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         fprintf(stderr, _("%s: munmap failed: %s\n"),
  50                 program_name, 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->lock_count_ == 0);
  88   if (this->descriptor_ >= 0)
  89     {
  90       if (close(this->descriptor_) < 0)
  91         fprintf(stderr, _("%s: warning: close(%s) failed: %s"),
  92                 program_name, 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 std::string& name)
 103 {
 104   gold_assert(this->lock_count_ == 0
 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         {
 116           fprintf(stderr, _("%s: %s: fstat failed: %s"), program_name,
 117                   this->name_.c_str(), strerror(errno));
 118           gold_exit(false);
 119         }
 120       this->size_ = s.st_size;
 121     }
 122
 123   ++this->lock_count_;
 124
 125   return this->descriptor_ >= 0;
 126 }
 127
 128 // Open the file for testing purposes.
 129
 130 bool
 131 File_read::open(const std::string& name, const unsigned char* contents,
 132                 off_t size)
 133 {
 134   gold_assert(this->lock_count_ == 0
 135               && this->descriptor_ < 0
 136               && this->name_.empty());
 137   this->name_ = name;
 138   this->contents_ = contents;
 139   this->size_ = size;
 140   ++this->lock_count_;
 141   return true;
 142 }
 143
 144 void
 145 File_read::lock()
 146 {
 147   ++this->lock_count_;
 148 }
 149
 150 void
 151 File_read::unlock()
 152 {
 153   gold_assert(this->lock_count_ > 0);
 154   --this->lock_count_;
 155   if (this->lock_count_ == 0)
 156     {
 157       File_read::total_mapped_bytes += this->mapped_bytes_;
 158       File_read::current_mapped_bytes += this->mapped_bytes_;
 159       this->mapped_bytes_ = 0;
 160       if (File_read::current_mapped_bytes > File_read::maximum_mapped_bytes)
 161         File_read::maximum_mapped_bytes = File_read::current_mapped_bytes;
 162
 163       this->clear_views(false);
 164     }
 165 }
 166
 167 bool
 168 File_read::is_locked()
 169 {
 170   return this->lock_count_ > 0;
 171 }
 172
 173 // See if we have a view which covers the file starting at START for
 174 // SIZE bytes.  Return a pointer to the View if found, NULL if not.
 175
 176 inline File_read::View*
 177 File_read::find_view(off_t start, off_t size)
 178 {
 179   off_t page = File_read::page_offset(start);
 180   Views::iterator p = this->views_.find(page);
 181   if (p == this->views_.end())
 182     return NULL;
 183   if (p->second->size() - (start - page) < size)
 184     return NULL;
 185   return p->second;
 186 }
 187
 188 // Read SIZE bytes from the file starting at offset START.  Read into
 189 // the buffer at P.
 190
 191 void
 192 File_read::do_read(off_t start, off_t size, void* p)
 193 {
 194   gold_assert(this->lock_count_ > 0);
 195
 196   off_t bytes;
 197   if (this->contents_ != NULL)
 198     {
 199       bytes = this->size_ - start;
 200       if (bytes >= size)
 201         {
 202           memcpy(p, this->contents_ + start, size);
 203           return;
 204         }
 205     }
 206   else
 207     {
 208       bytes = ::pread(this->descriptor_, p, size, start);
 209       if (bytes == size)
 210         return;
 211
 212       if (bytes < 0)
 213         {
 214           fprintf(stderr, _("%s: %s: pread failed: %s\n"),
 215                   program_name, this->filename().c_str(), strerror(errno));
 216           gold_exit(false);
 217         }
 218     }
 219
 220   fprintf(stderr,
 221           _("%s: %s: file too short: read only %lld of %lld bytes at %lld\n"),
 222           program_name, this->filename().c_str(),
 223           static_cast<long long>(bytes),
 224           static_cast<long long>(size),
 225           static_cast<long long>(start));
 226   gold_exit(false);
 227 }
 228
 229 // Read data from the file.
 230
 231 void
 232 File_read::read(off_t start, off_t size, void* p)
 233 {
 234   gold_assert(this->lock_count_ > 0);
 235
 236   File_read::View* pv = this->find_view(start, size);
 237   if (pv != NULL)
 238     {
 239       memcpy(p, pv->data() + (start - pv->start()), size);
 240       return;
 241     }
 242
 243   this->do_read(start, size, p);
 244 }
 245
 246 // Find an existing view or make a new one.
