gold/fileread.cc

   1 // fileread.cc -- read files 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 <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 "debug.h"
  34 #include "parameters.h"
  35 #include "options.h"
  36 #include "dirsearch.h"
  37 #include "target.h"
  38 #include "binary.h"
  39 #include "fileread.h"
  40
  41 namespace gold
  42 {
  43
  44 // Class File_read::View.
  45
  46 File_read::View::~View()
  47 {
  48   gold_assert(!this->is_locked());
  49   if (!this->mapped_)
  50     delete[] this->data_;
  51   else
  52     {
  53       if (::munmap(const_cast<unsigned char*>(this->data_), this->size_) != 0)
  54         gold_warning(_("munmap failed: %s"), strerror(errno));
  55
  56       File_read::current_mapped_bytes -= this->size_;
  57     }
  58 }
  59
  60 void
  61 File_read::View::lock()
  62 {
  63   ++this->lock_count_;
  64 }
  65
  66 void
  67 File_read::View::unlock()
  68 {
  69   gold_assert(this->lock_count_ > 0);
  70   --this->lock_count_;
  71 }
  72
  73 bool
  74 File_read::View::is_locked()
  75 {
  76   return this->lock_count_ > 0;
  77 }
  78
  79 // Class File_read.
  80
  81 // The File_read static variables.
  82 unsigned long long File_read::total_mapped_bytes;
  83 unsigned long long File_read::current_mapped_bytes;
  84 unsigned long long File_read::maximum_mapped_bytes;
  85
  86 // The File_read class is designed to support file descriptor caching,
  87 // but this is not currently implemented.
  88
  89 File_read::~File_read()
  90 {
  91   gold_assert(this->token_.is_writable());
  92   if (this->descriptor_ >= 0)
  93     {
  94       if (close(this->descriptor_) < 0)
  95         gold_warning(_("close of %s failed: %s"),
  96                      this->name_.c_str(), strerror(errno));
  97       this->descriptor_ = -1;
  98     }
  99   this->name_.clear();
 100   this->clear_views(true);
 101 }
 102
 103 // Open the file.
 104
 105 bool
 106 File_read::open(const Task* task, const std::string& name)
 107 {
 108   gold_assert(this->token_.is_writable()
 109               && this->descriptor_ < 0
 110               && this->name_.empty());
 111   this->name_ = name;
 112
 113   this->descriptor_ = ::open(this->name_.c_str(), O_RDONLY);
 114
 115   if (this->descriptor_ >= 0)
 116     {
 117       struct stat s;
 118       if (::fstat(this->descriptor_, &s) < 0)
 119         gold_error(_("%s: fstat failed: %s"),
 120                    this->name_.c_str(), strerror(errno));
 121       this->size_ = s.st_size;
 122       gold_debug(DEBUG_FILES, "Attempt to open %s succeeded",
 123                  this->name_.c_str());
 124     }
 125
 126   this->token_.add_writer(task);
 127
 128   return this->descriptor_ >= 0;
 129 }
 130
 131 // Open the file with the contents in memory.
 132
 133 bool
 134 File_read::open(const Task* task, const std::string& name,
 135                 const unsigned char* contents, off_t size)
 136 {
 137   gold_assert(this->token_.is_writable()
 138               && this->descriptor_ < 0
 139               && this->name_.empty());
 140   this->name_ = name;
 141   this->contents_ = contents;
 142   this->size_ = size;
 143   this->token_.add_writer(task);
 144   return true;
 145 }
 146
 147 // Release the file.  This is called when we are done with the file in
 148 // a Task.
 149
 150 void
 151 File_read::release()
 152 {
 153   gold_assert(this->is_locked());
 154
 155   File_read::total_mapped_bytes += this->mapped_bytes_;
 156   File_read::current_mapped_bytes += this->mapped_bytes_;
 157   this->mapped_bytes_ = 0;
 158   if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)
 159     File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;
 160
 161   this->clear_views(false);
 162
 163   this->released_ = true;
 164 }
 165
 166 // Lock the file.
 167
 168 void
 169 File_read::lock(const Task* task)
 170 {
 171   gold_assert(this->released_);
 172   this->token_.add_writer(task);
 173   this->released_ = false;
 174 }
 175
 176 // Unlock the file.
 177
 178 void
 179 File_read::unlock(const Task* task)
 180 {
 181   this->release();
 182   this->token_.remove_writer(task);
 183 }
 184
 185 // Return whether the file is locked.
