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