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()
 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   gold_assert(this->lock_count_ > 0);
 227
 228   File_read::View* pv = this->find_view(start, size);
 229   if (pv != NULL)
 230     {
 231       memcpy(p, pv->data() + (start - pv->start()), size);
 232       return;
 233     }
 234
 235   this->do_read(start, size, p);
 236 }
 237
 238 // Find an existing view or make a new one.
 239
 240 File_read::View*
 241 File_read::find_or_make_view(off_t start, off_t size, bool cache)
 242 {
 243   gold_assert(this->lock_count_ > 0);
 244
 245   off_t poff = File_read::page_offset(start);
 246
 247   File_read::View* const vnull = NULL;
 248   std::pair<Views::iterator, bool> ins =
 249     this->views_.insert(std::make_pair(poff, vnull));
 250
 251   if (!ins.second)
 252     {
 253       // There was an existing view at this offset.
 254       File_read::View* v = ins.first->second;
 255       if (v->size() - (start - v->start()) >= size)
 256         {
 257           if (cache)
 258             v->set_cache();
 259           return v;
 260         }
 261
 262       // This view is not large enough.
 263       this->saved_views_.push_back(v);
 264     }
 265
 266   // We need to read data from the file.  We read full pages for
 267   // greater efficiency on small files.
 268
 269   off_t psize = File_read::pages(size + (start - poff));
 270
 271   if (poff + psize >= this->size_)
 272     {
 273       psize = this->size_ - poff;
 274       gold_assert(psize >= size);
 275     }
 276
 277   File_read::View* v;
 278
 279   if (this->contents_ != NULL)
 280     {
 281       unsigned char* p = new unsigned char[psize];
 282       this->do_read(poff, psize, p);
 283       v = new File_read::View(poff, psize, p, cache, false);
 284     }
 285   else
 286     {
 287       void* p = ::mmap(NULL, psize, PROT_READ, MAP_SHARED,
 288                        this->descriptor_, poff);
 289       if (p == MAP_FAILED)
 290         gold_fatal(_("%s: mmap offset %lld size %lld failed: %s"),
 291                    this->filename().c_str(),
 292                    static_cast<long long>(poff),
 293                    static_cast<long long>(psize),
 294                    strerror(errno));
 295
 296       this->mapped_bytes_ += psize;
 297
 298       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 299       v = new File_read::View(poff, psize, pbytes, cache, true);
 300     }
 301
 302   ins.first->second = v;
 303   return v;
 304 }
 305
 306 // This implementation of get_view just reads into a memory buffer,
 307 // which we store on view_list_.  At some point we should support
 308 // mmap.
 309
 310 const unsigned char*
 311 File_read::get_view(off_t start, off_t size, bool cache)
 312 {
 313   gold_assert(this->lock_count_ > 0);
 314   File_read::View* pv = this->find_or_make_view(start, size, cache);
 315   return pv->data() + (start - pv->start());
 316 }
 317
 318 File_view*
 319 File_read::get_lasting_view(off_t start, off_t size, bool cache)
 320 {
 321   gold_assert(this->lock_count_ > 0);
 322   File_read::View* pv = this->find_or_make_view(start, size, cache);
 323   pv->lock();
 324   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 325 }
 326
 327 // Remove all the file views.
 328
 329 void
 330 File_read::clear_views(bool destroying)
 331 {
 332   Views::iterator p = this->views_.begin();
 333   while (p != this->views_.end())
 334     {
 335       if (!p->second->is_locked()
 336           && (destroying || !p->second->should_cache()))
 337         {
 338           delete p->second;
 339
 340           // map::erase invalidates only the iterator to the deleted
 341           // element.
 342           Views::iterator pe = p;
 343           ++p;
 344           this->views_.erase(pe);
 345         }
 346       else
 347         {
 348           gold_assert(!destroying);
 349           ++p;
 350         }
 351     }
 352
 353   Saved_views::iterator q = this->saved_views_.begin();
 354   while (q != this->saved_views_.end())
 355     {
 356       if (!(*q)->is_locked()
 357           && (destroying || !(*q)->should_cache()))
 358         {
 359           delete *q;
 360           q = this->saved_views_.erase(q);
 361         }
 362       else
 363         {
 364           gold_assert(!destroying);
 365           ++q;
 366         }
 367     }
 368 }
 369
 370 // Print statistical information to stderr.  This is used for --stats.
