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 <sys/uio.h>
  31 #include "filenames.h"
  32
  33 #include "options.h"
  34 #include "dirsearch.h"
  35 #include "fileread.h"
  36
  37 namespace gold
  38 {
  39
  40 // Class File_read::View.
  41
  42 File_read::View::~View()
  43 {
  44   gold_assert(!this->is_locked());
  45   if (!this->mapped_)
  46     delete[] this->data_;
  47   else
  48     {
  49       if (::munmap(const_cast<unsigned char*>(this->data_), this->size_) != 0)
  50         gold_warning(_("munmap failed: %s"), strerror(errno));
  51
  52       File_read::current_mapped_bytes -= this->size_;
  53     }
  54 }
  55
  56 void
  57 File_read::View::lock()
  58 {
  59   ++this->lock_count_;
  60 }
  61
  62 void
  63 File_read::View::unlock()
  64 {
  65   gold_assert(this->lock_count_ > 0);
  66   --this->lock_count_;
  67 }
  68
  69 bool
  70 File_read::View::is_locked()
  71 {
  72   return this->lock_count_ > 0;
  73 }
  74
  75 // Class File_read.
  76
  77 // The File_read static variables.
  78 unsigned long long File_read::total_mapped_bytes;
  79 unsigned long long File_read::current_mapped_bytes;
  80 unsigned long long File_read::maximum_mapped_bytes;
  81
  82 // The File_read class is designed to support file descriptor caching,
  83 // but this is not currently implemented.
  84
  85 File_read::~File_read()
  86 {
  87   gold_assert(this->token_.is_writable());
  88   if (this->descriptor_ >= 0)
  89     {
  90       if (close(this->descriptor_) < 0)
  91         gold_warning(_("close of %s failed: %s"),
  92                      this->name_.c_str(), strerror(errno));
  93       this->descriptor_ = -1;
  94     }
  95   this->name_.clear();
  96   this->clear_views(true);
  97 }
  98
  99 // Open the file.
 100
 101 bool
 102 File_read::open(const Task* task, const std::string& name)
 103 {
 104   gold_assert(this->token_.is_writable()
 105               && this->descriptor_ < 0
 106               && this->name_.empty());
 107   this->name_ = name;
 108
 109   this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
 110
 111   if (this->descriptor_ >= 0)
 112     {
 113       struct stat s;
 114       if (::fstat(this->descriptor_, &s) < 0)
 115         gold_error(_("%s: fstat failed: %s"),
 116                    this->name_.c_str(), strerror(errno));
 117       this->size_ = s.st_size;
 118     }
 119
 120   this->token_.add_writer(task);
 121
 122   return this->descriptor_ >= 0;
 123 }
 124
 125 // Open the file for testing purposes.
 126
 127 bool
 128 File_read::open(const Task* task, const std::string& name,
 129                 const unsigned char* contents, off_t size)
 130 {
 131   gold_assert(this->token_.is_writable()
 132               && this->descriptor_ < 0
 133               && this->name_.empty());
 134   this->name_ = name;
 135   this->contents_ = contents;
 136   this->size_ = size;
 137   this->token_.add_writer(task);
 138   return true;
 139 }
 140
 141 // Release the file.  This is called when we are done with the file in
 142 // a Task.
 143
 144 void
 145 File_read::release()
 146 {
 147   gold_assert(this->is_locked());
 148
 149   File_read::total_mapped_bytes += this->mapped_bytes_;
 150   File_read::current_mapped_bytes += this->mapped_bytes_;
 151   this->mapped_bytes_ = 0;
 152   if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)
 153     File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;
 154
 155   this->clear_views(false);
 156
 157   this->released_ = true;
 158 }
 159
 160 // Lock the file.
 161
 162 void
 163 File_read::lock(const Task* task)
 164 {
 165   gold_assert(this->released_);
 166   this->token_.add_writer(task);
 167   this->released_ = false;
 168 }
 169
 170 // Unlock the file.