 186
 187 bool
 188 File_read::is_locked() const
 189 {
 190   if (!this->token_.is_writable())
 191     return true;
 192   // The file is not locked, so it should have been released.
 193   gold_assert(this->released_);
 194   return false;
 195 }
 196
 197 // See if we have a view which covers the file starting at START for
 198 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 199
 200 inline File_read::View*
 201 File_read::find_view(off_t start, section_size_type size) const
 202 {
 203   off_t page = File_read::page_offset(start);
 204
 205   Views::const_iterator p = this->views_.lower_bound(page);
 206   if (p == this->views_.end() || p->first > page)
 207     {
 208       if (p == this->views_.begin())
 209         return NULL;
 210       --p;
 211     }
 212
 213   if (p->second->start() + static_cast<off_t>(p->second->size())
 214       < start + static_cast<off_t>(size))
 215     return NULL;
 216
 217   p->second->set_accessed();
 218
 219   return p->second;
 220 }
 221
 222 // Read SIZE bytes from the file starting at offset START.  Read into
 223 // the buffer at P.
 224
 225 void
 226 File_read::do_read(off_t start, section_size_type size, void* p) const
 227 {
 228   ssize_t bytes;
 229   if (this->contents_ != NULL)
 230     {
 231       bytes = this->size_ - start;
 232       if (static_cast<section_size_type>(bytes) >= size)
 233         {
 234           memcpy(p, this->contents_ + start, size);
 235           return;
 236         }
 237     }
 238   else
 239     {
 240       bytes = ::pread(this->descriptor_, p, size, start);
 241       if (static_cast<section_size_type>(bytes) == size)
 242         return;
 243
 244       if (bytes < 0)
 245         {
 246           gold_fatal(_("%s: pread failed: %s"),
 247                      this->filename().c_str(), strerror(errno));
 248           return;
 249         }
 250     }
 251
 252   gold_fatal(_("%s: file too short: read only %lld of %lld bytes at %lld"),
 253              this->filename().c_str(),
 254              static_cast<long long>(bytes),
 255              static_cast<long long>(size),
 256              static_cast<long long>(start));
 257 }
 258
 259 // Read data from the file.
 260
 261 void
 262 File_read::read(off_t start, section_size_type size, void* p) const
 263 {
 264   const File_read::View* pv = this->find_view(start, size);
 265   if (pv != NULL)
 266     {
 267       memcpy(p, pv->data() + (start - pv->start()), size);
 268       return;
 269     }
 270
 271   this->do_read(start, size, p);
 272 }
 273
 274 // Find an existing view or make a new one.
 275
 276 File_read::View*
 277 File_read::find_or_make_view(off_t start, section_size_type size, bool cache)
 278 {
 279   gold_assert(!this->token_.is_writable());
 280   this->released_ = false;
 281
 282   File_read::View* v = this->find_view(start, size);
 283   if (v != NULL)
 284     {
 285       if (cache)
 286         v->set_cache();
 287       return v;
 288     }
 289
 290   off_t poff = File_read::page_offset(start);
 291
 292   File_read::View* const vnull = NULL;
 293   std::pair<Views::iterator, bool> ins =
 294     this->views_.insert(std::make_pair(poff, vnull));
 295
 296   if (!ins.second)
 297     {
 298       // There was an existing view at this offset.  It must not be
 299       // large enough.  We can't delete it here, since something might
 300       // be using it; put it on a list to be deleted when the file is
 301       // unlocked.
 302       v = ins.first->second;
 303       gold_assert(v->size() - (start - v->start()) < size);
 304       if (v->should_cache())
 305         cache = true;
 306       v->clear_cache();
 307       this->saved_views_.push_back(v);
 308     }
 309
 310   // We need to map data from the file.
 311
 312   section_size_type psize = File_read::pages(size + (start - poff));
 313
 314   if (poff + static_cast<off_t>(psize) >= this->size_)
 315     {
 316       psize = this->size_ - poff;
 317       gold_assert(psize >= size);
 318     }
 319
 320   if (this->contents_ != NULL)
 321     {
 322       unsigned char* p = new unsigned char[psize];
 323       this->do_read(poff, psize, p);
 324       v = new File_read::View(poff, psize, p, cache, false);
 325     }
 326   else
 327     {
 328       void* p = ::mmap(NULL, psize, PROT_READ, MAP_PRIVATE,
 329                        this->descriptor_, poff);
 330       if (p == MAP_FAILED)
 331         gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),
 332                    this->filename().c_str(),
 333                    static_cast<long long>(poff),
 334                    static_cast<long long>(psize),
 335                    strerror(errno));
 336
 337       this->mapped_bytes_ += psize;
 338
 339       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 340       v = new File_read::View(poff, psize, pbytes, cache, true);
 341     }
 342
 343   ins.first->second = v;
 344   return v;
 345 }
 346
 347 // Get a view into the file.