 371
 372 void
 373 File_read::print_stats()
 374 {
 375   fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
 376           program_name, File_read::total_mapped_bytes);
 377   fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
 378           program_name, File_read::maximum_mapped_bytes);
 379 }
 380
 381 // Class File_view.
 382
 383 File_view::~File_view()
 384 {
 385   gold_assert(this->file_.is_locked());
 386   this->view_->unlock();
 387 }
 388
 389 // Class Input_file.
 390
 391 // Create a file for testing.
 392
 393 Input_file::Input_file(const char* name, const unsigned char* contents,
 394                        off_t size)
 395   : file_()
 396 {
 397   this->input_argument_ =
 398     new Input_file_argument(name, false, "", Position_dependent_options());
 399   bool ok = file_.open(name, contents, size);
 400   gold_assert(ok);
 401 }
 402
 403 // Open the file.
 404
 405 // If the filename is not absolute, we assume it is in the current
 406 // directory *except* when:
 407 //    A) input_argument_->is_lib() is true; or
 408 //    B) input_argument_->extra_search_path() is not empty.
 409 // In both cases, we look in extra_search_path + library_path to find
 410 // the file location, rather than the current directory.
 411
 412 bool
 413 Input_file::open(const General_options& options, const Dirsearch& dirpath)
 414 {
 415   std::string name;
 416
 417   // Case 1: name is an absolute file, just try to open it
 418   // Case 2: name is relative but is_lib is false and extra_search_path
 419   //         is empty
 420   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 421       || (!this->input_argument_->is_lib()
 422           && this->input_argument_->extra_search_path() == NULL))
 423     {
 424       name = this->input_argument_->name();
 425       this->found_name_ = name;
 426     }
 427   // Case 3: is_lib is true
 428   else if (this->input_argument_->is_lib())
 429     {
 430       // We don't yet support extra_search_path with -l.
 431       gold_assert(this->input_argument_->extra_search_path() == NULL);
 432       std::string n1("lib");
 433       n1 += this->input_argument_->name();
 434       std::string n2;
 435       if (options.is_static()
 436           || this->input_argument_->options().do_static_search())
 437         n1 += ".a";
 438       else
 439         {
 440           n2 = n1 + ".a";
 441           n1 += ".so";
 442         }
 443       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 444       if (name.empty())
 445         {
 446           gold_error(_("cannot find -l%s"),
 447                      this->input_argument_->name());
 448           return false;
 449         }
 450       if (n2.empty() || name[name.length() - 1] == 'o')
 451         this->found_name_ = n1;
 452       else
 453         this->found_name_ = n2;
 454     }
 455   // Case 4: extra_search_path is not empty
 456   else
 457     {
 458       gold_assert(this->input_argument_->extra_search_path() != NULL);
 459
 460       // First, check extra_search_path.
 461       name = this->input_argument_->extra_search_path();
 462       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 463         name += '/';
 464       name += this->input_argument_->name();
 465       struct stat dummy_stat;
 466       if (::stat(name.c_str(), &dummy_stat) < 0)
 467         {
 468           // extra_search_path failed, so check the normal search-path.
 469           name = dirpath.find(this->input_argument_->name(), "",
 470                               &this->is_in_sysroot_);
 471           if (name.empty())
 472             {
 473               gold_error(_("cannot find %s"),
 474                          this->input_argument_->name());
 475               return false;
 476             }
 477         }
 478       this->found_name_ = this->input_argument_->name();
 479     }
 480
 481   // Now that we've figured out where the file lives, try to open it.
 482   if (!this->file_.open(name))
 483     {
 484       gold_error(_("cannot open %s: %s"),
 485                  name.c_str(), strerror(errno));
 486       return false;
 487     }
 488
 489   return true;
 490 }
 491
 492 } // End namespace gold.