 171
 172 void
 173 File_read::unlock(const Task* task)
 174 {
 175   this->release();
 176   this->token_.remove_writer(task);
 177 }
 178
 179 // Return whether the file is locked.
 180
 181 bool
 182 File_read::is_locked() const
 183 {
 184   if (!this->token_.is_writable())
 185     return true;
 186   // The file is not locked, so it should have been released.
 187   gold_assert(this->released_);
 188   return false;
 189 }
 190
 191 // See if we have a view which covers the file starting at START for
 192 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 193
 194 inline File_read::View*
 195 File_read::find_view(off_t start, section_size_type size) const
 196 {
 197   off_t page = File_read::page_offset(start);
 198
 199   Views::const_iterator p = this->views_.lower_bound(page);
 200   if (p == this->views_.end() || p->first > page)
 201     {
 202       if (p == this->views_.begin())
 203         return NULL;
 204       --p;
 205     }
 206
 207   if (p->second->start() + static_cast<off_t>(p->second->size())
 208       < start + static_cast<off_t>(size))
 209     return NULL;
 210
 211   p->second->set_accessed();
 212
 213   return p->second;
 214 }
 215
 216 // Read SIZE bytes from the file starting at offset START.  Read into
 217 // the buffer at P.
 218
 219 void
 220 File_read::do_read(off_t start, section_size_type size, void* p) const
 221 {
 222   ssize_t bytes;
 223   if (this->contents_ != NULL)
 224     {
 225       bytes = this->size_ - start;
 226       if (static_cast<section_size_type>(bytes) >= size)
 227         {
 228           memcpy(p, this->contents_ + start, size);
 229           return;
 230         }
 231     }
 232   else
 233     {
 234       bytes = ::pread(this->descriptor_, p, size, start);
 235       if (static_cast<section_size_type>(bytes) == size)
 236         return;
 237
 238       if (bytes < 0)
 239         {
 240           gold_fatal(_("%s: pread failed: %s"),
 241                      this->filename().c_str(), strerror(errno));
 242           return;
 243         }
 244     }
 245
 246   gold_fatal(_("%s: file too short: read only %lld of %lld bytes at %lld"),
 247              this->filename().c_str(),
 248              static_cast<long long>(bytes),
 249              static_cast<long long>(size),
 250              static_cast<long long>(start));
 251 }
 252
 253 // Read data from the file.
 254
 255 void
 256 File_read::read(off_t start, section_size_type size, void* p) const
 257 {
 258   const File_read::View* pv = this->find_view(start, size);
 259   if (pv != NULL)
 260     {
 261       memcpy(p, pv->data() + (start - pv->start()), size);
 262       return;
 263     }
 264
 265   this->do_read(start, size, p);
 266 }
 267
 268 // Find an existing view or make a new one.
 269
 270 File_read::View*
 271 File_read::find_or_make_view(off_t start, section_size_type size, bool cache)
 272 {
 273   gold_assert(!this->token_.is_writable());
 274   this->released_ = false;
 275
 276   File_read::View* v = this->find_view(start, size);
 277   if (v != NULL)
 278     {
 279       if (cache)
 280         v->set_cache();
 281       return v;
 282     }
 283
 284   off_t poff = File_read::page_offset(start);
 285
 286   File_read::View* const vnull = NULL;
 287   std::pair<Views::iterator, bool> ins =
 288     this->views_.insert(std::make_pair(poff, vnull));
 289
 290   if (!ins.second)
 291     {
 292       // There was an existing view at this offset.  It must not be
 293       // large enough.  We can't delete it here, since something might
 294       // be using it; put it on a list to be deleted when the file is
 295       // unlocked.
 296       v = ins.first->second;
 297       gold_assert(v->size() - (start - v->start()) < size);
 298       if (v->should_cache())
 299         cache = true;
 300       v->clear_cache();
 301       this->saved_views_.push_back(v);
 302     }
 303
 304   // We need to map data from the file.