 348
 349 const unsigned char*
 350 File_read::get_view(off_t start, section_size_type size, bool cache)
 351 {
 352   File_read::View* pv = this->find_or_make_view(start, size, cache);
 353   return pv->data() + (start - pv->start());
 354 }
 355
 356 File_view*
 357 File_read::get_lasting_view(off_t start, section_size_type size, bool cache)
 358 {
 359   File_read::View* pv = this->find_or_make_view(start, size, cache);
 360   pv->lock();
 361   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 362 }
 363
 364 // Use readv to read COUNT entries from RM starting at START.  BASE
 365 // must be added to all file offsets in RM.
 366
 367 void
 368 File_read::do_readv(off_t base, const Read_multiple& rm, size_t start,
 369                     size_t count)
 370 {
 371   unsigned char discard[File_read::page_size];
 372   iovec iov[File_read::max_readv_entries * 2];
 373   size_t iov_index = 0;
 374
 375   off_t first_offset = rm[start].file_offset;
 376   off_t last_offset = first_offset;
 377   ssize_t want = 0;
 378   for (size_t i = 0; i < count; ++i)
 379     {
 380       const Read_multiple_entry& i_entry(rm[start + i]);
 381
 382       if (i_entry.file_offset > last_offset)
 383         {
 384           size_t skip = i_entry.file_offset - last_offset;
 385           gold_assert(skip <= sizeof discard);
 386
 387           iov[iov_index].iov_base = discard;
 388           iov[iov_index].iov_len = skip;
 389           ++iov_index;
 390
 391           want += skip;
 392         }
 393
 394       iov[iov_index].iov_base = i_entry.buffer;
 395       iov[iov_index].iov_len = i_entry.size;
 396       ++iov_index;
 397
 398       want += i_entry.size;
 399
 400       last_offset = i_entry.file_offset + i_entry.size;
 401     }
 402
 403   gold_assert(iov_index < sizeof iov / sizeof iov[0]);
 404
 405   if (::lseek(this->descriptor_, base + first_offset, SEEK_SET) < 0)
 406     gold_fatal(_("%s: lseek failed: %s"),
 407                this->filename().c_str(), strerror(errno));
 408
 409   ssize_t got = ::readv(this->descriptor_, iov, iov_index);
 410
 411   if (got < 0)
 412     gold_fatal(_("%s: readv failed: %s"),
 413                this->filename().c_str(), strerror(errno));
 414   if (got != want)
 415     gold_fatal(_("%s: file too short: read only %zd of %zd bytes at %lld"),
 416                this->filename().c_str(),
 417                got, want, static_cast<long long>(base + first_offset));
 418 }
 419
 420 // Read several pieces of data from the file.
 421
 422 void
 423 File_read::read_multiple(off_t base, const Read_multiple& rm)
 424 {
 425   size_t count = rm.size();
 426   size_t i = 0;
 427   while (i < count)
 428     {
 429       // Find up to MAX_READV_ENTRIES consecutive entries which are
 430       // less than one page apart.