 247
 248 File_read::View*
 249 File_read::find_or_make_view(off_t start, off_t size, bool cache)
 250 {
 251   gold_assert(this->lock_count_ > 0);
 252
 253   off_t poff = File_read::page_offset(start);
 254
 255   File_read::View* const vnull = NULL;
 256   std::pair<Views::iterator, bool> ins =
 257     this->views_.insert(std::make_pair(poff, vnull));
 258
 259   if (!ins.second)
 260     {
 261       // There was an existing view at this offset.
 262       File_read::View* v = ins.first->second;
 263       if (v->size() - (start - v->start()) >= size)
 264         {
 265           if (cache)
 266             v->set_cache();
 267           return v;
 268         }
 269
 270       // This view is not large enough.
 271       this->saved_views_.push_back(v);
 272     }
 273
 274   // We need to read data from the file.  We read full pages for
 275   // greater efficiency on small files.
 276
 277   off_t psize = File_read::pages(size + (start - poff));
 278
 279   if (poff + psize >= this->size_)
 280     {
 281       psize = this->size_ - poff;
 282       gold_assert(psize >= size);
 283     }
 284
 285   File_read::View* v;
 286
 287   if (this->contents_ != NULL)
 288     {
 289       unsigned char* p = new unsigned char[psize];
 290       this->do_read(poff, psize, p);
 291       v = new File_read::View(poff, psize, p, cache, false);
 292     }
 293   else
 294     {
 295       void* p = ::mmap(NULL, psize, PROT_READ, MAP_SHARED,
 296                        this->descriptor_, poff);
 297       if (p == MAP_FAILED)
 298         {
 299           fprintf(stderr, _("%s: %s: mmap offset %lld size %lld failed: %s\n"),
 300                   program_name, this->filename().c_str(),
 301                   static_cast<long long>(poff),
 302                   static_cast<long long>(psize),
 303                   strerror(errno));
 304           gold_exit(false);
 305         }
 306
 307       this->mapped_bytes_ += psize;
 308
 309       const unsigned char* pbytes = static_cast<const unsigned char*>(p);
 310       v = new File_read::View(poff, psize, pbytes, cache, true);
 311     }
 312
 313   ins.first->second = v;
 314   return v;
 315 }
 316
 317 // This implementation of get_view just reads into a memory buffer,
 318 // which we store on view_list_.  At some point we should support
 319 // mmap.
 320
 321 const unsigned char*
 322 File_read::get_view(off_t start, off_t size, bool cache)
 323 {
 324   gold_assert(this->lock_count_ > 0);
 325   File_read::View* pv = this->find_or_make_view(start, size, cache);
 326   return pv->data() + (start - pv->start());
 327 }
 328
 329 File_view*
 330 File_read::get_lasting_view(off_t start, off_t size, bool cache)
 331 {
 332   gold_assert(this->lock_count_ > 0);
 333   File_read::View* pv = this->find_or_make_view(start, size, cache);
 334   pv->lock();
 335   return new File_view(*this, pv, pv->data() + (start - pv->start()));
 336 }
 337
 338 // Remove all the file views.
 339
 340 void
 341 File_read::clear_views(bool destroying)
 342 {
 343   for (Views::iterator p = this->views_.begin();
 344        p != this->views_.end();
 345        ++p)
 346     {
 347       if (!p->second->is_locked()
 348           && (destroying || !p->second->should_cache()))
 349         delete p->second;
 350       else
 351         {
 352           gold_assert(!destroying);
 353           this->saved_views_.push_back(p->second);
 354         }
 355     }
 356   this->views_.clear();
 357
 358   Saved_views::iterator p = this->saved_views_.begin();
 359   while (p != this->saved_views_.end())
 360     {
 361       if (!(*p)->is_locked()
 362           && (destroying || !(*p)->should_cache()))
 363         {
 364           delete *p;
 365           p = this->saved_views_.erase(p);
 366         }
 367       else
 368         {
 369           gold_assert(!destroying);
 370           ++p;
 371         }
 372     }
 373 }
 374
 375 // Print statistical information to stderr.  This is used for --stats.