 305
 306   section_size_type psize = File_read::pages(size + (start - poff));
 307
 308   if (poff + static_cast<off_t>(psize) >= this->size_)
 309     {
 310       psize = this->size_ - poff;
 311       gold_assert(psize >= size);
 312     }
 313
 314   if (this->contents_ != NULL)
 315     {
 316       unsigned char* p = new unsigned char[psize];
 317       this->do_read(poff, psize, p);
 318       v = new File_read::View(poff, psize, p, cache, false);
 319     }
 320   else
 321     {
 322       void* p = ::mmap(NULL, psize, PROT_READ, MAP_PRIVATE,
 323                        this->descriptor_, poff);
 324       if (p == MAP_FAILED)
 325         gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),
 326                    this->filename().c_str(),
 327                    static_cast<long long>(poff),
 328                    static_cast<long long>(psize),
 329                    strerror(errno));
 330
 331       this->mapped_bytes_ += psize;
 332
 333       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 334       v = new File_read::View(poff, psize, pbytes, cache, true);
 335     }
 336
 337   ins.first->second = v;
 338   return v;
 339 }
 340
 341 // Get a view into the file.
 342
 343 const unsigned char*
 344 File_read::get_view(off_t start, section_size_type size, bool cache)
 345 {
 346   File_read::View* pv = this->find_or_make_view(start, size, cache);
 347   return pv->data() + (start - pv->start());
 348 }
 349
 350 File_view*
 351 File_read::get_lasting_view(off_t start, section_size_type size, bool cache)
 352 {
 353   File_read::View* pv = this->find_or_make_view(start, size, cache);
 354   pv->lock();
 355   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 356 }
 357
 358 // Use readv to read COUNT entries from RM starting at START.  BASE
 359 // must be added to all file offsets in RM.
 360
 361 void
 362 File_read::do_readv(off_t base, const Read_multiple& rm, size_t start,
 363                     size_t count)
 364 {
 365   unsigned char discard[File_read::page_size];
 366   iovec iov[File_read::max_readv_entries * 2];
 367   size_t iov_index = 0;
 368
 369   off_t first_offset = rm[start].file_offset;
 370   off_t last_offset = first_offset;
 371   ssize_t want = 0;
 372   for (size_t i = 0; i < count; ++i)
 373     {
 374       const Read_multiple_entry& i_entry(rm[start + i]);
 375
 376       if (i_entry.file_offset > last_offset)
 377         {
 378           size_t skip = i_entry.file_offset - last_offset;
 379           gold_assert(skip <= sizeof discard);
 380
 381           iov[iov_index].iov_base = discard;
 382           iov[iov_index].iov_len = skip;
 383           ++iov_index;
 384
 385           want += skip;
 386         }
 387
 388       iov[iov_index].iov_base = i_entry.buffer;
 389       iov[iov_index].iov_len = i_entry.size;
 390       ++iov_index;
 391
 392       want += i_entry.size;
 393
 394       last_offset = i_entry.file_offset + i_entry.size;
 395     }
 396
 397   gold_assert(iov_index < sizeof iov / sizeof iov[0]);
 398
 399   if (::lseek(this->descriptor_, base + first_offset, SEEK_SET) < 0)
 400     gold_fatal(_("%s: lseek failed: %s"),
 401                this->filename().c_str(), strerror(errno));
 402
 403   ssize_t got = ::readv(this->descriptor_, iov, iov_index);
 404
 405   if (got < 0)
 406     gold_fatal(_("%s: readv failed: %s"),
 407                this->filename().c_str(), strerror(errno));
 408   if (got != want)
 409     gold_fatal(_("%s: file too short: read only %zd of %zd bytes at %lld"),
 410                this->filename().c_str(),
 411                got, want, static_cast<long long>(base + first_offset));
 412 }
 413
 414 // Read several pieces of data from the file.
 415
 416 void
 417 File_read::read_multiple(off_t base, const Read_multiple& rm)
 418 {
 419   size_t count = rm.size();
 420   size_t i = 0;
 421   while (i < count)
 422     {
 423       // Find up to MAX_READV_ENTRIES consecutive entries which are
 424       // less than one page apart.