 431       const Read_multiple_entry& i_entry(rm[i]);
 432       off_t i_off = i_entry.file_offset;
 433       off_t end_off = i_off + i_entry.size;
 434       size_t j;
 435       for (j = i + 1; j < count; ++j)
 436         {
 437           if (j - i >= File_read::max_readv_entries)
 438             break;
 439           const Read_multiple_entry& j_entry(rm[j]);
 440           off_t j_off = j_entry.file_offset;
 441           gold_assert(j_off >= end_off);
 442           off_t j_end_off = j_off + j_entry.size;
 443           if (j_end_off - end_off >= File_read::page_size)
 444             break;
 445           end_off = j_end_off;
 446         }
 447
 448       if (j == i + 1)
 449         this->read(base + i_off, i_entry.size, i_entry.buffer);
 450       else
 451         {
 452           File_read::View* view = this->find_view(base + i_off,
 453                                                   end_off - i_off);
 454           if (view == NULL)
 455             this->do_readv(base, rm, i, j - i);
 456           else
 457             {
 458               const unsigned char* v = (view->data()
 459                                         + (base + i_off - view->start()));
 460               for (size_t k = i; k < j; ++k)
 461                 {
 462                   const Read_multiple_entry& k_entry(rm[k]);
 463                   gold_assert((convert_to_section_size_type(k_entry.file_offset
 464                                                            - i_off)
 465                                + k_entry.size)
 466                               <= convert_to_section_size_type(end_off
 467                                                               - i_off));
 468                   memcpy(k_entry.buffer,
 469                          v + (k_entry.file_offset - i_off),
 470                          k_entry.size);
 471                 }
 472             }
 473         }
 474
 475       i = j;
 476     }
 477 }
 478
 479 // Mark all views as no longer cached.
 480
 481 void
 482 File_read::clear_view_cache_marks()
 483 {
 484   // Just ignore this if there are multiple objects associated with
 485   // the file.  Otherwise we will wind up uncaching and freeing some
 486   // views for other objects.
 487   if (this->object_count_ > 1)
 488     return;
 489
 490   for (Views::iterator p = this->views_.begin();
 491        p != this->views_.end();
 492        ++p)
 493     p->second->clear_cache();
 494   for (Saved_views::iterator p = this->saved_views_.begin();
 495        p != this->saved_views_.end();
 496        ++p)
 497     (*p)->clear_cache();
 498 }
 499
 500 // Remove all the file views.  For a file which has multiple
 501 // associated objects (i.e., an archive), we keep accessed views
 502 // around until next time, in the hopes that they will be useful for
 503 // the next object.
 504
 505 void
 506 File_read::clear_views(bool destroying)
 507 {
 508   Views::iterator p = this->views_.begin();
 509   while (p != this->views_.end())
 510     {
 511       bool should_delete;
 512       if (p->second->is_locked())
 513         should_delete = false;
 514       else if (destroying)
 515         should_delete = true;
 516       else if (p->second->should_cache())
 517         should_delete = false;
 518       else if (this->object_count_ > 1 && p->second->accessed())
 519         should_delete = false;
 520       else
 521         should_delete = true;
 522
 523       if (should_delete)
 524         {
 525           delete p->second;
 526
 527           // map::erase invalidates only the iterator to the deleted
 528           // element.
 529           Views::iterator pe = p;
 530           ++p;
 531           this->views_.erase(pe);
 532         }
 533       else
 534         {
 535           gold_assert(!destroying);
 536           p->second->clear_accessed();
 537           ++p;
 538         }
 539     }
 540
 541   Saved_views::iterator q = this->saved_views_.begin();
 542   while (q != this->saved_views_.end())
 543     {
 544       if (!(*q)->is_locked())
 545         {
 546           delete *q;
 547           q = this->saved_views_.erase(q);
 548         }
 549       else
 550         {
 551           gold_assert(!destroying);
 552           ++q;
 553         }
 554     }
 555 }
 556
 557 // Print statistical information to stderr.  This is used for --stats.
 558
 559 void
 560 File_read::print_stats()
 561 {
 562   fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
 563           program_name, File_read::total_mapped_bytes);
 564   fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
 565           program_name, File_read::maximum_mapped_bytes);
 566 }
 567
 568 // Class File_view.
 569
 570 File_view::~File_view()
 571 {
 572   gold_assert(this->file_.is_locked());
 573   this->view_->unlock();
 574 }
 575
 576 // Class Input_file.
 577
 578 // Create a file for testing.
 579
 580 Input_file::Input_file(const Task* task, const char* name,
 581                        const unsigned char* contents, off_t size)
 582   : file_()
 583 {
 584   this->input_argument_ =
 585     new Input_file_argument(name, false, "", false,
 586                             Position_dependent_options());
 587   bool ok = file_.open(task, name, contents, size);
 588   gold_assert(ok);
 589 }
 590
 591 // Return the position dependent options in force for this file.
 592
 593 const Position_dependent_options&
 594 Input_file::options() const
 595 {
 596   return this->input_argument_->options();
 597 }
 598
 599 // Return the name given by the user.  For -lc this will return "c".
 600
 601 const char*
 602 Input_file::name() const
 603 {
 604   return this->input_argument_->name();
 605 }
 606
 607 // Return whether we are only reading symbols.