 376
 377 void
 378 File_read::print_stats()
 379 {
 380   fprintf(stderr, _("%s: total bytes mapped for read: %llu\n"),
 381           program_name, File_read::total_mapped_bytes);
 382   fprintf(stderr, _("%s: maximum bytes mapped for read at one time: %llu\n"),
 383           program_name, File_read::maximum_mapped_bytes);
 384 }
 385
 386 // Class File_view.
 387
 388 File_view::~File_view()
 389 {
 390   gold_assert(this->file_.is_locked());
 391   this->view_->unlock();
 392 }
 393
 394 // Class Input_file.
 395
 396 // Create a file for testing.
 397
 398 Input_file::Input_file(const char* name, const unsigned char* contents,
 399                        off_t size)
 400   : file_()
 401 {
 402   this->input_argument_ =
 403     new Input_file_argument(name, false, "", Position_dependent_options());
 404   bool ok = file_.open(name, contents, size);
 405   gold_assert(ok);
 406 }
 407
 408 // Open the file.
 409
 410 // If the filename is not absolute, we assume it is in the current
 411 // directory *except* when:
 412 //    A) input_argument_->is_lib() is true; or
 413 //    B) input_argument_->extra_search_path() is not empty.
 414 // In both cases, we look in extra_search_path + library_path to find
 415 // the file location, rather than the current directory.
 416
 417 void
 418 Input_file::open(const General_options& options, const Dirsearch& dirpath)
 419 {
 420   std::string name;
 421
 422   // Case 1: name is an absolute file, just try to open it
 423   // Case 2: name is relative but is_lib is false and extra_search_path
 424   //         is empty
 425   if (IS_ABSOLUTE_PATH (this->input_argument_->name())
 426       || (!this->input_argument_->is_lib()
 427           && this->input_argument_->extra_search_path() == NULL))
 428     {
 429       name = this->input_argument_->name();
 430       this->found_name_ = name;
 431     }
 432   // Case 3: is_lib is true
 433   else if (this->input_argument_->is_lib())
 434     {
 435       // We don't yet support extra_search_path with -l.
 436       gold_assert(this->input_argument_->extra_search_path() == NULL);
 437       std::string n1("lib");
 438       n1 += this->input_argument_->name();
 439       std::string n2;
 440       if (options.is_static())
 441         n1 += ".a";
 442       else
 443         {
 444           n2 = n1 + ".a";
 445           n1 += ".so";
 446         }
 447       name = dirpath.find(n1, n2, &this->is_in_sysroot_);
 448       if (name.empty())
 449         {
 450           fprintf(stderr, _("%s: cannot find -l%s\n"), program_name,
 451                   this->input_argument_->name());
 452           gold_exit(false);
 453         }
 454       if (n2.empty() || name[name.length() - 1] == 'o')
 455         this->found_name_ = n1;
 456       else
 457         this->found_name_ = n2;
 458     }
 459   // Case 4: extra_search_path is not empty
 460   else
 461     {
 462       gold_assert(this->input_argument_->extra_search_path() != NULL);
 463
 464       // First, check extra_search_path.
 465       name = this->input_argument_->extra_search_path();
 466       if (!IS_DIR_SEPARATOR (name[name.length() - 1]))
 467         name += '/';
 468       name += this->input_argument_->name();
 469       struct stat dummy_stat;
 470       if (::stat(name.c_str(), &dummy_stat) < 0)
 471         {
 472           // extra_search_path failed, so check the normal search-path.
 473           name = dirpath.find(this->input_argument_->name(), "",
 474                               &this->is_in_sysroot_);
 475           if (name.empty())
 476             {
 477               fprintf(stderr, _("%s: cannot find %s\n"), program_name,
 478                       this->input_argument_->name());
 479               gold_exit(false);
 480             }
 481         }
 482       this->found_name_ = this->input_argument_->name();
 483     }
 484
 485   // Now that we've figured out where the file lives, try to open it.
 486   if (!this->file_.open(name))
 487     {
 488       fprintf(stderr, _("%s: cannot open %s: %s\n"), program_name,
 489               name.c_str(), strerror(errno));
 490       gold_exit(false);
 491     }
 492 }
 493
 494 } // End namespace gold.