 425       const Read_multiple_entry& i_entry(rm[i]);
 426       off_t i_off = i_entry.file_offset;
 427       off_t end_off = i_off + i_entry.size;
 428       size_t j;
 429       for (j = i + 1; j < count; ++j)
 430         {
 431           if (j - i >= File_read::max_readv_entries)
 432             break;
 433           const Read_multiple_entry& j_entry(rm[j]);
 434           off_t j_off = j_entry.file_offset;
 435           gold_assert(j_off >= end_off);
 436           off_t j_end_off = j_off + j_entry.size;
 437           if (j_end_off - end_off >= File_read::page_size)
 438             break;
 439           end_off = j_end_off;
 440         }
 441
 442       if (j == i + 1)
 443         this->read(base + i_off, i_entry.size, i_entry.buffer);
 444       else
 445         {
 446           File_read::View* view = this->find_view(base + i_off,
 447                                                   end_off - i_off);
 448           if (view == NULL)
 449             this->do_readv(base, rm, i, j - i);
 450           else
 451             {
 452               const unsigned char* v = (view->data()
 453                                         + (base + i_off - view->start()));
 454               for (size_t k = i; k < j; ++k)
 455                 {
 456                   const Read_multiple_entry& k_entry(rm[k]);
 457                   gold_assert((convert_to_section_size_type(k_entry.file_offset
 458                                                            - i_off)
 459                                + k_entry.size)
 460                               <= convert_to_section_size_type(end_off
 461                                                               - i_off));
 462                   memcpy(k_entry.buffer,
 463                          v + (k_entry.file_offset - i_off),
 464                          k_entry.size);
 465                 }
 466             }
 467         }
 468
 469       i = j;
 470     }
 471 }
 472
 473 // Mark all views as no longer cached.
 474
 475 void
 476 File_read::clear_view_cache_marks()
 477 {
 478   // Just ignore this if there are multiple objects associated with
 479   // the file.  Otherwise we will wind up uncaching and freeing some
 480   // views for other objects.
 481   if (this->object_count_ > 1)
 482     return;
 483
 484   for (Views::iterator p = this->views_.begin();
 485        p != this->views_.end();
 486        ++p)
 487     p->second->clear_cache();
 488   for (Saved_views::iterator p = this->saved_views_.begin();
 489        p != this->saved_views_.end();
 490        ++p)
 491     (*p)->clear_cache();
 492 }
 493
 494 // Remove all the file views.  For a file which has multiple
 495 // associated objects (i.e., an archive), we keep accessed views
 496 // around until next time, in the hopes that they will be useful for
 497 // the next object.
 498
 499 void
 500 File_read::clear_views(bool destroying)
 501 {
 502   Views::iterator p = this->views_.begin();
 503   while (p != this->views_.end())
 504     {
 505       bool should_delete;
 506       if (p->second->is_locked())
 507         should_delete = false;
 508       else if (destroying)
 509         should_delete = true;
 510       else if (p->second->should_cache())
 511         should_delete = false;
 512       else if (this->object_count_ > 1 && p->second->accessed())
 513         should_delete = false;
 514       else
 515         should_delete = true;
 516
 517       if (should_delete)
 518         {
 519           delete p->second;
 520
 521           // map::erase invalidates only the iterator to the deleted
 522           // element.
 523           Views::iterator pe = p;
 524           ++p;
 525           this->views_.erase(pe);
 526         }
 527       else
 528         {
 529           gold_assert(!destroying);
 530           p->second->clear_accessed();
 531           ++p;
 532         }
 533     }
 534
 535   Saved_views::iterator q = this->saved_views_.begin();
 536   while (q != this->saved_views_.end())
 537     {
 538       if (!(*q)->is_locked())
 539         {
 540           delete *q;
 541           q = this->saved_views_.erase(q);
 542         }
 543       else
 544         {
 545           gold_assert(!destroying);
 546           ++q;
 547         }
 548     }
 549 }
 550
 551 // Print statistical information to stderr.  This is used for --stats.