 608
 609 bool
 610 Input_file::just_symbols() const
 611 {
 612   return this->input_argument_->just_symbols();
 613 }
 614
 615 // Open the file.
 616
 617 // If the filename is not absolute, we assume it is in the current
 618 // directory *except* when:
 619 //    A) input_argument_->is_lib() is true; or
 620 //    B) input_argument_->extra_search_path() is not empty.
 621 // In both cases, we look in extra_search_path + library_path to find
 622 // the file location, rather than the current directory.
 623
 624 bool
 625 Input_file::open(const General_options& options, const Dirsearch& dirpath,
 626                  const Task* task)
 627 {
 628   std::string name;
 629
 630   // Case 1: name is an absolute file, just try to open it
 631   // Case 2: name is relative but is_lib is false and extra_search_path
 632   //         is empty
 633   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 634       || (!this->input_argument_->is_lib()
 635           && this->input_argument_->extra_search_path() == NULL))
 636     {
 637       name = this->input_argument_->name();
 638       this->found_name_ = name;
 639     }
 640   // Case 3: is_lib is true
 641   else if (this->input_argument_->is_lib())
 642     {
 643       // We don't yet support extra_search_path with -l.
 644       gold_assert(this->input_argument_->extra_search_path() == NULL);
 645       std::string n1("lib");
 646       n1 += this->input_argument_->name();
 647       std::string n2;
 648       if (options.is_static()
 649           || !this->input_argument_->options().Bdynamic())
 650         n1 += ".a";
 651       else
 652         {
 653           n2 = n1 + ".a";
 654           n1 += ".so";
 655         }
 656       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 657       if (name.empty())
 658         {
 659           gold_error(_("cannot find -l%s"),
 660                      this->input_argument_->name());
 661           return false;
 662         }
 663       if (n2.empty() || name[name.length() - 1] == 'o')
 664         this->found_name_ = n1;
 665       else
 666         this->found_name_ = n2;
 667     }
 668   // Case 4: extra_search_path is not empty
 669   else
 670     {
 671       gold_assert(this->input_argument_->extra_search_path() != NULL);
 672
 673       // First, check extra_search_path.
 674       name = this->input_argument_->extra_search_path();
 675       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 676         name += '/';
 677       name += this->input_argument_->name();
 678       struct stat dummy_stat;
 679       if (::stat(name.c_str(), &dummy_stat) < 0)
 680         {
 681           // extra_search_path failed, so check the normal search-path.
 682           name = dirpath.find(this->input_argument_->name(), "",
 683                               &this->is_in_sysroot_);
 684           if (name.empty())
 685             {
 686               gold_error(_("cannot find %s"),
 687                          this->input_argument_->name());
 688               return false;
 689             }
 690         }
 691       this->found_name_ = this->input_argument_->name();
 692     }
 693
 694   // Now that we've figured out where the file lives, try to open it.
 695
 696   General_options::Object_format format =
 697     this->input_argument_->options().format_enum();
 698   bool ok;
 699   if (format == General_options::OBJECT_FORMAT_ELF)
 700     ok = this->file_.open(task, name);
 701   else
 702     {
 703       gold_assert(format == General_options::OBJECT_FORMAT_BINARY);
 704       ok = this->open_binary(options, task, name);
 705     }
 706
 707   if (!ok)
 708     {
 709       gold_error(_("cannot open %s: %s"),
 710                  name.c_str(), strerror(errno));
 711       return false;
 712     }
 713
 714   return true;
 715 }
 716
 717 // Open a file for --format binary.
 718
 719 bool
 720 Input_file::open_binary(const General_options&,
 721                         const Task* task, const std::string& name)
 722 {
 723   // In order to open a binary file, we need machine code, size, and
 724   // endianness.  We may not have a valid target at this point, in
 725   // which case we use the default target.
 726   const Target* target;
 727   if (parameters->target_valid())
 728     target = &parameters->target();
 729   else
 730     target = &parameters->default_target();
 731
 732   Binary_to_elf binary_to_elf(target->machine_code(),
 733                               target->get_size(),
 734                               target->is_big_endian(),
 735                               name);
 736   if (!binary_to_elf.convert(task))
 737     return false;
 738   return this->file_.open(task, name, binary_to_elf.converted_data_leak(),
 739                           binary_to_elf.converted_size());
 740 }
 741
 742 } // End namespace gold.