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->lock_count_ == 0);
  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 std::string& name)
 102 {
 103   gold_assert(this->lock_count_ == 0
 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->lock_count_;
 120
 121   return this->descriptor_ >= 0;
 122 }
 123
 124 // Open the file for testing purposes.
 125
 126 bool
 127 File_read::open(const std::string& name, const unsigned char* contents,
 128                 off_t size)
 129 {
 130   gold_assert(this->lock_count_ == 0
 131               && this->descriptor_ < 0
 132               && this->name_.empty());
 133   this->name_ = name;
 134   this->contents_ = contents;
 135   this->size_ = size;
 136   ++this->lock_count_;
 137   return true;
 138 }
 139
 140 void
 141 File_read::lock()
 142 {
 143   ++this->lock_count_;
 144 }
 145
 146 void
 147 File_read::unlock()
 148 {
 149   gold_assert(this->lock_count_ > 0);
 150   --this->lock_count_;
 151   if (this->lock_count_ == 0)
 152     {
 153       File_read::total_mapped_bytes += this->mapped_bytes_;
 154       File_read::current_mapped_bytes += this->mapped_bytes_;
 155       this->mapped_bytes_ = 0;
 156       if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)
 157         File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;
 158
 159       this->clear_views(false);
 160     }
 161 }
 162
 163 bool
 164 File_read::is_locked() const
 165 {
 166   return this->lock_count_ > 0;
 167 }
 168
 169 // See if we have a view which covers the file starting at START for
 170 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 171
 172 inline File_read::View*
 173 File_read::find_view(off_t start, off_t size) const
 174 {
 175   off_t page = File_read::page_offset(start);
 176   Views::const_iterator p = this->views_.find(page);
 177   if (p == this->views_.end())
 178     return NULL;
 179   if (p->second->size() - (start - page) < size)
 180     return NULL;
 181   return p->second;
 182 }
 183
 184 // Read SIZE bytes from the file starting at offset START.  Read into
 185 // the buffer at P.
 186
 187 void
 188 File_read::do_read(off_t start, off_t size, void* p) const
 189 {
 190   off_t bytes;
 191   if (this->contents_ != NULL)
 192     {
 193       bytes = this->size_ - start;
 194       if (bytes >= size)
 195         {
 196           memcpy(p, this->contents_ + start, size);
 197           return;
 198         }
 199     }
 200   else
 201     {
 202       bytes = ::pread(this->descriptor_, p, size, start);
 203       if (bytes == size)
 204         return;
 205
 206       if (bytes < 0)
 207         {
 208           gold_fatal(_("%s: pread failed: %s"),
 209                      this->filename().c_str(), strerror(errno));
 210           return;
 211         }
 212     }
 213
 214   gold_fatal(_("%s: file too short: read only %lld of %lld bytes at %lld"),
 215              this->filename().c_str(),
 216              static_cast<long long>(bytes),
 217              static_cast<long long>(size),
 218              static_cast<long long>(start));
 219 }
 220
 221 // Read data from the file.
 222
 223 void
 224 File_read::read(off_t start, off_t size, void* p) const
 225 {
 226   File_read::View* pv = this->find_view(start, size);
 227   if (pv != NULL)
 228     {
 229       memcpy(p, pv->data() + (start - pv->start()), size);
 230       return;
 231     }
 232
 233   this->do_read(start, size, p);
 234 }
 235
 236 // Find an existing view or make a new one.
 237
 238 File_read::View*
 239 File_read::find_or_make_view(off_t start, off_t size, bool cache)
 240 {
 241   gold_assert(this->lock_count_ > 0);
 242
 243   off_t poff = File_read::page_offset(start);
 244
 245   File_read::View* const vnull = NULL;
 246   std::pair<Views::iterator, bool> ins =
 247     this->views_.insert(std::make_pair(poff, vnull));
 248
 249   if (!ins.second)
 250     {
 251       // There was an existing view at this offset.
 252       File_read::View* v = ins.first->second;
 253       if (v->size() - (start - v->start()) >= size)
 254         {
 255           if (cache)
 256             v->set_cache();
 257           return v;
 258         }
 259
 260       // This view is not large enough.
 261       this->saved_views_.push_back(v);
 262     }
 263
 264   // We need to read data from the file.  We read full pages for
 265   // greater efficiency on small files.
 266
 267   off_t psize = File_read::pages(size + (start - poff));
 268
 269   if (poff + psize >= this->size_)
 270     {
 271       psize = this->size_ - poff;
 272       gold_assert(psize >= size);
 273     }
 274
 275   File_read::View* v;
 276
 277   if (this->contents_ != NULL)
 278     {
 279       unsigned char* p = new unsigned char[psize];
 280       this->do_read(poff, psize, p);
 281       v = new File_read::View(poff, psize, p, cache, false);
 282     }
 283   else
 284     {
 285       void* p = ::mmap(NULL, psize, PROT_READ, MAP_SHARED,
 286                        this->descriptor_, poff);
 287       if (p == MAP_FAILED)
 288         gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),
 289                    this->filename().c_str(),
 290                    static_cast<long long>(poff),
 291                    static_cast<long long>(psize),
 292                    strerror(errno));
 293
 294       this->mapped_bytes_ += psize;
 295
 296       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 297       v = new File_read::View(poff, psize, pbytes, cache, true);
 298     }
 299
 300   ins.first->second = v;
 301   return v;
 302 }
 303
 304 // This implementation of get_view just reads into a memory buffer,
 305 // which we store on view_list_.  At some point we should support
 306 // mmap.