 552
 553 void
 554 File_read::print_stats()
 555 {
 556   fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
 557           program_name, File_read::total_mapped_bytes);
 558   fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
 559           program_name, File_read::maximum_mapped_bytes);
 560 }
 561
 562 // Class File_view.
 563
 564 File_view::~File_view()
 565 {
 566   gold_assert(this->file_.is_locked());
 567   this->view_->unlock();
 568 }
 569
 570 // Class Input_file.
 571
 572 // Create a file for testing.
 573
 574 Input_file::Input_file(const Task* task, const char* name,
 575                        const unsigned char* contents, off_t size)
 576   : file_()
 577 {
 578   this->input_argument_ =
 579     new Input_file_argument(name, false, "", Position_dependent_options());
 580   bool ok = file_.open(task, name, contents, size);
 581   gold_assert(ok);
 582 }
 583
 584 // Open the file.
 585
 586 // If the filename is not absolute, we assume it is in the current
 587 // directory *except* when:
 588 //    A) input_argument_->is_lib() is true; or
 589 //    B) input_argument_->extra_search_path() is not empty.
 590 // In both cases, we look in extra_search_path + library_path to find
 591 // the file location, rather than the current directory.
 592
 593 bool
 594 Input_file::open(const General_options& options, const Dirsearch& dirpath,
 595                  const Task* task)
 596 {
 597   std::string name;
 598
 599   // Case 1: name is an absolute file, just try to open it
 600   // Case 2: name is relative but is_lib is false and extra_search_path
 601   //         is empty
 602   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 603       || (!this->input_argument_->is_lib()
 604           && this->input_argument_->extra_search_path() == NULL))
 605     {
 606       name = this->input_argument_->name();
 607       this->found_name_ = name;
 608     }
 609   // Case 3: is_lib is true
 610   else if (this->input_argument_->is_lib())
 611     {
 612       // We don't yet support extra_search_path with -l.
 613       gold_assert(this->input_argument_->extra_search_path() == NULL);
 614       std::string n1("lib");
 615       n1 += this->input_argument_->name();
 616       std::string n2;
 617       if (options.is_static()
 618           || this->input_argument_->options().do_static_search())
 619         n1 += ".a";
 620       else
 621         {
 622           n2 = n1 + ".a";
 623           n1 += ".so";
 624         }
 625       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 626       if (name.empty())
 627         {
 628           gold_error(_("cannot find -l%s"),
 629                      this->input_argument_->name());
 630           return false;
 631         }
 632       if (n2.empty() || name[name.length() - 1] == 'o')
 633         this->found_name_ = n1;
 634       else
 635         this->found_name_ = n2;
 636     }
 637   // Case 4: extra_search_path is not empty
 638   else
 639     {
 640       gold_assert(this->input_argument_->extra_search_path() != NULL);
 641
 642       // First, check extra_search_path.
 643       name = this->input_argument_->extra_search_path();
 644       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 645         name += '/';
 646       name += this->input_argument_->name();
 647       struct stat dummy_stat;
 648       if (::stat(name.c_str(), &dummy_stat) < 0)
 649         {
 650           // extra_search_path failed, so check the normal search-path.
 651           name = dirpath.find(this->input_argument_->name(), "",
 652                               &this->is_in_sysroot_);
 653           if (name.empty())
 654             {
 655               gold_error(_("cannot find %s"),
 656                          this->input_argument_->name());
 657               return false;
 658             }
 659         }
 660       this->found_name_ = this->input_argument_->name();
 661     }
 662
 663   // Now that we've figured out where the file lives, try to open it.
 664   if (!this->file_.open(task, name))
 665     {
 666       gold_error(_("cannot open %s: %s"),
 667                  name.c_str(), strerror(errno));
 668       return false;
 669     }
 670
 671   return true;
 672 }
 673
 674 } // End namespace gold.