second->should_cache()))
 353         {
 354           delete p->second;
 355
 356           // map::erase invalidates only the iterator to the deleted
 357           // element.
 358           Views::iterator pe = p;
 359           ++p;
 360           this->views_.erase(pe);
 361         }
 362       else
 363         {
 364           gold_assert(!destroying);
 365           ++p;
 366         }
 367     }
 368
 369   Saved_views::iterator q = this->saved_views_.begin();
 370   while (q != this->saved_views_.end())
 371     {
 372       if (!(*q)->is_locked()
 373           && (destroying || !(*q)->should_cache()))
 374         {
 375           delete *q;
 376           q = this->saved_views_.erase(q);
 377         }
 378       else
 379         {
 380           gold_assert(!destroying);
 381           ++q;
 382         }
 383     }
 384 }
 385
 386 // Print statistical information to stderr.  This is used for --stats.
 387
 388 void
 389 File_read::print_stats()
 390 {
 391   fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
 392           program_name, File_read::total_mapped_bytes);
 393   fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
 394           program_name, File_read::maximum_mapped_bytes);
 395 }
 396
 397 // Class File_view.
 398
 399 File_view::~File_view()
 400 {
 401   gold_assert(this->file_.is_locked());
 402   this->view_->unlock();
 403 }
 404
 405 // Class Input_file.
 406
 407 // Create a file for testing.
 408
 409 Input_file::Input_file(const Task* task, const char* name,
 410                        const unsigned char* contents, off_t size)
 411   : file_()
 412 {
 413   this->input_argument_ =
 414     new Input_file_argument(name, false, "", Position_dependent_options());
 415   bool ok = file_.open(task, name, contents, size);
 416   gold_assert(ok);
 417 }
 418
 419 // Open the file.
 420
 421 // If the filename is not absolute, we assume it is in the current
 422 // directory *except* when:
 423 //    A) input_argument_->is_lib() is true; or
 424 //    B) input_argument_->extra_search_path() is not empty.
 425 // In both cases, we look in extra_search_path + library_path to find
 426 // the file location, rather than the current directory.
 427
 428 bool
 429 Input_file::open(const General_options& options, const Dirsearch& dirpath,
 430                  const Task* task)
 431 {
 432   std::string name;
 433
 434   // Case 1: name is an absolute file, just try to open it
 435   // Case 2: name is relative but is_lib is false and extra_search_path
 436   //         is empty
 437   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 438       || (!this->input_argument_->is_lib()
 439           && this->input_argument_->extra_search_path() == NULL))
 440     {
 441       name = this->input_argument_->name();
 442       this->found_name_ = name;
 443     }
 444   // Case 3: is_lib is true
 445   else if (this->input_argument_->is_lib())
 446     {
 447       // We don't yet support extra_search_path with -l.
 448       gold_assert(this->input_argument_->extra_search_path() == NULL);
 449       std::string n1("lib");
 450       n1 += this->input_argument_->name();
 451       std::string n2;
 452       if (options.is_static()
 453           || this->input_argument_->options().do_static_search())
 454         n1 += ".a";
 455       else
 456         {
 457           n2 = n1 + ".a";
 458           n1 += ".so";
 459         }
 460       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 461       if (name.empty())
 462         {
 463           gold_error(_("cannot find -l%s"),
 464                      this->input_argument_->name());
 465           return false;
 466         }
 467       if (n2.empty() || name[name.length() - 1] == 'o')
 468         this->found_name_ = n1;
 469       else
 470         this->found_name_ = n2;
 471     }
 472   // Case 4: extra_search_path is not empty
 473   else
 474     {
 475       gold_assert(this->input_argument_->extra_search_path() != NULL);
 476
 477       // First, check extra_search_path.
 478       name = this->input_argument_->extra_search_path();
 479       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 480         name += '/';
 481       name += this->input_argument_->name();
 482       struct stat dummy_stat;
 483       if (::stat(name.c_str(), &dummy_stat) < 0)
 484         {
 485           // extra_search_path failed, so check the normal search-path.
 486           name = dirpath.find(this->input_argument_->name(), "",
 487                               &this->is_in_sysroot_);
 488           if (name.empty())
 489             {
 490               gold_error(_("cannot find %s"),
 491                          this->input_argument_->name());
 492               return false;
 493             }
 494         }
 495       this->found_name_ = this->input_argument_->name();
 496     }
 497
 498   // Now that we've figured out where the file lives, try to open it.
 499   if (!this->file_.open(task, name))
 500     {
 501       gold_error(_("cannot open %s: %s"),
 502                  name.c_str(), strerror(errno));
 503       return false;
 504     }
 505
 506   return true;
 507 }
 508
 509 } // End namespace gold.