 307
 308 const unsigned char*
 309 File_read::get_view(off_t start, off_t size, bool cache)
 310 {
 311   gold_assert(this->lock_count_ > 0);
 312   File_read::View* pv = this->find_or_make_view(start, size, cache);
 313   return pv->data() + (start - pv->start());
 314 }
 315
 316 File_view*
 317 File_read::get_lasting_view(off_t start, off_t size, bool cache)
 318 {
 319   gold_assert(this->lock_count_ > 0);
 320   File_read::View* pv = this->find_or_make_view(start, size, cache);
 321   pv->lock();
 322   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 323 }
 324
 325 // Remove all the file views.
 326
 327 void
 328 File_read::clear_views(bool destroying)
 329 {
 330   Views::iterator p = this->views_.begin();
 331   while (p != this->views_.end())
 332     {
 333       if (!p->second->is_locked()
 334           && (destroying || !p->second->should_cache()))
 335         {
 336           delete p->second;
 337
 338           // map::erase invalidates only the iterator to the deleted
 339           // element.
 340           Views::iterator pe = p;
 341           ++p;
 342           this->views_.erase(pe);
 343         }
 344       else
 345         {
 346           gold_assert(!destroying);
 347           ++p;
 348         }
 349     }
 350
 351   Saved_views::iterator q = this->saved_views_.begin();
 352   while (q != this->saved_views_.end())
 353     {
 354       if (!(*q)->is_locked()
 355           && (destroying || !(*q)->should_cache()))
 356         {
 357           delete *q;
 358           q = this->saved_views_.erase(q);
 359         }
 360       else
 361         {
 362           gold_assert(!destroying);
 363           ++q;
 364         }
 365     }
 366 }
 367
 368 // Print statistical information to stderr.  This is used for --stats.
 369
 370 void
 371 File_read::print_stats()
 372 {
 373   fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
 374           program_name, File_read::total_mapped_bytes);
 375   fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
 376           program_name, File_read::maximum_mapped_bytes);
 377 }
 378
 379 // Class File_view.
 380
 381 File_view::~File_view()
 382 {
 383   gold_assert(this->file_.is_locked());
 384   this->view_->unlock();
 385 }
 386
 387 // Class Input_file.
 388
 389 // Create a file for testing.
 390
 391 Input_file::Input_file(const char* name, const unsigned char* contents,
 392                        off_t size)
 393   : file_()
 394 {
 395   this->input_argument_ =
 396     new Input_file_argument(name, false, "", Position_dependent_options());
 397   bool ok = file_.open(name, contents, size);
 398   gold_assert(ok);
 399 }
 400
 401 // Open the file.
 402
 403 // If the filename is not absolute, we assume it is in the current
 404 // directory *except* when:
 405 //    A) input_argument_->is_lib() is true; or
 406 //    B) input_argument_->extra_search_path() is not empty.
 407 // In both cases, we look in extra_search_path + library_path to find
 408 // the file location, rather than the current directory.
 409
 410 bool
 411 Input_file::open(const General_options& options, const Dirsearch& dirpath)
 412 {
 413   std::string name;
 414
 415   // Case 1: name is an absolute file, just try to open it
 416   // Case 2: name is relative but is_lib is false and extra_search_path
 417   //         is empty
 418   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 419       || (!this->input_argument_->is_lib()
 420           && this->input_argument_->extra_search_path() == NULL))
 421     {
 422       name = this->input_argument_->name();
 423       this->found_name_ = name;
 424     }
 425   // Case 3: is_lib is true
 426   else if (this->input_argument_->is_lib())
 427     {
 428       // We don't yet support extra_search_path with -l.
 429       gold_assert(this->input_argument_->extra_search_path() == NULL);
 430       std::string n1("lib");
 431       n1 += this->input_argument_->name();
 432       std::string n2;
 433       if (options.is_static()
 434           || this->input_argument_->options().do_static_search())
 435         n1 += ".a";
 436       else
 437         {
 438           n2 = n1 + ".a";
 439           n1 += ".so";
 440         }
 441       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 442       if (name.empty())
 443         {
 444           gold_error(_("cannot find -l%s"),
 445                      this->input_argument_->name());
 446           return false;
 447         }
 448       if (n2.empty() || name[name.length() - 1] == 'o')
 449         this->found_name_ = n1;
 450       else
 451         this->found_name_ = n2;
 452     }
 453   // Case 4: extra_search_path is not empty
 454   else
 455     {
 456       gold_assert(this->input_argument_->extra_search_path() != NULL);
 457
 458       // First, check extra_search_path.
 459       name = this->input_argument_->extra_search_path();
 460       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 461         name += '/';
 462       name += this->input_argument_->name();
 463       struct stat dummy_stat;
 464       if (::stat(name.c_str(), &dummy_stat) < 0)
 465         {
 466           // extra_search_path failed, so check the normal search-path.
 467           name = dirpath.find(this->input_argument_->name(), "",
 468                               &this->is_in_sysroot_);
 469           if (name.empty())
 470             {
 471               gold_error(_("cannot find %s"),
 472                          this->input_argument_->name());
 473               return false;
 474             }
 475         }
 476       this->found_name_ = this->input_argument_->name();
 477     }
 478
 479   // Now that we've figured out where the file lives, try to open it.
 480   if (!this->file_.open(name))
 481     {
 482       gold_error(_("cannot open %s: %s"),
 483                  name.c_str(), strerror(errno));
 484       return false;
 485     }
 486
 487   return true;
 488 }
 489
 490 } // End namespace gold.